// Copyright (c) 2026 Alexander Medvednikov. All rights reserved.
// Use of this source code is governed by an MIT license
// that can be found in the LICENSE file.
// vtest build: macos
module transformer

import os
import v2.ast
import v2.parser
import v2.pref as vpref
import v2.token
import v2.types

// Helper to create a minimal transformer for testing
fn create_test_transformer() &Transformer {
    env := &types.Environment{}
    return &Transformer{
        pref:                        &vpref.Preferences{}
        env:                         unsafe { env }
        needed_clone_fns:            map[string]string{}
        needed_array_contains_fns:   map[string]ArrayMethodInfo{}
        needed_array_index_fns:      map[string]ArrayMethodInfo{}
        needed_array_last_index_fns: map[string]ArrayMethodInfo{}
        local_decl_types:            map[string]types.Type{}
    }
}

// Helper to create a transformer with a scope containing variable types
fn create_transformer_with_vars(vars map[string]types.Type) &Transformer {
    env := &types.Environment{}
    mut scope := types.new_scope(unsafe { nil })
    for name, typ in vars {
        scope.insert(name, value_object_from_type(typ))
    }
    return &Transformer{
        pref:                        &vpref.Preferences{}
        env:                         unsafe { env }
        scope:                       scope
        needed_clone_fns:            map[string]string{}
        needed_array_contains_fns:   map[string]ArrayMethodInfo{}
        needed_array_index_fns:      map[string]ArrayMethodInfo{}
        needed_array_last_index_fns: map[string]ArrayMethodInfo{}
        local_decl_types:            map[string]types.Type{}
    }
}

fn test_value_object_from_type_stores_value_symbol_type() {
    obj := value_object_from_type(types.Type(types.int_))
    assert obj is types.TypeObject
    assert obj.typ() is types.Primitive
}

fn test_worker_clone_owns_mutable_maps() {
    prefs := &vpref.Preferences{}
    env := types.Environment.new()
    mut transformer := Transformer.new_with_pref(env, prefs)
    transformer.synth_pos_counter = -73
    scope := types.new_scope(unsafe { nil })
    transformer.elided_fns = {
        'main__skipped': true
    }
    transformer.cached_scopes = {
        'main': scope
    }
    transformer.cached_fn_scopes = {
        'main__known': scope
    }
    transformer.cached_method_keys = ['main__Foo']
    transformer.generic_fn_value_names = {
        'handler': true
    }

    mut worker := transformer.new_worker_clone(1)
    assert worker.next_synth_pos().id == -100073
    worker.elided_fns['main__worker_skipped'] = true
    worker.cached_scopes['worker'] = scope
    worker.cached_fn_scopes['main__worker'] = scope
    worker.cached_method_keys << 'main__Bar'
    worker.generic_fn_value_names['worker_handler'] = true

    assert 'main__worker_skipped' !in transformer.elided_fns
    assert 'worker' !in transformer.cached_scopes
    assert 'main__worker' !in transformer.cached_fn_scopes
    assert transformer.cached_method_keys == ['main__Foo']
    assert 'worker_handler' !in transformer.generic_fn_value_names

    transformer.merge_worker(worker)
    assert transformer.elided_fns['main__worker_skipped']
    assert transformer.cached_fn_scopes['main__worker'] == scope
}

fn transform_code_for_test(code string) []ast.File {
    prefs := &vpref.Preferences{
        backend:     .cleanc
        no_parallel: true
    }
    return transform_code_with_prefs_for_test(code, prefs)
}

fn transform_code_with_prefs_for_test(code string, prefs &vpref.Preferences) []ast.File {
    tmp_file := '/tmp/v2_transformer_test_${os.getpid()}.v'
    os.write_file(tmp_file, code) or { panic('failed to write temp file') }
    defer {
        os.rm(tmp_file) or {}
    }
    mut file_set := token.FileSet.new()
    mut par := parser.Parser.new(prefs)
    files := par.parse_files([tmp_file], mut file_set)
    mut env := types.Environment.new()
    mut checker := types.Checker.new(prefs, file_set, env)
    checker.check_files(files)
    mut transformer := Transformer.new_with_pref(env, prefs)
    return transformer.transform_files(files)
}

fn transform_code_with_env_for_test(code string) (&types.Environment, []ast.File) {
    tmp_file := '/tmp/v2_transformer_env_test_${os.getpid()}.v'
    os.write_file(tmp_file, code) or { panic('failed to write temp file') }
    defer {
        os.rm(tmp_file) or {}
    }
    prefs := &vpref.Preferences{
        backend:     .cleanc
        no_parallel: true
    }
    mut file_set := token.FileSet.new()
    mut par := parser.Parser.new(prefs)
    files := par.parse_files([tmp_file], mut file_set)
    mut env := types.Environment.new()
    mut checker := types.Checker.new(prefs, file_set, env)
    checker.check_files(files)
    mut transformer := Transformer.new_with_pref(env, prefs)
    transformed := transformer.transform_files(files)
    return env, transformed
}

struct TestSource {
    rel  string
    code string
}

fn transform_sources_for_test(sources []TestSource) []ast.File {
    tmp_dir := os.join_path(os.temp_dir(), 'v2_transformer_sources_${os.getpid()}')
    os.rmdir_all(tmp_dir) or {}
    os.mkdir_all(tmp_dir) or { panic(err) }
    defer {
        os.rmdir_all(tmp_dir) or {}
    }
    mut paths := []string{cap: sources.len}
    for source in sources {
        path := os.join_path(tmp_dir, source.rel)
        os.mkdir_all(os.dir(path)) or { panic(err) }
        os.write_file(path, source.code) or { panic('failed to write ${path}') }
        paths << path
    }
    prefs := &vpref.Preferences{
        backend:     .cleanc
        no_parallel: true
    }
    mut file_set := token.FileSet.new()
    mut par := parser.Parser.new(prefs)
    files := par.parse_files(paths, mut file_set)
    mut env := types.Environment.new()
    mut checker := types.Checker.new(prefs, file_set, env)
    checker.check_files(files)
    mut transformer := Transformer.new_with_pref(env, prefs)
    return transformer.transform_files(files)
}

fn transform_sources_with_env_for_test(sources []TestSource) (&types.Environment, []ast.File) {
    tmp_dir := os.join_path(os.temp_dir(), 'v2_transformer_sources_env_${os.getpid()}')
    os.rmdir_all(tmp_dir) or {}
    os.mkdir_all(tmp_dir) or { panic(err) }
    defer {
        os.rmdir_all(tmp_dir) or {}
    }
    mut paths := []string{cap: sources.len}
    for source in sources {
        path := os.join_path(tmp_dir, source.rel)
        os.mkdir_all(os.dir(path)) or { panic(err) }
        os.write_file(path, source.code) or { panic('failed to write ${path}') }
        paths << path
    }
    prefs := &vpref.Preferences{
        backend:     .cleanc
        no_parallel: true
    }
    mut file_set := token.FileSet.new()
    mut par := parser.Parser.new(prefs)
    files := par.parse_files(paths, mut file_set)
    mut env := types.Environment.new()
    mut checker := types.Checker.new(prefs, file_set, env)
    checker.check_files(files)
    mut transformer := Transformer.new_with_pref(env, prefs)
    transformed := transformer.transform_files(files)
    return env, transformed
}

fn ident_name_from_expr_for_test(expr ast.Expr) ?string {
    if expr is ast.Ident {
        return expr.name
    }
    if expr is ast.ModifierExpr && expr.expr is ast.Ident {
        return expr.expr.name
    }
    return none
}

fn test_sort_selector_path_after_root_keeps_nested_fields() {
    t := create_test_transformer()
    expr := ast.Expr(ast.SelectorExpr{
        lhs: ast.Expr(ast.SelectorExpr{
            lhs: ast.Expr(ast.Ident{
                name: 'a'
            })
            rhs: ast.Ident{
                name: 'path'
            }
        })
        rhs: ast.Ident{
            name: 'len'
        }
    })
    path := t.selector_path_after_root(expr, 'a') or { panic('missing selector path') }

    assert path.len == 2
    assert path[0] == 'path'
    assert path[1] == 'len'
}

fn test_get_expr_type_selector_prefers_struct_field_over_stale_pos_type() {
    mut env := types.Environment.new()
    env.set_expr_type(91, types.string_)
    value_kind_type := types.Type(types.Enum{
        name: 'json2__ValueKind'
    })
    value_info_type := types.Type(types.Struct{
        name:   'json2__ValueInfo'
        fields: [
            types.Field{
                name: 'value_kind'
                typ:  value_kind_type
            },
        ]
    })
    mut scope := types.new_scope(unsafe { nil })
    scope.insert('struct_info', value_object_from_type(value_info_type))
    mut t := Transformer{
        pref:             &vpref.Preferences{}
        env:              unsafe { env }
        scope:            scope
        local_decl_types: map[string]types.Type{}
    }
    typ := t.get_expr_type(ast.SelectorExpr{
        lhs: ast.Ident{
            name: 'struct_info'
        }
        rhs: ast.Ident{
            name: 'value_kind'
        }
        pos: token.Pos{
            id: 91
        }
    }) or { panic('missing selector type') }
    assert typ is types.Enum
    assert (typ as types.Enum).name == 'json2__ValueKind'
}

fn test_get_expr_type_selector_prefers_struct_field_over_stale_synth_type() {
    value_kind_type := types.Type(types.Enum{
        name: 'json2__ValueKind'
    })
    value_info_type := types.Type(types.Struct{
        name:   'json2__ValueInfo'
        fields: [
            types.Field{
                name: 'value_kind'
                typ:  value_kind_type
            },
        ]
    })
    mut scope := types.new_scope(unsafe { nil })
    scope.insert('struct_info', value_object_from_type(value_info_type))
    mut t := Transformer{
        pref:             &vpref.Preferences{}
        env:              unsafe { types.Environment.new() }
        scope:            scope
        local_decl_types: map[string]types.Type{}
    }
    pos := token.Pos{
        id: 92
    }
    t.register_synth_type(pos, types.Type(types.string_))
    typ := t.get_expr_type(ast.SelectorExpr{
        lhs: ast.Ident{
            name: 'struct_info'
        }
        rhs: ast.Ident{
            name: 'value_kind'
        }
        pos: pos
    }) or { panic('missing selector type') }
    assert typ is types.Enum
    assert (typ as types.Enum).name == 'json2__ValueKind'
}

fn test_string_interpolation_prefers_declared_selector_type_over_stale_string_pos() {
    value_kind_type := types.Type(types.Enum{
        name: 'json2__ValueKind'
    })
    value_info_type := types.Type(types.Struct{
        name:   'json2__ValueInfo'
        fields: [
            types.Field{
                name: 'value_kind'
                typ:  value_kind_type
            },
        ]
    })
    mut env := types.Environment.new()
    env.set_expr_type(93, types.Type(types.string_))
    mut scope := types.new_scope(unsafe { nil })
    scope.insert('struct_info', value_object_from_type(value_info_type))
    mut t := Transformer{
        pref:                &vpref.Preferences{}
        env:                 unsafe { env }
        scope:               scope
        local_decl_types:    map[string]types.Type{}
        needed_str_fns:      map[string]string{}
        needed_enum_str_fns: map[string]types.Enum{}
        synth_types:         map[int]types.Type{}
    }
    inter_expr := ast.Expr(ast.SelectorExpr{
        lhs: ast.Ident{
            name: 'struct_info'
        }
        rhs: ast.Ident{
            name: 'value_kind'
        }
        pos: token.Pos{
            id: 93
        }
    })
    inter := ast.StringInter{
        expr: inter_expr
    }
    assert t.resolve_sprintf_format(inter) == '%s'
    arg := t.transform_sprintf_arg(inter)
    assert arg is ast.SelectorExpr
    call := (arg as ast.SelectorExpr).lhs
    assert call is ast.CallExpr
    lhs := (call as ast.CallExpr).lhs
    assert lhs is ast.Ident
    assert (lhs as ast.Ident).name == 'json2__ValueKind__str'

    stale_arg := ast.Expr(ast.SelectorExpr{
        lhs: ast.Expr(ast.CallExpr{
            lhs:  ast.Ident{
                name: 'string__str'
            }
            args: [inter_expr]
            pos:  token.Pos{
                id: 94
            }
        })
        rhs: ast.Ident{
            name: 'str'
        }
        pos: token.Pos{
            id: 95
        }
    })
    lit := t.transform_string_inter_literal(ast.StringInterLiteral{
        values: ["'Expected object, but got ", "'"]
        inters: [
            ast.StringInter{
                expr: stale_arg
            },
        ]
    })
    assert lit is ast.StringInterLiteral
    repaired := (lit as ast.StringInterLiteral).inters[0].expr
    assert repaired is ast.SelectorExpr
    repaired_call := (repaired as ast.SelectorExpr).lhs
    assert repaired_call is ast.CallExpr
    repaired_lhs := (repaired_call as ast.CallExpr).lhs
    assert repaired_lhs is ast.Ident
    assert (repaired_lhs as ast.Ident).name == 'json2__ValueKind__str'

    cloned := t.clone_expr_with_bindings_and_fields(ast.Expr(ast.StringInterLiteral{
        values: ["'Expected object, but got ", "'"]
        inters: [
            ast.StringInter{
                expr: stale_arg
            },
        ]
    }), map[string]types.Type{}, []CloneComptimeFieldCtx{})
    assert cloned is ast.StringInterLiteral
    cloned_arg := (cloned as ast.StringInterLiteral).inters[0].expr
    assert cloned_arg is ast.SelectorExpr
    cloned_call := (cloned_arg as ast.SelectorExpr).lhs
    assert cloned_call is ast.CallExpr
    cloned_lhs := (cloned_call as ast.CallExpr).lhs
    assert cloned_lhs is ast.Ident
    assert (cloned_lhs as ast.Ident).name == 'json2__ValueKind__str'
}

fn collect_call_names_from_stmt(stmt ast.Stmt, mut names []string) {
    match stmt {
        ast.AssignStmt {
            for expr in stmt.lhs {
                collect_call_names_from_expr(expr, mut names)
            }
            for expr in stmt.rhs {
                collect_call_names_from_expr(expr, mut names)
            }
        }
        ast.AssertStmt {
            collect_call_names_from_expr(stmt.expr, mut names)
            collect_call_names_from_expr(stmt.extra, mut names)
        }
        ast.BlockStmt {
            for nested in stmt.stmts {
                collect_call_names_from_stmt(nested, mut names)
            }
        }
        ast.ComptimeStmt {
            collect_call_names_from_stmt(stmt.stmt, mut names)
        }
        ast.DeferStmt {
            for nested in stmt.stmts {
                collect_call_names_from_stmt(nested, mut names)
            }
        }
        ast.ExprStmt {
            collect_call_names_from_expr(stmt.expr, mut names)
        }
        ast.ForInStmt {
            collect_call_names_from_expr(stmt.key, mut names)
            collect_call_names_from_expr(stmt.value, mut names)
            collect_call_names_from_expr(stmt.expr, mut names)
        }
        ast.ForStmt {
            collect_call_names_from_stmt(stmt.init, mut names)
            collect_call_names_from_expr(stmt.cond, mut names)
            collect_call_names_from_stmt(stmt.post, mut names)
            for nested in stmt.stmts {
                collect_call_names_from_stmt(nested, mut names)
            }
        }
        ast.LabelStmt {
            collect_call_names_from_stmt(stmt.stmt, mut names)
        }
        ast.ReturnStmt {
            for expr in stmt.exprs {
                collect_call_names_from_expr(expr, mut names)
            }
        }
        else {}
    }
}

fn collect_call_names_from_expr(expr ast.Expr, mut names []string) {
    match expr {
        ast.ArrayInitExpr {
            collect_call_names_from_expr(expr.init, mut names)
            collect_call_names_from_expr(expr.cap, mut names)
            collect_call_names_from_expr(expr.len, mut names)
            for item in expr.exprs {
                collect_call_names_from_expr(item, mut names)
            }
        }
        ast.AsCastExpr {
            collect_call_names_from_expr(expr.expr, mut names)
        }
        ast.AssocExpr {
            collect_call_names_from_expr(expr.expr, mut names)
            for field in expr.fields {
                collect_call_names_from_expr(field.value, mut names)
            }
        }
        ast.CallExpr {
            if expr.lhs is ast.Ident {
                names << expr.lhs.name
            }
            collect_call_names_from_expr(expr.lhs, mut names)
            for arg in expr.args {
                collect_call_names_from_expr(arg, mut names)
            }
        }
        ast.CallOrCastExpr {
            collect_call_names_from_expr(expr.lhs, mut names)
            collect_call_names_from_expr(expr.expr, mut names)
        }
        ast.CastExpr {
            collect_call_names_from_expr(expr.expr, mut names)
        }
        ast.FieldInit {
            collect_call_names_from_expr(expr.value, mut names)
        }
        ast.FnLiteral {
            for nested in expr.stmts {
                collect_call_names_from_stmt(nested, mut names)
            }
        }
        ast.GenericArgOrIndexExpr {
            collect_call_names_from_expr(expr.lhs, mut names)
            collect_call_names_from_expr(expr.expr, mut names)
        }
        ast.GenericArgs {
            collect_call_names_from_expr(expr.lhs, mut names)
            for arg in expr.args {
                collect_call_names_from_expr(arg, mut names)
            }
        }
        ast.IfExpr {
            collect_call_names_from_expr(expr.cond, mut names)
            for nested in expr.stmts {
                collect_call_names_from_stmt(nested, mut names)
            }
            collect_call_names_from_expr(expr.else_expr, mut names)
        }
        ast.IndexExpr {
            collect_call_names_from_expr(expr.lhs, mut names)
            collect_call_names_from_expr(expr.expr, mut names)
        }
        ast.InfixExpr {
            collect_call_names_from_expr(expr.lhs, mut names)
            collect_call_names_from_expr(expr.rhs, mut names)
        }
        ast.InitExpr {
            for field in expr.fields {
                collect_call_names_from_expr(field.value, mut names)
            }
        }
        ast.LambdaExpr {
            collect_call_names_from_expr(expr.expr, mut names)
        }
        ast.LockExpr {
            for nested in expr.stmts {
                collect_call_names_from_stmt(nested, mut names)
            }
        }
        ast.MapInitExpr {
            for key in expr.keys {
                collect_call_names_from_expr(key, mut names)
            }
            for val in expr.vals {
                collect_call_names_from_expr(val, mut names)
            }
        }
        ast.MatchExpr {
            collect_call_names_from_expr(expr.expr, mut names)
            for branch in expr.branches {
                for cond in branch.cond {
                    collect_call_names_from_expr(cond, mut names)
                }
                for nested in branch.stmts {
                    collect_call_names_from_stmt(nested, mut names)
                }
            }
        }
        ast.ModifierExpr {
            collect_call_names_from_expr(expr.expr, mut names)
        }
        ast.OrExpr {
            collect_call_names_from_expr(expr.expr, mut names)
            for nested in expr.stmts {
                collect_call_names_from_stmt(nested, mut names)
            }
        }
        ast.ParenExpr {
            collect_call_names_from_expr(expr.expr, mut names)
        }
        ast.PostfixExpr {
            collect_call_names_from_expr(expr.expr, mut names)
        }
        ast.PrefixExpr {
            collect_call_names_from_expr(expr.expr, mut names)
        }
        ast.RangeExpr {
            collect_call_names_from_expr(expr.start, mut names)
            collect_call_names_from_expr(expr.end, mut names)
        }
        ast.SelectExpr {
            collect_call_names_from_stmt(expr.stmt, mut names)
            for nested in expr.stmts {
                collect_call_names_from_stmt(nested, mut names)
            }
            collect_call_names_from_expr(expr.next, mut names)
        }
        ast.SelectorExpr {
            collect_call_names_from_expr(expr.lhs, mut names)
        }
        ast.StringInterLiteral {
            for inter in expr.inters {
                collect_call_names_from_expr(inter.expr, mut names)
                collect_call_names_from_expr(inter.format_expr, mut names)
            }
        }
        ast.Tuple {
            for item in expr.exprs {
                collect_call_names_from_expr(item, mut names)
            }
        }
        ast.UnsafeExpr {
            for nested in expr.stmts {
                collect_call_names_from_stmt(nested, mut names)
            }
        }
        else {}
    }
}

fn call_names_for_fn(files []ast.File, fn_name string) []string {
    mut names := []string{}
    for file in files {
        for stmt in file.stmts {
            if stmt is ast.FnDecl && stmt.name == fn_name {
                for nested in stmt.stmts {
                    collect_call_names_from_stmt(nested, mut names)
                }
            }
        }
    }
    return names
}

fn test_println_rune_lowers_to_rune_str_call() {
    mut t := create_transformer_with_vars({
        'r': types.Type(types.rune_)
    })
    out := t.transform_call_expr(ast.CallExpr{
        lhs:  ast.Ident{
            name: 'println'
        }
        args: [ast.Expr(ast.Ident{
            name: 'r'
        })]
    })
    assert out is ast.CallExpr
    call := out as ast.CallExpr
    assert call.args.len == 1
    assert call.args[0] is ast.CallExpr
    str_call := call.args[0] as ast.CallExpr
    assert str_call.lhs is ast.Ident
    assert (str_call.lhs as ast.Ident).name == 'rune__str'
    assert 'rune__str' in t.needed_str_fns
}

fn test_println_i64_call_or_cast_lowers_to_i64_str_call() {
    mut t := create_test_transformer()
    out := t.transform_call_expr(ast.CallExpr{
        lhs:  ast.Ident{
            name: 'println'
        }
        args: [
            ast.Expr(ast.CallOrCastExpr{
                lhs:  ast.Ident{
                    name: 'i64'
                }
                expr: ast.BasicLiteral{
                    kind:  .number
                    value: '4294967296'
                }
            }),
        ]
    })
    assert out is ast.CallExpr
    call := out as ast.CallExpr
    assert call.args.len == 1
    assert call.args[0] is ast.CallExpr
    str_call := call.args[0] as ast.CallExpr
    assert str_call.lhs is ast.Ident
    assert (str_call.lhs as ast.Ident).name == 'i64__str'
    assert 'i64__str' in t.needed_str_fns
}

fn call_names_for_fn_suffix(files []ast.File, fn_suffix string) []string {
    mut names := []string{}
    for file in files {
        for stmt in file.stmts {
            if stmt is ast.FnDecl && stmt.name.ends_with(fn_suffix) {
                for nested in stmt.stmts {
                    collect_call_names_from_stmt(nested, mut names)
                }
            }
        }
    }
    return names
}

fn test_transform_generic_call_uses_sumtype_match_smartcast_for_inference() {
    files := transform_code_for_test('
struct Point {
    x int
}

type Primitive = []int | []string | []Point | bool | int | string | Point

fn wrap_first[T](values []T) Primitive {
    return Primitive(values[0])
}

fn check(value Primitive) {
    match value {
        []int {
            _ := wrap_first(value)
        }
        []string {
            _ := wrap_first(value)
        }
        []Point {
            _ := wrap_first(value)
        }
        else {}
    }
}
')
    names := call_names_for_fn(files, 'check')
    assert 'wrap_first_T_int' in names
    assert 'wrap_first_T_string' in names
    assert 'wrap_first_T_Point' in names
    assert 'wrap_first' !in names
}

fn test_transform_generic_receiver_methods_use_concrete_specializations() {
    files := transform_sources_for_test([
        TestSource{
            rel:  'x/json2/decode.v'
            code: '
module json2

struct ValueInfo {
    x int
}

struct Node[T] {
mut:
    value T
    next  &Node[T] = unsafe { nil }
}

struct Decoder {
mut:
    values_info LinkedList[ValueInfo]
}

struct LinkedList[T] {
mut:
    head &Node[T] = unsafe { nil }
    tail &Node[T] = unsafe { nil }
    len  int
}

fn (mut list LinkedList[T]) push(value T) {
    _ = value
}

fn (list &LinkedList[T]) last() &T {
    return &list.tail.value
}
'
        },
        TestSource{
            rel:  'x/json2/check.v'
            code: '
module json2

fn (mut checker Decoder) check() {
    mut actual_value_info_pointer := unsafe { nil }
    checker.values_info.push(ValueInfo{})
    actual_value_info_pointer = checker.values_info.last()
    _ = actual_value_info_pointer
}
'
        },
    ])
    names := call_names_for_fn(files, 'check')
    assert names.any(it.contains('json2__LinkedList__push_T_') && it.contains('json2_ValueInfo')), 'expected specialized push call, got ${names}'

    assert names.any(it.contains('json2__LinkedList__last_T_') && it.contains('json2_ValueInfo')), 'expected specialized last call, got ${names}'

    assert 'LinkedList__push' !in names
    assert 'LinkedList__last' !in names
    assert 'json2__LinkedList__push' !in names
    assert 'json2__LinkedList__last' !in names
}

fn test_transform_nested_generic_receiver_method_call_in_monomorphized_clone() {
    files := transform_sources_for_test([
        TestSource{
            rel:  'x/json2/encode.v'
            code: '
module json2

pub struct EncoderOptions {}

pub struct Any {}

struct Encoder {}

pub fn encode[T](val T, config EncoderOptions) string {
    _ = config
    mut encoder := Encoder{}
    encoder.encode_value[T](val)
    return ""
}

fn (mut encoder Encoder) encode_value[T](val T) {
    _ = encoder
    _ = val
}
'
        },
        TestSource{
            rel:  'main.v'
            code: '
module main

import json2

fn use() {
    _ = json2.encode(json2.Any{}, json2.EncoderOptions{})
}
'
        },
    ])
    mut fn_names := []string{}
    for file in files {
        for stmt in file.stmts {
            if stmt is ast.FnDecl {
                fn_names << stmt.name
            }
        }
    }
    assert 'json2__encode_T_json2_Any' in fn_names
    assert 'encode_value_T_json2_Any' in fn_names
    call_names := call_names_for_fn(files, 'json2__encode_T_json2_Any')
    assert 'json2__Encoder__encode_value_T_json2_Any' in call_names
    assert 'encode_value_T_json2_Any' !in call_names
}

fn test_transform_eventbus_receiver_generic_method_call_is_monomorphized() {
    files := transform_sources_for_test([
        TestSource{
            rel:  'eventbus/eventbus.v'
            code: '
module eventbus

pub type EventHandlerFn = fn (receiver voidptr, args voidptr, sender voidptr)

pub struct Subscriber[T] {}

pub fn new_subscriber[T]() Subscriber[T] {
    return Subscriber[T]{}
}

pub fn (mut s Subscriber[T]) subscribe_method(name T, handler EventHandlerFn, receiver voidptr) {
    _ = s
    _ = name
    _ = handler
    _ = receiver
}
'
        },
        TestSource{
            rel:  'main.v'
            code: "
module main

import eventbus

fn handler(receiver voidptr, args voidptr, sender voidptr) {
    _ = receiver
    _ = args
    _ = sender
}

fn use() {
    mut subscriber := eventbus.new_subscriber[string]()
    subscriber.subscribe_method('ready', handler, unsafe { nil })
}
"
        },
    ])
    mut fn_names := []string{}
    for file in files {
        for stmt in file.stmts {
            if stmt is ast.FnDecl {
                fn_names << stmt.name
            }
        }
    }
    assert 'subscribe_method_T_string' in fn_names

    call_names := call_names_for_fn(files, 'use')
    assert 'eventbus__Subscriber__subscribe_method_T_string' in call_names
    assert 'eventbus__Subscriber__subscribe_method' !in call_names
}

fn test_transform_embedded_method_promotion_keeps_owner_method_precedence() {
    mut t := create_test_transformer()
    t.collect_declared_method_fns([
        ast.File{
            mod:   'main'
            stmts: [
                ast.Stmt(ast.FnDecl{
                    name:      'redirect_to_index'
                    is_method: true
                    receiver:  ast.Parameter{
                        name: 'ctx'
                        typ:  ast.Expr(ast.Ident{
                            name: 'Context'
                        })
                    }
                }),
            ]
        },
    ])
    recv_type := types.Type(types.Struct{
        name: 'Context'
    })
    resolved := t.resolve_cached_method_fn_name_for_type(recv_type, 'redirect_to_index', 'Context') or {
        panic('missing declared owner method')
    }
    assert resolved == 'Context__redirect_to_index'
    assert 'Context__redirect_to_index' in t.declared_method_fns
}

fn test_generic_receiver_bindings_prefer_declared_selector_over_stale_wrapper_type() {
    value_info_type := types.Type(types.Struct{
        name: 'json2__ValueInfo'
    })
    template_type := types.Type(types.Struct{
        name:           'json2__LinkedList'
        generic_params: ['T']
        fields:         [
            types.Field{
                name: 'item'
                typ:  types.Type(types.NamedType('T'))
            },
        ]
    })
    concrete_type := types.Type(types.Struct{
        name:   'json2__LinkedList'
        fields: [
            types.Field{
                name: 'item'
                typ:  value_info_type
            },
        ]
    })
    decoder_type := types.Type(types.Struct{
        name:   'json2__Decoder'
        fields: [
            types.Field{
                name: 'values_info'
                typ:  concrete_type
            },
        ]
    })
    mut env := types.Environment.new()
    env.set_expr_type(701, template_type)
    mut scope := types.new_scope(unsafe { nil })
    scope.insert('checker', value_object_from_type(decoder_type))
    scope.insert_type('LinkedList', template_type)
    scope.insert_type('json2__LinkedList', template_type)
    mut t := Transformer{
        pref:             &vpref.Preferences{}
        env:              unsafe { env }
        scope:            scope
        cur_module:       'json2'
        cached_scopes:    {
            'json2': scope
        }
        local_decl_types: map[string]types.Type{}
    }
    receiver := ast.Expr(ast.ParenExpr{
        expr: ast.Expr(ast.SelectorExpr{
            lhs: ast.Ident{
                name: 'checker'
            }
            rhs: ast.Ident{
                name: 'values_info'
            }
        })
        pos:  token.Pos{
            id: 701
        }
    })
    decl := ast.FnDecl{
        name:      'last'
        is_method: true
        receiver:  ast.Parameter{
            name: 'list'
            typ:  ast.Expr(ast.PrefixExpr{
                op:   .amp
                expr: ast.Expr(ast.GenericArgOrIndexExpr{
                    lhs:  ast.Expr(ast.Ident{
                        name: 'LinkedList'
                    })
                    expr: ast.Expr(ast.Ident{
                        name: 'T'
                    })
                })
            })
        }
    }
    bindings := t.generic_bindings_from_method_receiver(decl, receiver, 'json2__LinkedList__last') or {
        panic('missing receiver bindings')
    }
    binding := bindings['T'] or { panic('missing T binding') }
    assert binding is types.Struct
    assert (binding as types.Struct).name == 'json2__ValueInfo'
}

fn test_decl_assign_rune_arithmetic_keeps_rune_storage_type() {
    mut t := create_transformer_with_vars({
        'unicode_point':  types.builtin_type('rune') or { rune_type() }
        'unicode_point2': types.builtin_type('rune') or { rune_type() }
    })
    mut env := types.Environment.new()
    env.set_expr_type(93, types.Type(types.int_))
    env.set_expr_type(94, types.Type(types.int_))
    env.set_expr_type(95, types.Type(types.int_))
    t.env = unsafe { env }
    lhs := ast.Expr(ast.Ident{
        name: 'final_unicode_point'
        pos:  token.Pos{
            id: 93
        }
    })
    cast_rhs := ast.Expr(ast.CastExpr{
        typ:  ast.Expr(ast.Ident{
            name: 'rune'
        })
        expr: ast.Expr(ast.BasicLiteral{
            kind:  .number
            value: '0'
        })
    })
    cast_typ := t.decl_assign_storage_type(lhs, cast_rhs) or { panic('missing cast type') }
    assert cast_typ is types.Rune
    rhs := ast.Expr(ast.InfixExpr{
        op:  .plus
        lhs: ast.Expr(ast.InfixExpr{
            op:  .amp
            lhs: ast.Expr(ast.Ident{
                name: 'unicode_point2'
                pos:  token.Pos{
                    id: 94
                }
            })
            rhs: ast.Expr(ast.BasicLiteral{
                kind:  .number
                value: '0x3FF'
            })
        })
        rhs: ast.Expr(ast.InfixExpr{
            op:  .left_shift
            lhs: ast.Expr(ast.InfixExpr{
                op:  .amp
                lhs: ast.Expr(ast.Ident{
                    name: 'unicode_point'
                    pos:  token.Pos{
                        id: 95
                    }
                })
                rhs: ast.Expr(ast.BasicLiteral{
                    kind:  .number
                    value: '0x3FF'
                })
            })
            rhs: ast.Expr(ast.BasicLiteral{
                kind:  .number
                value: '10'
            })
        })
    })
    typ := t.decl_assign_storage_type(lhs, rhs) or { panic('missing rune arithmetic type') }
    assert typ is types.Rune
}

fn test_runtime_const_init_main_calls_run_main_consts_after_module_inits() {
    mut t := create_test_transformer()
    t.runtime_const_modules << 'main'
    t.runtime_const_init_fn_name['main'] = '__v_init_consts_main'
    files := [
        ast.File{
            mod:   'main'
            stmts: [
                ast.Stmt(ast.FnDecl{
                    name: 'main'
                }),
            ]
        },
        ast.File{
            mod:   'rand'
            stmts: [
                ast.Stmt(ast.FnDecl{
                    name: 'init'
                }),
            ]
        },
    ]
    calls := t.runtime_const_init_main_calls_parts(files)
    mut names := []string{}
    for call_stmt in calls {
        collect_call_names_from_stmt(call_stmt, mut names)
    }
    assert names == ['rand__init', '__v_init_consts_main']
}

fn stmt_has_assign_op(stmt ast.Stmt, op token.Token) bool {
    match stmt {
        ast.AssignStmt {
            return stmt.op == op
        }
        ast.BlockStmt {
            for nested in stmt.stmts {
                if stmt_has_assign_op(nested, op) {
                    return true
                }
            }
        }
        ast.ExprStmt {
            return expr_has_assign_op(stmt.expr, op)
        }
        ast.ForStmt {
            if stmt_has_assign_op(stmt.init, op) || stmt_has_assign_op(stmt.post, op) {
                return true
            }
            for nested in stmt.stmts {
                if stmt_has_assign_op(nested, op) {
                    return true
                }
            }
        }
        ast.LabelStmt {
            return stmt_has_assign_op(stmt.stmt, op)
        }
        else {}
    }

    return false
}

fn expr_has_assign_op(expr ast.Expr, op token.Token) bool {
    match expr {
        ast.IfExpr {
            for stmt in expr.stmts {
                if stmt_has_assign_op(stmt, op) {
                    return true
                }
            }
            return expr_has_assign_op(expr.else_expr, op)
        }
        ast.MatchExpr {
            for branch in expr.branches {
                for stmt in branch.stmts {
                    if stmt_has_assign_op(stmt, op) {
                        return true
                    }
                }
            }
        }
        ast.UnsafeExpr {
            for stmt in expr.stmts {
                if stmt_has_assign_op(stmt, op) {
                    return true
                }
            }
        }
        else {}
    }

    return false
}

fn fn_has_assign_op(files []ast.File, fn_name string, op token.Token) bool {
    for file in files {
        for stmt in file.stmts {
            if stmt is ast.FnDecl && stmt.name == fn_name {
                for nested in stmt.stmts {
                    if stmt_has_assign_op(nested, op) {
                        return true
                    }
                }
            }
        }
    }
    return false
}

fn count_label_name_in_files(files []ast.File, fn_name string, label string) int {
    mut count := 0
    for file in files {
        for stmt in file.stmts {
            if stmt is ast.FnDecl && stmt.name == fn_name {
                count += count_label_name_in_stmts(stmt.stmts, label)
            }
        }
    }
    return count
}

fn count_label_name_in_stmts(stmts []ast.Stmt, label string) int {
    mut count := 0
    for stmt in stmts {
        count += count_label_name_in_stmt(stmt, label)
    }
    return count
}

fn count_label_name_in_stmt(stmt ast.Stmt, label string) int {
    match stmt {
        ast.BlockStmt {
            return count_label_name_in_stmts(stmt.stmts, label)
        }
        ast.ComptimeStmt {
            return count_label_name_in_stmt(stmt.stmt, label)
        }
        ast.DeferStmt {
            return count_label_name_in_stmts(stmt.stmts, label)
        }
        ast.ExprStmt {
            return count_label_name_in_expr(stmt.expr, label)
        }
        ast.ForStmt {
            return count_label_name_in_stmt(stmt.init, label) +
                count_label_name_in_stmt(stmt.post, label) +
                count_label_name_in_expr(stmt.cond, label) +
                count_label_name_in_stmts(stmt.stmts, label)
        }
        ast.LabelStmt {
            mut count := if stmt.name == label { 1 } else { 0 }
            count += count_label_name_in_stmt(stmt.stmt, label)
            return count
        }
        ast.ReturnStmt {
            mut count := 0
            for expr in stmt.exprs {
                count += count_label_name_in_expr(expr, label)
            }
            return count
        }
        else {
            return 0
        }
    }
}

fn count_label_name_in_expr(expr ast.Expr, label string) int {
    match expr {
        ast.IfExpr {
            return count_label_name_in_expr(expr.cond, label) +
                count_label_name_in_stmts(expr.stmts, label) +
                count_label_name_in_expr(expr.else_expr, label)
        }
        ast.MatchExpr {
            mut count := 0
            for branch in expr.branches {
                count += count_label_name_in_stmts(branch.stmts, label)
            }
            return count
        }
        ast.UnsafeExpr {
            return count_label_name_in_stmts(expr.stmts, label)
        }
        else {
            return 0
        }
    }
}

fn find_call_with_lhs_suffix_in_stmts(stmts []ast.Stmt, suffix string) ?ast.CallExpr {
    for stmt in stmts {
        if call := find_call_with_lhs_suffix_in_stmt(stmt, suffix) {
            return call
        }
    }
    return none
}

fn find_call_with_lhs_suffix_in_stmt(stmt ast.Stmt, suffix string) ?ast.CallExpr {
    match stmt {
        ast.AssignStmt {
            for expr in stmt.lhs {
                if call := find_call_with_lhs_suffix_in_expr(expr, suffix) {
                    return call
                }
            }
            for expr in stmt.rhs {
                if call := find_call_with_lhs_suffix_in_expr(expr, suffix) {
                    return call
                }
            }
        }
        ast.BlockStmt {
            return find_call_with_lhs_suffix_in_stmts(stmt.stmts, suffix)
        }
        ast.ExprStmt {
            return find_call_with_lhs_suffix_in_expr(stmt.expr, suffix)
        }
        ast.ForInStmt {
            if call := find_call_with_lhs_suffix_in_expr(stmt.expr, suffix) {
                return call
            }
        }
        ast.ForStmt {
            if call := find_call_with_lhs_suffix_in_stmt(stmt.init, suffix) {
                return call
            }
            if call := find_call_with_lhs_suffix_in_expr(stmt.cond, suffix) {
                return call
            }
            if call := find_call_with_lhs_suffix_in_stmt(stmt.post, suffix) {
                return call
            }
            return find_call_with_lhs_suffix_in_stmts(stmt.stmts, suffix)
        }
        ast.FnDecl {
            return find_call_with_lhs_suffix_in_stmts(stmt.stmts, suffix)
        }
        ast.ReturnStmt {
            for expr in stmt.exprs {
                if call := find_call_with_lhs_suffix_in_expr(expr, suffix) {
                    return call
                }
            }
        }
        else {}
    }

    return none
}

fn find_call_with_lhs_suffix_in_expr(expr ast.Expr, suffix string) ?ast.CallExpr {
    match expr {
        ast.ArrayInitExpr {
            for item in expr.exprs {
                if call := find_call_with_lhs_suffix_in_expr(item, suffix) {
                    return call
                }
            }
        }
        ast.CallExpr {
            if expr.lhs is ast.Ident && (expr.lhs as ast.Ident).name.ends_with(suffix) {
                return expr
            }
            if call := find_call_with_lhs_suffix_in_expr(expr.lhs, suffix) {
                return call
            }
            for arg in expr.args {
                if call := find_call_with_lhs_suffix_in_expr(arg, suffix) {
                    return call
                }
            }
        }
        ast.CastExpr {
            return find_call_with_lhs_suffix_in_expr(expr.expr, suffix)
        }
        ast.FieldInit {
            return find_call_with_lhs_suffix_in_expr(expr.value, suffix)
        }
        ast.IfExpr {
            if call := find_call_with_lhs_suffix_in_expr(expr.cond, suffix) {
                return call
            }
            if call := find_call_with_lhs_suffix_in_stmts(expr.stmts, suffix) {
                return call
            }
            return find_call_with_lhs_suffix_in_expr(expr.else_expr, suffix)
        }
        ast.InfixExpr {
            if call := find_call_with_lhs_suffix_in_expr(expr.lhs, suffix) {
                return call
            }
            return find_call_with_lhs_suffix_in_expr(expr.rhs, suffix)
        }
        ast.InitExpr {
            for field in expr.fields {
                if call := find_call_with_lhs_suffix_in_expr(field.value, suffix) {
                    return call
                }
            }
        }
        ast.MatchExpr {
            if call := find_call_with_lhs_suffix_in_expr(expr.expr, suffix) {
                return call
            }
            for branch in expr.branches {
                if call := find_call_with_lhs_suffix_in_stmts(branch.stmts, suffix) {
                    return call
                }
            }
        }
        ast.ModifierExpr {
            return find_call_with_lhs_suffix_in_expr(expr.expr, suffix)
        }
        ast.ParenExpr {
            return find_call_with_lhs_suffix_in_expr(expr.expr, suffix)
        }
        ast.PostfixExpr {
            return find_call_with_lhs_suffix_in_expr(expr.expr, suffix)
        }
        ast.PrefixExpr {
            return find_call_with_lhs_suffix_in_expr(expr.expr, suffix)
        }
        ast.SelectorExpr {
            return find_call_with_lhs_suffix_in_expr(expr.lhs, suffix)
        }
        ast.UnsafeExpr {
            return find_call_with_lhs_suffix_in_stmts(expr.stmts, suffix)
        }
        else {}
    }

    return none
}

// string_type returns the builtin v2 string type.
fn string_type() types.Type {
    return types.string_
}

fn test_transform_decl_assign_keeps_explicit_as_cast_type_with_stale_lhs_name_scope() {
    env := &types.Environment{}
    mut scope := types.new_scope(unsafe { nil })
    scope.insert('inner', types.Type(types.Struct{
        name: 'ast__Expr'
    }))
    mut t := &Transformer{
        pref:                        &vpref.Preferences{}
        env:                         unsafe { env }
        scope:                       scope
        needed_clone_fns:            map[string]string{}
        needed_array_contains_fns:   map[string]ArrayMethodInfo{}
        needed_array_index_fns:      map[string]ArrayMethodInfo{}
        needed_array_last_index_fns: map[string]ArrayMethodInfo{}
    }
    result := t.transform_assign_stmt(ast.AssignStmt{
        op:  .decl_assign
        lhs: [
            ast.Expr(ast.Ident{
                name: 'inner'
            }),
        ]
        rhs: [
            ast.Expr(ast.AsCastExpr{
                expr: ast.Expr(ast.Ident{
                    name: 'node'
                })
                typ:  ast.Expr(ast.SelectorExpr{
                    lhs: ast.Expr(ast.Ident{
                        name: 'ast'
                    })
                    rhs: ast.Ident{
                        name: 'PrefixExpr'
                    }
                })
            }),
        ]
    })
    assert result.rhs[0] is ast.AsCastExpr
}

fn test_transform_decl_assign_does_not_wrap_rhs_with_stale_lhs_sumtype_scope() {
    env := &types.Environment{}
    type_sum := types.Type(types.SumType{
        name:     'types__Type'
        variants: [string_type()]
    })
    mut scope := types.new_scope(unsafe { nil })
    scope.insert('receiver_type', type_sum)
    mut types_scope := types.new_scope(unsafe { nil })
    types_scope.insert('Type', type_sum)
    mut t := &Transformer{
        pref:                        &vpref.Preferences{}
        env:                         unsafe { env }
        scope:                       scope
        cur_module:                  'transformer'
        cached_scopes:               {
            'types': types_scope
        }
        needed_clone_fns:            map[string]string{}
        needed_array_contains_fns:   map[string]ArrayMethodInfo{}
        needed_array_index_fns:      map[string]ArrayMethodInfo{}
        needed_array_last_index_fns: map[string]ArrayMethodInfo{}
    }
    result := t.transform_assign_stmt(ast.AssignStmt{
        op:  .decl_assign
        lhs: [
            ast.Expr(ast.Ident{
                name: 'receiver_type'
            }),
        ]
        rhs: [
            ast.Expr(ast.StringLiteral{
                value: 'flag'
                kind:  .v
            }),
        ]
    })
    assert result.rhs[0] is ast.StringLiteral
}

fn test_transform_decl_assign_registers_smartcast_selector_type() {
    env := &types.Environment{}
    mut ast_scope := types.new_scope(unsafe { nil })
    ast_scope.insert('Interface', types.Type(types.Struct{
        name: 'ast__Interface'
    }))
    mut fn_scope := types.new_scope(unsafe { nil })
    mut t := &Transformer{
        pref:                        &vpref.Preferences{}
        env:                         unsafe { env }
        scope:                       fn_scope
        fn_root_scope:               fn_scope
        cur_module:                  'checker'
        cached_scopes:               {
            'ast': ast_scope
        }
        needed_clone_fns:            map[string]string{}
        needed_array_contains_fns:   map[string]ArrayMethodInfo{}
        needed_array_index_fns:      map[string]ArrayMethodInfo{}
        needed_array_last_index_fns: map[string]ArrayMethodInfo{}
    }
    t.push_smartcast_full('parent_sym.info', 'ast__Interface', 'ast__Interface', 'ast__TypeInfo')
    _ := t.transform_assign_stmt(ast.AssignStmt{
        op:  .decl_assign
        lhs: [ast.Expr(ast.Ident{
            name: 'generic_info'
        })]
        rhs: [
            ast.Expr(ast.SelectorExpr{
                lhs: ast.Expr(ast.Ident{
                    name: 'parent_sym'
                })
                rhs: ast.Ident{
                    name: 'info'
                }
            }),
        ]
    })
    typ := fn_scope.lookup_var_type('generic_info') or {
        assert false, 'generic_info type was not registered'
        return
    }
    assert typ is types.Struct
    assert (typ as types.Struct).name == 'ast__Interface'
}

fn test_smartcast_method_call_prefers_variant_method_over_sumtype_method() {
    files := transform_code_for_test('
struct Primitive {}

struct Enum {
    name string
}

type Type = Primitive | Enum

fn (t Type) name() string {
    _ = t
    return "type"
}

fn (t Primitive) name() string {
    _ = t
    return "primitive"
}

fn (t Enum) name() string {
    return t.name
}

fn type_name(t Type) string {
    return match t {
        Primitive, Enum { t.name() }
    }
}
')
    call_names := call_names_for_fn(files, 'type_name')
    assert 'Primitive__name' in call_names
    assert 'Enum__name' in call_names
    assert 'Type__name' !in call_names
}

fn test_flag_enum_set_on_local_variable_lowers_to_assignment() {
    files := transform_code_for_test('
@[flag]
enum Flags {
    empty
    enabled
}

fn set_flag() Flags {
    mut attrs := Flags.empty
    attrs.set(.enabled)
    return attrs
}
')
    call_names := call_names_for_fn(files, 'set_flag')
    assert 'Flags__set' !in call_names
    assert fn_has_assign_op(files, 'set_flag', .or_assign)
}

fn test_flag_enum_set_inside_statement_match_lowers_to_assignment() {
    files := transform_code_for_test('
@[flag]
enum Flags {
    empty
    enabled
}

fn set_flag(names []string) Flags {
    mut attrs := Flags.empty
    for name in names {
        match name {
            "enabled" { attrs.set(.enabled) }
            else {}
        }
    }
    return attrs
}
')
    call_names := call_names_for_fn(files, 'set_flag')
    assert 'Flags__set' !in call_names
    assert fn_has_assign_op(files, 'set_flag', .or_assign)
}

fn test_embedded_struct_selector_uses_embedded_method_owner() {
    files := transform_code_for_test('
struct Request {}
struct Response {}

struct SilentStreamingDownloader {}

fn (mut d SilentStreamingDownloader) on_finish(request &Request, response &Response) ! {
    _ = request
    _ = response
}

struct TerminalStreamingDownloader {
    SilentStreamingDownloader
}

fn finish(mut d TerminalStreamingDownloader, request &Request, response &Response) ! {
    d.SilentStreamingDownloader.on_finish(request, response)!
}
')
    call_names := call_names_for_fn(files, 'finish')
    assert 'SilentStreamingDownloader__on_finish' in call_names
    assert 'int__on_finish' !in call_names
}

fn test_promoted_embedded_generic_method_call_lowers_to_concrete_method() {
    files := transform_code_for_test('
struct Options[T] {
    handler fn (mut ctx T) bool
}

struct Middleware[T] {}

fn (mut m Middleware[T]) use(options Options[T]) {
    _ = options
}

struct Context {}

struct App {
    Middleware[Context]
}

fn (mut app App) before_request(mut ctx Context) bool {
    _ = ctx
    return true
}

fn main() {
    mut app := App{}
    app.use(handler: app.before_request)
}
')
    mut fn_names := []string{}
    for file in files {
        for stmt in file.stmts {
            if stmt is ast.FnDecl {
                fn_names << stmt.name
            }
        }
    }
    call_names := call_names_for_fn(files, 'main')
    assert 'use_T_Context' in fn_names
    assert 'Middleware__use_T_Context' in call_names
    assert 'app.use' !in call_names
}

fn test_promoted_embedded_generic_method_uses_live_struct_metadata() {
    files := transform_code_for_test('
struct Result {}

struct BaseContext {}

fn (mut ctx BaseContext) json[T](j T) Result {
    _ = j
    return Result{}
}

struct Context {
    BaseContext
}

struct App {}

fn (mut app App) index(mut ctx Context) Result {
    _ = app
    return ctx.json("ok")
}

fn main() {
    mut app := App{}
    mut ctx := Context{}
    _ = app.index(mut ctx)
}
')
    call_names := call_names_for_fn(files, 'index')
    assert 'BaseContext__json_T_string' in call_names
    assert 'ctx.json' !in call_names
}

fn test_alias_receiver_method_is_resolved_before_base_container_method() {
    files := transform_code_for_test('
type Builder = []u8

fn (mut b Builder) str() string {
    _ = b
    return ""
}

fn builder_str() string {
    mut b := Builder([]u8{})
    return b.str()
}
')
    call_names := call_names_for_fn(files, 'builder_str')
    assert 'Builder__str' in call_names
    assert 'array__str' !in call_names
}

fn test_string_interpolation_does_not_generate_default_over_explicit_str_method() {
    files := transform_code_for_test('
module globset

pub struct ErrorKind {}

pub fn (kind ErrorKind) str() string {
    _ = kind
    return "custom"
}

pub fn message(kind ErrorKind) string {
    return "\${kind}"
}
')
    mut explicit_methods := 0
    mut generated_defaults := 0
    for file in files {
        for stmt in file.stmts {
            if stmt is ast.FnDecl {
                if stmt.is_method && stmt.name == 'str' {
                    explicit_methods++
                }
                if !stmt.is_method && stmt.name == 'globset__ErrorKind__str' {
                    generated_defaults++
                }
            }
        }
    }
    call_names := call_names_for_fn(files, 'message')
    assert explicit_methods == 1
    assert generated_defaults == 0
    assert 'globset__ErrorKind__str' in call_names
}

fn test_array_str_call_uses_element_specific_helper() {
    files := transform_code_for_test('
module globset

pub struct Token {}

pub fn (tok Token) str() string {
    _ = tok
    return "Token"
}

pub fn show(tokens []Token) string {
    return tokens.str()
}
')
    call_names := call_names_for_fn(files, 'show')
    assert 'Array_globset__Token_str' in call_names
    assert 'array__str' !in call_names
}

fn test_string_array_str_call_keeps_builtin_method() {
    files := transform_code_for_test('
module builtin

fn (a []string) str() string {
    _ = a
    return ""
}

fn show(values []string) string {
    return values.str()
}
')
    call_names := call_names_for_fn(files, 'show')
    assert 'Array_string__str' in call_names
    assert 'Array_string_str' !in call_names
}

fn test_qualified_alias_receiver_uses_concrete_base_method_with_same_short_name() {
    files := transform_sources_for_test([
        TestSource{
            rel:  'base/base.v'
            code: 'module base

pub struct SSLConn {}

pub fn (mut s SSLConn) connect() {
    _ = s
}
'
        },
        TestSource{
            rel:  'ssl/ssl.v'
            code: 'module ssl

import base

pub type SSLConn = base.SSLConn
'
        },
        TestSource{
            rel:  'main.v'
            code: 'module main

import ssl

fn call(mut s ssl.SSLConn) {
    s.connect()
}
'
        },
    ])
    call_names := call_names_for_fn(files, 'call')
    assert 'base__SSLConn__connect' in call_names, 'expected base method owner, got ${call_names}'
    assert 'ssl__SSLConn__connect' !in call_names
}

fn test_imported_global_receiver_method_uses_global_type() {
    files := transform_sources_for_test([
        TestSource{
            rel:  'ast/ast.v'
            code: 'module ast

pub type Type = u32

pub struct Table {}

pub __global global_table = &Table(unsafe { nil })

pub fn (t &Table) type_to_str(typ Type) string {
    _ = t
    _ = typ
    return ""
}
'
        },
        TestSource{
            rel:  'main.v'
            code: 'module transformer

import ast

struct Param {
    typ ast.Type
}

struct FnDecl {
    receiver Param
}

fn call(node &FnDecl) string {
    return ast.global_table.type_to_str(node.receiver.typ)
}
'
        },
    ])
    call_names := call_names_for_fn(files, 'call')
    assert 'ast__Table__type_to_str' in call_names, 'expected ast.Table method owner, got ${call_names}'
    assert 'int__type_to_str' !in call_names
}

fn test_sumtype_type_name_on_imported_struct_field_is_lowered() {
    files := transform_sources_for_test([
        TestSource{
            rel:  'astx/astx.v'
            code: 'module astx

pub type Expr = Ident | Number

pub struct Ident {}

pub struct Number {}

pub struct CallExpr {
pub:
    lhs Expr
}
'
        },
        TestSource{
            rel:  'main.v'
            code: 'module main

import astx

fn call_target_kind(expr astx.CallExpr) string {
    return expr.lhs.type_name()
}
'
        },
    ])
    call_names := call_names_for_fn(files, 'call_target_kind')
    assert 'astx__Expr__type_name' !in call_names
    assert 'Expr__type_name' !in call_names
}

fn test_map_alias_field_clone_lowers_to_builtin_map_clone() {
    files := transform_code_for_test('
type TypeID = int

struct TypeStore {
    cache map[string]TypeID
}

struct Module {
    type_store TypeStore
}

fn clone_cache(m Module) map[string]TypeID {
    return m.type_store.cache.clone()
}
')
    call_names := call_names_for_fn(files, 'clone_cache')
    assert 'map__clone' in call_names
    assert 'Map_string_TypeID__clone' !in call_names
    assert 'Map_string_main__TypeID__clone' !in call_names
}

fn test_string_index_byte_methods_on_nested_receiver_fields_use_u8_receiver() {
    files := transform_code_for_test('
struct Scanner {
    src string
    offset int
}

struct Parser {
    scanner &Scanner
}

fn (c u8) is_space() bool {
    return true
}

fn (c u8) is_letter() bool {
    return true
}

fn (p &Parser) peek_dollar_keyword() string {
    if p.scanner.offset >= p.scanner.src.len {
        return ""
    }
    mut idx := p.scanner.offset
    for idx < p.scanner.src.len && p.scanner.src[idx].is_space() {
        idx++
    }
    start := idx
    for idx < p.scanner.src.len && p.scanner.src[idx].is_letter() {
        idx++
    }
    return p.scanner.src[start..idx]
}
')
    call_names := call_names_for_fn(files, 'peek_dollar_keyword')
    assert 'u8__is_space' in call_names
    assert 'u8__is_letter' in call_names
    assert 'int__is_space' !in call_names
    assert 'int__is_letter' !in call_names
}

fn test_smartcast_call_arg_keeps_original_sumtype_when_param_expects_sumtype() {
    files := transform_code_for_test('
struct Table {}

struct Checker {
    table Table
}

struct GlobalField {}
struct Var {}

type ScopeObject = GlobalField | Var

fn (t Table) is_interface_var(obj ScopeObject) bool {
    _ = t
    _ = obj
    return true
}

fn uses_scope_object(mut c Checker, mut obj ScopeObject) bool {
    match mut obj {
        Var {
            return c.table.is_interface_var(obj)
        }
        else {}
    }
    return false
}
')
    for file in files {
        for stmt in file.stmts {
            if stmt is ast.FnDecl && stmt.name == 'uses_scope_object' {
                call := find_call_with_lhs_suffix_in_stmts(stmt.stmts, '__is_interface_var') or {
                    assert false, 'expected transformed is_interface_var call'
                    return
                }
                assert call.args.len > 0
                arg := call.args[call.args.len - 1]
                assert arg is ast.Ident, 'sumtype call arg was wrapped as ${arg.type_name()}'
                assert (arg as ast.Ident).name == 'obj'
                return
            }
        }
    }
    assert false, 'uses_scope_object was not found'
}

fn test_smartcast_method_call_arg_keeps_original_sumtype_when_param_expects_sumtype() {
    files := transform_code_for_test('
struct Holder {}
struct Gen {}

type Type = Holder | int

fn (mut g Gen) use_type(value Type, holder Holder) {
    _ = g
    _ = value
    _ = holder
}

fn use_smartcasted_type(mut g Gen, concrete Type) {
    if concrete is Holder {
        g.use_type(concrete, concrete as Holder)
    }
}
')
    for file in files {
        for stmt in file.stmts {
            if stmt is ast.FnDecl && stmt.name == 'use_smartcasted_type' {
                call := find_call_with_lhs_suffix_in_stmts(stmt.stmts, 'Gen__use_type') or {
                    assert false, 'expected transformed Gen__use_type call'
                    return
                }
                assert call.args.len == 3
                arg := call.args[1]
                assert arg is ast.Ident, 'sumtype method call arg was wrapped as ${arg.type_name()}'
                assert (arg as ast.Ident).name == 'concrete'
                return
            }
        }
    }
    assert false, 'use_smartcasted_type was not found'
}

fn test_map_index_or_decl_keeps_declared_sumtype_for_later_smartcast_call_arg() {
    files := transform_code_for_test('
struct Holder {}
struct Gen {}

type Type = Holder | int

fn (mut g Gen) use_type(value Type, holder Holder) {
    _ = g
    _ = value
    _ = holder
}

fn use_map_or_smartcasted_type(mut g Gen, active map[string]Type, name string) {
    concrete := active[name] or { return }
    if concrete !is Holder {
        return
    }
    g.use_type(concrete, concrete as Holder)
}
')
    for file in files {
        for stmt in file.stmts {
            if stmt is ast.FnDecl && stmt.name == 'use_map_or_smartcasted_type' {
                call := find_call_with_lhs_suffix_in_stmts(stmt.stmts, 'Gen__use_type') or {
                    assert false, 'expected transformed Gen__use_type call'
                    return
                }
                assert call.args.len == 3
                arg := call.args[1]
                assert arg is ast.Ident, 'sumtype method call arg was wrapped as ${arg.type_name()}'
                assert (arg as ast.Ident).name == 'concrete'
                return
            }
        }
    }
    assert false, 'use_map_or_smartcasted_type was not found'
}

fn test_sumtype_call_arg_uses_declared_local_type_when_current_type_is_narrowed() {
    global_field_type := types.Type(types.Struct{
        name: 'GlobalField'
    })
    var_type := types.Type(types.Struct{
        name: 'Var'
    })
    scope_object_type := types.Type(types.SumType{
        name:     'ScopeObject'
        variants: [global_field_type, var_type]
    })
    mut scope := types.new_scope(unsafe { nil })
    scope.insert('GlobalField', global_field_type)
    scope.insert('Var', var_type)
    scope.insert('ScopeObject', scope_object_type)
    scope.insert_or_update('obj', var_type)
    mut env := types.Environment.new()
    obj_pos := token.Pos{
        id: 8901
    }
    env.set_expr_type(obj_pos.id, var_type)
    mut t := &Transformer{
        pref:                        &vpref.Preferences{}
        env:                         unsafe { env }
        scope:                       scope
        fn_root_scope:               scope
        cached_scopes:               {
            'main': scope
        }
        local_decl_types:            {
            'obj': scope_object_type
        }
        needed_clone_fns:            map[string]string{}
        needed_array_contains_fns:   map[string]ArrayMethodInfo{}
        needed_array_index_fns:      map[string]ArrayMethodInfo{}
        needed_array_last_index_fns: map[string]ArrayMethodInfo{}
        smartcast_expr_counts:       map[string]int{}
    }
    arg := ast.Expr(ast.Ident{
        name: 'obj'
        pos:  obj_pos
    })
    out := t.transform_call_arg_with_sumtype_check(arg, CallFnInfo{
        param_types: [scope_object_type]
    }, 0)
    assert out is ast.Ident, 'declared sumtype local was wrapped as ${out.type_name()}'
    assert (out as ast.Ident).name == 'obj'
}

fn test_is_pointer_type_handles_unresolved_alias_base_type() {
    t := create_test_transformer()
    assert !t.is_pointer_type(types.Type(types.Alias{
        name: 'UnresolvedAlias'
    }))
}

fn test_expr_to_string_handles_no_arg_selector_call_for_smartcasts() {
    t := create_test_transformer()
    call := ast.Expr(ast.CallExpr{
        lhs: ast.Expr(ast.SelectorExpr{
            lhs: ast.Expr(ast.SelectorExpr{
                lhs: ast.Expr(ast.Ident{
                    name: 'branch'
                })
                rhs: ast.Ident{
                    name: 'stmts'
                }
            })
            rhs: ast.Ident{
                name: 'last'
            }
        })
    })
    assert t.expr_to_string(call) == 'branch.stmts.last()'
}

fn test_expr_to_string_handles_indexed_selector_for_smartcasts() {
    t := create_test_transformer()
    expr := ast.Expr(ast.SelectorExpr{
        lhs: ast.Expr(ast.IndexExpr{
            lhs:  ast.Expr(ast.SelectorExpr{
                lhs: ast.Expr(ast.Ident{
                    name: 'node'
                })
                rhs: ast.Ident{
                    name: 'branches'
                }
            })
            expr: ast.Expr(ast.BasicLiteral{
                kind:  .number
                value: '0'
            })
        })
        rhs: ast.Ident{
            name: 'cond'
        }
    })
    assert t.expr_to_string(expr) == 'node.branches[0].cond'
}

fn test_smartcast_context_from_lowered_tag_check_uses_sumtype_metadata() {
    variants := [
        types.Type(types.Struct{
            name: 'ast__Ident'
        }),
        types.Type(types.Struct{
            name: 'ast__BasicLiteral'
        }),
    ]
    sum_type := types.Type(types.SumType{
        name:     'ast__Expr'
        variants: variants
    })
    mut ast_scope := types.new_scope(unsafe { nil })
    ast_scope.insert('Expr', sum_type)
    ast_scope.insert('Ident', variants[0])
    mut fn_scope := types.new_scope(unsafe { nil })
    fn_scope.insert('node', sum_type)
    env := &types.Environment{}
    t := &Transformer{
        pref:                        &vpref.Preferences{}
        env:                         unsafe { env }
        scope:                       fn_scope
        cur_module:                  'checker'
        cached_scopes:               {
            'ast': ast_scope
        }
        needed_clone_fns:            map[string]string{}
        needed_array_contains_fns:   map[string]ArrayMethodInfo{}
        needed_array_index_fns:      map[string]ArrayMethodInfo{}
        needed_array_last_index_fns: map[string]ArrayMethodInfo{}
    }
    ctx := t.smartcast_context_from_condition_term(ast.InfixExpr{
        op:  .eq
        lhs: ast.Expr(ast.SelectorExpr{
            lhs: ast.Expr(ast.Ident{
                name: 'node'
            })
            rhs: ast.Ident{
                name: '_tag'
            }
        })
        rhs: ast.Expr(ast.BasicLiteral{
            kind:  .number
            value: '0'
        })
    }) or {
        assert false, 'lowered tag check did not recover smartcast context'
        return
    }
    assert ctx.expr == 'node'
    assert ctx.variant == 'ast__Ident'
    assert ctx.variant_full == 'ast__Ident'
    assert ctx.sumtype == 'ast__Expr'
}

fn test_if_mut_selector_smartcast_rewrites_body_selector() {
    expr_sum_type := types.Type(types.SumType{
        name:     'ast__Expr'
        variants: [
            types.Type(types.Struct{
                name:   'ast__Ident'
                fields: [
                    types.Field{
                        name: 'language'
                        typ:  types.Type(types.Enum{
                            name: 'ast__Language'
                        })
                    },
                ]
            }),
            types.Type(types.Struct{
                name: 'ast__BasicLiteral'
            }),
        ]
    })
    mut ast_scope := types.new_scope(unsafe { nil })
    ast_scope.insert('Expr', expr_sum_type)
    ast_scope.insert('Ident', types.Type(types.Struct{
        name:   'ast__Ident'
        fields: [
            types.Field{
                name: 'language'
                typ:  types.Type(types.Enum{
                    name: 'ast__Language'
                })
            },
        ]
    }))
    ast_scope.insert('EnumField', types.Type(types.Struct{
        name:   'ast__EnumField'
        fields: [
            types.Field{
                name: 'expr'
                typ:  expr_sum_type
            },
        ]
    }))
    mut fn_scope := types.new_scope(unsafe { nil })
    fn_scope.insert('field', types.Type(types.Pointer{
        base_type: types.Type(types.Struct{
            name: 'ast__EnumField'
        })
    }))
    env := &types.Environment{}
    mut t := &Transformer{
        pref:                        &vpref.Preferences{}
        env:                         unsafe { env }
        scope:                       fn_scope
        cur_module:                  'checker'
        cached_scopes:               {
            'ast': ast_scope
        }
        needed_clone_fns:            map[string]string{}
        needed_array_contains_fns:   map[string]ArrayMethodInfo{}
        needed_array_index_fns:      map[string]ArrayMethodInfo{}
        needed_array_last_index_fns: map[string]ArrayMethodInfo{}
        synth_types:                 map[int]types.Type{}
        smartcast_expr_counts:       map[string]int{}
    }
    field_expr := ast.Expr(ast.SelectorExpr{
        lhs: ast.Expr(ast.Ident{
            name: 'field'
        })
        rhs: ast.Ident{
            name: 'expr'
        }
    })
    result := t.transform_expr(ast.Expr(ast.IfExpr{
        cond:  ast.Expr(ast.InfixExpr{
            op:  .key_is
            lhs: ast.Expr(ast.ModifierExpr{
                kind: .key_mut
                expr: field_expr
            })
            rhs: ast.Expr(ast.SelectorExpr{
                lhs: ast.Expr(ast.Ident{
                    name: 'ast'
                })
                rhs: ast.Ident{
                    name: 'Ident'
                }
            })
        })
        stmts: [
            ast.Stmt(ast.ExprStmt{
                expr: ast.Expr(ast.SelectorExpr{
                    lhs: field_expr
                    rhs: ast.Ident{
                        name: 'language'
                    }
                })
            }),
        ]
    }))
    assert result is ast.IfExpr
    if_expr := result as ast.IfExpr
    assert if_expr.stmts.len == 1
    assert if_expr.stmts[0] is ast.ExprStmt
    stmt := if_expr.stmts[0] as ast.ExprStmt
    assert stmt.expr is ast.SelectorExpr
    selector := stmt.expr as ast.SelectorExpr
    assert selector.lhs is ast.CastExpr, 'selector lhs was not narrowed: ${selector.lhs.type_name()}'
    cast := selector.lhs as ast.CastExpr
    assert cast.typ.name() == 'ast__Ident*'
}

fn test_for_mut_selector_smartcast_rewrites_assignment_rhs_selector() {
    type_info_type := types.Type(types.SumType{
        name:     'ast__TypeInfo'
        variants: [
            types.Type(types.Struct{
                name:   'ast__Array'
                fields: [
                    types.Field{
                        name: 'elem_type'
                        typ:  types.Type(types.Struct{
                            name: 'ast__Type'
                        })
                    },
                ]
            }),
            types.Type(types.Struct{
                name: 'ast__Struct'
            }),
        ]
    })
    mut ast_scope := types.new_scope(unsafe { nil })
    ast_scope.insert('TypeInfo', type_info_type)
    ast_scope.insert('Array', types.Type(types.Struct{
        name:   'ast__Array'
        fields: [
            types.Field{
                name: 'elem_type'
                typ:  types.Type(types.Struct{
                    name: 'ast__Type'
                })
            },
        ]
    }))
    ast_scope.insert('TypeSymbol', types.Type(types.Struct{
        name:   'ast__TypeSymbol'
        fields: [
            types.Field{
                name: 'info'
                typ:  type_info_type
            },
        ]
    }))
    type_type := types.Type(types.Struct{
        name: 'ast__Type'
    })
    mut fn_scope := types.new_scope(unsafe { nil })
    fn_scope.insert('elem_sym', types.Type(types.Pointer{
        base_type: types.Type(types.Struct{
            name: 'ast__TypeSymbol'
        })
    }))
    fn_scope.insert('elem_type', type_type)
    env := &types.Environment{}
    mut t := &Transformer{
        pref:                        &vpref.Preferences{}
        env:                         unsafe { env }
        scope:                       fn_scope
        cur_module:                  'ast'
        cached_scopes:               {
            'ast': ast_scope
        }
        needed_clone_fns:            map[string]string{}
        needed_array_contains_fns:   map[string]ArrayMethodInfo{}
        needed_array_index_fns:      map[string]ArrayMethodInfo{}
        needed_array_last_index_fns: map[string]ArrayMethodInfo{}
        synth_types:                 map[int]types.Type{}
        smartcast_expr_counts:       map[string]int{}
    }
    info_expr := ast.Expr(ast.SelectorExpr{
        lhs: ast.Expr(ast.Ident{
            name: 'elem_sym'
        })
        rhs: ast.Ident{
            name: 'info'
        }
    })
    result := t.transform_stmt(ast.Stmt(ast.ForStmt{
        cond:  ast.Expr(ast.InfixExpr{
            op:  .key_is
            lhs: ast.Expr(ast.ModifierExpr{
                kind: .key_mut
                expr: info_expr
            })
            rhs: ast.Expr(ast.Ident{
                name: 'Array'
            })
        })
        stmts: [
            ast.Stmt(ast.AssignStmt{
                op:  .assign
                lhs: [
                    ast.Expr(ast.Ident{
                        name: 'elem_type'
                    }),
                ]
                rhs: [
                    ast.Expr(ast.SelectorExpr{
                        lhs: info_expr
                        rhs: ast.Ident{
                            name: 'elem_type'
                        }
                    }),
                ]
            }),
        ]
    }))
    assert result is ast.ForStmt
    for_stmt := result as ast.ForStmt
    assert for_stmt.stmts.len == 1
    assert for_stmt.stmts[0] is ast.AssignStmt
    assign_stmt := for_stmt.stmts[0] as ast.AssignStmt
    assert assign_stmt.rhs[0] is ast.SelectorExpr
    selector := assign_stmt.rhs[0] as ast.SelectorExpr
    assert selector.lhs is ast.CastExpr, 'selector lhs was not narrowed: ${selector.lhs.type_name()}'
    cast := selector.lhs as ast.CastExpr
    assert cast.typ.name() == 'ast__Array*'
}

fn test_checked_for_mut_selector_smartcast_rewrites_assignment_rhs_selector() {
    files := transform_code_for_test('
module main

struct Type {}

struct Array {
    elem_type Type
}

struct Struct {}

type TypeInfo = Array | Struct

struct TypeSymbol {
mut:
    info TypeInfo
}

fn f(mut elem_sym TypeSymbol) {
    mut elem_type := Type{}
    for mut elem_sym.info is Array {
        elem_type = elem_sym.info.elem_type
    }
}
')
    for file in files {
        for stmt in file.stmts {
            if stmt is ast.FnDecl && stmt.name == 'f' {
                for nested in stmt.stmts {
                    if nested is ast.ForStmt {
                        assert nested.stmts.len == 1
                        assert nested.stmts[0] is ast.AssignStmt
                        assign_stmt := nested.stmts[0] as ast.AssignStmt
                        assert assign_stmt.rhs[0] is ast.SelectorExpr
                        selector := assign_stmt.rhs[0] as ast.SelectorExpr
                        assert selector.lhs is ast.CastExpr, 'selector lhs was not narrowed: ${selector.lhs.type_name()}'
                        cast := selector.lhs as ast.CastExpr
                        assert cast.typ.name() == 'Array*'
                        return
                    }
                }
            }
        }
    }
    assert false, 'function f loop was not found'
}

fn test_label_detection_ignores_empty_ast_slots() {
    assert !transformer_expr_contains_label_stmt(ast.empty_expr)
    assert !transformer_stmt_contains_label_stmt(ast.empty_stmt)
    assert !transformer_expr_contains_label_stmt(ast.IfExpr{
        cond:  ast.BasicLiteral{
            kind:  .key_true
            value: 'true'
        }
        stmts: []
    })
}

fn test_lowered_tag_check_selector_smartcast_rewrites_body_selector() {
    expr_sum_type := types.Type(types.SumType{
        name:     'ast__Expr'
        variants: [
            types.Type(types.Struct{
                name:   'ast__Ident'
                fields: [
                    types.Field{
                        name: 'language'
                        typ:  types.Type(types.Enum{
                            name: 'ast__Language'
                        })
                    },
                ]
            }),
            types.Type(types.Struct{
                name: 'ast__BasicLiteral'
            }),
        ]
    })
    mut ast_scope := types.new_scope(unsafe { nil })
    ast_scope.insert('Expr', expr_sum_type)
    ast_scope.insert('Ident', types.Type(types.Struct{
        name:   'ast__Ident'
        fields: [
            types.Field{
                name: 'language'
                typ:  types.Type(types.Enum{
                    name: 'ast__Language'
                })
            },
        ]
    }))
    ast_scope.insert('EnumField', types.Type(types.Struct{
        name:   'ast__EnumField'
        fields: [
            types.Field{
                name: 'expr'
                typ:  expr_sum_type
            },
        ]
    }))
    mut fn_scope := types.new_scope(unsafe { nil })
    fn_scope.insert('field', types.Type(types.Pointer{
        base_type: types.Type(types.Struct{
            name: 'ast__EnumField'
        })
    }))
    env := &types.Environment{}
    mut t := &Transformer{
        pref:                        &vpref.Preferences{}
        env:                         unsafe { env }
        scope:                       fn_scope
        cur_module:                  'checker'
        cached_scopes:               {
            'ast': ast_scope
        }
        needed_clone_fns:            map[string]string{}
        needed_array_contains_fns:   map[string]ArrayMethodInfo{}
        needed_array_index_fns:      map[string]ArrayMethodInfo{}
        needed_array_last_index_fns: map[string]ArrayMethodInfo{}
        synth_types:                 map[int]types.Type{}
        smartcast_expr_counts:       map[string]int{}
    }
    field_expr := ast.Expr(ast.SelectorExpr{
        lhs: ast.Expr(ast.Ident{
            name: 'field'
        })
        rhs: ast.Ident{
            name: 'expr'
        }
    })
    result := t.transform_expr(ast.Expr(ast.IfExpr{
        cond:  ast.Expr(ast.InfixExpr{
            op:  .eq
            lhs: ast.Expr(ast.SelectorExpr{
                lhs: field_expr
                rhs: ast.Ident{
                    name: '_tag'
                }
            })
            rhs: ast.Expr(ast.BasicLiteral{
                kind:  .number
                value: '0'
            })
        })
        stmts: [
            ast.Stmt(ast.ExprStmt{
                expr: ast.Expr(ast.SelectorExpr{
                    lhs: field_expr
                    rhs: ast.Ident{
                        name: 'language'
                    }
                })
            }),
        ]
    }))
    assert result is ast.IfExpr
    if_expr := result as ast.IfExpr
    assert if_expr.stmts.len == 1
    assert if_expr.stmts[0] is ast.ExprStmt
    stmt := if_expr.stmts[0] as ast.ExprStmt
    assert stmt.expr is ast.SelectorExpr
    selector := stmt.expr as ast.SelectorExpr
    assert selector.lhs is ast.CastExpr, 'selector lhs was not narrowed: ${selector.lhs.type_name()}'
    cast := selector.lhs as ast.CastExpr
    assert cast.typ.name() == 'ast__Ident*'
}

fn test_assignment_rhs_call_or_cast_lhs_preserves_nested_smartcast() {
    stmt_sum_type := types.Type(types.SumType{
        name:     'ast__Stmt'
        variants: [
            types.Type(types.Struct{
                name: 'ast__ExprStmt'
            }),
        ]
    })
    expr_sum_type := types.Type(types.SumType{
        name:     'ast__Expr'
        variants: [
            types.Type(types.Struct{
                name: 'ast__CallExpr'
            }),
            types.Type(types.Struct{
                name: 'ast__InfixExpr'
            }),
        ]
    })
    or_expr_type := types.Type(types.Struct{
        name:   'ast__OrExpr'
        fields: [
            types.Field{
                name: 'scope'
                typ:  types.Type(types.Struct{
                    name: 'ast__Scope'
                })
            },
            types.Field{
                name: 'err_used'
                typ:  types.Type(types.bool_)
            },
        ]
    })
    mut ast_scope := types.new_scope(unsafe { nil })
    ast_scope.insert('Stmt', stmt_sum_type)
    ast_scope.insert('Expr', expr_sum_type)
    ast_scope.insert('ExprStmt', types.Type(types.Struct{
        name:   'ast__ExprStmt'
        fields: [
            types.Field{
                name: 'expr'
                typ:  expr_sum_type
            },
        ]
    }))
    ast_scope.insert('InfixExpr', types.Type(types.Struct{
        name:   'ast__InfixExpr'
        fields: [
            types.Field{
                name: 'or_block'
                typ:  or_expr_type
            },
            types.Field{
                name: 'right'
                typ:  expr_sum_type
            },
        ]
    }))
    ast_scope.insert('CallExpr', types.Type(types.Struct{
        name: 'ast__CallExpr'
    }))
    mut fn_scope := types.new_scope(unsafe { nil })
    fn_scope.insert('node', stmt_sum_type)
    env := &types.Environment{}
    mut t := &Transformer{
        pref:                        &vpref.Preferences{}
        env:                         unsafe { env }
        scope:                       fn_scope
        cur_module:                  'checker'
        cached_scopes:               {
            'ast': ast_scope
        }
        needed_clone_fns:            map[string]string{}
        needed_array_contains_fns:   map[string]ArrayMethodInfo{}
        needed_array_index_fns:      map[string]ArrayMethodInfo{}
        needed_array_last_index_fns: map[string]ArrayMethodInfo{}
        synth_types:                 map[int]types.Type{}
        smartcast_expr_counts:       map[string]int{}
    }
    t.push_smartcast_full('node', 'ast__ExprStmt', 'ast__ExprStmt', 'ast__Stmt')
    t.push_smartcast_full('node.expr', 'ast__InfixExpr', 'ast__InfixExpr', 'ast__Expr')
    t.push_smartcast_full('node.expr.right', 'ast__CallExpr', 'ast__CallExpr', 'ast__Expr')
    node_ident := ast.Expr(ast.Ident{
        name: 'node'
    })
    node_expr := ast.Expr(ast.SelectorExpr{
        lhs: node_ident
        rhs: ast.Ident{
            name: 'expr'
        }
    })
    node_or_block := ast.Expr(ast.SelectorExpr{
        lhs: node_expr
        rhs: ast.Ident{
            name: 'or_block'
        }
    })
    node_scope := ast.Expr(ast.SelectorExpr{
        lhs: node_or_block
        rhs: ast.Ident{
            name: 'scope'
        }
    })
    transformed := t.transform_assign_stmt(ast.AssignStmt{
        op:  .assign
        lhs: [
            ast.Expr(ast.SelectorExpr{
                lhs: node_or_block
                rhs: ast.Ident{
                    name: 'err_used'
                }
            }),
        ]
        rhs: [
            ast.Expr(ast.CallOrCastExpr{
                lhs:  ast.Expr(ast.SelectorExpr{
                    lhs: node_scope
                    rhs: ast.Ident{
                        name: 'known_var'
                    }
                })
                expr: ast.Expr(ast.StringLiteral{
                    kind:  .v
                    value: "'err'"
                })
            }),
        ]
    })
    assert transformed.rhs[0] is ast.CallExpr
    call := transformed.rhs[0] as ast.CallExpr
    assert call.lhs is ast.SelectorExpr
    call_lhs := call.lhs as ast.SelectorExpr
    assert call_lhs.lhs is ast.SelectorExpr
    scope_sel := call_lhs.lhs as ast.SelectorExpr
    assert scope_sel.lhs is ast.SelectorExpr
    or_block_sel := scope_sel.lhs as ast.SelectorExpr
    assert or_block_sel.lhs is ast.CastExpr, 'rhs call lhs lost node.expr smartcast: ${or_block_sel.lhs.type_name()}'
}

fn test_transform_folds_string_literal_concat() {
    mut t := create_test_transformer()
    result := t.transform_expr(ast.InfixExpr{
        op:  .plus
        lhs: ast.Expr(ast.StringLiteral{
            kind:  .v
            value: "'left-'"
        })
        rhs: ast.Expr(ast.StringLiteral{
            kind:  .v
            value: "'right'"
        })
    })

    assert result is ast.StringLiteral, 'expected StringLiteral, got ${result.type_name()}'
    lit := result as ast.StringLiteral
    assert lit.kind == .v
    assert lit.value == 'left-right'
}

fn test_transform_keeps_generic_array_elem_equality_as_infix() {
    mut t := create_transformer_with_vars({
        'a': types.Type(types.Array{
            elem_type: types.Type(types.NamedType('T'))
        })
        'e': types.Type(types.NamedType('T'))
    })
    t.cur_fn_generic_params = ['T']
    t.generic_var_type_params = {
        'a': 'T'
    }
    t.env.set_expr_type(101, types.string_)
    t.env.set_expr_type(102, types.string_)

    result := t.transform_infix_expr(ast.InfixExpr{
        op:  .eq
        lhs: ast.Expr(ast.IndexExpr{
            lhs:  ast.Expr(ast.Ident{
                name: 'a'
            })
            expr: ast.Expr(ast.Ident{
                name: 'idx'
            })
            pos:  token.Pos{
                id: 101
            }
        })
        rhs: ast.Expr(ast.Ident{
            pos:  token.Pos{
                id: 102
            }
            name: 'e'
        })
    })

    assert result is ast.InfixExpr, 'generic equality should stay for specialized codegen'
}

fn test_transform_generic_module_call_uses_specialized_name() {
    mut t := create_test_transformer()
    mut scope := types.new_scope(unsafe { nil })
    scope.insert('json', types.Module{
        name: 'x.json2'
    })
    t.scope = scope

    result := t.transform_expr(ast.CallExpr{
        lhs:  ast.Expr(ast.GenericArgOrIndexExpr{
            lhs:  ast.Expr(ast.SelectorExpr{
                lhs: ast.Expr(ast.Ident{
                    name: 'json'
                })
                rhs: ast.Ident{
                    name: 'decode'
                }
            })
            expr: ast.Expr(ast.Ident{
                name: 'GitHubRepoInfo'
            })
        })
        args: [
            ast.Expr(ast.Ident{
                name: 'body'
            }),
        ]
    })

    assert result is ast.CallExpr, 'expected CallExpr, got ${result.type_name()}'
    call := result as ast.CallExpr
    assert call.lhs is ast.Ident
    assert (call.lhs as ast.Ident).name == 'json2__decode_T_GitHubRepoInfo'
    assert call.args.len == 1
}

fn test_transform_generic_module_call_or_cast_uses_specialized_name() {
    mut t := create_test_transformer()
    mut scope := types.new_scope(unsafe { nil })
    scope.insert('json', types.Module{
        name: 'x.json2'
    })
    t.scope = scope

    result := t.transform_expr(ast.CallOrCastExpr{
        lhs:  ast.Expr(ast.GenericArgOrIndexExpr{
            lhs:  ast.Expr(ast.SelectorExpr{
                lhs: ast.Expr(ast.Ident{
                    name: 'json'
                })
                rhs: ast.Ident{
                    name: 'decode'
                }
            })
            expr: ast.Expr(ast.Ident{
                name: 'GitHubRepoInfo'
            })
        })
        expr: ast.Expr(ast.SelectorExpr{
            lhs: ast.Expr(ast.Ident{
                name: 'resp'
            })
            rhs: ast.Ident{
                name: 'body'
            }
        })
    })

    assert result is ast.CallExpr, 'expected CallExpr, got ${result.type_name()}'
    call := result as ast.CallExpr
    assert call.lhs is ast.Ident
    assert (call.lhs as ast.Ident).name == 'json2__decode_T_GitHubRepoInfo'
    assert call.args.len == 1
}

fn test_transform_generic_module_call_or_cast_uses_array_specialized_name() {
    mut t := create_test_transformer()
    mut scope := types.new_scope(unsafe { nil })
    scope.insert('json', types.Module{
        name: 'x.json2'
    })
    t.scope = scope

    result := t.transform_expr(ast.CallOrCastExpr{
        lhs:  ast.Expr(ast.GenericArgOrIndexExpr{
            lhs:  ast.Expr(ast.SelectorExpr{
                lhs: ast.Expr(ast.Ident{
                    name: 'json'
                })
                rhs: ast.Ident{
                    name: 'decode'
                }
            })
            expr: ast.Expr(ast.Type(ast.ArrayType{
                elem_type: ast.Expr(ast.Ident{
                    name: 'GitHubContributor'
                })
            }))
        })
        expr: ast.Expr(ast.SelectorExpr{
            lhs: ast.Expr(ast.Ident{
                name: 'resp'
            })
            rhs: ast.Ident{
                name: 'body'
            }
        })
    })

    assert result is ast.CallExpr, 'expected CallExpr, got ${result.type_name()}'
    call := result as ast.CallExpr
    assert call.lhs is ast.Ident
    assert (call.lhs as ast.Ident).name == 'json2__decode_T_Array_GitHubContributor'
    assert call.args.len == 1
}

fn test_transform_monomorphizes_imported_generic_module_call() {
    files := transform_sources_for_test([
        TestSource{
            rel:  'x/json2/decode.v'
            code: '
module json2

struct Decoder {}

fn (mut decoder Decoder) decode_value[T](mut value T) ! {
    _ = value
}

pub fn decode[T]() !T {
    mut decoder := Decoder{}
    mut result := T{}
    decoder.decode_value(mut result)!
    return result
}
'
        },
        TestSource{
            rel:  'main.v'
            code: '
module main

import x.json2

struct Payload {
    value int
}

fn main() {
    _ := json2.decode[Payload]() or { Payload{} }
}
'
        },
    ])
    call_names := call_names_for_fn(files, 'main')
    assert 'json2__decode_T_Payload' in call_names
    assert 'decode_T_Payload' !in call_names

    mut found_prefixed_clone := false
    mut found_unprefixed_clone := false
    mut found_method_clone := false
    mut found_generic_decl := false
    for file in files {
        for stmt in file.stmts {
            if stmt is ast.FnDecl {
                if stmt.name == 'json2__decode_T_Payload' {
                    found_prefixed_clone = true
                    assert stmt.typ.generic_params.len == 0
                }
                if stmt.name == 'decode_T_Payload' {
                    found_unprefixed_clone = true
                }
                if stmt.name == 'decode_value_T_Payload' {
                    found_method_clone = true
                    assert stmt.typ.generic_params.len == 0
                }
                if stmt.name == 'decode' && decl_generic_param_names(stmt).len > 0 {
                    found_generic_decl = true
                }
            }
        }
    }
    assert found_prefixed_clone
    assert !found_unprefixed_clone
    assert found_method_clone
    assert !found_generic_decl
}

fn test_transform_nested_module_selector_respects_local_shadow() {
    mut t := create_test_transformer()
    mut checker_scope := types.new_scope(unsafe { nil })
    checker_scope.insert('checker', types.Module{
        name: 'checker'
    })
    mut fn_scope := types.new_scope(checker_scope)
    fn_scope.insert('checker', types.Type(types.Struct{
        name: 'checker__Checker'
    }))
    t.cur_module = 'checker'
    t.scope = fn_scope
    t.cached_scopes = {
        'checker':       checker_scope
        'type_resolver': types.new_scope(unsafe { nil })
    }

    result := t.transform_expr(ast.SelectorExpr{
        lhs: ast.Expr(ast.SelectorExpr{
            lhs: ast.Expr(ast.Ident{
                name: 'checker'
            })
            rhs: ast.Ident{
                name: 'type_resolver'
            }
        })
        rhs: ast.Ident{
            name: 'info'
        }
    })

    assert result is ast.SelectorExpr, 'local field chain must not become a module symbol'
    outer := result as ast.SelectorExpr
    assert outer.lhs is ast.SelectorExpr
    inner := outer.lhs as ast.SelectorExpr
    assert inner.lhs is ast.Ident
    assert (inner.lhs as ast.Ident).name == 'checker'
    assert inner.rhs.name == 'type_resolver'
    assert outer.rhs.name == 'info'
}

fn test_expr_to_string_keeps_as_cast_selector_paths_distinct() {
    t := create_test_transformer()
    node_right := ast.Expr(ast.SelectorExpr{
        lhs: ast.Expr(ast.Ident{
            name: 'node'
        })
        rhs: ast.Ident{
            name: 'right'
        }
    })
    ast_as_cast := ast.Expr(ast.SelectorExpr{
        lhs: ast.Expr(ast.Ident{
            name: 'ast'
        })
        rhs: ast.Ident{
            name: 'AsCast'
        }
    })
    ast_par_expr := ast.Expr(ast.SelectorExpr{
        lhs: ast.Expr(ast.Ident{
            name: 'ast'
        })
        rhs: ast.Ident{
            name: 'ParExpr'
        }
    })
    as_cast_payload_expr := ast.Expr(ast.SelectorExpr{
        lhs: ast.Expr(ast.AsCastExpr{
            expr: ast.Expr(ast.SelectorExpr{
                lhs: node_right
                rhs: ast.Ident{
                    name: 'expr'
                }
            })
            typ:  ast_as_cast
        })
        rhs: ast.Ident{
            name: 'expr'
        }
    })
    par_expr_payload_expr := ast.Expr(ast.SelectorExpr{
        lhs: ast.Expr(ast.AsCastExpr{
            expr: node_right
            typ:  ast_par_expr
        })
        rhs: ast.Ident{
            name: 'expr'
        }
    })

    assert t.expr_to_string(as_cast_payload_expr) == '(node.right.expr as ast__AsCast).expr'
    assert t.expr_to_string(par_expr_payload_expr) == '(node.right as ast__ParExpr).expr'
    assert t.expr_to_string(as_cast_payload_expr) != t.expr_to_string(par_expr_payload_expr)
}

fn test_transform_bare_generic_call_uses_specialized_name() {
    mut t := create_test_transformer()
    result := t.transform_expr(ast.CallExpr{
        lhs:  ast.Expr(ast.GenericArgs{
            lhs:  ast.Expr(ast.Ident{
                name: 'run_new'
            })
            args: [
                ast.Expr(ast.Ident{
                    name: 'A'
                }),
                ast.Expr(ast.Ident{
                    name: 'X'
                }),
            ]
        })
        args: [
            ast.Expr(ast.Ident{
                name: 'app'
            }),
            ast.Expr(ast.Ident{
                name: 'params'
            }),
        ]
    })

    assert result is ast.CallExpr, 'expected CallExpr, got ${result.type_name()}'
    call := result as ast.CallExpr
    assert call.lhs is ast.Ident
    assert (call.lhs as ast.Ident).name == 'run_new_T_A_X'
    assert call.args.len == 2
}

fn test_transform_transitive_generic_call_in_clone_emits_callee_clone() {
    files := transform_sources_for_test([
        TestSource{
            rel:  'webx/webx.v'
            code: 'module webx

pub fn run_at[A, X]() ! {
    run_new[A, X]()!
}

pub fn run_new[A, X]() ! {}
'
        },
        TestSource{
            rel:  'main.v'
            code: 'module main

import webx

struct App {}
struct Context {}

fn boot() {
    webx.run_at[App, Context]() or {}
}
'
        },
    ])
    mut fn_names := []string{}
    mut webx_fn_names := []string{}
    mut main_fn_names := []string{}
    for file in files {
        for stmt in file.stmts {
            if stmt is ast.FnDecl {
                fn_names << stmt.name
                if file.mod == 'webx' {
                    webx_fn_names << stmt.name
                }
                if file.mod == 'main' {
                    main_fn_names << stmt.name
                }
            }
        }
    }
    assert 'webx__run_at_T_App_Context' in fn_names
    assert 'webx__run_new_T_App_Context' in fn_names
    assert 'webx__run_at_T_App_Context' in main_fn_names
    assert 'webx__run_new_T_App_Context' in main_fn_names
    assert 'webx__run_at_T_App_Context' !in webx_fn_names
    assert 'webx__run_new_T_App_Context' !in webx_fn_names
}

fn test_transform_transitive_generic_call_with_mut_arg_in_clone_emits_callee_clone() {
    files := transform_sources_for_test([
        TestSource{
            rel:  'webx/webx.v'
            code: 'module webx

pub struct RunParams {}

pub fn run_at[A, X](mut global_app A, params RunParams) ! {
    run_new[A, X](mut global_app, params)!
}

pub fn run_new[A, X](mut global_app A, params RunParams) ! {}
'
        },
        TestSource{
            rel:  'main.v'
            code: 'module main

import webx

struct App {}
struct Context {}

fn boot() {
    mut app := App{}
    webx.run_at[App, Context](mut app, webx.RunParams{}) or {}
}
'
        },
    ])
    mut fn_names := []string{}
    mut webx_fn_names := []string{}
    mut main_fn_names := []string{}
    for file in files {
        for stmt in file.stmts {
            if stmt is ast.FnDecl {
                fn_names << stmt.name
                if file.mod == 'webx' {
                    webx_fn_names << stmt.name
                }
                if file.mod == 'main' {
                    main_fn_names << stmt.name
                }
            }
        }
    }
    assert 'webx__run_at_T_App_Context' in fn_names
    assert 'webx__run_new_T_App_Context' in fn_names
    assert 'webx__run_at_T_App_Context' in main_fn_names
    assert 'webx__run_new_T_App_Context' in main_fn_names
    assert 'webx__run_at_T_App_Context' !in webx_fn_names
    assert 'webx__run_new_T_App_Context' !in webx_fn_names
}

fn test_transform_transitive_generic_function_value_in_clone_emits_full_callee_clone() {
    files := transform_sources_for_test([
        TestSource{
            rel:  'webx/webx.v'
            code: 'module webx

pub struct ServerConfig {
    handler fn (req int) int
}

pub struct Context {}

pub fn run_at[A, X]() {
    run_new[A, X]()
}

pub fn run_new[A, X]() {
    _ := ServerConfig{
        handler: parallel_request_handler[A, X]
    }
}

fn parallel_request_handler[A, X](req int) int {
    return route[A, X](req)
}

fn route[A, X](req int) int {
    return req
}
'
        },
        TestSource{
            rel:  'main.v'
            code: 'module main

import webx

struct App {}
struct Context {}

fn boot() {
    webx.run_at[App, Context]()
}
'
        },
    ])
    mut main_fn_names := []string{}
    mut handler_name := ''
    for file in files {
        if file.mod != 'main' {
            continue
        }
        for stmt in file.stmts {
            if stmt is ast.FnDecl {
                main_fn_names << stmt.name
                if stmt.name == 'webx__run_new_T_App_Context' {
                    assign := stmt.stmts[0] as ast.AssignStmt
                    init := assign.rhs[0] as ast.InitExpr
                    if init.fields[0].value is ast.Ident {
                        handler_name = (init.fields[0].value as ast.Ident).name
                    } else {
                        handler_name = init.fields[0].value.type_name()
                    }
                }
            }
        }
    }
    assert 'webx__run_new_T_App_Context' in main_fn_names
    assert handler_name == 'webx__parallel_request_handler_T_App_Context'
    assert 'webx__parallel_request_handler_T_App_Context' in main_fn_names
    assert 'webx__route_T_App_Context' in main_fn_names
}

fn test_transform_imported_clone_substituted_init_type_keeps_declaring_module_context() {
    files := transform_sources_for_test([
        TestSource{
            rel:  'webx/webx.v'
            code: 'module webx

pub struct Context {}

pub fn make[A, X]() {
    ctx := &Context{}
    mut user_context := X{
        Context: ctx
    }
    route[A, X](mut user_context)
}

fn route[A, X](mut user_context X) {
    _ = user_context
}
'
        },
        TestSource{
            rel:  'main.v'
            code: 'module main

import webx

struct App {}

struct Context {
    webx.Context
}

fn boot() {
    webx.make[App, Context]()
}
'
        },
    ])
    mut init_type_name := ''
    mut main_fn_names := []string{}
    for file in files {
        if file.mod != 'main' {
            continue
        }
        for stmt in file.stmts {
            if stmt is ast.FnDecl && stmt.name == 'webx__make_T_App_Context' {
                main_fn_names << stmt.name
                assign := stmt.stmts[1] as ast.AssignStmt
                init := assign.rhs[0] as ast.InitExpr
                init_type := init.typ as ast.Ident
                init_type_name = init_type.name
            } else if stmt is ast.FnDecl {
                main_fn_names << stmt.name
            }
        }
    }
    assert init_type_name == 'Context'
    assert 'webx__route_T_App_Context' in main_fn_names
}

fn test_transform_generic_struct_clone_qualifies_module_type_arg_in_fn_field() {
    files := transform_sources_for_test([
        TestSource{
            rel:  'veb/veb.v'
            code: 'module veb

pub struct Context {}

pub struct MiddlewareOptions[T] {
    handler fn (mut ctx T) bool
}

pub fn make[T]() MiddlewareOptions[T] {
    return MiddlewareOptions[T]{}
}
'
        },
        TestSource{
            rel:  'main.v'
            code: 'module main

import veb

struct Context {}

fn boot() {
    _ := veb.make[veb.Context]()
}
'
        },
    ])
    mut clone_name := ''
    mut handler_param_name := ''
    for file in files {
        if file.mod != 'veb' {
            continue
        }
        for stmt in file.stmts {
            if stmt is ast.StructDecl && stmt.name == 'MiddlewareOptions_T_veb_Context' {
                clone_name = stmt.name
                field_typ := stmt.fields[0].typ as ast.Type
                fn_typ := field_typ as ast.FnType
                param_ident := fn_typ.params[0].typ as ast.Ident
                handler_param_name = param_ident.name
            }
        }
    }
    assert clone_name == 'MiddlewareOptions_T_veb_Context'
    assert handler_param_name == 'veb__Context'
}

fn test_transform_embedded_generic_method_options_do_not_emit_bare_import_context() {
    files := transform_sources_for_test([
        TestSource{
            rel:  'veb/veb.v'
            code: 'module veb

pub struct Context {}

pub struct Middleware[T] {}

@[params]
pub struct MiddlewareOptions[T] {
    handler fn (mut ctx T) bool
}

pub fn (mut m Middleware[T]) use(options MiddlewareOptions[T]) {
    _ = options
}
'
        },
        TestSource{
            rel:  'main.v'
            code: 'module main

import veb

struct App {
    veb.Middleware[Context]
}

struct Context {
    veb.Context
}

fn (app &App) before_request(mut ctx Context) bool {
    return true
}

fn boot() {
    mut app := App{}
    app.use(handler: app.before_request)
}
'
        },
    ])
    mut import_handler_param := ''
    mut main_handler_param := ''
    for file in files {
        for stmt in file.stmts {
            match stmt {
                ast.StructDecl {
                    if !stmt.name.contains('MiddlewareOptions_T') {
                        continue
                    }
                    field_typ := stmt.fields[0].typ as ast.Type
                    fn_typ := field_typ as ast.FnType
                    param_ident := fn_typ.params[0].typ as ast.Ident
                    if file.mod == 'veb' && stmt.name == 'MiddlewareOptions_T_veb_Context' {
                        import_handler_param = param_ident.name
                    }
                    if file.mod == 'main' && stmt.name == 'veb__MiddlewareOptions_T_Context' {
                        main_handler_param = param_ident.name
                    }
                }
                else {}
            }
        }
    }
    assert import_handler_param == '' || import_handler_param == 'veb__Context', 'import_handler_param=${import_handler_param}, main_handler_param=${main_handler_param}'

    assert main_handler_param == '' || main_handler_param == 'Context', 'import_handler_param=${import_handler_param}, main_handler_param=${main_handler_param}'
}

fn test_transform_imported_generic_struct_with_local_type_stays_in_call_file() {
    files := transform_sources_for_test([
        TestSource{
            rel:  'json2/json2.v'
            code: 'module json2

pub struct StructKeyDecodeResult[T] {
    value T
}

pub fn decode[T]() StructKeyDecodeResult[T] {
    return StructKeyDecodeResult[T]{}
}
'
        },
        TestSource{
            rel:  'main.v'
            code: 'module main

import json2

struct LocalResponse {}

fn boot() {
    _ := json2.decode[LocalResponse]()
}
'
        },
    ])
    mut import_struct_found := false
    mut import_fn_found := false
    mut main_struct_found := false
    mut main_fn_found := false
    mut main_field_typ := ''
    for file in files {
        for stmt in file.stmts {
            match stmt {
                ast.StructDecl {
                    if stmt.name == 'json2__StructKeyDecodeResult_T_LocalResponse'
                        || stmt.name == 'StructKeyDecodeResult_T_LocalResponse' {
                        if file.mod == 'json2' {
                            import_struct_found = true
                        }
                        if file.mod == 'main'
                            && stmt.name == 'json2__StructKeyDecodeResult_T_LocalResponse' {
                            main_struct_found = true
                            field_typ := stmt.fields[0].typ as ast.Ident
                            main_field_typ = field_typ.name
                        }
                    }
                }
                ast.FnDecl {
                    if stmt.name == 'json2__decode_T_LocalResponse'
                        || stmt.name == 'decode_T_LocalResponse' {
                        if file.mod == 'json2' {
                            import_fn_found = true
                        }
                        if file.mod == 'main' && stmt.name == 'json2__decode_T_LocalResponse' {
                            main_fn_found = true
                        }
                    }
                }
                else {}
            }
        }
    }
    assert !import_struct_found
    assert !import_fn_found
    assert main_struct_found
    assert main_fn_found
    assert main_field_typ == 'LocalResponse'
}

fn test_transform_generic_struct_emits_module_clone_after_file_local_clone() {
    files := transform_sources_for_test([
        TestSource{
            rel:  'other/other.v'
            code: 'module other

pub struct Type {}
'
        },
        TestSource{
            rel:  'm/m.v'
            code: 'module m

import other

pub struct Box[T] {
    value T
}

pub fn use_external() Box[other.Type] {
    return Box[other.Type]{}
}

pub fn use_int() Box[int] {
    return Box[int]{}
}
'
        },
        TestSource{
            rel:  'main.v'
            code: 'module main

import m

fn boot() {
    _ := m.use_external()
    _ := m.use_int()
}
'
        },
    ])
    mut m_structs := []string{}
    for file in files {
        if file.mod != 'm' {
            continue
        }
        for stmt in file.stmts {
            if stmt is ast.StructDecl {
                m_structs << stmt.name
            }
        }
    }
    assert 'Box_T_other_Type' in m_structs
    assert 'Box_T_int' in m_structs
}

fn test_transform_moved_generic_struct_qualifies_source_module_field_types() {
    files := transform_sources_for_test([
        TestSource{
            rel:  'boxlib/boxlib.v'
            code: 'module boxlib

pub struct Helper {}

pub struct Box[T] {
    Helper
    helper Helper
    values []Helper
    value T
}

pub fn make[T]() Box[T] {
    return Box[T]{}
}
'
        },
        TestSource{
            rel:  'main.v'
            code: 'module main

import boxlib

struct LocalResponse {}

fn boot() {
    _ := boxlib.make[LocalResponse]()
}
'
        },
    ])
    mut moved_struct_found := false
    mut embedded_typ := ''
    mut helper_typ := ''
    mut values_elem_typ := ''
    mut value_typ := ''
    for file in files {
        if file.mod != 'main' {
            continue
        }
        for stmt in file.stmts {
            if stmt is ast.StructDecl && stmt.name == 'boxlib__Box_T_LocalResponse' {
                moved_struct_found = true
                if stmt.embedded.len > 0 {
                    embedded_ident := stmt.embedded[0] as ast.Ident
                    embedded_typ = embedded_ident.name
                }
                for field in stmt.fields {
                    match field.name {
                        'helper' {
                            helper_ident := field.typ as ast.Ident
                            helper_typ = helper_ident.name
                        }
                        'values' {
                            array_typ := field.typ as ast.Type
                            values_array := array_typ as ast.ArrayType
                            values_elem_ident := values_array.elem_type as ast.Ident
                            values_elem_typ = values_elem_ident.name
                        }
                        'value' {
                            value_ident := field.typ as ast.Ident
                            value_typ = value_ident.name
                        }
                        else {}
                    }
                }
            }
        }
    }
    assert moved_struct_found
    assert embedded_typ == 'boxlib__Helper'
    assert helper_typ == 'boxlib__Helper'
    assert values_elem_typ == 'boxlib__Helper'
    assert value_typ == 'LocalResponse'
}

fn test_transform_transitive_imported_clone_substitutes_nested_generic_route_context() {
    env, files := transform_sources_with_env_for_test([
        TestSource{
            rel:  'webx/webx.v'
            code: 'module webx

pub struct Request {
    route int
}

pub struct ServerConfig {
    handler fn (req Request) &Context
}

pub struct Context {
    current_path string
}

pub fn run_new[A, X](mut global_app A) {
    _ := ServerConfig{
        handler: parallel_request_handler[A, X]
    }
    _ = global_app
}

fn parallel_request_handler[A, X](req Request) &Context {
    mut app := A{}
    return handle_request_and_route[A, X](mut app, req)
}

fn handle_request_and_route[A, X](mut app A, req Request) &Context {
    mut ctx := &Context{}
    mut user_context := X{
        Context: ctx
    }
    handle_route[A, X](mut app, mut user_context, req.route)
    return ctx
}

fn handle_route[A, X](mut app A, mut user_context X, route int) {
    _ = app
    _ = user_context
    _ = route
}
'
        },
        TestSource{
            rel:  'main.v'
            code: 'module main

import webx

struct App {}

struct Context {
    webx.Context
}

fn boot() {
    mut app := App{}
    webx.run_new[App, Context](mut app)
}
'
        },
    ])
    mut main_fn_names := []string{}
    mut init_type_name := ''
    mut route_call_name := ''
    for file in files {
        if file.mod != 'main' {
            continue
        }
        for stmt in file.stmts {
            if stmt is ast.FnDecl {
                main_fn_names << stmt.name
                if stmt.name == 'webx__handle_request_and_route_T_App_Context' {
                    for inner in stmt.stmts {
                        if inner is ast.AssignStmt && inner.lhs.len == 1 && inner.rhs.len == 1 {
                            lhs_name := ident_name_from_expr_for_test(inner.lhs[0]) or { '' }
                            if lhs_name == 'user_context' && inner.rhs[0] is ast.InitExpr {
                                init := inner.rhs[0] as ast.InitExpr
                                init_type := init.typ as ast.Ident
                                init_type_name = init_type.name
                            }
                        }
                        if inner is ast.ExprStmt && inner.expr is ast.CallExpr {
                            call := inner.expr as ast.CallExpr
                            if call.lhs is ast.Ident {
                                route_call_name = (call.lhs as ast.Ident).name
                            } else {
                                route_call_name = call.lhs.type_name()
                            }
                        }
                    }
                }
            }
        }
    }
    assert 'webx__parallel_request_handler_T_App_Context' in main_fn_names
    assert 'webx__handle_request_and_route_T_App_Context' in main_fn_names
    assert 'webx__handle_route_T_App_Context' in main_fn_names
    assert init_type_name == 'Context'
    assert route_call_name == 'webx__handle_route_T_App_Context'
    route_scope := env.get_fn_scope('main', 'webx__handle_route_T_App_Context') or {
        panic('missing imported route clone scope')
    }
    user_context_type := route_scope.lookup_var_type('user_context') or {
        panic('missing user_context type')
    }
    assert user_context_type.name() == 'Context'
}

fn test_transform_inferred_generic_method_call_uses_specialized_name() {
    files := transform_code_for_test('
module main

struct Job {}

struct Item {
    value int
}

struct Out {
mut:
    value int
}

fn fill(item Item, mut out Out) {
    out.value = item.value
}

fn (job &Job) apply[K, D, F](items []K, mut out []D, f F) {
    _ = job
    if items.len > 0 && out.len > 0 {
        f(items[0], mut out[0])
    }
}

fn use_apply() int {
    job := Job{}
    items := [Item{
        value: 7
    }]
    mut out := []Out{len: 1}
    job.apply(items, mut out, fill)
    return out[0].value
}
')
    call_names := call_names_for_fn(files, 'use_apply')
    assert 'Job__apply_T_Item_Out_fn_item_Item_out_Out_void' in call_names
    assert 'Job__apply' !in call_names

    mut found_clone := false
    for file in files {
        for stmt in file.stmts {
            if stmt is ast.FnDecl && stmt.name == 'apply_T_Item_Out_fn_item_Item_out_Out_void' {
                found_clone = true
                assert stmt.typ.generic_params.len == 0
                assert stmt.typ.params.len == 3
                assert stmt.typ.params[2].typ is ast.Type
                fn_param_type := stmt.typ.params[2].typ as ast.Type
                assert fn_param_type is ast.FnType
            }
        }
    }
    assert found_clone
}

fn test_transform_non_generic_method_does_not_match_generic_method_short_name() {
    files := transform_code_for_test('
module main

struct Vec3[T] {
    x T
    y T
    z T
}

fn (v Vec3[T]) div(u Vec3[T]) Vec3[T] {
    _ = u
    return v
}

struct Float3 {
    x f32
    y f32
    z f32
}

fn (a Float3) div(s f32) Float3 {
    _ = s
    return a
}

fn use_float(a Float3) {
    _ = a.div(f32(2))
}
')
    call_names := call_names_for_fn(files, 'use_float')
    assert 'Float3__div' in call_names
    assert 'Float3__div_T_f32' !in call_names
}

fn test_transform_inferred_generic_fn_call_uses_specialized_fn_arg_name() {
    files := transform_code_for_test('
module main

struct Alpha {}

fn use_alpha(mut a Alpha) {
    _ = a
}

fn call_cb[T, F](mut value T, cb F) {
    cb(mut value)
}

fn main() {
    mut a := Alpha{}
    call_cb(mut a, use_alpha)
}
')
    call_names := call_names_for_fn(files, 'main')
    assert 'call_cb_T_Alpha_fn_a_Alpha_void' in call_names
    assert 'call_cb' !in call_names
    assert 'call_cb_T_Alpha_voidptr' !in call_names
}

fn test_transform_records_inferred_generic_binding_before_monomorphize() {
    files := transform_code_for_test('
module main

fn clamp[T](a T, x T, b T) T {
    mut min := T(0)
    if x < b {
        min = x
    } else {
        min = b
    }
    return if min < a { a } else { min }
}

fn main() {
    ratio := f32(0.5)
    _ = clamp(f32(0), ratio, 1.0)
}
')
    call_names := call_names_for_fn(files, 'main')
    assert 'clamp_T_f32' in call_names
    mut found_clone := false
    for file in files {
        for stmt in file.stmts {
            if stmt is ast.FnDecl && stmt.name == 'clamp_T_f32' {
                found_clone = true
                assert stmt.typ.generic_params.len == 0
                assert stmt.stmts.len > 0
            }
        }
    }
    assert found_clone
}

fn stmts_have_defer(stmts []ast.Stmt) bool {
    for stmt in stmts {
        match stmt {
            ast.BlockStmt {
                if stmts_have_defer(stmt.stmts) {
                    return true
                }
            }
            ast.ComptimeStmt {
                if stmts_have_defer([stmt.stmt]) {
                    return true
                }
            }
            ast.DeferStmt {
                return true
            }
            ast.ExprStmt {
                if stmt.expr is ast.IfExpr {
                    if stmts_have_defer(stmt.expr.stmts) {
                        return true
                    }
                }
            }
            ast.ForStmt {
                if stmts_have_defer(stmt.stmts) {
                    return true
                }
            }
            else {}
        }
    }
    return false
}

fn test_lower_defer_stmts_lowers_defer_inside_comptime_stmt() {
    mut t := create_test_transformer()
    cleanup_stmt := ast.Stmt(ast.ExprStmt{
        expr: ast.Expr(ast.Ident{
            name: 'cleanup'
        })
    })
    body_stmt := ast.Stmt(ast.ExprStmt{
        expr: ast.Expr(ast.Ident{
            name: 'body'
        })
    })
    lowered := t.lower_defer_stmts([
        ast.Stmt(ast.ComptimeStmt{
            stmt: ast.Stmt(ast.ForStmt{
                stmts: [
                    body_stmt,
                    ast.Stmt(ast.DeferStmt{
                        stmts: [cleanup_stmt]
                    }),
                ]
            })
        }),
    ], false, types.Type(types.void_))

    assert !stmts_have_defer(lowered)
    assert lowered.len == 1
    assert lowered[0] is ast.ComptimeStmt
    comptime_stmt := lowered[0] as ast.ComptimeStmt
    assert comptime_stmt.stmt is ast.ForStmt
    for_stmt := comptime_stmt.stmt as ast.ForStmt
    assert for_stmt.stmts.len == 2
    assert for_stmt.stmts[1] is ast.ExprStmt
    assert (for_stmt.stmts[1] as ast.ExprStmt).expr.name() == 'cleanup'
}

fn test_lower_defer_fn_inside_loop_runs_on_function_exit() {
    mut t := create_test_transformer()
    cleanup_stmt := ast.Stmt(ast.ExprStmt{
        expr: ast.Expr(ast.Ident{
            name: 'cleanup'
        })
    })
    body_stmt := ast.Stmt(ast.ExprStmt{
        expr: ast.Expr(ast.Ident{
            name: 'body'
        })
    })
    lowered := t.lower_defer_stmts([
        ast.Stmt(ast.ForStmt{
            stmts: [
                ast.Stmt(ast.DeferStmt{
                    mode:  .function
                    stmts: [cleanup_stmt]
                }),
                body_stmt,
            ]
        }),
        ast.Stmt(ast.ReturnStmt{
            exprs: [
                ast.Expr(ast.Ident{
                    name: 'x'
                }),
            ]
        }),
    ], true, types.Type(types.int_))

    assert !stmts_have_defer(lowered)
    assert lowered.len == 5
    assert lowered[0] is ast.AssignStmt
    flag_decl := lowered[0] as ast.AssignStmt
    assert flag_decl.op == .decl_assign
    assert flag_decl.lhs[0] is ast.Ident
    flag_name := (flag_decl.lhs[0] as ast.Ident).name

    assert lowered[1] is ast.ForStmt
    for_stmt := lowered[1] as ast.ForStmt
    assert for_stmt.stmts.len == 2
    assert for_stmt.stmts[0] is ast.AssignStmt
    flag_assign := for_stmt.stmts[0] as ast.AssignStmt
    assert flag_assign.op == .assign
    assert flag_assign.lhs[0] is ast.Ident
    assert (flag_assign.lhs[0] as ast.Ident).name == flag_name
    assert for_stmt.stmts[1] is ast.ExprStmt
    assert (for_stmt.stmts[1] as ast.ExprStmt).expr.name() == 'body'

    assert lowered[3] is ast.ExprStmt
    guard_stmt := lowered[3] as ast.ExprStmt
    assert guard_stmt.expr is ast.IfExpr
    guard := guard_stmt.expr as ast.IfExpr
    assert guard.cond is ast.Ident
    assert (guard.cond as ast.Ident).name == flag_name
    assert guard.stmts.len == 1
    assert guard.stmts[0] is ast.ExprStmt
    assert (guard.stmts[0] as ast.ExprStmt).expr.name() == 'cleanup'
}

fn test_defer_return_temp_uses_value_type_for_pointer_expr_returning_value() {
    mut scope := types.new_scope(unsafe { nil })
    mut env := types.Environment.new()
    stmt_type := types.Type(types.SumType{
        name: 'ast__Stmt'
    })
    ptr_stmt_type := types.Type(types.Pointer{
        base_type: stmt_type
    })
    pos := token.Pos{
        id: 99101
    }
    env.set_expr_type(pos.id, ptr_stmt_type)
    mut t := &Transformer{
        pref:                        &vpref.Preferences{}
        env:                         unsafe { env }
        scope:                       scope
        fn_root_scope:               scope
        needed_clone_fns:            map[string]string{}
        needed_array_contains_fns:   map[string]ArrayMethodInfo{}
        needed_array_index_fns:      map[string]ArrayMethodInfo{}
        needed_array_last_index_fns: map[string]ArrayMethodInfo{}
        local_decl_types:            map[string]types.Type{}
    }
    t.register_defer_return_temp('_defer_t1', ast.Expr(ast.Ident{
        name: 'node'
        pos:  pos
    }), stmt_type, map[string]types.Type{})
    obj := scope.lookup_parent('_defer_t1', 0) or { panic('missing defer temp') }
    assert obj.typ().name() == 'ast__Stmt'
}

fn test_defer_return_temp_uses_sum_return_type_for_smartcast_variant() {
    temp_type := defer_return_temp_type(types.Type(types.Struct{
        name: 'ast__ForStmt'
    }), types.Type(types.SumType{
        name:     'ast__Stmt'
        variants: [
            types.Type(types.Struct{
                name: 'ast__ForCStmt'
            }),
            types.Type(types.Struct{
                name: 'ast__ForInStmt'
            }),
            types.Type(types.Struct{
                name: 'ast__ForStmt'
            }),
        ]
    }))
    assert temp_type.name() == 'ast__Stmt'
}

fn test_transform_persists_defer_return_temp_scope_for_codegen() {
    env, _ := transform_code_with_env_for_test('
type Stmt = EmptyStmt | ForInStmt

struct EmptyStmt {}

struct ForInStmt {
    val int
}

struct G {
mut:
    values map[string]int
}

fn cleanup() {}

fn (mut g G) stmt(node Stmt) Stmt {
    if node is ForInStmt {
        defer(fn) {
            cleanup()
        }
        mut new_node := ForInStmt{
            ...node
        }
        return Stmt(new_node)
    }
    return node
}
')
    fn_scope := env.get_fn_scope('main', 'G__stmt') or { panic('missing transformed fn scope') }
    mut found_defer_temp := false
    for name, obj in fn_scope.objects {
        if !name.starts_with('_defer_t') {
            continue
        }
        found_defer_temp = true
        assert obj.typ() !is types.Pointer
        assert obj.typ().name().ends_with('Stmt')
    }
    assert found_defer_temp
}

fn test_scoped_defer_return_err_temp_uses_ierror_type() {
    mut scope := types.new_scope(unsafe { nil })
    mut t := create_test_transformer()
    t.scope = scope
    t.fn_root_scope = scope
    t.set_synth_pos_counter(-1)
    err_type := types.Type(types.Struct{
        name: 'IError'
    })
    t.register_defer_return_temp('_defer_t_err', ast.Expr(ast.Ident{
        name: 'err'
    }), types.Type(types.ResultType{
        base_type: types.Type(types.SumType{
            name: 'ast__Expr'
        })
    }), {
        'err': err_type
    })
    mut found_ierror_temp := false
    mut temp_types := []string{}
    for name, obj in scope.objects {
        if !name.starts_with('_defer_t') {
            continue
        }
        temp_types << '${name}:${obj.typ().name()}'
        if obj.typ().name() == 'IError' {
            found_ierror_temp = true
        }
    }
    assert found_ierror_temp, temp_types.str()
}

fn test_defer_decl_tracking_prefers_rhs_type_for_err_decl() {
    mut scope := types.new_scope(unsafe { nil })
    scope.insert_or_update('err', types.Type(types.Struct{
        name: 'ast__NodeError'
    }))
    mut t := create_test_transformer()
    t.scope = scope
    t.set_synth_pos_counter(-1)
    t.synth_types = map[int]types.Type{}
    or_tmp := ast.Expr(ast.Ident{
        name: '_or_t1'
    })
    mut decls := map[string]types.Type{}
    t.add_decl_types_from_stmt(mut decls, ast.Stmt(ast.AssignStmt{
        op:  .decl_assign
        lhs: [ast.Expr(ast.Ident{
            name: 'err'
        })]
        rhs: [
            t.synth_selector(or_tmp, 'err', types.Type(types.Struct{
                name: 'IError'
            })),
        ]
    }))
    err_type := decls['err'] or {
        assert false, 'err declaration type was not tracked'
        return
    }
    assert err_type.name() == 'IError'
}

fn test_transform_string_inter_smartcast_temp_uses_variant_type() {
    env, _ := transform_code_with_env_for_test('
type Value = int | string

struct Entry {
    key Value
}

fn entry_string(entry Entry) string {
    key_text := if entry.key is string {
        "\${entry.key}"
    } else {
        "other"
    }
    return key_text
}
')
    fn_scope := env.get_fn_scope('main', 'entry_string') or {
        panic('missing transformed fn scope')
    }
    mut found_string_temp := false
    for name, obj in fn_scope.objects {
        if !name.starts_with('_or_t') {
            continue
        }
        if obj.typ().name() == 'string' {
            found_string_temp = true
        }
        assert obj.typ().name() != 'Value'
    }
    assert found_string_temp
}

fn test_lower_defer_fn_captures_block_local_values() {
    mut t := create_transformer_with_vars({
        'old': types.Type(types.bool_)
    })
    old_decl := ast.Stmt(ast.AssignStmt{
        op:  .decl_assign
        lhs: [ast.Expr(ast.Ident{
            name: 'old'
        })]
        rhs: [ast.Expr(ast.BasicLiteral{
            kind:  .key_false
            value: 'false'
        })]
    })
    defer_stmt := ast.Stmt(ast.DeferStmt{
        mode:  .function
        stmts: [
            ast.Stmt(ast.AssignStmt{
                op:  .assign
                lhs: [
                    ast.Expr(ast.SelectorExpr{
                        lhs: ast.Ident{
                            name: 'g'
                        }
                        rhs: ast.Ident{
                            name: 'inside_smartcast'
                        }
                    }),
                ]
                rhs: [
                    ast.Expr(ast.Ident{
                        name: 'old'
                    }),
                ]
            }),
        ]
    })
    lowered := t.lower_defer_stmts([
        ast.Stmt(ast.BlockStmt{
            stmts: [old_decl, defer_stmt]
        }),
    ], false, types.Type(types.void_))

    assert lowered.len == 4
    assert lowered[1] is ast.AssignStmt
    capture_decl := lowered[1] as ast.AssignStmt
    assert capture_decl.lhs[0] is ast.Ident
    capture_name := (capture_decl.lhs[0] as ast.Ident).name
    assert capture_name.starts_with('_defer_cap')

    assert lowered[2] is ast.BlockStmt
    block_stmt := lowered[2] as ast.BlockStmt
    assert block_stmt.stmts.len == 3
    assert block_stmt.stmts[1] is ast.AssignStmt
    capture_assign := block_stmt.stmts[1] as ast.AssignStmt
    assert capture_assign.lhs[0] is ast.Ident
    assert (capture_assign.lhs[0] as ast.Ident).name == capture_name

    assert lowered[3] is ast.ExprStmt
    guard := (lowered[3] as ast.ExprStmt).expr as ast.IfExpr
    restore := guard.stmts[0] as ast.AssignStmt
    assert restore.rhs[0] is ast.Ident
    assert (restore.rhs[0] as ast.Ident).name == capture_name
}

fn test_lower_defer_fn_captures_block_local_values_in_string_interpolation() {
    mut t := create_transformer_with_vars({
        'old': types.Type(types.string_)
    })
    old_decl := ast.Stmt(ast.AssignStmt{
        op:  .decl_assign
        lhs: [ast.Expr(ast.Ident{
            name: 'old'
        })]
        rhs: [ast.Expr(ast.StringLiteral{
            kind:  .v
            value: 'old'
        })]
    })
    defer_stmt := ast.Stmt(ast.DeferStmt{
        mode:  .function
        stmts: [
            ast.Stmt(ast.ExprStmt{
                expr: ast.Expr(ast.CallExpr{
                    lhs:  ast.Ident{
                        name: 'cleanup'
                    }
                    args: [
                        ast.Expr(ast.StringInterLiteral{
                            kind:   .v
                            values: ['value=', '']
                            inters: [ast.StringInter{
                                expr: ast.Expr(ast.Ident{
                                    name: 'old'
                                })
                            }]
                        }),
                    ]
                })
            }),
        ]
    })
    lowered := t.lower_defer_stmts([
        ast.Stmt(ast.BlockStmt{
            stmts: [old_decl, defer_stmt]
        }),
    ], false, types.Type(types.void_))

    assert lowered.len == 4
    capture_decl := lowered[1] as ast.AssignStmt
    capture_name := (capture_decl.lhs[0] as ast.Ident).name
    assert capture_name.starts_with('_defer_cap')

    block_stmt := lowered[2] as ast.BlockStmt
    capture_assign := block_stmt.stmts[1] as ast.AssignStmt
    assert (capture_assign.lhs[0] as ast.Ident).name == capture_name

    guard := (lowered[3] as ast.ExprStmt).expr as ast.IfExpr
    cleanup := (guard.stmts[0] as ast.ExprStmt).expr as ast.CallExpr
    inter_lit := cleanup.args[0] as ast.StringInterLiteral
    assert inter_lit.inters[0].expr is ast.Ident
    assert (inter_lit.inters[0].expr as ast.Ident).name == capture_name
}

fn test_lower_defer_fn_captures_parent_block_values_from_nested_if() {
    mut t := create_test_transformer()
    old_decl := ast.Stmt(ast.AssignStmt{
        op:  .decl_assign
        lhs: [ast.Expr(ast.Ident{
            name: 'old'
        })]
        rhs: [ast.Expr(ast.BasicLiteral{
            kind:  .key_false
            value: 'false'
        })]
    })
    defer_stmt := ast.Stmt(ast.DeferStmt{
        mode:  .function
        stmts: [
            ast.Stmt(ast.AssignStmt{
                op:  .assign
                lhs: [
                    ast.Expr(ast.SelectorExpr{
                        lhs: ast.Ident{
                            name: 'g'
                        }
                        rhs: ast.Ident{
                            name: 'inside_smartcast'
                        }
                    }),
                ]
                rhs: [
                    ast.Expr(ast.Ident{
                        name: 'old'
                    }),
                ]
            }),
        ]
    })
    lowered := t.lower_defer_stmts([
        old_decl,
        ast.Stmt(ast.ExprStmt{
            expr: ast.Expr(ast.IfExpr{
                cond:  ast.Expr(ast.BasicLiteral{
                    kind:  .key_true
                    value: 'true'
                })
                stmts: [defer_stmt]
            })
        }),
    ], false, types.Type(types.void_))

    assert lowered.len == 5
    capture_decl := lowered[1] as ast.AssignStmt
    capture_name := (capture_decl.lhs[0] as ast.Ident).name
    assert capture_name.starts_with('_defer_cap')

    if_stmt := lowered[3] as ast.ExprStmt
    if_expr := if_stmt.expr as ast.IfExpr
    assert if_expr.stmts.len == 2
    capture_assign := if_expr.stmts[0] as ast.AssignStmt
    assert (capture_assign.lhs[0] as ast.Ident).name == capture_name

    guard := (lowered[4] as ast.ExprStmt).expr as ast.IfExpr
    restore := guard.stmts[0] as ast.AssignStmt
    assert restore.rhs[0] is ast.Ident
    assert (restore.rhs[0] as ast.Ident).name == capture_name
}

fn test_transform_defer_fn_in_range_for_captures_loop_block_literals() {
    files := transform_code_for_test("
fn cleanup(s string) {}

fn main() {
    for i in 0 .. 2 {
        mut str_add_rhs_tmp := ''
        mut str_add_rhs_needs_free := false
        if i == 1 {
            str_add_rhs_tmp = 'x'
            str_add_rhs_needs_free = true
            defer(fn) {
                if str_add_rhs_needs_free {
                    cleanup('\${str_add_rhs_tmp}')
                }
            }
        }
    }
}
")
    mut main_fn := ast.FnDecl{}
    mut found_main := false
    for file in files {
        for stmt in file.stmts {
            if stmt is ast.FnDecl && stmt.name == 'main' {
                main_fn = stmt
                found_main = true
            }
        }
    }
    assert found_main
    mut capture_decl_count := 0
    for stmt in main_fn.stmts {
        if stmt is ast.AssignStmt && stmt.op == .decl_assign && stmt.lhs.len > 0
            && stmt.lhs[0] is ast.Ident && (stmt.lhs[0] as ast.Ident).name.starts_with('_defer_cap') {
            capture_decl_count++
        }
    }
    assert capture_decl_count == 2
}

fn test_transform_lowers_static_method_struct_shorthand_args() {
    files := transform_code_for_test('
struct Walker {
    table int
    count int
}

fn Walker.new(params Walker) &Walker {
    _ = params
    return &Walker{}
}

fn main() {
    table := 1
    _ = Walker.new(table: table, count: 2)
}
')
    mut found := false
    for file in files {
        for stmt in file.stmts {
            if stmt is ast.FnDecl && stmt.name == 'main' {
                for body_stmt in stmt.stmts {
                    if body_stmt is ast.AssignStmt && body_stmt.rhs.len == 1
                        && body_stmt.rhs[0] is ast.CallExpr {
                        call := body_stmt.rhs[0] as ast.CallExpr
                        if call.lhs is ast.Ident && (call.lhs as ast.Ident).name == 'Walker__new' {
                            found = true
                            assert call.args.len == 1
                            assert call.args[0] is ast.InitExpr
                        }
                    }
                }
            }
        }
    }
    assert found
}

fn test_explicit_as_cast_survives_smartcasted_selector_call_expr() {
    files := transform_code_for_test('
type Expr = ArrayDecompose | Ident

struct ArrayDecompose {}

struct Ident {}

struct CallArg {
    expr Expr
}

fn last(args []CallArg) CallArg {
    return args[0]
}

fn f(args []CallArg) {
    if last(args).expr is ArrayDecompose {
        array_decompose := last(args).expr as ArrayDecompose
        _ = array_decompose
    }
}
')
    mut found := false
    for file in files {
        for stmt in file.stmts {
            if stmt is ast.FnDecl && stmt.name == 'f' {
                for body_stmt in stmt.stmts {
                    if body_stmt is ast.ExprStmt && body_stmt.expr is ast.IfExpr {
                        if_expr := body_stmt.expr as ast.IfExpr
                        for inner in if_expr.stmts {
                            if inner is ast.AssignStmt && inner.op == .decl_assign
                                && inner.lhs.len == 1 && inner.lhs[0] is ast.Ident
                                && (inner.lhs[0] as ast.Ident).name == 'array_decompose' {
                                found = true
                                assert inner.rhs.len == 1
                                assert inner.rhs[0] is ast.AsCastExpr
                            }
                        }
                    }
                }
            }
        }
    }
    assert found
}

fn test_transform_lowers_index_parsed_generic_method_call() {
    files := transform_code_for_test('
struct File {}

struct PoolProcessor {}

fn (p &PoolProcessor) get_item[T](idx int) T {
    _ = p
    _ = idx
    return T(0)
}

fn main() {
    p := &PoolProcessor{}
    file := p.get_item[&File](0)
    _ = file
}
')
    mut found := false
    for file in files {
        for stmt in file.stmts {
            if stmt is ast.FnDecl && stmt.name == 'main' {
                for body_stmt in stmt.stmts {
                    if body_stmt is ast.AssignStmt && body_stmt.rhs.len == 1
                        && body_stmt.rhs[0] is ast.CallExpr {
                        call := body_stmt.rhs[0] as ast.CallExpr
                        if call.lhs is ast.Ident
                            && (call.lhs as ast.Ident).name == 'PoolProcessor__get_item_T_Fileptr' {
                            found = true
                            assert call.args.len == 2
                            assert call.args[0].name() == 'p'
                            assert call.args[1].name() == '0'
                        }
                    }
                }
            }
        }
    }
    assert found
}

// Create a rune-like type that returns 'rune' from name()
fn rune_type() types.Type {
    return types.Alias{
        name: 'rune'
    }
}

fn test_transform_comptime_embed_file_call_or_cast_expr_to_init_expr() {
    raw_dir := os.join_path(os.temp_dir(), 'v2_transformer_embed_file_${os.getpid()}')
    os.mkdir_all(raw_dir) or { panic(err) }
    tmp_dir := os.real_path(raw_dir)
    defer {
        os.rmdir_all(tmp_dir) or {}
    }
    source_path := os.join_path(tmp_dir, 'main.v')
    asset_path := os.join_path(tmp_dir, 'asset.txt')
    os.write_file(source_path, 'fn main() {}') or { panic(err) }
    os.write_file(asset_path, 'hello') or { panic(err) }

    mut t := create_test_transformer()
    t.cur_file_name = source_path

    result := t.transform_comptime_expr(ast.ComptimeExpr{
        expr: ast.Expr(ast.CallOrCastExpr{
            lhs:  ast.Expr(ast.Ident{
                name: 'embed_file'
            })
            expr: ast.Expr(ast.StringLiteral{
                kind:  .v
                value: "'asset.txt'"
            })
        })
    })

    assert t.needed_embed_file_helper
    assert result is ast.InitExpr, 'expected InitExpr, got ${result.type_name()}'
    init := result as ast.InitExpr
    assert init.typ is ast.Ident
    assert (init.typ as ast.Ident).name == embed_file_helper_type_name
    assert init.fields.len == 4
    assert init.fields[0].name == '_data'
    assert init.fields[0].value is ast.StringLiteral
    assert (init.fields[0].value as ast.StringLiteral).value == "'hello'"
    assert init.fields[1].name == 'len'
    assert init.fields[1].value is ast.BasicLiteral
    assert (init.fields[1].value as ast.BasicLiteral).value == '5'
    assert init.fields[2].name == 'path'
    assert init.fields[3].name == 'apath'
    assert init.fields[3].value is ast.StringLiteral
    assert (init.fields[3].value as ast.StringLiteral).value == quote_v_string_literal(asset_path)
}

fn test_transform_comptime_embed_file_chained_method_call() {
    raw_dir := os.join_path(os.temp_dir(), 'v2_transformer_embed_file_chain_${os.getpid()}')
    os.mkdir_all(raw_dir) or { panic(err) }
    tmp_dir := os.real_path(raw_dir)
    defer {
        os.rmdir_all(tmp_dir) or {}
    }
    source_path := os.join_path(tmp_dir, 'main.v')
    asset_path := os.join_path(tmp_dir, 'asset.txt')
    os.write_file(source_path, 'fn main() {}') or { panic(err) }
    os.write_file(asset_path, 'hello') or { panic(err) }

    mut t := create_test_transformer()
    t.cur_file_name = source_path

    result := t.transform_comptime_expr(ast.ComptimeExpr{
        expr: ast.Expr(ast.CallExpr{
            lhs:  ast.Expr(ast.SelectorExpr{
                lhs: ast.Expr(ast.CallOrCastExpr{
                    lhs:  ast.Expr(ast.Ident{
                        name: 'embed_file'
                    })
                    expr: ast.Expr(ast.StringLiteral{
                        kind:  .v
                        value: "'asset.txt'"
                    })
                })
                rhs: ast.Ident{
                    name: 'to_bytes'
                }
            })
            args: []
        })
    })

    assert t.needed_embed_file_helper
    assert result is ast.CallExpr, 'expected CallExpr, got ${result.type_name()}'
    call := result as ast.CallExpr
    assert call.lhs is ast.SelectorExpr
    sel := call.lhs as ast.SelectorExpr
    assert sel.lhs is ast.InitExpr
    init := sel.lhs as ast.InitExpr
    assert init.typ is ast.Ident
    assert (init.typ as ast.Ident).name == embed_file_helper_type_name
    assert sel.rhs.name == 'to_bytes'
    assert init.fields.len == 4
    assert init.fields[0].value is ast.StringLiteral
    assert (init.fields[0].value as ast.StringLiteral).value == "'hello'"
    assert init.fields[3].value is ast.StringLiteral
    assert (init.fields[3].value as ast.StringLiteral).value == quote_v_string_literal(asset_path)
}

fn test_inject_embed_file_helper_adds_builtin_helper_once() {
    mut t := create_test_transformer()
    mut files := [
        ast.File{
            mod:   'builtin'
            name:  'builtin.v'
            stmts: [
                ast.Stmt(ast.StructDecl{
                    name: 'Existing'
                }),
            ]
        },
        ast.File{
            mod:  'main'
            name: 'main.v'
        },
    ]

    t.inject_embed_file_helper(mut files)
    t.inject_embed_file_helper(mut files)

    assert files[0].stmts.len == 7
    assert files[0].stmts[1] is ast.StructDecl
    assert (files[0].stmts[1] as ast.StructDecl).name == embed_file_helper_type_name
    mut helper_count := 0
    for stmt in files[0].stmts {
        if stmt is ast.StructDecl && stmt.name == embed_file_helper_type_name {
            helper_count++
        }
    }
    assert helper_count == 1
}

fn test_transform_ident_vmodroot_to_string_literal() {
    mut t := create_test_transformer()
    t.comptime_vmodroot = '/tmp/v'
    result := t.transform_expr(ast.Ident{
        name: '@VMODROOT'
    })
    assert result is ast.StringLiteral, 'expected StringLiteral, got ${result.type_name()}'
    lit := result as ast.StringLiteral
    assert lit.kind == .v
    assert lit.value == "'/tmp/v'"
}

fn test_transform_ident_vmodroot_empty_root() {
    mut t := create_test_transformer()
    t.comptime_vmodroot = ''
    result := t.transform_expr(ast.Ident{
        name: '@VMODROOT'
    })
    assert result is ast.StringLiteral, 'expected StringLiteral, got ${result.type_name()}'
    lit := result as ast.StringLiteral
    assert lit.kind == .v
    assert lit.value == "''"
}

fn test_transform_autogenerates_clone_helpers_for_iclone_structs() {
    files := transform_code_for_test('
interface IClone {}

struct Inner implements IClone {
    name string
}

struct Outer implements IClone {
    inner Inner
    nums []int
}

fn use_clone(value Outer) Outer {
    return value.clone()
}
')
    assert files.len == 1
    file := files[0]
    mut saw_inner_clone := false
    mut saw_outer_clone := false
    mut saw_lowered_call := false
    for stmt in file.stmts {
        if stmt is ast.FnDecl && stmt.name == 'use_clone' {
            assert stmt.stmts.len == 1
            ret := stmt.stmts[0] as ast.ReturnStmt
            assert ret.exprs.len == 1
            assert ret.exprs[0] is ast.CallExpr
            call := ret.exprs[0] as ast.CallExpr
            assert call.lhs is ast.Ident
            assert (call.lhs as ast.Ident).name == 'Outer__clone'
            saw_lowered_call = true
        }
        if stmt is ast.FnDecl && stmt.name == 'Inner__clone' {
            saw_inner_clone = true
        }
        if stmt is ast.FnDecl && stmt.name == 'Outer__clone' {
            saw_outer_clone = true
            assert stmt.stmts.len == 1
            ret := stmt.stmts[0] as ast.ReturnStmt
            assert ret.exprs.len == 1
            assert ret.exprs[0] is ast.InitExpr
            init := ret.exprs[0] as ast.InitExpr
            assert init.fields.len == 2
            assert init.fields[0].name == 'inner'
            assert init.fields[0].value is ast.CallExpr
            inner_call := init.fields[0].value as ast.CallExpr
            assert inner_call.lhs is ast.Ident
            assert (inner_call.lhs as ast.Ident).name == 'Inner__clone'
            assert init.fields[1].name == 'nums'
            assert init.fields[1].value is ast.CallExpr
            nums_call := init.fields[1].value as ast.CallExpr
            assert nums_call.lhs is ast.Ident
            assert (nums_call.lhs as ast.Ident).name == 'array__clone'
        }
    }
    assert saw_lowered_call
    assert saw_inner_clone
    assert saw_outer_clone
}

fn test_transform_autogenerates_chained_clone_helpers_from_snapshot() {
    files := transform_code_for_test('
interface IClone {}

struct Leaf implements IClone {
    name string
}

struct Branch implements IClone {
    leaf Leaf
}

struct Root implements IClone {
    branch Branch
}

fn use_clone(value Root) Root {
    return value.clone()
}
')
    assert files.len == 1
    file := files[0]
    mut clone_names := map[string]bool{}
    for stmt in file.stmts {
        if stmt is ast.FnDecl {
            clone_names[stmt.name] = true
        }
    }
    assert clone_names['Root__clone']
    assert clone_names['Branch__clone']
    assert clone_names['Leaf__clone']
}

fn test_array_comparison_eq() {
    // Set up variable types so get_array_type_str can detect them
    mut t := create_transformer_with_vars({
        'arr1': types.Type(types.Array{ elem_type: types.int_ })
        'arr2': types.Type(types.Array{
            elem_type: types.int_
        })
    })

    // Create: arr1 == arr2
    expr := ast.InfixExpr{
        op:  .eq
        lhs: ast.Ident{
            name: 'arr1'
        }
        rhs: ast.Ident{
            name: 'arr2'
        }
    }

    result := t.transform_infix_expr(expr)

    // Should be transformed to: array__eq(arr1, arr2)
    assert result is ast.CallExpr, 'expected CallExpr, got ${result.type_name()}'
    call := result as ast.CallExpr
    assert call.lhs is ast.Ident
    call_name := (call.lhs as ast.Ident).name
    assert call_name == 'array__eq', 'expected array__eq, got ${call_name}'
    assert call.args.len == 2
}

fn test_array_comparison_ne() {
    mut t := create_transformer_with_vars({
        'arr1': types.Type(types.Array{ elem_type: types.int_ })
        'arr2': types.Type(types.Array{
            elem_type: types.int_
        })
    })

    // Create: arr1 != arr2
    expr := ast.InfixExpr{
        op:  .ne
        lhs: ast.Ident{
            name: 'arr1'
        }
        rhs: ast.Ident{
            name: 'arr2'
        }
    }

    result := t.transform_infix_expr(expr)

    // Should be transformed to: !array__eq(arr1, arr2)
    assert result is ast.PrefixExpr, 'expected PrefixExpr, got ${result.type_name()}'
    prefix := result as ast.PrefixExpr
    assert prefix.op == .not
    assert prefix.expr is ast.CallExpr
    call := prefix.expr as ast.CallExpr
    call_name := (call.lhs as ast.Ident).name
    assert call_name == 'array__eq', 'expected array__eq, got ${call_name}'
}

fn test_array_comparison_non_array_passthrough() {
    // Variables with non-array types
    mut t := create_transformer_with_vars({
        'x': types.Type(types.int_)
        'y': types.Type(types.int_)
    })

    // Create: x == y (non-array comparison)
    expr := ast.InfixExpr{
        op:  .eq
        lhs: ast.Ident{
            name: 'x'
        }
        rhs: ast.Ident{
            name: 'y'
        }
    }

    result := t.transform_infix_expr(expr)

    // Should remain as InfixExpr (not transformed)
    assert result is ast.InfixExpr, 'expected InfixExpr for non-array comparison'
}

fn test_transform_index_expr_string_slice_lowered() {
    mut t := create_transformer_with_vars({
        's': types.Type(string_type())
    })

    expr := ast.IndexExpr{
        lhs:  ast.Ident{
            name: 's'
        }
        expr: ast.RangeExpr{
            op:    .dotdot
            start: ast.BasicLiteral{
                kind:  .number
                value: '1'
            }
            end:   ast.BasicLiteral{
                kind:  .number
                value: '3'
            }
        }
    }

    result := t.transform_expr(expr)
    assert result is ast.CallExpr, 'expected CallExpr, got ${result.type_name()}'
    call := result as ast.CallExpr
    assert call.lhs is ast.Ident
    assert (call.lhs as ast.Ident).name == 'string__substr'
    assert call.args.len == 3
}

fn test_transform_index_expr_nested_selector_string_slice_lowered() {
    scanner_type := types.Type(types.Struct{
        name:   'scanner__Scanner'
        fields: [
            types.Field{
                name: 'src'
                typ:  types.Type(string_type())
            },
        ]
    })
    parser_type := types.Type(types.Struct{
        name:   'parser__Parser'
        fields: [
            types.Field{
                name: 'scanner'
                typ:  types.Type(types.Pointer{
                    base_type: scanner_type
                })
            },
        ]
    })
    mut t := create_transformer_with_vars({
        'p': types.Type(types.Pointer{
            base_type: parser_type
        })
    })

    expr := ast.IndexExpr{
        lhs:  ast.SelectorExpr{
            lhs: ast.SelectorExpr{
                lhs: ast.Ident{
                    name: 'p'
                }
                rhs: ast.Ident{
                    name: 'scanner'
                }
            }
            rhs: ast.Ident{
                name: 'src'
            }
        }
        expr: ast.RangeExpr{
            op:    .dotdot
            start: ast.BasicLiteral{
                kind:  .number
                value: '1'
            }
            end:   ast.BasicLiteral{
                kind:  .number
                value: '3'
            }
        }
    }

    result := t.transform_expr(expr)
    assert result is ast.CallExpr, 'expected CallExpr, got ${result.type_name()}'
    call := result as ast.CallExpr
    assert call.lhs is ast.Ident
    assert (call.lhs as ast.Ident).name == 'string__substr'
    assert call.args.len == 3
}

fn test_transform_index_expr_imported_nested_selector_string_slice_lowered() {
    files := transform_sources_for_test([
        TestSource{
            rel:  'v2/scanner/scanner.v'
            code: 'module scanner

pub struct Scanner {
pub mut:
    src string
    pos int
}
'
        },
        TestSource{
            rel:  'v2/parser/parser.v'
            code: 'module parser

import v2.scanner

pub struct Parser {
mut:
    scanner &scanner.Scanner
}

fn (mut p Parser) directive() string {
    start := 0
    end := p.scanner.src.len
    return p.scanner.src[start..end]
}
'
        },
    ])
    mut found_directive := false
    for file in files {
        for stmt in file.stmts {
            if stmt is ast.FnDecl && stmt.name == 'directive' {
                found_directive = true
                assert find_call_with_lhs_suffix_in_stmts(stmt.stmts, 'string__substr') != none
                assert find_call_with_lhs_suffix_in_stmts(stmt.stmts, 'array__slice') == none
            }
        }
    }
    assert found_directive
}

fn test_transform_selector_expr_on_nested_selector_string_slice_lowers_slice_lhs() {
    scanner_type := types.Type(types.Struct{
        name:   'scanner__Scanner'
        fields: [
            types.Field{
                name: 'src'
                typ:  types.Type(string_type())
            },
        ]
    })
    parser_type := types.Type(types.Struct{
        name:   'parser__Parser'
        fields: [
            types.Field{
                name: 'scanner'
                typ:  types.Type(types.Pointer{
                    base_type: scanner_type
                })
            },
        ]
    })
    mut t := create_transformer_with_vars({
        'p': types.Type(types.Pointer{
            base_type: parser_type
        })
    })

    expr := ast.SelectorExpr{
        lhs: ast.IndexExpr{
            lhs:  ast.SelectorExpr{
                lhs: ast.SelectorExpr{
                    lhs: ast.Ident{
                        name: 'p'
                    }
                    rhs: ast.Ident{
                        name: 'scanner'
                    }
                }
                rhs: ast.Ident{
                    name: 'src'
                }
            }
            expr: ast.RangeExpr{
                op:    .dotdot
                start: ast.BasicLiteral{
                    kind:  .number
                    value: '1'
                }
                end:   ast.BasicLiteral{
                    kind:  .number
                    value: '3'
                }
            }
        }
        rhs: ast.Ident{
            name: 'trim_space'
        }
    }

    result := t.transform_expr(expr)
    assert result is ast.SelectorExpr, 'expected SelectorExpr, got ${result.type_name()}'
    sel := result as ast.SelectorExpr
    assert sel.lhs is ast.CallExpr, 'expected transformed slice CallExpr, got ${sel.lhs.type_name()}'
    call := sel.lhs as ast.CallExpr
    assert call.lhs is ast.Ident
    assert (call.lhs as ast.Ident).name == 'string__substr'
}

fn test_transform_selector_expr_string_slice_uses_fn_root_scope_fallback() {
    full_scanner_type := types.Type(types.Struct{
        name:   'scanner__Scanner'
        fields: [
            types.Field{
                name: 'src'
                typ:  types.Type(string_type())
            },
        ]
    })
    stale_scanner_type := types.Type(types.Struct{
        name: 'scanner__Scanner'
    })
    parser_type := types.Type(types.Struct{
        name:   'parser__Parser'
        fields: [
            types.Field{
                name: 'scanner'
                typ:  types.Type(types.Pointer{
                    base_type: stale_scanner_type
                })
            },
        ]
    })
    mut root_scope := types.new_scope(unsafe { nil })
    root_scope.insert('p', types.Type(types.Pointer{
        base_type: parser_type
    }))
    mut scanner_scope := types.new_scope(unsafe { nil })
    scanner_scope.insert('Scanner', types.TypeObject{
        typ: full_scanner_type
    })
    mut t := create_test_transformer()
    t.fn_root_scope = root_scope
    t.scope = types.new_scope(unsafe { nil })
    t.cached_scopes = {
        'scanner': scanner_scope
    }

    expr := ast.SelectorExpr{
        lhs: ast.IndexExpr{
            lhs:  ast.SelectorExpr{
                lhs: ast.SelectorExpr{
                    lhs: ast.Ident{
                        name: 'p'
                    }
                    rhs: ast.Ident{
                        name: 'scanner'
                    }
                }
                rhs: ast.Ident{
                    name: 'src'
                }
            }
            expr: ast.RangeExpr{
                op:    .dotdot
                start: ast.BasicLiteral{
                    kind:  .number
                    value: '1'
                }
                end:   ast.BasicLiteral{
                    kind:  .number
                    value: '3'
                }
            }
        }
        rhs: ast.Ident{
            name: 'trim_space'
        }
    }

    result := t.transform_expr(expr)
    assert result is ast.SelectorExpr, 'expected SelectorExpr, got ${result.type_name()}'
    sel := result as ast.SelectorExpr
    assert sel.lhs is ast.CallExpr, 'expected transformed slice CallExpr, got ${sel.lhs.type_name()}'
    call := sel.lhs as ast.CallExpr
    assert call.lhs is ast.Ident
    assert (call.lhs as ast.Ident).name == 'string__substr'
}

fn test_transform_index_expr_string_call_slice_open_ended_uses_max_int() {
    mut env := &types.Environment{}
    env.set_expr_type(1, types.string_)
    mut t := &Transformer{
        pref:                        &vpref.Preferences{}
        env:                         unsafe { env }
        needed_array_contains_fns:   map[string]ArrayMethodInfo{}
        needed_array_index_fns:      map[string]ArrayMethodInfo{}
        needed_array_last_index_fns: map[string]ArrayMethodInfo{}
    }

    expr := ast.IndexExpr{
        lhs:  ast.CallExpr{
            lhs: ast.Ident{
                name: 'get_type'
            }
            pos: token.Pos{
                id: 1
            }
        }
        expr: ast.RangeExpr{
            op:    .dotdot
            start: ast.BasicLiteral{
                kind:  .number
                value: '2'
            }
            end:   ast.empty_expr
        }
    }

    result := t.transform_expr(expr)
    assert result is ast.CallExpr, 'expected CallExpr, got ${result.type_name()}'
    call := result as ast.CallExpr
    assert call.lhs is ast.Ident
    assert (call.lhs as ast.Ident).name == 'string__substr'
    assert call.args.len == 3
    assert call.args[0] is ast.CallExpr
    assert call.args[2] is ast.BasicLiteral
    end := call.args[2] as ast.BasicLiteral
    assert end.kind == .number
    assert end.value == '2147483647'
}

fn test_transform_index_expr_array_slice_lowered() {
    mut t := create_transformer_with_vars({
        'arr': types.Type(types.Array{ elem_type: types.int_ })
    })

    expr := ast.IndexExpr{
        lhs:  ast.Ident{
            name: 'arr'
        }
        expr: ast.RangeExpr{
            op:    .ellipsis
            start: ast.BasicLiteral{
                kind:  .number
                value: '0'
            }
            end:   ast.BasicLiteral{
                kind:  .number
                value: '4'
            }
        }
    }

    result := t.transform_expr(expr)
    assert result is ast.CallExpr, 'expected CallExpr, got ${result.type_name()}'
    call := result as ast.CallExpr
    assert call.lhs is ast.Ident
    assert (call.lhs as ast.Ident).name == 'array__slice'
    assert call.args.len == 3
    // Inclusive range `...` should become end + 1.
    assert call.args[2] is ast.InfixExpr
}

fn test_transform_index_expr_open_ended_array_slice_uses_slice_ni() {
    mut t := create_transformer_with_vars({
        'arr': types.Type(types.Array{ elem_type: types.string_ })
    })

    expr := ast.IndexExpr{
        lhs:  ast.Ident{
            name: 'arr'
        }
        expr: ast.RangeExpr{
            op:    .dotdot
            start: ast.BasicLiteral{
                kind:  .number
                value: '1'
            }
            end:   ast.empty_expr
        }
    }

    result := t.transform_expr(expr)
    assert result is ast.CallExpr, 'expected CallExpr, got ${result.type_name()}'
    call := result as ast.CallExpr
    assert call.lhs is ast.Ident
    assert (call.lhs as ast.Ident).name == 'array__slice_ni'
    assert call.args.len == 3
    assert call.args[2] is ast.SelectorExpr
}

fn test_transform_index_expr_fixed_array_slice_uses_start_address_and_length() {
    mut t := create_transformer_with_vars({
        'f': types.Type(types.ArrayFixed{
            len:       5
            elem_type: types.int_
        })
    })

    expr := ast.IndexExpr{
        lhs:  ast.Ident{
            name: 'f'
        }
        expr: ast.RangeExpr{
            op:    .dotdot
            start: ast.BasicLiteral{
                kind:  .number
                value: '1'
            }
            end:   ast.BasicLiteral{
                kind:  .number
                value: '4'
            }
        }
    }

    result := t.transform_expr(expr)
    assert result is ast.CallExpr, 'expected CallExpr, got ${result.type_name()}'
    call := result as ast.CallExpr
    assert call.lhs is ast.Ident
    assert (call.lhs as ast.Ident).name == 'new_array_from_c_array'
    assert call.args.len == 4
    assert call.args[0] is ast.InfixExpr
    len_expr := call.args[0] as ast.InfixExpr
    assert len_expr.op == .minus
    assert len_expr.lhs is ast.BasicLiteral
    assert (len_expr.lhs as ast.BasicLiteral).value == '4'
    assert len_expr.rhs is ast.BasicLiteral
    assert (len_expr.rhs as ast.BasicLiteral).value == '1'
    assert call.args[1] is ast.InfixExpr
    assert call.args[3] is ast.PrefixExpr
    ptr_expr := call.args[3] as ast.PrefixExpr
    assert ptr_expr.op == .amp
    assert ptr_expr.expr is ast.IndexExpr
    index_expr := ptr_expr.expr as ast.IndexExpr
    assert index_expr.lhs is ast.Ident
    assert (index_expr.lhs as ast.Ident).name == 'f'
    assert index_expr.expr is ast.BasicLiteral
    assert (index_expr.expr as ast.BasicLiteral).value == '1'
}

fn test_transform_call_or_cast_expr_array_contains_fixed_array() {
    mut t := create_transformer_with_vars({
        'a': types.Type(types.ArrayFixed{
            len:       3
            elem_type: types.int_
        })
    })
    expr := ast.CallOrCastExpr{
        lhs:  ast.SelectorExpr{
            lhs: ast.Ident{
                name: 'a'
            }
            rhs: ast.Ident{
                name: 'contains'
            }
        }
        expr: ast.BasicLiteral{
            kind:  .number
            value: '2'
        }
    }
    result := t.transform_call_or_cast_expr(expr)
    assert result is ast.CallExpr, 'expected CallExpr, got ${result.type_name()}'
    call := result as ast.CallExpr
    assert call.lhs is ast.Ident
    assert (call.lhs as ast.Ident).name == 'Array_fixed_int_3_contains'
    assert call.args.len == 2
    assert call.args[0] is ast.Ident
    assert (call.args[0] as ast.Ident).name == 'a'
    assert 'Array_fixed_int_3_contains' in t.needed_array_contains_fns
}

fn test_transform_prefers_declared_array_receiver_contains_method() {
    files := transform_code_for_test('
struct Attr {
    name string
}

fn (attrs []Attr) contains(str string) bool {
    _ = attrs
    _ = str
    return true
}

fn has_typedef(attrs []Attr) bool {
    return attrs.contains("typedef")
}
')
    mut found := false
    for file in files {
        for stmt in file.stmts {
            if stmt is ast.FnDecl && stmt.name == 'has_typedef' {
                assert stmt.stmts.len == 1
                assert stmt.stmts[0] is ast.ReturnStmt
                ret := stmt.stmts[0] as ast.ReturnStmt
                assert ret.exprs.len == 1
                assert ret.exprs[0] is ast.CallExpr
                call := ret.exprs[0] as ast.CallExpr
                assert call.lhs is ast.Ident
                assert (call.lhs as ast.Ident).name == 'Array_Attr__contains'
                assert call.args.len == 2
                found = true
            }
        }
    }
    assert found
}

fn test_transform_call_expr_array_contains_fixed_array() {
    mut t := create_transformer_with_vars({
        'a': types.Type(types.ArrayFixed{
            len:       3
            elem_type: types.int_
        })
    })
    expr := ast.CallExpr{
        lhs:  ast.Ident{
            name: 'array__contains'
        }
        args: [
            ast.Expr(ast.Ident{
                name: 'a'
            }),
            ast.Expr(ast.PrefixExpr{
                op:   .amp
                expr: ast.BasicLiteral{
                    kind:  .number
                    value: '2'
                }
            }),
        ]
    }
    result := t.transform_call_expr(expr)
    assert result is ast.CallExpr, 'expected CallExpr, got ${result.type_name()}'
    call := result as ast.CallExpr
    assert call.lhs is ast.Ident
    assert (call.lhs as ast.Ident).name == 'Array_fixed_int_3_contains'
    assert call.args.len == 2
    assert call.args[1] is ast.BasicLiteral
    assert 'Array_fixed_int_3_contains' in t.needed_array_contains_fns
}

fn test_generate_array_method_elem_expr_registers_elem_type() {
    mut t := create_test_transformer()
    elem_expr := t.generate_array_method_elem_expr(ArrayMethodInfo{
        array_type: 'Array_string'
        elem_type:  'string'
    }, ast.Expr(ast.Ident{
        name: 'i'
    }))
    assert elem_expr is ast.IndexExpr
    assert elem_expr.pos().id < 0
    elem_type := t.synth_types[elem_expr.pos().id] or {
        assert false, 'expected synthesized element type for array helper index expr'
        return
    }
    assert t.type_to_c_name(elem_type) == 'string'
}

fn test_type_to_c_decl_name_preserves_float_primitives() {
    t := create_test_transformer()
    assert t.type_to_c_decl_name(types.Type(types.Primitive{
        props: .float
        size:  32
    })) == 'f32'
    assert t.type_to_c_decl_name(types.Type(types.f64_)) == 'f64'
    assert t.type_to_c_decl_name(types.Type(types.Pointer{
        base_type: types.Type(types.f64_)
    })) == 'f64*'
}

fn test_resolve_expr_with_expected_type_resolves_enum_shorthand() {
    mut t := create_test_transformer()
    resolved := t.resolve_expr_with_expected_type(ast.Expr(ast.SelectorExpr{
        lhs: ast.empty_expr
        rhs: ast.Ident{
            name: 'v'
        }
    }), types.Type(types.Enum{
        name: 'ast__StringLiteralKind'
    }))
    assert resolved is ast.Ident
    assert (resolved as ast.Ident).name == 'ast__StringLiteralKind__v'
}

fn test_resolve_expr_with_expected_type_casts_none_to_option() {
    mut t := create_test_transformer()
    expected := types.Type(types.OptionType{
        base_type: types.Type(types.Array{
            elem_type: types.Type(types.u8_)
        })
    })
    resolved := t.resolve_expr_with_expected_type(ast.Expr(ast.Type(ast.NoneType{})), expected)
    assert resolved is ast.CastExpr
    cast := resolved as ast.CastExpr
    assert cast.expr is ast.Type
    assert cast.typ is ast.Type
    assert cast.typ as ast.Type is ast.OptionType
}

fn test_transform_return_match_branch_resolves_enum_shorthand_to_return_type() {
    enum_typ := types.Type(types.Enum{
        name: 'CompletionType'
    })
    mut scope := types.new_scope(unsafe { nil })
    scope.insert('CompletionType', enum_typ)
    mut t := create_test_transformer()
    t.cur_module = 'main'
    t.cur_fn_ret_type_name = 'CompletionType'
    t.preserve_match_branch_value = true
    t.cached_scopes = {
        'main': scope
    }
    stmts := [
        ast.Stmt(ast.ExprStmt{
            expr: ast.Expr(ast.SelectorExpr{
                lhs: ast.empty_expr
                rhs: ast.Ident{
                    name: 'encoding'
                }
            })
        }),
    ]
    transformed := t.transform_match_branch_stmts(stmts)
    assert transformed.len == 1
    assert transformed[0] is ast.ExprStmt
    expr := (transformed[0] as ast.ExprStmt).expr
    assert expr is ast.Ident
    assert (expr as ast.Ident).name == 'CompletionType__encoding'
}

fn test_transform_selector_enum_uses_declared_parent_owner() {
    enum_typ := types.Type(types.Enum{
        name: 'StrIntpType'
    })
    mut builtin_scope := types.new_scope(unsafe { nil })
    builtin_scope.insert('StrIntpType', enum_typ)
    mut c_scope := types.new_scope(builtin_scope)
    mut t := create_test_transformer()
    t.cur_module = 'c'
    t.cached_scopes = {
        'builtin': builtin_scope
        'c':       c_scope
    }
    result := t.transform_expr(ast.SelectorExpr{
        lhs: ast.Expr(ast.Ident{
            name: 'StrIntpType'
        })
        rhs: ast.Ident{
            name: 'si_no_str'
        }
    })
    assert result is ast.Ident
    assert (result as ast.Ident).name == 'StrIntpType__si_no_str'
}

fn test_resolve_enum_shorthand_uses_declared_parent_owner() {
    enum_typ := types.Type(types.Enum{
        name: 'ChanState'
    })
    mut builtin_scope := types.new_scope(unsafe { nil })
    builtin_scope.insert('ChanState', enum_typ)
    mut sync_scope := types.new_scope(builtin_scope)
    mut t := create_test_transformer()
    t.cur_module = 'sync'
    t.cached_scopes = {
        'builtin': builtin_scope
        'sync':    sync_scope
    }
    resolved := t.resolve_enum_shorthand(ast.Expr(ast.SelectorExpr{
        lhs: ast.empty_expr
        rhs: ast.Ident{
            name: 'closed'
        }
    }), 'sync__ChanState')
    assert resolved is ast.Ident
    assert (resolved as ast.Ident).name == 'ChanState__closed'
}

fn test_transform_selector_enum_keeps_direct_module_owner() {
    enum_typ := types.Type(types.Enum{
        name: 'Token'
    })
    mut token_scope := types.new_scope(unsafe { nil })
    token_scope.insert('Token', enum_typ)
    mut t := create_test_transformer()
    t.cur_module = 'token'
    t.cached_scopes = {
        'token': token_scope
    }
    result := t.transform_expr(ast.SelectorExpr{
        lhs: ast.Expr(ast.Ident{
            name: 'Token'
        })
        rhs: ast.Ident{
            name: 'name'
        }
    })
    assert result is ast.Ident
    assert (result as ast.Ident).name == 'token__Token__name'
}

fn test_transform_init_expr_resolves_imported_enum_shorthand() {
    env := &types.Environment{}
    mut ast_scope := types.new_scope(unsafe { nil })
    enum_typ := types.Type(types.Enum{
        name: 'ast__StringLiteralKind'
    })
    ast_scope.insert('StringLiteralKind', enum_typ)
    ast_scope.insert('StringLiteral', types.Type(types.Struct{
        name:   'ast__StringLiteral'
        fields: [
            types.Field{
                name: 'kind'
                typ:  enum_typ
            },
            types.Field{
                name: 'value'
                typ:  types.string_
            },
        ]
    }))
    lock env.scopes {
        env.scopes['ast'] = ast_scope
    }
    mut t := &Transformer{
        pref:                        &vpref.Preferences{}
        env:                         unsafe { env }
        cur_module:                  'main'
        cached_scopes:               {
            'ast': ast_scope
        }
        needed_array_contains_fns:   map[string]ArrayMethodInfo{}
        needed_array_index_fns:      map[string]ArrayMethodInfo{}
        needed_array_last_index_fns: map[string]ArrayMethodInfo{}
    }
    result := t.transform_init_expr(ast.InitExpr{
        typ:    ast.Expr(ast.SelectorExpr{
            lhs: ast.Expr(ast.Ident{
                name: 'ast'
            })
            rhs: ast.Ident{
                name: 'StringLiteral'
            }
        })
        fields: [
            ast.FieldInit{
                name:  'kind'
                value: ast.Expr(ast.SelectorExpr{
                    lhs: ast.empty_expr
                    rhs: ast.Ident{
                        name: 'v'
                    }
                })
            },
        ]
    })
    assert result is ast.InitExpr
    init := result as ast.InitExpr
    mut found_kind := false
    for field in init.fields {
        if field.name == 'kind' {
            found_kind = true
            assert field.value is ast.Ident
            assert (field.value as ast.Ident).name == 'ast__StringLiteralKind__v'
            break
        }
    }
    assert found_kind
}

fn test_transform_map_init_expr_non_empty_lowers_to_runtime_ctor() {
    mut t := create_test_transformer()

    expr := ast.MapInitExpr{
        keys: [
            ast.Expr(ast.StringLiteral{
                value: 'foo'
            }),
            ast.Expr(ast.StringLiteral{
                value: 'bar'
            }),
        ]
        vals: [
            ast.Expr(ast.BasicLiteral{
                kind:  .number
                value: '1'
            }),
            ast.Expr(ast.BasicLiteral{
                kind:  .number
                value: '2'
            }),
        ]
    }

    result := t.transform_map_init_expr(expr)

    assert result is ast.CallExpr, 'expected CallExpr, got ${result.type_name()}'
    call := result as ast.CallExpr
    assert call.lhs is ast.Ident
    assert (call.lhs as ast.Ident).name == 'new_map_init_noscan_value'
    assert call.args.len == 9, 'expected 9 args for map constructor, got ${call.args.len}'
    assert call.args[7] is ast.ArrayInitExpr, 'expected key array arg'
    assert call.args[8] is ast.ArrayInitExpr, 'expected value array arg'
}

fn test_transform_map_init_expr_empty_lowers_to_new_map() {
    mut t := create_test_transformer()

    expr := ast.MapInitExpr{
        typ: ast.Expr(ast.Type(ast.MapType{
            key_type:   ast.Ident{
                name: 'string'
            }
            value_type: ast.Ident{
                name: 'int'
            }
        }))
    }

    result := t.transform_map_init_expr(expr)
    assert result is ast.CallExpr, 'expected CallExpr, got ${result.type_name()}'
    call := result as ast.CallExpr
    assert call.lhs is ast.Ident
    assert (call.lhs as ast.Ident).name == 'new_map'
    assert call.args.len == 6
    assert call.args[2] is ast.PrefixExpr
    assert (call.args[2] as ast.PrefixExpr).op == .amp
    assert (call.args[2] as ast.PrefixExpr).expr is ast.Ident
    assert ((call.args[2] as ast.PrefixExpr).expr as ast.Ident).name == 'map_hash_string'
}

fn test_transform_struct_init_pointer_field_keeps_pointer_value() {
    files := transform_code_for_test('
type BytePtr = &u8

struct Dense {
    keys BytePtr = unsafe { nil }
}

fn make_ptr() BytePtr {
    return unsafe { nil }
}

fn new_dense() Dense {
    return Dense{
        keys: make_ptr()
    }
}
')
    mut found_field := false
    for stmt in files[0].stmts {
        if stmt is ast.FnDecl && stmt.name == 'new_dense' {
            for inner in stmt.stmts {
                if inner is ast.ReturnStmt && inner.exprs.len == 1 && inner.exprs[0] is ast.InitExpr {
                    init := inner.exprs[0] as ast.InitExpr
                    for field in init.fields {
                        if field.name == 'keys' {
                            found_field = true
                            assert field.value !is ast.PrefixExpr
                        }
                    }
                }
            }
        }
    }
    assert found_field
}

fn test_transform_index_expr_map_read_lowers_to_map_get() {
    mut t := create_transformer_with_vars({
        'm': types.Type(types.Map{
            key_type:   string_type()
            value_type: types.int_
        })
    })

    expr := ast.IndexExpr{
        lhs:  ast.Ident{
            name: 'm'
        }
        expr: ast.StringLiteral{
            kind:  .v
            value: "'foo'"
        }
    }

    result := t.transform_index_expr(expr)
    assert result is ast.UnsafeExpr, 'expected UnsafeExpr, got ${result.type_name()}'
    unsafe_expr := result as ast.UnsafeExpr
    assert unsafe_expr.stmts.len > 0
    last := unsafe_expr.stmts[unsafe_expr.stmts.len - 1]
    assert last is ast.ExprStmt
    last_expr := (last as ast.ExprStmt).expr
    assert last_expr is ast.ParenExpr
    paren := last_expr as ast.ParenExpr
    assert paren.expr is ast.PrefixExpr
    pref := paren.expr as ast.PrefixExpr
    assert pref.op == .mul
    assert pref.expr is ast.CastExpr
    cast := pref.expr as ast.CastExpr
    assert cast.expr is ast.CallExpr
    call := cast.expr as ast.CallExpr
    assert call.lhs is ast.Ident
    assert (call.lhs as ast.Ident).name == 'map__get'
    assert call.args.len == 3
}

fn test_transform_map_index_push_lowers_to_map_get_and_set() {
    mut t := create_transformer_with_vars({
        'lists': types.Type(types.Map{
            key_type:   types.int_
            value_type: types.Type(types.Array{
                elem_type: types.int_
            })
        })
    })

    result := t.try_transform_map_index_push(ast.ExprStmt{
        expr: ast.InfixExpr{
            op:  .left_shift
            lhs: ast.IndexExpr{
                lhs:  ast.Ident{
                    name: 'lists'
                }
                expr: ast.BasicLiteral{
                    kind:  .number
                    value: '2'
                }
            }
            rhs: ast.BasicLiteral{
                kind:  .number
                value: '1'
            }
        }
    }) or {
        assert false, 'expected map index push to be transformed'
        return
    }

    assert result is ast.ExprStmt
    expr_stmt := result as ast.ExprStmt
    assert expr_stmt.expr is ast.CallExpr
    push_call := expr_stmt.expr as ast.CallExpr
    assert push_call.lhs is ast.Ident
    assert (push_call.lhs as ast.Ident).name == 'array__push_noscan'
    assert push_call.args.len == 2
    assert push_call.args[0] is ast.CastExpr
    arr_ptr := push_call.args[0] as ast.CastExpr
    assert arr_ptr.expr is ast.CallExpr
    map_call := arr_ptr.expr as ast.CallExpr
    assert map_call.lhs is ast.Ident
    assert (map_call.lhs as ast.Ident).name == 'map__get_and_set'
    assert map_call.args.len == 3
}

fn test_transform_map_index_push_generic_arg_or_index_lowers_to_map_get_and_set() {
    mut t := create_transformer_with_vars({
        'lists': types.Type(types.Map{
            key_type:   types.int_
            value_type: types.Type(types.Array{
                elem_type: types.int_
            })
        })
    })

    result := t.try_transform_map_index_push(ast.ExprStmt{
        expr: ast.InfixExpr{
            op:  .left_shift
            lhs: ast.GenericArgOrIndexExpr{
                lhs:  ast.Ident{
                    name: 'lists'
                }
                expr: ast.BasicLiteral{
                    kind:  .number
                    value: '2'
                }
            }
            rhs: ast.BasicLiteral{
                kind:  .number
                value: '1'
            }
        }
    }) or {
        assert false, 'expected ambiguous map index push to be transformed'
        return
    }

    assert result is ast.ExprStmt
    expr_stmt := result as ast.ExprStmt
    assert expr_stmt.expr is ast.CallExpr
    mut call_names := []string{}
    collect_call_names_from_expr(expr_stmt.expr, mut call_names)
    assert 'map__get_and_set' in call_names
}

fn test_transform_map_index_push_generic_args_lowers_to_map_get_and_set() {
    mut t := create_transformer_with_vars({
        'lists': types.Type(types.Map{
            key_type:   types.int_
            value_type: types.Type(types.Array{
                elem_type: types.int_
            })
        })
    })

    result := t.try_transform_map_index_push(ast.ExprStmt{
        expr: ast.InfixExpr{
            op:  .left_shift
            lhs: ast.GenericArgs{
                lhs:  ast.Ident{
                    name: 'lists'
                }
                args: [
                    ast.Expr(ast.BasicLiteral{
                        kind:  .number
                        value: '2'
                    }),
                ]
            }
            rhs: ast.BasicLiteral{
                kind:  .number
                value: '1'
            }
        }
    }) or {
        assert false, 'expected generic-args map index push to be transformed'
        return
    }

    assert result is ast.ExprStmt
    expr_stmt := result as ast.ExprStmt
    assert expr_stmt.expr is ast.CallExpr
    mut call_names := []string{}
    collect_call_names_from_expr(expr_stmt.expr, mut call_names)
    assert 'map__get_and_set' in call_names
}

fn test_transform_map_index_push_refuses_pointer_map_value() {
    array_int_type := types.Type(types.Array{
        elem_type: types.int_
    })
    mut t := create_transformer_with_vars({
        'lists': types.Type(types.Map{
            key_type:   types.int_
            value_type: types.Type(types.Pointer{
                base_type: array_int_type
            })
        })
    })

    if _ := t.try_transform_map_index_push(ast.ExprStmt{
        expr: ast.InfixExpr{
            op:  .left_shift
            lhs: ast.IndexExpr{
                lhs:  ast.Ident{
                    name: 'lists'
                }
                expr: ast.BasicLiteral{
                    kind:  .number
                    value: '2'
                }
            }
            rhs: ast.BasicLiteral{
                kind:  .number
                value: '1'
            }
        }
    })
    {
        assert false, 'expected pointer map value push not to be transformed'
    }
}

fn test_transform_map_index_selector_postfix_lowers_to_map_get_and_set() {
    fn_type := types.Type(types.Struct{
        name:   'Fn'
        fields: [
            types.Field{
                name: 'usages'
                typ:  types.int_
            },
        ]
    })
    mut t := create_transformer_with_vars({
        'fns': types.Type(types.Map{
            key_type:   string_type()
            value_type: fn_type
        })
    })

    result := t.try_transform_map_index_postfix(ast.ExprStmt{
        expr: ast.PostfixExpr{
            op:   .inc
            expr: ast.SelectorExpr{
                lhs: ast.Expr(ast.IndexExpr{
                    lhs:  ast.Ident{
                        name: 'fns'
                    }
                    expr: ast.StringLiteral{
                        kind:  .v
                        value: "'main'"
                    }
                })
                rhs: ast.Ident{
                    name: 'usages'
                }
            }
        }
    }) or {
        assert false, 'expected map index selector postfix to be transformed'
        return
    }

    assert result is ast.AssignStmt
    assign_stmt := result as ast.AssignStmt
    assert assign_stmt.op == .plus_assign
    assert assign_stmt.lhs.len == 1
    assert assign_stmt.lhs[0] is ast.SelectorExpr
    lhs := assign_stmt.lhs[0] as ast.SelectorExpr
    assert lhs.rhs.name == 'usages'
    mut call_names := []string{}
    collect_call_names_from_expr(lhs.lhs, mut call_names)
    assert 'map__get_and_set' in call_names
}

fn test_transform_map_index_assign_uses_temp_for_const_key() {
    files := transform_code_for_test('
const int_type_idx = 8

fn set_print_type(mut print_types map[int]bool) {
    print_types[int_type_idx] = true
}
')
    call := find_call_with_lhs_suffix_in_stmts(files[0].stmts, 'map__set') or {
        assert false, 'expected map__set call'
        return
    }
    assert call.args.len == 3
    assert call.args[1] is ast.CastExpr
    key_cast := call.args[1] as ast.CastExpr
    assert key_cast.expr is ast.PrefixExpr
    key_addr := key_cast.expr as ast.PrefixExpr
    assert key_addr.expr is ast.Ident
    assert (key_addr.expr as ast.Ident).name != 'int_type_idx'
}

fn test_transform_map_index_assign_uses_temp_for_module_const_key() {
    files := transform_sources_for_test([
        TestSource{
            rel:  'ast/types.v'
            code: 'module ast
pub const int_type_idx = 8
'
        },
        TestSource{
            rel:  'main.v'
            code: 'module main
import ast

fn set_print_type(mut print_types map[int]bool) {
    print_types[ast.int_type_idx] = true
}
'
        },
    ])
    mut found := false
    for file in files {
        if file.mod != 'main' {
            continue
        }
        call := find_call_with_lhs_suffix_in_stmts(file.stmts, 'map__set') or { continue }
        assert call.args.len == 3
        assert call.args[1] is ast.CastExpr
        key_cast := call.args[1] as ast.CastExpr
        assert key_cast.expr is ast.PrefixExpr
        key_addr := key_cast.expr as ast.PrefixExpr
        assert key_addr.expr is ast.Ident
        assert (key_addr.expr as ast.Ident).name != 'ast__int_type_idx'
        found = true
    }
    assert found
}

fn test_addr_of_prefix_temp_materializes_selector_from_call_result() {
    mut t := create_test_transformer()
    mut prefix_stmts := []ast.Stmt{}
    addr := t.addr_of_with_prefix_temp(ast.Expr(ast.SelectorExpr{
        lhs: ast.Expr(ast.CallExpr{
            lhs: ast.Ident{
                name: 'pos'
            }
        })
        rhs: ast.Ident{
            name: 'pos'
        }
    }), types.int_, mut prefix_stmts)
    assert prefix_stmts.len == 1
    assert prefix_stmts[0] is ast.AssignStmt
    tmp_decl := prefix_stmts[0] as ast.AssignStmt
    assert tmp_decl.lhs[0] is ast.Ident
    assert addr is ast.PrefixExpr
    addr_expr := addr as ast.PrefixExpr
    assert addr_expr.expr is ast.Ident
    assert (addr_expr.expr as ast.Ident).name == (tmp_decl.lhs[0] as ast.Ident).name
}

fn test_transform_addr_of_call_or_cast_selector_lowers_to_pointer_cast_selector() {
    mut t := create_test_transformer()
    result := t.transform_expr(ast.Expr(ast.PrefixExpr{
        op:   .amp
        expr: ast.Expr(ast.SelectorExpr{
            lhs: ast.Expr(ast.CallOrCastExpr{
                lhs:  ast.Expr(ast.Ident{
                    name: 'int'
                })
                expr: ast.Expr(ast.Ident{
                    name: 'raw'
                })
            })
            rhs: ast.Ident{
                name: 'field'
            }
        })
    }))
    assert result is ast.SelectorExpr, 'expected SelectorExpr, got ${result.type_name()}'
    selector := result as ast.SelectorExpr
    assert selector.lhs is ast.CastExpr, 'selector lhs was not reduced: ${selector.lhs.type_name()}'
    cast := selector.lhs as ast.CastExpr
    assert cast.typ is ast.PrefixExpr
    cast_typ := cast.typ as ast.PrefixExpr
    assert cast_typ.op == .amp
    assert cast_typ.expr is ast.Ident
    assert (cast_typ.expr as ast.Ident).name == 'int'
    assert cast.expr is ast.Ident
    assert (cast.expr as ast.Ident).name == 'raw'
    assert selector.rhs.name == 'field'
}

fn test_transform_map_index_assign_with_or_rhs_lowers_to_map_set() {
    files := transform_code_for_test('
fn maybe_int() ?int {
    return 1
}

fn set_value(mut values map[string]int) {
    values["c"] = maybe_int() or { 0 }
}
')
    call := find_call_with_lhs_suffix_in_stmts(files[0].stmts, 'map__set') or {
        assert false, 'expected map__set call'
        return
    }
    assert call.args.len == 3
}

fn test_map_value_temp_expr_keeps_existing_sumtype_value() {
    sum_type := types.Type(types.SumType{
        name:     'types.Type'
        variants: [types.Type(types.string_), types.Type(types.int_)]
    })
    mut t := create_transformer_with_vars({
        'v': sum_type
    })
    expr := t.map_value_temp_expr(ast.Expr(ast.Ident{
        name: 'v'
    }), sum_type)
    assert expr is ast.Ident
    assert (expr as ast.Ident).name == 'v'
}

fn test_map_value_temp_expr_keeps_short_named_sumtype_value() {
    sum_type := types.Type(types.SumType{
        name:     'types.Type'
        variants: [types.Type(types.string_), types.Type(types.int_)]
    })
    mut t := create_transformer_with_vars({
        'v': types.Type(types.NamedType('Type'))
    })
    expr := t.map_value_temp_expr(ast.Expr(ast.Ident{
        name: 'v'
    }), sum_type)
    assert expr is ast.Ident
    assert (expr as ast.Ident).name == 'v'
}

fn test_for_in_var_registration_replaces_reused_loop_value_type() {
    sum_type := types.Type(types.SumType{
        name:     'types.Type'
        variants: [types.Type(types.string_), types.Type(types.int_)]
    })
    mut t := create_transformer_with_vars({})
    t.register_for_in_var_type('v', types.Type(types.string_))
    t.register_for_in_var_type('v', sum_type)
    expr := t.map_value_temp_expr(ast.Expr(ast.Ident{
        name: 'v'
    }), sum_type)
    assert expr is ast.Ident
    assert (expr as ast.Ident).name == 'v'
}

fn test_decl_assign_index_expr_records_lhs_type() {
    mut t := create_transformer_with_vars({
        'values': types.Type(types.Array{
            elem_type: types.int_
        })
    })
    lhs_pos := token.Pos{
        id: 4242
    }
    index_pos := token.Pos{
        id: 4243
    }
    t.env.set_expr_type(index_pos.id, types.Type(types.f64_))
    transformed := t.transform_assign_stmt(ast.AssignStmt{
        op:  .decl_assign
        lhs: [ast.Expr(ast.Ident{
            name: 'first'
            pos:  lhs_pos
        })]
        rhs: [
            ast.Expr(ast.IndexExpr{
                lhs:  ast.Expr(ast.Ident{
                    name: 'values'
                })
                expr: ast.Expr(ast.BasicLiteral{
                    kind:  .number
                    value: '0'
                })
                pos:  index_pos
            }),
        ]
    })
    assert transformed.op == .decl_assign
    local_type := t.lookup_local_decl_type('first') or {
        assert false, 'missing local declaration type for index expression'
        return
    }
    assert t.type_to_c_name(local_type) == 'int'
    synth_type := t.get_synth_type(lhs_pos) or {
        assert false, 'missing synth type for index declaration lhs'
        return
    }
    assert t.type_to_c_name(synth_type) == 'int'
}

fn test_unsafe_cast_deref_prefers_cast_target_over_stale_env_type() {
    mut t := create_test_transformer()
    unsafe_pos := token.Pos{
        id: 4250
    }
    deref_pos := token.Pos{
        id: 4251
    }
    t.env.set_expr_type(unsafe_pos.id, types.Type(types.f64_))
    t.env.set_expr_type(deref_pos.id, types.Type(types.f64_))
    typ := t.get_expr_type(ast.UnsafeExpr{
        stmts: [
            ast.Stmt(ast.ExprStmt{
                expr: ast.Expr(ast.PrefixExpr{
                    op:   .mul
                    expr: ast.Expr(ast.PrefixExpr{
                        op:   .amp
                        expr: ast.Expr(ast.CallOrCastExpr{
                            lhs:  ast.Expr(ast.Ident{
                                name: 'int'
                            })
                            expr: ast.Expr(ast.Ident{
                                name: 'raw'
                            })
                        })
                    })
                    pos:  deref_pos
                })
            }),
        ]
        pos:   unsafe_pos
    }) or {
        assert false, 'missing unsafe cast deref type'
        return
    }
    assert t.type_to_c_name(typ) == 'int'
}

fn test_decl_assign_unsafe_cast_deref_records_lhs_type() {
    mut t := create_test_transformer()
    lhs_pos := token.Pos{
        id: 4260
    }
    unsafe_pos := token.Pos{
        id: 4261
    }
    deref_pos := token.Pos{
        id: 4262
    }
    t.env.set_expr_type(unsafe_pos.id, types.Type(types.f64_))
    t.env.set_expr_type(deref_pos.id, types.Type(types.f64_))
    transformed := t.transform_assign_stmt(ast.AssignStmt{
        op:  .decl_assign
        lhs: [ast.Expr(ast.Ident{
            name: 'x'
            pos:  lhs_pos
        })]
        rhs: [
            ast.Expr(ast.UnsafeExpr{
                stmts: [
                    ast.Stmt(ast.ExprStmt{
                        expr: ast.Expr(ast.PrefixExpr{
                            op:   .mul
                            expr: ast.Expr(ast.PrefixExpr{
                                op:   .amp
                                expr: ast.Expr(ast.CallOrCastExpr{
                                    lhs:  ast.Expr(ast.Ident{
                                        name: 'int'
                                    })
                                    expr: ast.Expr(ast.Ident{
                                        name: 'raw'
                                    })
                                })
                            })
                            pos:  deref_pos
                        })
                    }),
                ]
                pos:   unsafe_pos
            }),
        ]
    })
    assert transformed.op == .decl_assign
    local_type := t.lookup_local_decl_type('x') or {
        assert false, 'missing local declaration type for unsafe cast deref'
        return
    }
    assert t.type_to_c_name(local_type) == 'int'
    synth_type := t.get_synth_type(lhs_pos) or {
        assert false, 'missing synth type for unsafe cast deref declaration lhs'
        return
    }
    assert t.type_to_c_name(synth_type) == 'int'
}

fn test_is_enum_rvalue_stops_on_unresolved_alias() {
    t := create_test_transformer()
    unresolved_alias := types.Type(types.Alias{
        name: 'Unresolved'
    })
    assert !t.is_enum_rvalue(ast.Expr(ast.Ident{
        name: 'value'
    }), unresolved_alias)
}

fn test_transform_map_index_push_resolves_named_array_alias_value() {
    mut t := create_transformer_with_vars({
        'cleanups': types.Type(types.Map{
            key_type:   types.string_
            value_type: types.Type(types.NamedType('strings.Builder'))
        })
        'cleanup':  types.Type(types.NamedType('strings.Builder'))
    })
    mut strings_scope := types.new_scope(unsafe { nil })
    strings_scope.insert_type('Builder', types.Type(types.Alias{
        name:      'strings.Builder'
        base_type: types.Type(types.Array{
            elem_type: types.int_
        })
    }))
    t.cached_scopes = {
        'strings': strings_scope
    }

    result := t.try_transform_map_index_push(ast.ExprStmt{
        expr: ast.InfixExpr{
            op:  .left_shift
            lhs: ast.IndexExpr{
                lhs:  ast.Ident{
                    name: 'cleanups'
                }
                expr: ast.StringLiteral{
                    kind:  .v
                    value: "'main'"
                }
            }
            rhs: ast.Ident{
                name: 'cleanup'
            }
        }
    }) or {
        assert false, 'expected named alias map index push to be transformed'
        return
    }

    assert result is ast.ExprStmt
    expr_stmt := result as ast.ExprStmt
    assert expr_stmt.expr is ast.CallExpr
    push_call := expr_stmt.expr as ast.CallExpr
    assert push_call.lhs is ast.Ident
    assert (push_call.lhs as ast.Ident).name == 'array__push_many'
    assert push_call.args[0] is ast.CastExpr
    arr_ptr := push_call.args[0] as ast.CastExpr
    assert arr_ptr.expr is ast.CallExpr
    map_call := arr_ptr.expr as ast.CallExpr
    assert map_call.lhs is ast.Ident
    assert (map_call.lhs as ast.Ident).name == 'map__get_and_set'
}

fn test_transform_array_append_selector_array_field_uses_push_many() {
    ast_type := types.Type(types.NamedType('ast.Type'))
    array_ast_type := types.Type(types.Array{
        elem_type: ast_type
    })
    mut t := create_transformer_with_vars({
        'smartcasts': array_ast_type
        'field':      types.Type(types.Pointer{
            base_type: types.Type(types.Struct{
                name:   'ast.ScopeStructField'
                fields: [
                    types.Field{
                        name: 'smartcasts'
                        typ:  array_ast_type
                    },
                ]
            })
        })
    })

    result := t.transform_expr(ast.InfixExpr{
        op:  .left_shift
        lhs: ast.Ident{
            name: 'smartcasts'
        }
        rhs: ast.SelectorExpr{
            lhs: ast.Ident{
                name: 'field'
            }
            rhs: ast.Ident{
                name: 'smartcasts'
            }
        }
    })

    assert result is ast.CallExpr
    call := result as ast.CallExpr
    assert call.lhs is ast.Ident
    assert (call.lhs as ast.Ident).name == 'array__push_many'
    assert call.args.len == 3
}

fn test_transform_array_append_after_array_decl_uses_declared_array_type() {
    array_int_type := types.Type(types.Array{
        elem_type: types.int_
    })
    mut t := create_transformer_with_vars({
        'field': types.Type(types.Pointer{
            base_type: types.Type(types.Struct{
                name:   'Field'
                fields: [
                    types.Field{
                        name: 'values'
                        typ:  array_int_type
                    },
                ]
            })
        })
    })
    _ = t.transform_assign_stmt(ast.AssignStmt{
        op:  .decl_assign
        lhs: [ast.Expr(ast.Ident{
            name: 'values'
        })]
        rhs: [
            ast.Expr(ast.ArrayInitExpr{
                typ: ast.Expr(ast.Type(ast.ArrayType{
                    elem_type: ast.Ident{
                        name: 'int'
                    }
                }))
            }),
        ]
    })

    result := t.transform_expr(ast.InfixExpr{
        op:  .left_shift
        lhs: ast.Ident{
            name: 'values'
        }
        rhs: ast.SelectorExpr{
            lhs: ast.Ident{
                name: 'field'
            }
            rhs: ast.Ident{
                name: 'values'
            }
        }
    })

    assert result is ast.CallExpr
    call := result as ast.CallExpr
    assert call.lhs is ast.Ident
    assert (call.lhs as ast.Ident).name == 'array__push_many'
}

fn test_transform_array_alias_mut_receiver_append_uses_receiver_pointer() {
    files := transform_code_for_test('
type Builder = []u8

fn (mut b Builder) add_zero() {
    b << u8(0)
}

fn main() {
    mut b := Builder([]u8{})
    b.add_zero()
}
')
    mut found := false
    for file in files {
        for stmt in file.stmts {
            if stmt is ast.FnDecl && stmt.name == 'add_zero' {
                assert stmt.stmts.len == 1
                assert stmt.stmts[0] is ast.ExprStmt
                expr_stmt := stmt.stmts[0] as ast.ExprStmt
                assert expr_stmt.expr is ast.CallExpr
                call := expr_stmt.expr as ast.CallExpr
                assert call.lhs is ast.Ident
                assert (call.lhs as ast.Ident).name == 'builtin__array_push_noscan'
                assert call.args.len == 2
                assert call.args[0] is ast.CastExpr
                arr_ptr := call.args[0] as ast.CastExpr
                assert arr_ptr.expr is ast.Ident
                assert (arr_ptr.expr as ast.Ident).name == 'b'
                found = true
            }
        }
    }
    assert found
}

fn test_array_elem_type_uses_checker_ident_metadata() {
    env := types.Environment.new()
    mut scope := types.new_scope(unsafe { nil })
    mut t := &Transformer{
        pref:                        &vpref.Preferences{}
        env:                         env
        scope:                       scope
        needed_clone_fns:            map[string]string{}
        needed_array_contains_fns:   map[string]ArrayMethodInfo{}
        needed_array_index_fns:      map[string]ArrayMethodInfo{}
        needed_array_last_index_fns: map[string]ArrayMethodInfo{}
    }
    mut env_mut := unsafe { env }
    env_mut.set_expr_type(42, types.Type(types.Array{
        elem_type: types.Type(types.NamedType('ast.Type'))
    }))

    elem_type := t.get_array_elem_type_str(ast.Expr(ast.Ident{
        name: 'smartcasts'
        pos:  token.Pos{
            id: 42
        }
    })) or {
        assert false, 'expected array element type from checker metadata'
        return
    }
    assert elem_type == 'ast__Type'
}

fn test_transform_array_append_preserves_alias_element_type_for_push_many() {
    files := transform_code_for_test('
type Type = u32

struct ScopeStructField {
    smartcasts []Type
}

fn f(field &ScopeStructField) {
    mut smartcasts := []Type{}
    smartcasts << field.smartcasts
}
')
    mut found := false
    for file in files {
        for stmt in file.stmts {
            if stmt is ast.FnDecl && stmt.name == 'f' {
                assert stmt.stmts.len == 2
                assert stmt.stmts[1] is ast.ExprStmt
                expr_stmt := stmt.stmts[1] as ast.ExprStmt
                assert expr_stmt.expr is ast.CallExpr
                call := expr_stmt.expr as ast.CallExpr
                assert call.lhs is ast.Ident
                assert (call.lhs as ast.Ident).name == 'array__push_many'
                found = true
            }
        }
    }
    assert found
}

fn test_transform_nested_array_append_literal_pushes_single_array_value() {
    files := transform_code_for_test('
fn f(column_name string) {
    mut groups := [][]string{}
    groups << [column_name]
}
')
    mut found := false
    for file in files {
        for stmt in file.stmts {
            if stmt is ast.FnDecl && stmt.name == 'f' {
                assert stmt.stmts.len == 3
                assert stmt.stmts[1] is ast.AssignStmt
                tmp_assign := stmt.stmts[1] as ast.AssignStmt
                assert tmp_assign.op == .decl_assign
                assert tmp_assign.lhs.len == 1
                assert tmp_assign.lhs[0] is ast.Ident
                tmp_name := (tmp_assign.lhs[0] as ast.Ident).name
                assert tmp_name.starts_with('_ap_t')
                assert tmp_assign.rhs.len == 1
                assert tmp_assign.rhs[0] is ast.ArrayInitExpr
                assert stmt.stmts[2] is ast.ExprStmt
                expr_stmt := stmt.stmts[2] as ast.ExprStmt
                assert expr_stmt.expr is ast.CallExpr
                call := expr_stmt.expr as ast.CallExpr
                assert call.lhs is ast.Ident
                assert (call.lhs as ast.Ident).name == 'builtin__array_push_noscan'
                assert call.args.len == 2
                assert call.args[1] is ast.ArrayInitExpr
                outer_arr := call.args[1] as ast.ArrayInitExpr
                assert outer_arr.typ is ast.Type
                assert outer_arr.typ as ast.Type is ast.ArrayType
                outer_type := outer_arr.typ as ast.Type
                outer_array_type := outer_type as ast.ArrayType
                assert outer_array_type.elem_type is ast.Ident
                assert (outer_array_type.elem_type as ast.Ident).name == 'Array_string'
                assert outer_arr.exprs.len == 1
                assert outer_arr.exprs[0] is ast.Ident
                assert (outer_arr.exprs[0] as ast.Ident).name == tmp_name
                found = true
            }
        }
    }
    assert found
}

fn test_transform_nested_array_append_call_result_uses_temp() {
    files := transform_code_for_test('
fn make_items() []string {
    return ["x"]
}

fn f() {
    mut groups := [][]string{}
    groups << make_items()
}
')
    mut found := false
    for file in files {
        for stmt in file.stmts {
            if stmt is ast.FnDecl && stmt.name == 'f' {
                assert stmt.stmts.len == 3
                assert stmt.stmts[1] is ast.AssignStmt
                tmp_assign := stmt.stmts[1] as ast.AssignStmt
                assert tmp_assign.op == .decl_assign
                assert tmp_assign.lhs.len == 1
                assert tmp_assign.lhs[0] is ast.Ident
                tmp_name := (tmp_assign.lhs[0] as ast.Ident).name
                assert tmp_name.starts_with('_ap_t')
                assert tmp_assign.rhs.len == 1
                assert tmp_assign.rhs[0] is ast.CallExpr
                rhs_call := tmp_assign.rhs[0] as ast.CallExpr
                assert rhs_call.lhs is ast.Ident
                assert (rhs_call.lhs as ast.Ident).name == 'make_items'
                assert stmt.stmts[2] is ast.ExprStmt
                expr_stmt := stmt.stmts[2] as ast.ExprStmt
                assert expr_stmt.expr is ast.CallExpr
                call := expr_stmt.expr as ast.CallExpr
                assert call.lhs is ast.Ident
                assert (call.lhs as ast.Ident).name == 'builtin__array_push_noscan'
                assert call.args.len == 2
                assert call.args[1] is ast.ArrayInitExpr
                outer_arr := call.args[1] as ast.ArrayInitExpr
                assert outer_arr.exprs.len == 1
                assert outer_arr.exprs[0] is ast.Ident
                assert (outer_arr.exprs[0] as ast.Ident).name == tmp_name
                found = true
            }
        }
    }
    assert found
}

fn assert_array_append_arg_is_addressed_ident(arg ast.Expr, name string) {
    assert arg is ast.CastExpr
    arr_ptr := arg as ast.CastExpr
    assert arr_ptr.expr is ast.PrefixExpr
    prefix := arr_ptr.expr as ast.PrefixExpr
    assert prefix.op == .amp
    assert prefix.expr is ast.Ident
    assert (prefix.expr as ast.Ident).name == name
}

fn test_transform_array_append_mut_array_param_uses_local_storage_address() {
    files := transform_code_for_test('
fn add_seen(mut seen []string, name string) {
    seen << name
}

fn push_path(mut patterns [][]string, path []string) {
    patterns << path
}

fn push_many_paths(mut patterns [][]string, paths [][]string) {
    patterns << paths
}
')
    mut found_seen := false
    mut found_path := false
    mut found_many := false
    for file in files {
        for stmt in file.stmts {
            if stmt is ast.FnDecl && stmt.name in ['add_seen', 'push_path', 'push_many_paths'] {
                assert stmt.stmts.len == 1
                assert stmt.stmts[0] is ast.ExprStmt
                expr_stmt := stmt.stmts[0] as ast.ExprStmt
                assert expr_stmt.expr is ast.CallExpr
                call := expr_stmt.expr as ast.CallExpr
                assert call.lhs is ast.Ident
                call_name := (call.lhs as ast.Ident).name
                assert call.args.len >= 2
                if stmt.name == 'add_seen' {
                    assert call_name == 'builtin__array_push_noscan'
                    assert_array_append_arg_is_addressed_ident(call.args[0], 'seen')
                    found_seen = true
                } else if stmt.name == 'push_path' {
                    assert call_name == 'builtin__array_push_noscan'
                    assert_array_append_arg_is_addressed_ident(call.args[0], 'patterns')
                    found_path = true
                } else if stmt.name == 'push_many_paths' {
                    assert call_name == 'array__push_many'
                    assert_array_append_arg_is_addressed_ident(call.args[0], 'patterns')
                    found_many = true
                }
            }
        }
    }
    assert found_seen
    assert found_path
    assert found_many
}

fn test_transform_nested_array_literal_single_push_uses_temp_and_param_storage_address() {
    files := transform_code_for_test('
fn push_literal_path(mut patterns [][]string, path []string) {
    patterns << [path]
}
')
    mut found := false
    for file in files {
        for stmt in file.stmts {
            if stmt is ast.FnDecl && stmt.name == 'push_literal_path' {
                assert stmt.stmts.len == 1
                assert stmt.stmts[0] is ast.ExprStmt
                expr_stmt := stmt.stmts[0] as ast.ExprStmt
                assert expr_stmt.expr is ast.CallExpr
                call := expr_stmt.expr as ast.CallExpr
                assert call.lhs is ast.Ident
                assert (call.lhs as ast.Ident).name == 'builtin__array_push_noscan'
                assert call.args.len == 2
                assert_array_append_arg_is_addressed_ident(call.args[0], 'patterns')
                assert call.args[1] is ast.ArrayInitExpr
                outer_arr := call.args[1] as ast.ArrayInitExpr
                assert outer_arr.exprs.len == 1
                assert outer_arr.exprs[0] is ast.Ident
                assert (outer_arr.exprs[0] as ast.Ident).name == 'path'
                found = true
            }
        }
    }
    assert found
}

fn test_transform_for_in_nested_array_value_uses_array_index() {
    files := transform_code_for_test('
fn f(groups [][]string) []int {
    mut counts := []int{}
    for group in groups {
        counts << group.len
    }
    return counts
}
')
    mut found := false
    for file in files {
        for stmt in file.stmts {
            if stmt is ast.FnDecl && stmt.name == 'f' {
                assert stmt.stmts.len >= 2
                assert stmt.stmts[1] is ast.ForStmt
                for_stmt := stmt.stmts[1] as ast.ForStmt
                assert for_stmt.stmts.len > 0
                assert for_stmt.stmts[0] is ast.AssignStmt
                value_assign := for_stmt.stmts[0] as ast.AssignStmt
                assert value_assign.lhs.len == 1
                assert value_assign.lhs[0] is ast.Ident
                assert (value_assign.lhs[0] as ast.Ident).name == 'group'
                assert value_assign.rhs.len == 1
                assert value_assign.rhs[0] is ast.IndexExpr
                index_expr := value_assign.rhs[0] as ast.IndexExpr
                assert index_expr.lhs !is ast.CastExpr
                found = true
            }
        }
    }
    assert found
}

fn test_transform_for_in_prefers_scope_iter_type_over_position_type() {
    mut env := types.Environment.new()
    iter_pos := token.Pos{
        id: 42
    }
    env.set_expr_type(iter_pos.id, types.Type(types.Array{
        elem_type: types.Type(types.int_)
    }))
    mut scope := types.new_scope(unsafe { nil })
    scope.insert('s', value_object_from_type(types.Type(types.string_)))
    mut t := &Transformer{
        pref:                        &vpref.Preferences{}
        env:                         env
        scope:                       scope
        needed_clone_fns:            map[string]string{}
        needed_array_contains_fns:   map[string]ArrayMethodInfo{}
        needed_array_index_fns:      map[string]ArrayMethodInfo{}
        needed_array_last_index_fns: map[string]ArrayMethodInfo{}
        local_decl_types:            map[string]types.Type{}
    }
    result := t.transform_for_stmt(ast.ForStmt{
        init: ast.Stmt(ast.ForInStmt{
            value: ast.Expr(ast.Ident{
                name: 'ch'
            })
            expr:  ast.Expr(ast.ParenExpr{
                expr: ast.Expr(ast.Ident{
                    name: 's'
                    pos:  iter_pos
                })
            })
        })
    })
    assert result.stmts.len > 0
    assert result.stmts[0] is ast.AssignStmt
    value_assign := result.stmts[0] as ast.AssignStmt
    assert value_assign.rhs.len == 1
    assert value_assign.rhs[0] is ast.IndexExpr
    index_expr := value_assign.rhs[0] as ast.IndexExpr
    mut index_lhs := index_expr.lhs
    for _ in 0 .. 4 {
        if index_lhs is ast.ParenExpr {
            index_lhs = index_lhs.expr
            continue
        }
        break
    }
    assert index_lhs is ast.Ident
    assert (index_lhs as ast.Ident).name == 's'
}

fn test_transform_for_in_fixed_array_value_uses_array_index() {
    files := transform_code_for_test('
fn f(pairs [][2]int) []int {
    mut out := []int{}
    for pair in pairs {
        out << pair[1]
    }
    return out
}
')
    mut found := false
    for file in files {
        for stmt in file.stmts {
            if stmt is ast.FnDecl && stmt.name == 'f' {
                assert stmt.stmts.len >= 2
                assert stmt.stmts[1] is ast.ForStmt
                for_stmt := stmt.stmts[1] as ast.ForStmt
                assert for_stmt.stmts.len > 0
                assert for_stmt.stmts[0] is ast.AssignStmt
                value_assign := for_stmt.stmts[0] as ast.AssignStmt
                assert value_assign.lhs.len == 1
                assert value_assign.lhs[0] is ast.Ident
                assert (value_assign.lhs[0] as ast.Ident).name == 'pair'
                assert value_assign.rhs.len == 1
                assert value_assign.rhs[0] is ast.IndexExpr
                index_expr := value_assign.rhs[0] as ast.IndexExpr
                assert index_expr.lhs !is ast.CastExpr
                found = true
            }
        }
    }
    assert found
}

fn test_transform_for_in_struct_value_uses_typed_array_index() {
    files := transform_code_for_test('
struct Field {
    typ int
}

fn f(fields []Field) int {
    mut out := 0
    for field in fields {
        out += field.typ
    }
    return out
}
')
    mut found := false
    for file in files {
        for stmt in file.stmts {
            if stmt is ast.FnDecl && stmt.name == 'f' {
                assert stmt.stmts.len >= 2
                assert stmt.stmts[1] is ast.ForStmt
                for_stmt := stmt.stmts[1] as ast.ForStmt
                assert for_stmt.stmts.len > 0
                assert for_stmt.stmts[0] is ast.AssignStmt
                value_assign := for_stmt.stmts[0] as ast.AssignStmt
                assert value_assign.lhs.len == 1
                assert value_assign.lhs[0] is ast.Ident
                assert (value_assign.lhs[0] as ast.Ident).name == 'field'
                assert value_assign.rhs.len == 1
                assert value_assign.rhs[0] is ast.IndexExpr
                index_expr := value_assign.rhs[0] as ast.IndexExpr
                assert index_expr.lhs !is ast.CastExpr
                found = true
            }
        }
    }
    assert found
}

fn test_transform_for_in_smartcast_variant_array_field_keeps_element_type() {
    field_type := types.Type(types.Struct{
        name:   'Field'
        fields: [
            types.Field{
                name: 'name'
                typ:  types.Type(types.string_)
            },
        ]
    })
    enum_type := types.Type(types.Struct{
        name:   'Enum'
        fields: [
            types.Field{
                name: 'fields'
                typ:  types.Type(types.Array{
                    elem_type: field_type
                })
            },
        ]
    })
    sum_type := types.Type(types.SumType{
        name:     'Type'
        variants: [enum_type]
    })
    mut local_scope := types.new_scope(unsafe { nil })
    local_scope.insert('typ', value_object_from_type(sum_type))
    mut module_scope := types.new_scope(unsafe { nil })
    module_scope.insert_type('Enum', enum_type)
    module_scope.insert_type('Type', sum_type)
    mut t := create_test_transformer()
    t.scope = local_scope
    t.cur_module = 'main'
    t.cached_scopes = {
        'main': module_scope
    }
    t.push_smartcast_full('typ', 'Enum', 'Enum', 'Type')
    result := t.transform_for_stmt(ast.ForStmt{
        init: ast.Stmt(ast.ForInStmt{
            value: ast.Expr(ast.Ident{
                name: 'field'
            })
            expr:  ast.Expr(ast.SelectorExpr{
                lhs: ast.Expr(ast.Ident{
                    name: 'typ'
                })
                rhs: ast.Ident{
                    name: 'fields'
                }
            })
        })
    })
    assert result.stmts.len > 0
    assert result.stmts[0] is ast.AssignStmt
    value_assign := result.stmts[0] as ast.AssignStmt
    assert value_assign.lhs.len == 1
    assert value_assign.lhs[0] is ast.Ident
    value_ident := value_assign.lhs[0] as ast.Ident
    value_typ := t.get_synth_type(value_ident.pos) or {
        panic('missing smartcast for-in value type')
    }
    assert value_typ.name() == 'Field'
    assert value_assign.rhs.len == 1
    assert value_assign.rhs[0] is ast.IndexExpr
    index_expr := value_assign.rhs[0] as ast.IndexExpr
    index_typ := t.get_synth_type(index_expr.pos) or {
        panic('missing smartcast for-in index type')
    }
    assert index_typ.name() == 'Field'
}

fn test_transform_for_in_nested_fixed_array_value_registers_decl_type() {
    elem_type := types.Type(types.ArrayFixed{
        len:       3
        elem_type: types.Type(types.f32_)
    })
    iter_type := types.Type(types.ArrayFixed{
        len:       4
        elem_type: elem_type
    })
    mut t := create_transformer_with_vars({
        'corners': iter_type
    })
    result := t.transform_for_stmt(ast.ForStmt{
        init:  ast.Stmt(ast.ForInStmt{
            value: ast.Expr(ast.Ident{
                name: 'c'
            })
            expr:  ast.Expr(ast.Ident{
                name: 'corners'
            })
        })
        stmts: [
            ast.Stmt(ast.ExprStmt{
                expr: ast.Expr(ast.IndexExpr{
                    lhs:  ast.Expr(ast.Ident{
                        name: 'c'
                    })
                    expr: ast.Expr(ast.BasicLiteral{
                        kind:  .number
                        value: '0'
                    })
                })
            }),
        ]
    })
    assert result.stmts.len > 0
    assert result.stmts[0] is ast.AssignStmt
    value_assign := result.stmts[0] as ast.AssignStmt
    assert value_assign.lhs.len == 1
    assert value_assign.lhs[0] is ast.Ident
    value_ident := value_assign.lhs[0] as ast.Ident
    assert value_ident.name == 'c'
    assert value_ident.pos.id != 0
    value_decl_type := t.get_synth_type(value_ident.pos) or {
        assert false, 'missing for-in value declaration type'
        return
    }
    assert value_decl_type == elem_type
}

fn test_transform_fixed_array_of_array_literals_keeps_inner_arrays_dynamic() {
    env, files := transform_code_with_env_for_test('
fn f() {
    corners := [[f32(1), 2, 3], [f32(4), 5, 6]]!
    for c in corners {
        _ = c[0]
    }
}
')
    mut found_decl := false
    mut found_loop := false
    for file in files {
        for stmt in file.stmts {
            if stmt is ast.FnDecl && stmt.name == 'f' {
                assert stmt.stmts.len >= 2
                assert stmt.stmts[0] is ast.AssignStmt
                corners_decl := stmt.stmts[0] as ast.AssignStmt
                assert corners_decl.rhs.len == 1
                assert corners_decl.rhs[0] is ast.ArrayInitExpr
                corners_init := corners_decl.rhs[0] as ast.ArrayInitExpr
                assert corners_init.typ is ast.Type
                assert corners_init.typ as ast.Type is ast.ArrayFixedType
                corners_type := corners_init.typ as ast.Type
                fixed_type := corners_type as ast.ArrayFixedType
                assert fixed_type.elem_type is ast.Type
                assert fixed_type.elem_type as ast.Type is ast.ArrayType
                assert corners_init.exprs.len == 2
                assert corners_init.exprs[0] is ast.CallExpr
                assert corners_init.exprs[1] is ast.CallExpr
                found_decl = true

                assert stmt.stmts[1] is ast.ForStmt
                for_stmt := stmt.stmts[1] as ast.ForStmt
                assert for_stmt.stmts.len > 0
                assert for_stmt.stmts[0] is ast.AssignStmt
                value_assign := for_stmt.stmts[0] as ast.AssignStmt
                assert value_assign.lhs.len == 1
                assert value_assign.lhs[0] is ast.Ident
                value_ident := value_assign.lhs[0] as ast.Ident
                value_type := env.get_expr_type(value_ident.pos.id) or {
                    assert false, 'missing loop value type'
                    return
                }
                assert value_type is types.Array
                found_loop = true
            }
        }
    }
    assert found_decl
    assert found_loop
}

fn test_transform_for_in_mixed_float_array_uses_float_data_cast() {
    files := transform_code_for_test('
fn f() {
    for _, i in [8.0, 1000, 175_616] {
        _ = i
    }
}
')
    mut found := false
    for file in files {
        for stmt in file.stmts {
            if stmt is ast.FnDecl && stmt.name == 'f' {
                assert stmt.stmts.len == 1
                assert stmt.stmts[0] is ast.ForStmt
                for_stmt := stmt.stmts[0] as ast.ForStmt
                assert for_stmt.stmts.len > 0
                assert for_stmt.stmts[0] is ast.AssignStmt
                value_assign := for_stmt.stmts[0] as ast.AssignStmt
                assert value_assign.rhs.len == 1
                assert value_assign.rhs[0] is ast.IndexExpr
                index_expr := value_assign.rhs[0] as ast.IndexExpr
                assert index_expr.lhs is ast.CastExpr
                cast_expr := index_expr.lhs as ast.CastExpr
                assert cast_expr.typ is ast.Ident
                assert (cast_expr.typ as ast.Ident).name == 'f64*'
                found = true
            }
        }
    }
    assert found
}

fn test_transform_selector_field_index_method_receiver_stays_index_expr() {
    files := transform_code_for_test('
struct EmbeddedFile {
    bytes []u8
}

fn (b u8) hex() string {
    return "x"
}

fn f(emfile EmbeddedFile) string {
    return emfile.bytes[0].hex()
}
')
    mut found := false
    for file in files {
        for stmt in file.stmts {
            if stmt is ast.FnDecl && stmt.name == 'f' {
                call := find_call_with_lhs_suffix_in_stmts(stmt.stmts, 'u8__hex') or {
                    assert false, 'missing transformed u8.hex call'
                    return
                }
                assert call.args.len == 1
                assert call.args[0] is ast.IndexExpr, 'method receiver should stay an index expression, got ${call.args[0].type_name()}'
                found = true
            }
        }
    }
    assert found
}

fn test_map_index_or_assign_uses_selector_field_map_type() {
    map_type := types.Type(types.Map{
        key_type:   string_type()
        value_type: string_type()
    })
    handler_type := types.Type(types.Struct{
        name:   'Handler'
        fields: [
            types.Field{
                name: 'files'
                typ:  map_type
            },
        ]
    })
    mut module_scope := types.new_scope(unsafe { nil })
    module_scope.insert('Handler', handler_type)
    mut t := create_transformer_with_vars({
        'handler': handler_type
    })
    t.cur_module = 'main'
    t.cached_scopes = {
        'main': module_scope
    }

    or_expr := ast.OrExpr{
        expr:  ast.IndexExpr{
            lhs:  ast.SelectorExpr{
                lhs: ast.Ident{
                    name: 'handler'
                }
                rhs: ast.Ident{
                    name: 'files'
                }
            }
            expr: ast.StringLiteral{
                kind:  .v
                value: "'index.html'"
            }
        }
        stmts: [
            ast.Stmt(ast.ReturnStmt{
                exprs: [
                    ast.Expr(ast.StringLiteral{
                        kind:  .v
                        value: "''"
                    }),
                ]
            }),
        ]
    }
    result := t.try_expand_map_index_or_assign(ast.AssignStmt{
        op:  .decl_assign
        lhs: [ast.Expr(ast.Ident{
            name: 'file'
        })]
        rhs: [ast.Expr(or_expr)]
    }, or_expr) or {
        assert false, 'expected selector-field map or assignment to be expanded'
        return
    }

    assert result.len == 3
    temp_assign := result[0]
    assert temp_assign is ast.AssignStmt
    temp_rhs := (temp_assign as ast.AssignStmt).rhs[0]
    assert temp_rhs is ast.CallExpr
    temp_call := temp_rhs as ast.CallExpr
    assert temp_call.lhs is ast.Ident
    assert (temp_call.lhs as ast.Ident).name == 'map__get_check'
}

fn test_transform_init_expr_empty_typed_map_lowers_to_new_map() {
    mut t := create_test_transformer()

    expr := ast.InitExpr{
        typ: ast.Expr(ast.Type(ast.MapType{
            key_type:   ast.Ident{
                name: 'string'
            }
            value_type: ast.Ident{
                name: 'int'
            }
        }))
    }

    result := t.transform_init_expr(expr)
    assert result is ast.CallExpr, 'expected CallExpr, got ${result.type_name()}'
    call := result as ast.CallExpr
    assert call.lhs is ast.Ident
    assert (call.lhs as ast.Ident).name == 'new_map'
    assert call.args.len == 6
}

fn test_transform_string_index_or_assign_expands_to_bounds_check() {
    mut t := create_transformer_with_vars({
        's': types.Type(types.string_)
        'i': types.Type(types.int_)
    })
    or_expr := ast.OrExpr{
        expr:  ast.IndexExpr{
            lhs:  ast.Ident{
                name: 's'
            }
            expr: ast.Ident{
                name: 'i'
            }
        }
        stmts: [
            ast.Stmt(ast.ReturnStmt{
                exprs: [
                    ast.Expr(ast.BasicLiteral{
                        kind:  .number
                        value: '0'
                    }),
                ]
            }),
        ]
    }
    result := t.try_expand_array_index_or_assign(ast.AssignStmt{
        op:  .decl_assign
        lhs: [ast.Expr(ast.Ident{
            name: 'ch'
        })]
        rhs: [ast.Expr(or_expr)]
    }, or_expr) or {
        assert false, 'expected string index or assignment to be expanded'
        return
    }
    assert result.len == 2
    assert result[0] is ast.AssignStmt
    if_stmt := (result[1] as ast.ExprStmt).expr as ast.IfExpr
    assert if_stmt.cond is ast.InfixExpr
    cond := if_stmt.cond as ast.InfixExpr
    assert cond.op == .lt
    assert cond.rhs is ast.SelectorExpr
    assert (cond.rhs as ast.SelectorExpr).rhs.name == 'len'
}

fn test_array_index_or_assign_with_void_fallback_does_not_assign_void() {
    mut t := create_transformer_with_vars({
        'items': types.Type(types.Array{
            elem_type: types.string_
        })
        'i':     types.Type(types.int_)
        'path':  types.Type(types.string_)
    })
    or_expr := ast.OrExpr{
        expr:  ast.IndexExpr{
            lhs:  ast.Ident{
                name: 'items'
            }
            expr: ast.Ident{
                name: 'i'
            }
        }
        stmts: [
            ast.Stmt(ast.ExprStmt{
                expr: ast.CallExpr{
                    lhs: ast.Ident{
                        name: 'eprintln_exit'
                    }
                }
            }),
        ]
    }
    result := t.try_expand_array_index_or_assign(ast.AssignStmt{
        op:  .assign
        lhs: [ast.Expr(ast.Ident{
            name: 'path'
        })]
        rhs: [ast.Expr(or_expr)]
    }, or_expr) or {
        assert false, 'expected array index or assignment to be expanded'
        return
    }
    if_stmt := (result[0] as ast.ExprStmt).expr as ast.IfExpr
    else_if := if_stmt.else_expr as ast.IfExpr
    assert else_if.stmts.len == 1
    assert else_if.stmts[0] is ast.ExprStmt
    assert else_if.stmts[0] !is ast.AssignStmt
}

fn test_is_string_expr_string_literal() {
    mut t := create_test_transformer()

    expr := ast.StringLiteral{
        value: 'hello'
    }

    assert t.is_string_expr(expr), 'StringLiteral should be detected as string'
}

fn test_is_string_expr_basic_literal_string() {
    mut t := create_test_transformer()

    expr := ast.BasicLiteral{
        value: 'hello'
        kind:  .string
    }

    assert t.is_string_expr(expr), 'BasicLiteral with .string kind should be detected as string'
}

fn test_is_string_expr_cast_to_string() {
    mut t := create_test_transformer()

    // Create: (string){...}
    expr := ast.CastExpr{
        typ:  ast.Ident{
            name: 'string'
        }
        expr: ast.BasicLiteral{
            value: 'test'
            kind:  .string
        }
    }

    assert t.is_string_expr(expr), 'CastExpr to string should be detected as string'
}

fn test_is_string_expr_method_call() {
    mut t := create_test_transformer()

    // Create: s.to_upper()
    expr := ast.CallExpr{
        lhs:  ast.SelectorExpr{
            lhs: ast.Ident{
                name: 's'
            }
            rhs: ast.Ident{
                name: 'to_upper'
            }
        }
        args: []
    }

    assert t.is_string_expr(expr), 'method call to_upper() should be detected as string'
}

fn test_is_string_returning_method() {
    t := create_test_transformer()

    // Test various string-returning methods
    assert t.is_string_returning_method('str')
    assert t.is_string_returning_method('string')
    assert t.is_string_returning_method('to_upper')
    assert t.is_string_returning_method('to_lower')
    assert t.is_string_returning_method('substr')
    assert t.is_string_returning_method('hex')
    assert t.is_string_returning_method('join')

    // Non-string methods
    assert !t.is_string_returning_method('len')
    assert !t.is_string_returning_method('push')
}

// --- OrExpr expansion tests ---

fn test_expand_single_or_expr_defaults_to_result() {
    // When type lookup fails (empty environment), expand_single_or_expr
    // should default to Result expansion instead of returning OrExpr unchanged.
    mut t := create_test_transformer()

    // Build: some_call() or { 0 }
    or_expr := ast.OrExpr{
        expr:  ast.CallExpr{
            lhs:  ast.Ident{
                name: 'some_call'
            }
            args: []
        }
        stmts: [
            ast.Stmt(ast.ExprStmt{
                expr: ast.BasicLiteral{
                    kind:  .number
                    value: '0'
                }
            }),
        ]
    }

    mut prefix_stmts := []ast.Stmt{}
    result := t.expand_single_or_expr(or_expr, mut prefix_stmts)

    // Should generate prefix statements (temp assign + if-check)
    assert prefix_stmts.len == 2, 'expected 2 prefix stmts (assign + if), got ${prefix_stmts.len}'

    // First prefix stmt: _or_t1 := some_call()
    assert prefix_stmts[0] is ast.AssignStmt
    assign := prefix_stmts[0] as ast.AssignStmt
    assert assign.op == .decl_assign
    assert assign.lhs.len == 1
    temp_ident := assign.lhs[0]
    assert temp_ident is ast.Ident
    temp_name := (temp_ident as ast.Ident).name
    assert temp_name.starts_with('_or_t'), 'expected temp name starting with _or_t, got ${temp_name}'

    // Second prefix stmt: if _or_t1.is_error { ... } (Result pattern, not Option pattern)
    assert prefix_stmts[1] is ast.ExprStmt
    if_stmt := (prefix_stmts[1] as ast.ExprStmt).expr
    assert if_stmt is ast.IfExpr
    if_expr := if_stmt as ast.IfExpr
    // For Result: condition is _or_t1.is_error (SelectorExpr)
    assert if_expr.cond is ast.SelectorExpr, 'expected SelectorExpr (Result pattern), got ${if_expr.cond.type_name()}'
    sel := if_expr.cond as ast.SelectorExpr
    assert sel.rhs.name == 'is_error', 'expected is_error selector for Result, got ${sel.rhs.name}'

    // base_type is unknown (empty env), defaults to 'int' => not void => returns data access
    assert result is ast.SelectorExpr, 'expected SelectorExpr (.data access) for default base type, got ${result.type_name()}'
}

fn test_expand_single_or_expr_with_return_in_or_block() {
    // Or-block with return statement (control flow pattern):
    // some_call() or { return }
    mut t := create_test_transformer()

    or_expr := ast.OrExpr{
        expr:  ast.CallExpr{
            lhs:  ast.Ident{
                name: 'some_call'
            }
            args: []
        }
        stmts: [ast.Stmt(ast.FlowControlStmt{
            op: .key_return
        })]
    }

    mut prefix_stmts := []ast.Stmt{}
    result := t.expand_single_or_expr(or_expr, mut prefix_stmts)

    // Should still generate prefix statements
    assert prefix_stmts.len == 2, 'expected 2 prefix stmts, got ${prefix_stmts.len}'

    // The if-block body should contain only the return statement (err not used, so no err assign)
    if_stmt := (prefix_stmts[1] as ast.ExprStmt).expr as ast.IfExpr
    assert if_stmt.stmts.len == 2, 'expected 2 stmt in if body (return only, err not used), got ${if_stmt.stmts.len}'

    // base_type is unknown => defaults to 'int' => not void => returns data access
    assert result is ast.SelectorExpr, 'expected SelectorExpr (.data access) for default base type'
}

fn test_transform_expr_or_expr_wraps_in_unsafe() {
    // transform_expr with OrExpr should wrap in UnsafeExpr (compound expression)
    mut t := create_test_transformer()

    or_expr := ast.OrExpr{
        expr:  ast.CallExpr{
            lhs:  ast.Ident{
                name: 'get_value'
            }
            args: []
        }
        stmts: [
            ast.Stmt(ast.ExprStmt{
                expr: ast.BasicLiteral{
                    kind:  .number
                    value: '42'
                }
            }),
        ]
    }

    result := t.transform_expr(or_expr)

    // Should be wrapped in UnsafeExpr (GCC compound expression)
    assert result is ast.UnsafeExpr, 'expected UnsafeExpr wrapper, got ${result.type_name()}'
    unsafe_expr := result as ast.UnsafeExpr
    // Stmts: temp assign, if-check, and the result ExprStmt
    assert unsafe_expr.stmts.len == 3, 'expected 3 stmts in UnsafeExpr, got ${unsafe_expr.stmts.len}'

    // First stmt: temp assign
    assert unsafe_expr.stmts[0] is ast.AssignStmt

    // Second stmt: if-check with is_error (Result pattern)
    assert unsafe_expr.stmts[1] is ast.ExprStmt
    if_check := (unsafe_expr.stmts[1] as ast.ExprStmt).expr
    assert if_check is ast.IfExpr

    // Last stmt should be ExprStmt with the result expression
    last := unsafe_expr.stmts[2]
    assert last is ast.ExprStmt
}

fn test_get_or_block_stmts_and_value_ignores_trailing_empty_stmt() {
    mut t := create_test_transformer()

    stmts := [
        ast.Stmt(ast.ExprStmt{
            expr: ast.Tuple{
                exprs: [
                    ast.Expr(ast.BasicLiteral{
                        kind:  .number
                        value: '1'
                    }),
                    ast.Expr(ast.BasicLiteral{
                        kind:  .number
                        value: '2'
                    }),
                ]
            }
        }),
        ast.empty_stmt,
    ]

    side_effects, value := t.get_or_block_stmts_and_value(stmts)

    assert side_effects.len == 0
    assert value is ast.Tuple
    assert (value as ast.Tuple).exprs.len == 2
}

// --- IfGuardExpr expansion tests ---

fn test_transform_expr_if_guard_standalone_evaluates_rhs() {
    // Standalone IfGuardExpr in transform_expr should just evaluate RHS
    mut t := create_test_transformer()

    guard := ast.IfGuardExpr{
        stmt: ast.AssignStmt{
            op:  .decl_assign
            lhs: [ast.Expr(ast.Ident{
                name: 'x'
            })]
            rhs: [
                ast.Expr(ast.CallExpr{
                    lhs:  ast.Ident{
                        name: 'some_func'
                    }
                    args: []
                }),
            ]
        }
    }

    result := t.transform_expr(guard)

    // Should evaluate to the RHS (the call expression)
    assert result is ast.CallExpr, 'expected CallExpr, got ${result.type_name()}'
    call := result as ast.CallExpr
    assert call.lhs is ast.Ident
    assert (call.lhs as ast.Ident).name == 'some_func'
}

fn test_transform_expr_if_guard_empty_rhs() {
    // IfGuardExpr with empty RHS should pass through
    mut t := create_test_transformer()

    guard := ast.IfGuardExpr{
        stmt: ast.AssignStmt{
            op:  .decl_assign
            lhs: [ast.Expr(ast.Ident{
                name: 'x'
            })]
            rhs: []
        }
    }

    result := t.transform_expr(guard)

    // With empty RHS, should return the guard as-is
    assert result is ast.IfGuardExpr
}

fn test_transform_if_expr_with_if_guard_result_uses_temp_var() {
    // IfExpr with IfGuardExpr condition for Result type should use temp var pattern
    // Since env is empty, type lookups fail, so this hits the non-option path
    // which does map/array/simple transformation
    mut t := create_test_transformer()

    // Build: if x := result_call() { body } else { else_body }
    if_expr := ast.IfExpr{
        cond:      ast.IfGuardExpr{
            stmt: ast.AssignStmt{
                op:  .decl_assign
                lhs: [ast.Expr(ast.Ident{
                    name: 'x'
                })]
                rhs: [
                    ast.Expr(ast.CallExpr{
                        lhs:  ast.Ident{
                            name: 'result_call'
                        }
                        args: []
                    }),
                ]
            }
        }
        stmts:     [ast.Stmt(ast.ExprStmt{
            expr: ast.Ident{
                name: 'x'
            }
        })]
        else_expr: ast.BasicLiteral{
            kind:  .number
            value: '0'
        }
    }

    result := t.transform_if_expr(if_expr)

    // The IfGuardExpr should be expanded - result should NOT contain IfGuardExpr
    // It should be a regular IfExpr with a non-guard condition
    assert result is ast.IfExpr, 'expected IfExpr, got ${result.type_name()}'
    result_if := result as ast.IfExpr
    assert result_if.cond !is ast.IfGuardExpr, 'IfGuardExpr should have been expanded'
}

fn test_transform_if_expr_with_if_guard_blank_lhs() {
    // if _ := some_call() { body }  — blank LHS should skip variable assignment
    mut t := create_test_transformer()

    if_expr := ast.IfExpr{
        cond:      ast.IfGuardExpr{
            stmt: ast.AssignStmt{
                op:  .decl_assign
                lhs: [ast.Expr(ast.Ident{
                    name: '_'
                })]
                rhs: [
                    ast.Expr(ast.CallExpr{
                        lhs:  ast.Ident{
                            name: 'some_call'
                        }
                        args: []
                    }),
                ]
            }
        }
        stmts:     [
            ast.Stmt(ast.ExprStmt{
                expr: ast.BasicLiteral{
                    kind:  .number
                    value: '1'
                }
            }),
        ]
        else_expr: ast.BasicLiteral{
            kind:  .number
            value: '0'
        }
    }

    result := t.transform_if_expr(if_expr)

    assert result is ast.IfExpr, 'expected IfExpr, got ${result.type_name()}'
    result_if := result as ast.IfExpr
    assert result_if.cond !is ast.IfGuardExpr, 'IfGuardExpr should have been expanded'
    // With blank LHS, the body should NOT have a guard assignment prepended
    // Body should just have the original statement (transformed)
    assert result_if.stmts.len == 1, 'expected 1 stmt in body (no guard assign for blank), got ${result_if.stmts.len}'
}

fn test_if_guard_option_payload_assignment_uses_unwrapped_lhs_type() {
    opt_string := types.Type(types.OptionType{
        base_type: types.string_
    })
    mut env := types.Environment.new()
    call_pos := token.Pos{
        id: 1001
    }
    guard_pos := token.Pos{
        id: 1002
    }
    if_pos := token.Pos{
        id: 1003
    }
    env.set_expr_type(call_pos.id, opt_string)
    env.set_expr_type(guard_pos.id, opt_string)
    env.set_expr_type(if_pos.id, types.Type(types.Array{
        elem_type: types.string_
    }))
    mut scope := types.new_scope(unsafe { nil })
    scope.insert('resolved_mod', opt_string)
    mut t := &Transformer{
        pref:                        &vpref.Preferences{}
        env:                         unsafe { env }
        scope:                       scope
        fn_root_scope:               scope
        needed_clone_fns:            map[string]string{}
        needed_array_contains_fns:   map[string]ArrayMethodInfo{}
        needed_array_index_fns:      map[string]ArrayMethodInfo{}
        needed_array_last_index_fns: map[string]ArrayMethodInfo{}
        synth_types:                 map[int]types.Type{}
    }
    stmt := ast.ExprStmt{
        expr: ast.Expr(ast.IfExpr{
            pos:   if_pos
            cond:  ast.Expr(ast.IfGuardExpr{
                stmt: ast.AssignStmt{
                    op:  .decl_assign
                    lhs: [
                        ast.Expr(ast.Ident{
                            name: 'resolved_mod'
                            pos:  guard_pos
                        }),
                    ]
                    rhs: [
                        ast.Expr(ast.CallExpr{
                            lhs: ast.Expr(ast.Ident{
                                name: 'resolve_mod'
                            })
                            pos: call_pos
                        }),
                    ]
                }
            })
            stmts: [
                ast.Stmt(ast.ExprStmt{
                    expr: ast.Expr(ast.Ident{
                        name: 'resolved_mod'
                    })
                }),
            ]
        })
    }
    expanded := t.try_expand_if_guard_stmt(stmt) or {
        assert false, 'if-guard did not expand'
        return
    }
    assert expanded.len == 2
    assert expanded[0] is ast.AssignStmt
    temp_assign := expanded[0] as ast.AssignStmt
    assert temp_assign.lhs[0] is ast.Ident
    temp_ident := temp_assign.lhs[0] as ast.Ident
    temp_type := t.synth_types[temp_ident.pos.id] or {
        assert false, 'guard temp type was not registered'
        return
    }
    assert temp_type.name() == '?string'
    assert expanded[1] is ast.ExprStmt
    if_stmt := (expanded[1] as ast.ExprStmt).expr as ast.IfExpr
    assert if_stmt.stmts[0] is ast.AssignStmt
    guard_assign := if_stmt.stmts[0] as ast.AssignStmt
    assert guard_assign.rhs[0] is ast.SelectorExpr, 'payload assignment was wrapped in ${guard_assign.rhs[0].type_name()}'
    payload := guard_assign.rhs[0] as ast.SelectorExpr
    assert payload.rhs.name == 'data'
    lhs_type := t.lookup_var_type('resolved_mod') or {
        assert false, 'guard payload variable type was not registered'
        return
    }
    assert lhs_type.name() == 'string'
}

fn test_if_guard_map_lookup_temp_keeps_pointer_type() {
    map_type := types.Type(types.Map{
        key_type:   types.Type(types.string_)
        value_type: types.Type(types.string_)
    })
    mut t := create_transformer_with_vars({
        'import_aliases': map_type
        'key':            types.Type(types.string_)
    })
    t.synth_types = map[int]types.Type{}
    if_pos := token.Pos{
        id: 9101
    }
    t.env.set_expr_type(if_pos.id, types.Type(types.string_))
    stmt := ast.ExprStmt{
        expr: ast.Expr(ast.IfExpr{
            pos:       if_pos
            cond:      ast.Expr(ast.IfGuardExpr{
                stmt: ast.AssignStmt{
                    op:  .decl_assign
                    lhs: [
                        ast.Expr(ast.Ident{
                            name: 'alias'
                        }),
                    ]
                    rhs: [
                        ast.Expr(ast.IndexExpr{
                            lhs:  ast.Expr(ast.Ident{
                                name: 'import_aliases'
                            })
                            expr: ast.Expr(ast.Ident{
                                name: 'key'
                            })
                        }),
                    ]
                }
            })
            stmts:     [
                ast.Stmt(ast.ExprStmt{
                    expr: ast.Expr(ast.Ident{
                        name: 'alias'
                    })
                }),
            ]
            else_expr: ast.Expr(ast.StringLiteral{
                kind:  .v
                value: 'missing'
            })
        })
    }
    expanded := t.try_expand_if_guard_stmt(stmt) or {
        assert false, 'map if-guard did not expand'
        return
    }
    assert expanded.len == 2
    assert expanded[0] is ast.AssignStmt
    temp_assign := expanded[0] as ast.AssignStmt
    assert temp_assign.lhs[0] is ast.Ident
    temp_ident := temp_assign.lhs[0] as ast.Ident
    temp_type := t.synth_types[temp_ident.pos.id] or {
        assert false, 'map guard temp type was not registered'
        return
    }
    assert temp_type is types.Pointer
    temp_pointer := temp_type as types.Pointer
    assert temp_pointer.base_type.name() == 'string'
    assert expanded[1] is ast.ExprStmt
    if_stmt := (expanded[1] as ast.ExprStmt).expr as ast.IfExpr
    assert if_stmt.pos.id != temp_ident.pos.id
    if_type := t.synth_types[if_stmt.pos.id] or {
        assert false, 'rewritten if expression type was not registered'
        return
    }
    assert if_type.name() == 'string'
}

fn test_native_smartcast_alias_variant_uses_direct_data_cast() {
    mut ast_scope := types.new_scope(unsafe { nil })
    ast_scope.insert('EmptyExpr', types.Type(types.Alias{
        name:      'EmptyExpr'
        base_type: types.Type(types.Primitive{
            props: .integer | .unsigned
            size:  8
        })
    }))
    mut t := create_test_transformer()
    t.pref.backend = .arm64
    t.cached_scopes['ast'] = ast_scope
    ctx := SmartcastContext{
        expr:         'else_if.cond'
        variant:      'ast__EmptyExpr'
        variant_full: 'ast__EmptyExpr'
        sumtype:      'ast__Expr'
    }
    out := t.apply_smartcast_direct_ctx(ast.Expr(ast.SelectorExpr{
        lhs: ast.Expr(ast.Ident{
            name: 'else_if'
        })
        rhs: ast.Ident{
            name: 'cond'
        }
    }), ctx)
    assert out is ast.ParenExpr
    cast := (out as ast.ParenExpr).expr
    assert cast is ast.CastExpr, 'direct-data alias smartcast must not dereference _data'
    assert (cast as ast.CastExpr).typ is ast.Ident
    assert ((cast as ast.CastExpr).typ as ast.Ident).name == 'ast__EmptyExpr'
}

fn test_sumtype_alias_variant_init_uses_direct_data() {
    empty_expr_type := types.Type(types.Alias{
        name:      'EmptyExpr'
        base_type: types.Type(types.Primitive{
            props: .integer | .unsigned
            size:  8
        })
    })
    mut ast_scope := types.new_scope(unsafe { nil })
    ast_scope.insert('EmptyExpr', empty_expr_type)
    ast_scope.insert('FnType', types.Type(types.Struct{
        name: 'FnType'
    }))
    ast_scope.insert('Expr', types.Type(types.SumType{
        name:     'Expr'
        variants: [empty_expr_type]
    }))
    mut t := create_test_transformer()
    t.cur_module = 'ast'
    t.cached_scopes['ast'] = ast_scope
    assert t.sumtype_variant_init_data_is_direct('EmptyExpr')
    assert !t.sumtype_variant_init_data_is_direct('FnType')
    wrapped := t.build_sumtype_init(ast.Expr(ast.CastExpr{
        typ:  ast.Expr(ast.Ident{
            name: 'EmptyExpr'
        })
        expr: ast.Expr(ast.BasicLiteral{
            kind:  .number
            value: '0'
        })
    }), 'EmptyExpr', 'Expr') or {
        assert false, 'EmptyExpr should be wrapped as Expr'
        return
    }
    assert wrapped is ast.InitExpr
    init := wrapped as ast.InitExpr
    assert init.fields.len == 2
    data_value := init.fields[1].value
    assert data_value is ast.CastExpr
    data_cast := data_value as ast.CastExpr
    assert data_cast.expr is ast.CastExpr, 'alias-to-scalar variants should be stored inline'
    assert data_cast.expr !is ast.CallExpr, 'alias-to-scalar variants should not be copied with memdup'
}

fn test_transform_if_expr_preserves_else() {
    // Ensure else branch is preserved during IfGuardExpr expansion
    mut t := create_test_transformer()

    if_expr := ast.IfExpr{
        cond:      ast.IfGuardExpr{
            stmt: ast.AssignStmt{
                op:  .decl_assign
                lhs: [ast.Expr(ast.Ident{
                    name: 'val'
                })]
                rhs: [
                    ast.Expr(ast.CallExpr{
                        lhs:  ast.Ident{
                            name: 'try_get'
                        }
                        args: []
                    }),
                ]
            }
        }
        stmts:     [ast.Stmt(ast.ExprStmt{
            expr: ast.Ident{
                name: 'val'
            }
        })]
        else_expr: ast.BasicLiteral{
            kind:  .number
            value: '-1'
        }
    }

    result := t.transform_if_expr(if_expr)

    // Result should have an else branch
    if result is ast.IfExpr {
        assert result.else_expr !is ast.EmptyExpr, 'else branch should be preserved'
    } else if result is ast.UnsafeExpr {
        // Result expansion wraps in UnsafeExpr; find the inner IfExpr
        mut found_if := false
        for s in result.stmts {
            if s is ast.ExprStmt {
                if s.expr is ast.IfExpr {
                    assert s.expr.else_expr !is ast.EmptyExpr, 'else branch should be preserved in UnsafeExpr'
                    found_if = true
                }
            }
        }
        assert found_if, 'expected IfExpr inside UnsafeExpr'
    } else {
        assert false, 'expected IfExpr or UnsafeExpr, got ${result.type_name()}'
    }
}

fn test_transform_for_in_stmt_lowers_to_for_stmt() {
    mut t := create_test_transformer()
    result := t.transform_for_in_stmt(ast.ForInStmt{
        value: ast.Ident{
            name: 'v'
        }
        expr:  ast.Ident{
            name: 'items'
        }
    })

    // NOTE: transform_for_in_stmt returns `ast.ForStmt` directly.
    assert result.init is ast.AssignStmt, 'expected lowered init AssignStmt, got ${result.init.type_name()}'
}

fn test_static_method_call_treats_type_object_receiver_as_static() {
    mut scope := types.new_scope(unsafe { nil })
    scope.insert('LineBufferReader', types.TypeObject{
        typ: types.Type(types.Struct{
            name: 'LineBufferReader'
        })
    })
    mut t := create_test_transformer()
    t.scope = scope
    assert t.is_static_method_call(ast.Expr(ast.Ident{
        name: 'LineBufferReader'
    }))
}

// --- Inline array `in` optimization tests ---

fn test_transform_in_inline_array_expands_to_eq_chain() {
    // x in [1, 2, 3] => (x == 1 || x == 2 || x == 3)
    mut t := create_transformer_with_vars({
        'x': types.Type(types.int_)
    })

    expr := ast.InfixExpr{
        op:  .key_in
        lhs: ast.Ident{
            name: 'x'
        }
        rhs: ast.ArrayInitExpr{
            exprs: [
                ast.Expr(ast.BasicLiteral{
                    kind:  .number
                    value: '1'
                }),
                ast.Expr(ast.BasicLiteral{
                    kind:  .number
                    value: '2'
                }),
                ast.Expr(ast.BasicLiteral{
                    kind:  .number
                    value: '3'
                }),
            ]
        }
    }

    result := t.transform_infix_expr(expr)

    // Should be: (x == 1 || x == 2 || x == 3)
    // Top level: (x == 1 || x == 2) || (x == 3)
    assert result is ast.InfixExpr, 'expected InfixExpr (||), got ${result.type_name()}'
    top := result as ast.InfixExpr
    assert top.op == .logical_or, 'expected || at top, got ${top.op}'
    // RHS should be x == 3
    assert top.rhs is ast.InfixExpr
    rhs := top.rhs as ast.InfixExpr
    assert rhs.op == .eq
    assert rhs.lhs is ast.Ident
    assert (rhs.lhs as ast.Ident).name == 'x'
    assert rhs.rhs is ast.BasicLiteral
    assert (rhs.rhs as ast.BasicLiteral).value == '3'
}

fn test_transform_in_inline_array_single_element() {
    // x in [5] => x == 5
    mut t := create_transformer_with_vars({
        'x': types.Type(types.int_)
    })

    expr := ast.InfixExpr{
        op:  .key_in
        lhs: ast.Ident{
            name: 'x'
        }
        rhs: ast.ArrayInitExpr{
            exprs: [
                ast.Expr(ast.BasicLiteral{
                    kind:  .number
                    value: '5'
                }),
            ]
        }
    }

    result := t.transform_infix_expr(expr)

    // Single element: x == 5
    assert result is ast.InfixExpr, 'expected InfixExpr (==), got ${result.type_name()}'
    eq := result as ast.InfixExpr
    assert eq.op == .eq
    assert eq.lhs is ast.Ident
    assert (eq.lhs as ast.Ident).name == 'x'
    assert eq.rhs is ast.BasicLiteral
    assert (eq.rhs as ast.BasicLiteral).value == '5'
}

fn test_transform_not_in_inline_array_wraps_with_not() {
    // x !in [1, 2] => !(x == 1 || x == 2)
    mut t := create_transformer_with_vars({
        'x': types.Type(types.int_)
    })

    expr := ast.InfixExpr{
        op:  .not_in
        lhs: ast.Ident{
            name: 'x'
        }
        rhs: ast.ArrayInitExpr{
            exprs: [
                ast.Expr(ast.BasicLiteral{
                    kind:  .number
                    value: '1'
                }),
                ast.Expr(ast.BasicLiteral{
                    kind:  .number
                    value: '2'
                }),
            ]
        }
    }

    result := t.transform_infix_expr(expr)

    // Should be: !(x == 1 || x == 2)
    assert result is ast.PrefixExpr, 'expected PrefixExpr (!), got ${result.type_name()}'
    prefix := result as ast.PrefixExpr
    assert prefix.op == .not
    assert prefix.expr is ast.InfixExpr
    inner := prefix.expr as ast.InfixExpr
    assert inner.op == .logical_or
}

fn test_transformer_preserves_pointer_lifetime_in_v_syntax_but_not_c_names() {
    mut t := create_test_transformer()
    ptr_type := types.Type(types.Pointer{
        base_type: types.Type(types.NamedType('Foo'))
        lifetime:  'a'
    })

    ast_expr := t.type_to_ast_type_expr(ptr_type)
    assert ast_expr is ast.Type
    assert (ast_expr as ast.Type) is ast.PointerType
    ptr_ast := (ast_expr as ast.Type) as ast.PointerType
    assert ptr_ast.lifetime == 'a'
    assert ptr_ast.base_type is ast.Ident
    assert (ptr_ast.base_type as ast.Ident).name == 'Foo'

    assert t.types_type_to_v(ptr_type) == '&^a Foo'
    assert t.type_to_c_name(ptr_type) == 'Fooptr'
}

fn test_transformer_uses_pointer_type_receiver_name_for_scope_key() {
    t := create_test_transformer()
    receiver := ast.Expr(ast.Type(ast.PointerType{
        base_type: ast.Expr(ast.Ident{
            name: 'Ignore'
        })
        lifetime:  'a'
    }))
    assert t.get_receiver_type_name(receiver) == 'Ignore'
}

fn test_transformer_uses_pointer_type_for_generic_specialization_token() {
    t := create_test_transformer()
    foo_ptr := ast.Expr(ast.Type(ast.PointerType{
        base_type: ast.Expr(ast.Ident{
            name: 'Foo'
        })
    }))
    bar_ptr := ast.Expr(ast.Type(ast.PointerType{
        base_type: ast.Expr(ast.Ident{
            name: 'Bar'
        })
    }))
    assert t.generic_specialization_token(foo_ptr) == 'Fooptr'
    assert t.generic_specialization_token(bar_ptr) == 'Barptr'
    assert t.generic_specialization_suffix([foo_ptr]) == '_T_Fooptr'
    assert t.generic_specialization_suffix([bar_ptr]) == '_T_Barptr'
}

fn test_expr_to_type_name_handles_array_pointer_type() {
    t := create_test_transformer()
    array_ptr := ast.Expr(ast.Type(ast.ArrayType{
        elem_type: ast.Expr(ast.Type(ast.PointerType{
            base_type: ast.Expr(ast.Ident{
                name: 'char'
            })
        }))
    }))
    assert t.expr_to_type_name(array_ptr) == 'Array_charptr'
}

fn test_c_name_to_type_resolves_builtin_pointer_aliases_without_scope_lookup() {
    t := create_test_transformer()
    voidptr_type := t.c_name_to_type('voidptr') or {
        assert false, 'voidptr should resolve as a builtin type'
        return
    }
    assert voidptr_type is types.Alias
    assert (voidptr_type as types.Alias).name == 'voidptr'

    array_type := t.c_name_to_type('Array_voidptr') or {
        assert false, 'Array_voidptr should resolve as a builtin array type'
        return
    }
    assert array_type is types.Array
    array_elem := (array_type as types.Array).elem_type
    assert array_elem is types.Alias
    assert (array_elem as types.Alias).name == 'voidptr'
}

fn test_get_array_init_expr_type_resolves_voidptr_element_type() {
    t := create_test_transformer()
    array_init := ast.ArrayInitExpr{
        typ: ast.Expr(ast.Type(ast.ArrayType{
            elem_type: ast.Expr(ast.Ident{
                name: 'voidptr'
            })
        }))
    }
    array_type := t.get_array_init_expr_type(array_init) or {
        assert false, '[]voidptr{} should produce an array type'
        return
    }
    assert array_type is types.Array
    array_elem := (array_type as types.Array).elem_type
    assert array_elem is types.Alias
    assert (array_elem as types.Alias).name == 'voidptr'
}

fn test_match_variant_resolves_fixed_array_c_name() {
    t := create_test_transformer()
    constructor_variant := t.match_variant('Array_fixed_u32_64', ['ArrayFixed']) or { '' }
    assert constructor_variant == 'ArrayFixed'
    fixed_array_variant := t.match_variant('Array_fixed_u32_64', ['[64]u32']) or { '' }
    assert fixed_array_variant == '[64]u32'
}

fn test_sumtype_return_wrap_prefers_init_constructor_over_contextual_type() {
    sum_type := types.Type(types.SumType{
        name:     'types__Type'
        variants: [
            types.Type(types.Struct{
                name: 'ArrayFixed'
            }),
        ]
    })
    mut types_scope := types.new_scope(unsafe { nil })
    types_scope.insert('Type', sum_type)
    mut env := types.Environment.new()
    pos := token.Pos{
        id: 9101
    }
    env.set_expr_type(pos.id, sum_type)
    mut t := &Transformer{
        pref:                        &vpref.Preferences{}
        env:                         unsafe { env }
        cached_scopes:               {
            'types': types_scope
        }
        needed_clone_fns:            map[string]string{}
        needed_array_contains_fns:   map[string]ArrayMethodInfo{}
        needed_array_index_fns:      map[string]ArrayMethodInfo{}
        needed_array_last_index_fns: map[string]ArrayMethodInfo{}
    }
    value := ast.Expr(ast.InitExpr{
        typ: ast.Expr(ast.SelectorExpr{
            lhs: ast.Expr(ast.Ident{
                name: 'types'
            })
            rhs: ast.Ident{
                name: 'ArrayFixed'
            }
        })
        pos: pos
    })
    variants := t.get_sum_type_variants('types__Type')
    assert variants == ['ArrayFixed']
    assert t.init_expr_sumtype_variant_name(value as ast.InitExpr, variants, 'types__Type') == 'ArrayFixed'
    wrapped := t.wrap_sumtype_value_transformed(value, 'types__Type') or {
        assert false, 'ArrayFixed constructor should be wrapped as types.Type'
        return
    }
    assert wrapped is ast.InitExpr
    wrapped_init := wrapped as ast.InitExpr
    assert wrapped_init.typ is ast.Ident
    assert (wrapped_init.typ as ast.Ident).name == 'types__Type'

    option_pos := token.Pos{
        id: 9102
    }
    env.set_expr_type(option_pos.id, types.Type(types.OptionType{
        base_type: sum_type
    }))
    option_context_value := ast.Expr(ast.InitExpr{
        typ: ast.Expr(ast.SelectorExpr{
            lhs: ast.Expr(ast.Ident{
                name: 'types'
            })
            rhs: ast.Ident{
                name: 'ArrayFixed'
            }
        })
        pos: option_pos
    })
    t.cur_fn_ret_type_name = 'types__Type'
    t.cur_fn_returns_option = true
    return_stmt := t.transform_return_stmt(ast.ReturnStmt{
        exprs: [option_context_value]
    })
    assert return_stmt.exprs.len == 1
    assert return_stmt.exprs[0] is ast.InitExpr
    return_init := return_stmt.exprs[0] as ast.InitExpr
    assert return_init.typ is ast.Ident
    assert (return_init.typ as ast.Ident).name == 'types__Type'

    or_context_value := ast.Expr(ast.InitExpr{
        typ:    ast.Expr(ast.SelectorExpr{
            lhs: ast.Expr(ast.Ident{
                name: 'types'
            })
            rhs: ast.Ident{
                name: 'ArrayFixed'
            }
        })
        fields: [
            ast.FieldInit{
                name:  'len'
                value: ast.Expr(ast.OrExpr{
                    expr:  ast.Expr(ast.CallExpr{
                        lhs: ast.Expr(ast.Ident{
                            name: 'parse_len'
                        })
                    })
                    stmts: [
                        ast.Stmt(ast.ExprStmt{
                            expr: ast.Expr(ast.BasicLiteral{
                                kind:  .number
                                value: '0'
                            })
                        }),
                    ]
                })
            },
        ]
    })
    expanded := t.try_expand_or_expr_return(ast.ReturnStmt{
        exprs: [or_context_value]
    }) or {
        assert false, 'return with nested or should expand'
        return
    }
    assert expanded.len > 0
    last_stmt := expanded[expanded.len - 1]
    assert last_stmt is ast.ReturnStmt
    expanded_return := last_stmt as ast.ReturnStmt
    assert expanded_return.exprs.len == 1
    assert expanded_return.exprs[0] is ast.InitExpr
    expanded_return_init := expanded_return.exprs[0] as ast.InitExpr
    assert expanded_return_init.typ is ast.Ident
    assert (expanded_return_init.typ as ast.Ident).name == 'types__Type'
}

fn test_return_match_expr_expands_to_branch_returns() {
    mut t := create_test_transformer()
    t.cur_fn_returns_option = true
    match_expr := ast.MatchExpr{
        expr:     ast.Expr(ast.Ident{
            name: 'name'
        })
        branches: [
            ast.MatchBranch{
                cond:  [
                    ast.Expr(ast.StringLiteral{
                        kind:  .v
                        value: 'int'
                    }),
                ]
                stmts: [
                    ast.Stmt(ast.ExprStmt{
                        expr: ast.Expr(ast.Ident{
                            name: 'int_type'
                        })
                    }),
                ]
            },
            ast.MatchBranch{
                stmts: [
                    ast.Stmt(ast.ExprStmt{
                        expr: ast.Expr(ast.Ident{
                            name: 'lookup_type'
                        })
                    }),
                ]
            },
        ]
    }
    expanded := t.try_expand_return_match_expr(ast.ReturnStmt{
        exprs: [ast.Expr(match_expr)]
    }) or {
        assert false, 'return match should expand'
        return
    }
    assert expanded.len == 1
    assert expanded[0] is ast.ExprStmt
    if_stmt := (expanded[0] as ast.ExprStmt).expr
    assert if_stmt is ast.IfExpr
    if_expr := if_stmt as ast.IfExpr
    assert if_expr.stmts.len == 1
    assert if_expr.stmts[0] is ast.ReturnStmt
    assert if_expr.else_expr is ast.IfExpr
    else_expr := if_expr.else_expr as ast.IfExpr
    assert else_expr.cond is ast.EmptyExpr
    assert else_expr.stmts.len == 1
    assert else_expr.stmts[0] is ast.ReturnStmt
}

fn test_return_match_void_branch_stays_side_effect() {
    mut t := create_test_transformer()
    match_expr := ast.MatchExpr{
        expr:     ast.Expr(ast.Ident{
            name: 'name'
        })
        branches: [
            ast.MatchBranch{
                cond:  [
                    ast.Expr(ast.StringLiteral{
                        kind:  .v
                        value: 'bad'
                    }),
                ]
                stmts: [
                    ast.Stmt(ast.ExprStmt{
                        expr: ast.Expr(ast.CallExpr{
                            lhs: ast.Expr(ast.Ident{
                                name: 'eprintln_exit'
                            })
                        })
                    }),
                ]
            },
            ast.MatchBranch{
                stmts: [
                    ast.Stmt(ast.ExprStmt{
                        expr: ast.Expr(ast.Ident{
                            name: 'fallback'
                        })
                    }),
                ]
            },
        ]
    }
    expanded := t.try_expand_return_match_expr(ast.ReturnStmt{
        exprs: [ast.Expr(match_expr)]
    }) or {
        assert false, 'return match should expand'
        return
    }
    if_stmt := (expanded[0] as ast.ExprStmt).expr as ast.IfExpr
    assert if_stmt.stmts.len == 1
    assert if_stmt.stmts[0] is ast.ExprStmt
    assert if_stmt.stmts[0] !is ast.ReturnStmt
}

fn test_return_match_or_branch_preserves_success_payload_return() {
    mut t := create_test_transformer()
    t.cur_fn_returns_option = true
    match_expr := ast.MatchExpr{
        expr:     ast.Expr(ast.Ident{
            name: 'name'
        })
        branches: [
            ast.MatchBranch{
                cond:  [
                    ast.Expr(ast.StringLiteral{
                        kind:  .v
                        value: 'rune'
                    }),
                ]
                stmts: [
                    ast.Stmt(ast.ExprStmt{
                        expr: ast.Expr(ast.OrExpr{
                            expr:  ast.Expr(ast.CallExpr{
                                lhs: ast.Expr(ast.Ident{
                                    name: 'lookup_type'
                                })
                            })
                            stmts: [
                                ast.Stmt(ast.ReturnStmt{
                                    exprs: [
                                        ast.Expr(ast.Ident{
                                            name: 'none'
                                        }),
                                    ]
                                }),
                            ]
                        })
                    }),
                ]
            },
            ast.MatchBranch{
                stmts: [
                    ast.Stmt(ast.ExprStmt{
                        expr: ast.Expr(ast.Ident{
                            name: 'none'
                        })
                    }),
                ]
            },
        ]
    }
    expanded := t.try_expand_return_match_expr(ast.ReturnStmt{
        exprs: [ast.Expr(match_expr)]
    }) or {
        assert false, 'return match should expand'
        return
    }
    assert expanded.len == 1
    if_stmt := (expanded[0] as ast.ExprStmt).expr as ast.IfExpr
    assert if_stmt.stmts.len == 1
    assert if_stmt.stmts[0] is ast.ReturnStmt
    ret := if_stmt.stmts[0] as ast.ReturnStmt
    assert ret.exprs.len == 1
    assert ret.exprs[0] is ast.UnsafeExpr, 'or payload should stay in value context, got ${ret.exprs[0].type_name()}'
    unsafe_expr := ret.exprs[0] as ast.UnsafeExpr
    assert unsafe_expr.stmts.len >= 3
    last_stmt := unsafe_expr.stmts[unsafe_expr.stmts.len - 1]
    assert last_stmt is ast.ExprStmt
    payload_expr := (last_stmt as ast.ExprStmt).expr
    assert payload_expr is ast.SelectorExpr, 'expected final or expression to return payload selector, got ${payload_expr.type_name()}'
    payload_selector := payload_expr as ast.SelectorExpr
    assert payload_selector.rhs.name == 'data'
}

fn test_transform_return_match_reprocesses_nested_return_if_expr() {
    mut t := create_test_transformer()
    t.cur_fn_returns_option = true
    match_expr := ast.MatchExpr{
        expr:     ast.Expr(ast.Ident{
            name: 'expr'
        })
        branches: [
            ast.MatchBranch{
                cond:  [
                    ast.Expr(ast.Ident{
                        name: 'CallOrCastExpr'
                    }),
                ]
                stmts: [
                    ast.Stmt(ast.ExprStmt{
                        expr: ast.Expr(ast.IfExpr{
                            cond:      ast.Expr(ast.Ident{
                                name: 'is_type_expr'
                            })
                            stmts:     [
                                ast.Stmt(ast.ExprStmt{
                                    expr: ast.Expr(ast.StringLiteral{
                                        kind:  .v
                                        value: 'type-name'
                                    })
                                }),
                            ]
                            else_expr: ast.Expr(ast.IfExpr{
                                cond:  ast.empty_expr
                                stmts: [
                                    ast.Stmt(ast.ExprStmt{
                                        expr: ast.Expr(ast.Ident{
                                            name: 'none'
                                        })
                                    }),
                                ]
                            })
                        })
                    }),
                ]
            },
            ast.MatchBranch{
                stmts: [
                    ast.Stmt(ast.ExprStmt{
                        expr: ast.Expr(ast.Ident{
                            name: 'none'
                        })
                    }),
                ]
            },
        ]
    }
    transformed := t.transform_stmts([
        ast.Stmt(ast.ReturnStmt{
            exprs: [ast.Expr(match_expr)]
        }),
    ])
    assert transformed.len == 1
    assert transformed[0] is ast.ExprStmt
    top_if := (transformed[0] as ast.ExprStmt).expr as ast.IfExpr
    assert top_if.stmts.len == 1
    assert top_if.stmts[0] is ast.ExprStmt
    nested_if := (top_if.stmts[0] as ast.ExprStmt).expr as ast.IfExpr
    assert nested_if.stmts.len == 1
    assert nested_if.stmts[0] is ast.ReturnStmt
    assert nested_if.else_expr is ast.IfExpr
    nested_else := nested_if.else_expr as ast.IfExpr
    assert nested_else.cond is ast.EmptyExpr
    assert nested_else.stmts.len == 1
    assert nested_else.stmts[0] is ast.ReturnStmt
}

fn test_return_match_expands_if_guard_unsafe_branch_value_to_statement_returns() {
    mut t := create_test_transformer()
    nested_guard_value := ast.Expr(ast.UnsafeExpr{
        stmts: [
            ast.Stmt(ast.AssignStmt{
                op:  .decl_assign
                lhs: [ast.Expr(ast.Ident{
                    name: '_or_t2'
                })]
                rhs: [
                    ast.Expr(ast.CallExpr{
                        lhs: ast.Expr(ast.Ident{
                            name: 'lookup_builtin'
                        })
                    }),
                ]
            }),
            ast.Stmt(ast.ExprStmt{
                expr: ast.Expr(ast.IfExpr{
                    cond:      ast.Expr(ast.Ident{
                        name: '_or_t2_ok'
                    })
                    stmts:     [
                        ast.Stmt(ast.ExprStmt{
                            expr: ast.Expr(ast.Ident{
                                name: 'const_expr2'
                            })
                        }),
                    ]
                    else_expr: ast.Expr(ast.IfExpr{
                        cond:  ast.empty_expr
                        stmts: [
                            ast.Stmt(ast.ExprStmt{
                                expr: ast.Expr(ast.Ident{
                                    name: 'none'
                                })
                            }),
                        ]
                    })
                })
            }),
        ]
    })
    outer_guard_value := ast.Expr(ast.UnsafeExpr{
        stmts: [
            ast.Stmt(ast.AssignStmt{
                op:  .decl_assign
                lhs: [ast.Expr(ast.Ident{
                    name: '_or_t1'
                })]
                rhs: [
                    ast.Expr(ast.CallExpr{
                        lhs: ast.Expr(ast.Ident{
                            name: 'lookup_current'
                        })
                    }),
                ]
            }),
            ast.Stmt(ast.ExprStmt{
                expr: ast.Expr(ast.IfExpr{
                    cond:      ast.Expr(ast.Ident{
                        name: '_or_t1_ok'
                    })
                    stmts:     [
                        ast.Stmt(ast.ExprStmt{
                            expr: ast.Expr(ast.Ident{
                                name: 'const_expr'
                            })
                        }),
                    ]
                    else_expr: nested_guard_value
                })
            }),
        ]
    })
    stmts := t.return_stmts_for_branch_expr(outer_guard_value, true)
    assert stmts.len == 2
    assert stmts[0] is ast.AssignStmt
    assert stmts[1] is ast.ExprStmt
    outer_if := (stmts[1] as ast.ExprStmt).expr as ast.IfExpr
    assert outer_if.stmts.len == 1
    assert outer_if.stmts[0] is ast.ReturnStmt
    assert outer_if.else_expr is ast.IfExpr
    outer_else := outer_if.else_expr as ast.IfExpr
    assert outer_else.cond is ast.EmptyExpr
    assert outer_else.stmts.len == 2
    assert outer_else.stmts[0] is ast.AssignStmt
    assert outer_else.stmts[1] is ast.ExprStmt
    inner_if := (outer_else.stmts[1] as ast.ExprStmt).expr as ast.IfExpr
    assert inner_if.stmts.len == 1
    assert inner_if.stmts[0] is ast.ReturnStmt
    assert inner_if.else_expr is ast.IfExpr
    inner_else := inner_if.else_expr as ast.IfExpr
    assert inner_else.cond is ast.EmptyExpr
    assert inner_else.stmts.len == 1
    assert inner_else.stmts[0] is ast.ReturnStmt
}

fn test_return_match_expr_without_else_keeps_empty_terminal_branch() {
    mut t := create_test_transformer()
    match_expr := ast.MatchExpr{
        expr:     ast.Expr(ast.Ident{
            name: 'kind'
        })
        branches: [
            ast.MatchBranch{
                cond:  [
                    ast.Expr(ast.StringLiteral{
                        kind:  .v
                        value: 'a'
                    }),
                ]
                stmts: [
                    ast.Stmt(ast.ExprStmt{
                        expr: ast.Expr(ast.StringLiteral{
                            kind:  .v
                            value: 'alpha'
                        })
                    }),
                ]
            },
            ast.MatchBranch{
                cond:  [
                    ast.Expr(ast.StringLiteral{
                        kind:  .v
                        value: 'b'
                    }),
                ]
                stmts: [
                    ast.Stmt(ast.ExprStmt{
                        expr: ast.Expr(ast.StringLiteral{
                            kind:  .v
                            value: 'beta'
                        })
                    }),
                ]
            },
        ]
    }
    expanded := t.try_expand_return_match_expr(ast.ReturnStmt{
        exprs: [ast.Expr(match_expr)]
    }) or {
        assert false, 'return match should expand'
        return
    }
    assert expanded.len == 1
    assert expanded[0] is ast.ExprStmt
    if_stmt := (expanded[0] as ast.ExprStmt).expr
    assert if_stmt is ast.IfExpr
    if_expr := if_stmt as ast.IfExpr
    assert if_expr.stmts.len == 1
    assert if_expr.stmts[0] is ast.ReturnStmt
    assert if_expr.else_expr is ast.IfExpr
    else_if := if_expr.else_expr as ast.IfExpr
    assert else_if.cond !is ast.EmptyExpr
    assert else_if.stmts.len == 1
    assert else_if.stmts[0] is ast.ReturnStmt
    assert else_if.else_expr is ast.EmptyExpr
}

fn test_transformer_preserves_lifetime_method_signature_and_nested_generic_return_type() {
    files := transform_code_for_test('
struct Ignore {}

struct DirEntry {}

struct Match[T] {
    value T
}

struct IgnoreMatch[^a] {
    ig &^a Ignore
}

fn (ig &^a Ignore) matched_dir_entry[^a](dent &DirEntry) Match[IgnoreMatch[^a]] {
    return Match[IgnoreMatch[^a]]{
        value: IgnoreMatch[^a]{
            ig: ig
        }
    }
}

fn main() {
    ig := Ignore{}
    dent := DirEntry{}
    ig.matched_dir_entry(&dent)
}
')
    assert files.len == 1
    file := files[0]
    mut saw_method := false
    mut saw_call := false
    for stmt in file.stmts {
        if stmt is ast.FnDecl && stmt.name == 'matched_dir_entry' {
            saw_method = true
            assert stmt.is_method
            assert stmt.stmts.len > 0
            assert stmt.receiver.typ is ast.Type
            receiver_type := stmt.receiver.typ as ast.Type
            assert receiver_type is ast.PointerType
            receiver_ptr := receiver_type as ast.PointerType
            assert receiver_ptr.lifetime == 'a'
            assert stmt.typ.generic_params.len == 1
            assert stmt.typ.generic_params[0] is ast.LifetimeExpr
            assert (stmt.typ.generic_params[0] as ast.LifetimeExpr).name == 'a'
            assert stmt.typ.return_type is ast.Type
            return_type := stmt.typ.return_type as ast.Type
            assert return_type is ast.GenericType
            outer_generic := return_type as ast.GenericType
            assert outer_generic.name is ast.Ident
            assert (outer_generic.name as ast.Ident).name == 'Match'
            assert outer_generic.params.len == 1
            assert outer_generic.params[0] is ast.Type
            inner_type := outer_generic.params[0] as ast.Type
            assert inner_type is ast.GenericType
            inner_generic := inner_type as ast.GenericType
            assert inner_generic.name is ast.Ident
            assert (inner_generic.name as ast.Ident).name == 'IgnoreMatch'
            assert inner_generic.params.len == 1
            assert inner_generic.params[0] is ast.LifetimeExpr
            assert (inner_generic.params[0] as ast.LifetimeExpr).name == 'a'
        }
        if stmt is ast.FnDecl && stmt.name == 'main' {
            assert stmt.stmts.len == 3
            assert stmt.stmts[2] is ast.ExprStmt
            expr_stmt := stmt.stmts[2] as ast.ExprStmt
            assert expr_stmt.expr is ast.CallExpr
            call := expr_stmt.expr as ast.CallExpr
            assert call.lhs is ast.Ident
            assert (call.lhs as ast.Ident).name == 'Ignore__matched_dir_entry'
            assert call.args.len == 2
            saw_call = true
        }
    }
    assert saw_method
    assert saw_call
}

fn test_nested_filter_map_filter_receiver_cache_names_are_unique() {
    files := transform_code_for_test('
fn nested_filter_map_filter(xs []int, keep []string) []string {
    unknown := xs.filter(it > 0).map(it.str()).filter(it !in keep)
    return unknown
}
')
    assert files.len == 1
    mut recv_names := []string{}
    for stmt in files[0].stmts {
        if stmt is ast.FnDecl && stmt.name == 'nested_filter_map_filter' {
            for inner in stmt.stmts {
                if inner is ast.AssignStmt {
                    for lhs in inner.lhs {
                        if lhs is ast.Ident && lhs.name.starts_with('_filter_recv') {
                            recv_names << lhs.name
                        }
                    }
                }
            }
        }
    }
    assert recv_names.len >= 2, 'expected receiver caches for nested map/filter, got ${recv_names}'
    mut seen := map[string]bool{}
    for name in recv_names {
        assert name !in seen, 'duplicate receiver cache name: ${name}'
        seen[name] = true
    }
}

fn test_for_in_filter_receiver_temp_is_hoisted_before_loop() {
    files := transform_code_for_test('
struct ImportSymbol {
    name string
}

struct Import {
    syms []ImportSymbol
}

fn use_filtered_imports(imports []Import, owner string) int {
    mut count := 0
    for import_sym in imports.filter(it.syms.any(it.name == owner)) {
        _ = import_sym
        count++
    }
    return count
}
')
    assert files.len == 1
    mut found_fn := false
    for stmt in files[0].stmts {
        if stmt is ast.FnDecl && stmt.name == 'use_filtered_imports' {
            found_fn = true
            mut saw_filter_temp_decl := false
            mut found_outer_loop := false
            for inner in stmt.stmts {
                if inner is ast.AssignStmt && inner.op == .decl_assign && inner.lhs.len > 0 {
                    if lhs := ident_name_from_expr_for_test(inner.lhs[0]) {
                        if lhs.starts_with('_filter_t') {
                            saw_filter_temp_decl = true
                        }
                    }
                }
                if inner is ast.ForStmt && inner.stmts.len > 0 {
                    first_body := inner.stmts[0]
                    if first_body is ast.AssignStmt && first_body.lhs.len > 0 {
                        if lhs := ident_name_from_expr_for_test(first_body.lhs[0]) {
                            if lhs == 'import_sym' {
                                found_outer_loop = true
                                assert saw_filter_temp_decl
                                for loop_stmt in inner.stmts {
                                    if loop_stmt is ast.AssignStmt && loop_stmt.op == .decl_assign
                                        && loop_stmt.lhs.len > 0 {
                                        if loop_lhs := ident_name_from_expr_for_test(loop_stmt.lhs[0]) {
                                            assert !loop_lhs.starts_with('_filter_t')
                                        }
                                    }
                                }
                            }
                        }
                    }
                }
            }
            assert found_outer_loop
        }
    }
    assert found_fn
}

fn test_filter_map_receiver_pending_stmts_precede_receiver_cache() {
    files := transform_code_for_test('
fn mapped_positive(xs []int) []string {
    parts := xs.filter(it > 0).map(it.str())
    return parts
}
')
    assert files.len == 1
    mut filter_pos := -1
    mut recv_pos := -1
    for stmt in files[0].stmts {
        if stmt is ast.FnDecl && stmt.name == 'mapped_positive' {
            for i, inner in stmt.stmts {
                if inner is ast.AssignStmt && inner.op == .decl_assign && inner.lhs.len > 0 {
                    if lhs := ident_name_from_expr_for_test(inner.lhs[0]) {
                        if lhs.starts_with('_filter_t') && filter_pos == -1 {
                            filter_pos = i
                        }
                        if lhs.starts_with('_filter_recv') && recv_pos == -1 {
                            recv_pos = i
                        }
                    }
                }
            }
        }
    }
    assert filter_pos >= 0
    assert recv_pos >= 0
    assert filter_pos < recv_pos
}

fn test_direct_or_assign_fn_pointer_result_declares_final_lhs() {
    files := transform_code_for_test('
fn use_sql(sql_from_v fn (int) !string) !string {
    mut col_typ := sql_from_v(1) or {
        sql_from_v(2)!
    }
    if col_typ == "" {
        return ""
    }
    return col_typ
}
')
    assert files.len == 1
    mut saw_fn := false
    mut col_decl_count := 0
    for stmt in files[0].stmts {
        if stmt is ast.FnDecl && stmt.name == 'use_sql' {
            saw_fn = true
            for inner in stmt.stmts {
                if inner is ast.AssignStmt && inner.op == .decl_assign && inner.lhs.len > 0 {
                    if lhs := ident_name_from_expr_for_test(inner.lhs[0]) {
                        if lhs == 'col_typ' {
                            col_decl_count++
                        }
                    }
                }
            }
        }
    }
    assert saw_fn
    assert col_decl_count == 1
}

fn test_sql_orm_vattribute_array_keeps_builtin_element_type() {
    attribute_kind_type := types.Type(types.Enum{
        name: 'AttributeKind'
    })
    vattribute_type := types.Type(types.Struct{
        name:   'VAttribute'
        fields: [
            types.Field{
                name: 'name'
                typ:  types.string_
            },
            types.Field{
                name: 'has_arg'
                typ:  types.Type(types.bool_)
            },
            types.Field{
                name: 'arg'
                typ:  types.string_
            },
            types.Field{
                name: 'kind'
                typ:  attribute_kind_type
            },
        ]
    })
    table_field_type := types.Type(types.Struct{
        name:   'orm__TableField'
        fields: [
            types.Field{
                name: 'name'
                typ:  types.string_
            },
            types.Field{
                name: 'typ'
                typ:  types.Type(types.int_)
            },
            types.Field{
                name: 'nullable'
                typ:  types.Type(types.bool_)
            },
            types.Field{
                name: 'default_val'
                typ:  types.string_
            },
            types.Field{
                name: 'attrs'
                typ:  types.Type(types.Array{
                    elem_type: vattribute_type
                })
            },
            types.Field{
                name: 'is_arr'
                typ:  types.Type(types.bool_)
            },
        ]
    })
    mut builtin_scope := types.new_scope(unsafe { nil })
    builtin_scope.insert('AttributeKind', attribute_kind_type)
    builtin_scope.insert('VAttribute', vattribute_type)
    mut orm_scope := types.new_scope(unsafe { nil })
    orm_scope.insert('TableField', table_field_type)
    mut t := create_test_transformer()
    t.cur_module = 'gitly'
    t.cached_scopes = {
        'builtin': builtin_scope
        'orm':     orm_scope
    }
    pos := token.Pos{
        id: 8123
    }
    attr := ast.Attribute{
        name:  'sql'
        value: ast.StringLiteral{
            kind:  .v
            value: "'serial'"
            pos:   pos
        }
    }
    expr := t.sql_orm_table_field_expr(types.Field{
        name:       'id'
        typ:        types.Type(types.int_)
        attributes: [attr]
    }, pos) or { panic('expected orm table field expression') }
    result := t.transform_expr(expr)
    assert result is ast.InitExpr
    init := result as ast.InitExpr
    mut saw_attrs := false
    for field in init.fields {
        if field.name != 'attrs' {
            continue
        }
        saw_attrs = true
        assert field.value is ast.CallExpr
        call := field.value as ast.CallExpr
        assert call.args.len == 4
        assert call.args[2] is ast.KeywordOperator
        sizeof_arg := call.args[2] as ast.KeywordOperator
        assert sizeof_arg.exprs.len == 1
        assert sizeof_arg.exprs[0] is ast.Ident
        assert (sizeof_arg.exprs[0] as ast.Ident).name == 'VAttribute'
        assert call.args[3] is ast.ArrayInitExpr
        inner := call.args[3] as ast.ArrayInitExpr
        assert inner.typ is ast.Type
        inner_typ := inner.typ as ast.Type
        assert inner_typ is ast.ArrayType
        inner_arr_typ := inner_typ as ast.ArrayType
        assert inner_arr_typ.elem_type is ast.Ident
        assert (inner_arr_typ.elem_type as ast.Ident).name == 'VAttribute'
        assert inner.exprs.len == 1
        assert inner.exprs[0] is ast.InitExpr
        attr_init := inner.exprs[0] as ast.InitExpr
        assert attr_init.typ is ast.Ident
        assert (attr_init.typ as ast.Ident).name == 'VAttribute'
    }
    assert saw_attrs
}

fn test_replace_it_ident_keeps_nested_any_body_scope() {
    mut t := create_test_transformer()
    nested_any := ast.Expr(ast.CallOrCastExpr{
        lhs:  ast.Expr(ast.SelectorExpr{
            lhs: ast.Expr(ast.SelectorExpr{
                lhs: ast.Expr(ast.Ident{
                    name: 'it'
                })
                rhs: ast.Ident{
                    name: 'exprs'
                }
            })
            rhs: ast.Ident{
                name: 'any'
            }
        })
        expr: ast.Expr(ast.CallExpr{
            lhs:  ast.Expr(ast.SelectorExpr{
                lhs: ast.Expr(ast.Ident{
                    name: 'g'
                })
                rhs: ast.Ident{
                    name: 'match_must_reset_if'
                }
            })
            args: [
                ast.Expr(ast.Ident{
                    name: 'it'
                }),
            ]
        })
    })
    replaced := t.replace_it_ident(nested_any, '_outer_it')
    assert replaced is ast.CallOrCastExpr
    call := replaced as ast.CallOrCastExpr
    assert call.lhs is ast.SelectorExpr
    outer_sel := call.lhs as ast.SelectorExpr
    assert outer_sel.lhs is ast.SelectorExpr
    exprs_sel := outer_sel.lhs as ast.SelectorExpr
    assert exprs_sel.lhs is ast.Ident
    assert (exprs_sel.lhs as ast.Ident).name == '_outer_it'
    assert call.expr is ast.CallExpr
    inner_call := call.expr as ast.CallExpr
    assert inner_call.args.len == 1
    assert inner_call.args[0] is ast.Ident
    assert (inner_call.args[0] as ast.Ident).name == 'it'
}

fn test_smartcast_and_all_condition_hoists_temp_before_inner_if() {
    files := transform_code_for_test('
struct Aggregate {
    types []int
}

struct Other {}

type Info = Aggregate | Other

struct Sym {
    info Info
}

fn use_all(sym Sym) bool {
    if sym.info is Aggregate && sym.info.types.all(it > 0) {
        return true
    }
    return false
}
')
    assert files.len == 1
    mut found := false
    for stmt in files[0].stmts {
        if stmt is ast.FnDecl && stmt.name == 'use_all' {
            found = true
            assert stmt.stmts.len >= 2
            assert stmt.stmts[0] is ast.ExprStmt
            outer_expr_stmt := stmt.stmts[0] as ast.ExprStmt
            assert outer_expr_stmt.expr is ast.IfExpr
            outer_if := outer_expr_stmt.expr as ast.IfExpr
            assert outer_if.stmts.len >= 3, 'expected condition expansion before inner if, got ${outer_if.stmts.len} stmts'
            assert outer_if.stmts[0] is ast.AssignStmt
            init_stmt := outer_if.stmts[0] as ast.AssignStmt
            assert init_stmt.lhs.len == 1
            assert init_stmt.lhs[0] is ast.ModifierExpr
            init_lhs := init_stmt.lhs[0] as ast.ModifierExpr
            assert init_lhs.expr is ast.Ident
            assert (init_lhs.expr as ast.Ident).name.starts_with('_filter_t')
            assert outer_if.stmts[1] is ast.ForStmt
            assert outer_if.stmts[2] is ast.ExprStmt
            inner_expr_stmt := outer_if.stmts[2] as ast.ExprStmt
            assert inner_expr_stmt.expr is ast.IfExpr
            inner_if := inner_expr_stmt.expr as ast.IfExpr
            assert inner_if.cond is ast.Ident
            assert (inner_if.cond as ast.Ident).name.starts_with('_filter_t')
        }
    }
    assert found
}

fn test_smartcast_and_else_if_label_branch_is_not_duplicated() {
    files := transform_code_for_test('
struct A {}
struct B {}
struct D {}

type Node = A | B | D

fn labeled_else_branch(left Node, right Node) {
    if left is A && right is B {
        return
    } else if right is D {
        out: for i := 0; i < 1; i++ {
            continue out
        }
    }
}
')
    assert count_label_name_in_files(files, 'labeled_else_branch', 'out') == 1
}

fn test_smartcasted_field_method_receiver_after_explicit_parent_cast() {
    files := transform_code_for_test('
type Expr = Ident | IndexExpr

struct Ident {
    flag bool
}

fn (i &Ident) is_mut() bool {
    return i.flag
}

struct IndexExpr {
    left  Expr
    index Expr
}

fn uses_smartcasted_field_method(init Expr) bool {
    return init is IndexExpr && (init as IndexExpr).left is Ident
        && (init as IndexExpr).left.is_mut()
}
')
    assert files.len == 1
    mut call_names := []string{}
    for stmt in files[0].stmts {
        if stmt is ast.FnDecl && stmt.name == 'uses_smartcasted_field_method' {
            for inner in stmt.stmts {
                collect_call_names_from_stmt(inner, mut call_names)
            }
        }
    }
    assert 'Ident__is_mut' in call_names, 'expected smartcasted method call, got ${call_names}'
}

fn struct_field_names(file ast.File, struct_name string) []string {
    for stmt in file.stmts {
        if stmt is ast.StructDecl && stmt.name == struct_name {
            mut names := []string{cap: stmt.fields.len}
            for field in stmt.fields {
                names << field.name
            }
            return names
        }
    }
    return []string{}
}

fn parse_code_with_defines_for_test(code string, defines []string) []ast.File {
    return parse_code_with_prefs_for_test(code, .cleanc, defines)
}

fn parse_code_with_prefs_for_test(code string, backend vpref.Backend, defines []string) []ast.File {
    prefs := &vpref.Preferences{
        backend:      backend
        no_parallel:  true
        user_defines: defines
    }
    return parse_code_with_custom_prefs_for_test(code, prefs)
}

fn parse_code_with_custom_prefs_for_test(code string, prefs &vpref.Preferences) []ast.File {
    tmp_file := '/tmp/v2_parser_cond_field_test_${os.getpid()}.v'
    os.write_file(tmp_file, code) or { panic('failed to write temp file') }
    defer {
        os.rm(tmp_file) or {}
    }
    mut file_set := token.FileSet.new()
    mut par := parser.Parser.new(prefs)
    return par.parse_files([tmp_file], mut file_set)
}

fn test_struct_comptime_if_field_block_default_branch() {
    files := parse_code_with_defines_for_test('
module main

struct Container {
$if my_feature ? {
    feature_val string = "on"
} $else {
    feature_val string = "off"
}
    always_present int
}
', [])
    assert files.len == 1
    assert struct_field_names(files[0], 'Container') == ['feature_val', 'always_present']
}

fn test_struct_comptime_if_field_block_selected_branch() {
    files := parse_code_with_defines_for_test('
module main

struct Container {
$if my_feature ? {
    feature_val string = "on"
} $else {
    feature_val string = "off"
}
    always_present int
}
', [
        'my_feature',
    ])
    assert files.len == 1
    assert struct_field_names(files[0], 'Container') == ['feature_val', 'always_present']
}

fn test_struct_comptime_if_field_block_omits_when_unset() {
    files := parse_code_with_defines_for_test('
module main

struct Container {
$if optional ? {
    opt_field int
}
    always int
}
', [])
    assert files.len == 1
    assert struct_field_names(files[0], 'Container') == ['always']
}

fn test_struct_comptime_else_if_chain_picks_first_match() {
    files := parse_code_with_defines_for_test('
module main

struct Container {
$if feat_a ? {
    tag string = "A"
} $else $if feat_b ? {
    tag string = "B"
} $else {
    tag string = "default"
}
}
', [
        'feat_b',
    ])
    assert files.len == 1
    names := struct_field_names(files[0], 'Container')
    assert names == ['tag']
}

fn test_struct_field_if_attribute_elides_when_false() {
    files := parse_code_with_defines_for_test('
module main

struct Container {
    name   string
    debug_only int @[if absent_flag ?]
}
', [])
    assert files.len == 1
    assert struct_field_names(files[0], 'Container') == ['name']
}

fn test_struct_field_if_attribute_keeps_when_true() {
    files := parse_code_with_defines_for_test('
module main

struct Container {
    name   string
    debug_only int @[if present_flag ?]
}
', [
        'present_flag',
    ])
    assert files.len == 1
    assert struct_field_names(files[0], 'Container') == ['name', 'debug_only']
}

fn test_struct_pkgconfig_fields_inactive_for_cross_target() {
    if !vpref.comptime_pkgconfig_value('sqlite3') {
        return
    }
    prefs := &vpref.Preferences{
        backend:        .cleanc
        no_parallel:    true
        target_os:      'cross'
        output_cross_c: true
    }
    files := parse_code_with_custom_prefs_for_test('
module main

struct Container {
$if $pkgconfig("sqlite3") {
    host_field HostSqliteField
} $else {
    cross_field int
}
attr_field int @[if $pkgconfig("sqlite3")]
    always int
}
',
        prefs)
    assert files.len == 1
    assert struct_field_names(files[0], 'Container') == ['cross_field', 'always']
}

fn test_transform_pkgconfig_branch_inactive_for_cross_target() {
    if !vpref.comptime_pkgconfig_value('sqlite3') {
        return
    }
    prefs := &vpref.Preferences{
        backend:        .cleanc
        no_parallel:    true
        target_os:      'cross'
        output_cross_c: true
    }
    files := transform_code_with_prefs_for_test('
module main

fn pick() int {
    $if $pkgconfig("sqlite3") {
        return 1
    } $else {
        return 2
    }
}
',
        prefs)
    assert files.len == 1
    for stmt in files[0].stmts {
        if stmt is ast.FnDecl && stmt.name == 'pick' {
            assert stmt.stmts.len == 1
            assert stmt.stmts[0] is ast.ReturnStmt
            ret := stmt.stmts[0] as ast.ReturnStmt
            assert ret.exprs.len == 1
            assert ret.exprs[0] is ast.BasicLiteral
            lit := ret.exprs[0] as ast.BasicLiteral
            assert lit.value == '2'
            return
        }
    }
    assert false
}

// Regression: `$else` starts on the line after `}`. The auto-inserted `;`
// between `}` and `$` must not hide the `$else` branch.
fn test_struct_comptime_else_on_next_line() {
    files := parse_code_with_defines_for_test('
module main

struct Container {
$if my_feature ? {
    val string = "on"
}
$else {
    val string = "off"
}
    always int
}
', [])
    assert files.len == 1
    assert struct_field_names(files[0], 'Container') == ['val', 'always']
}

// Regression: `{` starts on the line after `$if cond ?`. The scanner inserts
// a `;` after `?`, which must not block the opening brace.
fn test_struct_comptime_if_lcbr_on_next_line() {
    files := parse_code_with_defines_for_test('
module main

struct Container {
$if my_feature ?
{
    val string = "on"
}
$else
{
    val string = "off"
}
    always int
}
', [
        'my_feature',
    ])
    assert files.len == 1
    assert struct_field_names(files[0], 'Container') == ['val', 'always']
}

// Regression: `$else $if` chain where each `$else` starts on a new line.
fn test_struct_comptime_else_if_on_next_line() {
    files := parse_code_with_defines_for_test('
module main

struct Container {
$if feat_a ? {
    tag string = "A"
}
$else $if feat_b ? {
    tag string = "B"
}
$else {
    tag string = "default"
}
}
', [
        'feat_b',
    ])
    assert files.len == 1
    assert struct_field_names(files[0], 'Container') == ['tag']
}

// Native backend flags are recognized by the shared `pref.comptime_flag_value`.
// Confirms the parser sees the same flag set the transformer does.
fn test_struct_comptime_native_backend_flags() {
    files := parse_code_with_prefs_for_test('
module main

struct Container {
$if tinyc ? {
    tinyc_field string
}
$if no_backtrace ? {
    no_backtrace_field string
}
$if builtin_write_buf_to_fd_should_use_c_write ? {
    write_field string
}
$if new_int ? {
    never_field string
}
    always int
}
',
        .x64, [])
    assert files.len == 1
    assert struct_field_names(files[0], 'Container') == ['tinyc_field', 'no_backtrace_field',
        'write_field', 'always']
}