From 667f65bb5fde05bcf1148784049cc28088efd4fa Mon Sep 17 00:00:00 2001
From: yuyi <yuyi98@163.com>
Date: Fri, 23 Feb 2024 01:22:13 +0800
Subject: [PATCH] checker: check assigning immutable reference struct field
 (fix #20814) (#20883)

---
 cmd/tools/vast/vast.v                         |  8 +++---
 cmd/tools/vfmt.v                              | 14 ++++++----
 cmd/tools/vtest-parser.v                      |  3 +-
 cmd/tools/vvet/vvet.v                         |  4 +--
 doc/docs.md                                   |  4 +--
 vlib/v/ast/type_size_test.v                   |  4 +--
 vlib/v/ast/walker/walker_test.v               |  4 +--
 vlib/v/builder/builder.v                      | 10 +++----
 vlib/v/builder/cbuilder/cbuilder.v            |  2 +-
 vlib/v/builder/golangbuilder/golangbuilder.v  |  2 +-
 vlib/v/builder/jsbuilder/jsbuilder.v          |  2 +-
 vlib/v/builder/nativebuilder/nativebuilder.v  |  2 +-
 vlib/v/builder/wasmbuilder/wasmbuilder.v      |  2 +-
 vlib/v/checker/assign.v                       | 26 +++++++++++++++--
 ...n_immutable_reference_struct_field_err.out |  7 +++++
 ...gn_immutable_reference_struct_field_err.vv | 19 +++++++++++++
 vlib/v/doc/doc.v                              |  2 +-
 vlib/v/doc/module.v                           |  4 +--
 vlib/v/fmt/fmt.v                              |  6 ++--
 vlib/v/fmt/fmt_bin2v_test.v                   |  6 ++--
 vlib/v/fmt/fmt_keep_test.v                    |  6 ++--
 vlib/v/fmt/fmt_test.v                         |  6 ++--
 vlib/v/fmt/fmt_vlib_test.v                    |  6 ++--
 vlib/v/gen/c/cgen.v                           |  4 +--
 vlib/v/gen/golang/golang.v                    |  6 ++--
 vlib/v/gen/js/js.v                            |  2 +-
 vlib/v/gen/native/gen.v                       |  2 +-
 vlib/v/gen/wasm/gen.v                         |  2 +-
 vlib/v/markused/markused.v                    |  2 +-
 vlib/v/parser/comptime.v                      |  2 +-
 vlib/v/parser/parser.v                        | 17 +++++------
 vlib/v/parser/v_parser_test.v                 | 28 +++++++++----------
 vlib/v/tests/option_selector_assign_test.v    |  2 +-
 vlib/v/tests/parse_invalid_map_type_test.v    |  8 ++++--
 34 files changed, 138 insertions(+), 86 deletions(-)
 create mode 100644 vlib/v/checker/tests/assign_immutable_reference_struct_field_err.out
 create mode 100644 vlib/v/checker/tests/assign_immutable_reference_struct_field_err.vv

diff --git a/cmd/tools/vast/vast.v b/cmd/tools/vast/vast.v
index 9ea22164f..f53747572 100644
--- a/cmd/tools/vast/vast.v
+++ b/cmd/tools/vast/vast.v
@@ -131,7 +131,7 @@ fn json(file string) string {
 		pref: pref_
 	}
 	// parse file with comment
-	ast_file := parser.parse_file(file, t.table, .parse_comments, t.pref)
+	ast_file := parser.parse_file(file, mut t.table, .parse_comments, t.pref)
 	t.root = t.ast_file(ast_file)
 	// generate the ast string
 	s := json_print(t.root)
@@ -140,10 +140,10 @@ fn json(file string) string {
 
 // the ast tree
 struct Tree {
-	table &ast.Table        = unsafe { nil }
-	pref  &pref.Preferences = unsafe { nil }
+	pref &pref.Preferences = unsafe { nil }
 mut:
-	root Node // the root of tree
+	table &ast.Table = unsafe { nil }
+	root  Node // the root of tree
 }
 
 // tree node
diff --git a/cmd/tools/vfmt.v b/cmd/tools/vfmt.v
index 7b7d08b18..403b57648 100644
--- a/cmd/tools/vfmt.v
+++ b/cmd/tools/vfmt.v
@@ -160,10 +160,10 @@ fn (foptions &FormatOptions) vlog(msg string) {
 
 fn (foptions &FormatOptions) format_file(file string) {
 	foptions.vlog('vfmt2 running fmt.fmt over file: ${file}')
-	prefs, table := setup_preferences_and_table()
-	file_ast := parser.parse_file(file, table, .parse_comments, prefs)
+	prefs, mut table := setup_preferences_and_table()
+	file_ast := parser.parse_file(file, mut table, .parse_comments, prefs)
 	// checker.new_checker(table, prefs).check(file_ast)
-	formatted_content := fmt.fmt(file_ast, table, prefs, foptions.is_debug)
+	formatted_content := fmt.fmt(file_ast, mut table, prefs, foptions.is_debug)
 	file_name := os.file_name(file)
 	ulid := rand.ulid()
 	vfmt_output_path := os.join_path(vtmp_folder, 'vfmt_${ulid}_${file_name}')
@@ -174,11 +174,13 @@ fn (foptions &FormatOptions) format_file(file string) {
 
 fn (foptions &FormatOptions) format_pipe() {
 	foptions.vlog('vfmt2 running fmt.fmt over stdin')
-	prefs, table := setup_preferences_and_table()
+	prefs, mut table := setup_preferences_and_table()
 	input_text := os.get_raw_lines_joined()
-	file_ast := parser.parse_text(input_text, '', table, .parse_comments, prefs)
+	file_ast := parser.parse_text(input_text, '', mut table, .parse_comments, prefs)
 	// checker.new_checker(table, prefs).check(file_ast)
-	formatted_content := fmt.fmt(file_ast, table, prefs, foptions.is_debug, source_text: input_text)
+	formatted_content := fmt.fmt(file_ast, mut table, prefs, foptions.is_debug,
+		source_text: input_text
+	)
 	print(formatted_content)
 	flush_stdout()
 	foptions.vlog('fmt.fmt worked and ${formatted_content.len} bytes were written to stdout.')
diff --git a/cmd/tools/vtest-parser.v b/cmd/tools/vtest-parser.v
index 79e711277..33e469895 100644
--- a/cmd/tools/vtest-parser.v
+++ b/cmd/tools/vtest-parser.v
@@ -56,7 +56,8 @@ fn main() {
 			time.sleep(ms * time.millisecond)
 			exit(ecode_timeout)
 		}(context.timeout_ms)
-		_ := parser.parse_text(source, context.path, context.table, .skip_comments, context.pref)
+		_ := parser.parse_text(source, context.path, mut context.table, .skip_comments,
+			context.pref)
 		context.log('> worker ${pid:5} finished parsing ${context.path}')
 		exit(0)
 	} else {
diff --git a/cmd/tools/vvet/vvet.v b/cmd/tools/vvet/vvet.v
index 3a39c78c1..5a3fefdcc 100644
--- a/cmd/tools/vvet/vvet.v
+++ b/cmd/tools/vvet/vvet.v
@@ -103,9 +103,9 @@ fn (mut vt Vet) vet_file(path string) {
 	mut prefs := pref.new_preferences()
 	prefs.is_vet = true
 	prefs.is_vsh = path.ends_with('.vsh')
-	table := ast.new_table()
+	mut table := ast.new_table()
 	vt.vprintln("vetting file '${path}'...")
-	_, errors, notices := parser.parse_vet_file(path, table, prefs)
+	_, errors, notices := parser.parse_vet_file(path, mut table, prefs)
 	// Transfer errors from scanner and parser
 	vt.errors << errors
 	vt.notices << notices
diff --git a/doc/docs.md b/doc/docs.md
index 52adbdbb9..d046d6130 100644
--- a/doc/docs.md
+++ b/doc/docs.md
@@ -4943,7 +4943,7 @@ struct MyStruct {
 }
 
 fn main() {
-	m := MyStruct{}
+	mut m := MyStruct{}
 	mut r := RefStruct{
 		r: &m
 	}
@@ -5046,7 +5046,7 @@ fn use_stack() {
 }
 
 fn main() {
-	m := MyStruct{}
+	mut m := MyStruct{}
 	mut r := RefStruct{
 		r: &m
 	}
diff --git a/vlib/v/ast/type_size_test.v b/vlib/v/ast/type_size_test.v
index a92663471..63e33c8ad 100644
--- a/vlib/v/ast/type_size_test.v
+++ b/vlib/v/ast/type_size_test.v
@@ -35,9 +35,9 @@ fn test_type_size() {
 	mut b := builder.new_builder(pref_)
 	mut files := b.get_builtin_files()
 	b.set_module_lookup_paths()
-	parser.parse_files(files, b.table, b.pref)
+	parser.parse_files(files, mut b.table, b.pref)
 	b.parse_imports()
-	parser.parse_file(@FILE, b.table, .parse_comments, b.pref)
+	parser.parse_file(@FILE, mut b.table, .parse_comments, b.pref)
 
 	mut t := b.table
 
diff --git a/vlib/v/ast/walker/walker_test.v b/vlib/v/ast/walker/walker_test.v
index 4a370cacc..3e0d71825 100644
--- a/vlib/v/ast/walker/walker_test.v
+++ b/vlib/v/ast/walker/walker_test.v
@@ -4,9 +4,9 @@ import v.parser
 import v.pref
 
 fn parse_text(text string) &ast.File {
-	tbl := ast.new_table()
+	mut tbl := ast.new_table()
 	prefs := pref.new_preferences()
-	return parser.parse_text(text, '', tbl, .skip_comments, prefs)
+	return parser.parse_text(text, '', mut tbl, .skip_comments, prefs)
 }
 
 struct NodeByOffset {
diff --git a/vlib/v/builder/builder.v b/vlib/v/builder/builder.v
index 818f5f8d9..bd98be780 100644
--- a/vlib/v/builder/builder.v
+++ b/vlib/v/builder/builder.v
@@ -89,8 +89,8 @@ pub fn new_builder(pref_ &pref.Preferences) Builder {
 }
 
 pub fn (mut b Builder) interpret_text(code string, v_files []string) ! {
-	b.parsed_files = parser.parse_files(v_files, b.table, b.pref)
-	b.parsed_files << parser.parse_text(code, '', b.table, .skip_comments, b.pref)
+	b.parsed_files = parser.parse_files(v_files, mut b.table, b.pref)
+	b.parsed_files << parser.parse_text(code, '', mut b.table, .skip_comments, b.pref)
 	b.parse_imports()
 
 	if b.pref.only_check_syntax {
@@ -109,7 +109,7 @@ pub fn (mut b Builder) front_stages(v_files []string) ! {
 	util.timing_start('PARSE')
 
 	util.timing_start('Builder.front_stages.parse_files')
-	b.parsed_files = parser.parse_files(v_files, b.table, b.pref)
+	b.parsed_files = parser.parse_files(v_files, mut b.table, b.pref)
 	timers.show('Builder.front_stages.parse_files')
 
 	b.parse_imports()
@@ -144,7 +144,7 @@ pub fn (mut b Builder) middle_stages() ! {
 	//
 	b.table.complete_interface_check()
 	if b.pref.skip_unused {
-		markused.mark_used(mut b.table, b.pref, b.parsed_files)
+		markused.mark_used(mut b.table, mut b.pref, b.parsed_files)
 	}
 	if b.pref.show_callgraph {
 		callgraph.show(mut b.table, b.pref, b.parsed_files)
@@ -222,7 +222,7 @@ pub fn (mut b Builder) parse_imports() {
 			}
 			// eprintln('>> ast_file.path: $ast_file.path , done: $done_imports, `import $mod` => $v_files')
 			// Add all imports referenced by these libs
-			parsed_files := parser.parse_files(v_files, b.table, b.pref)
+			parsed_files := parser.parse_files(v_files, mut b.table, b.pref)
 			for file in parsed_files {
 				mut name := file.mod.name
 				if name == '' {
diff --git a/vlib/v/builder/cbuilder/cbuilder.v b/vlib/v/builder/cbuilder/cbuilder.v
index 3667f66cd..585dbff85 100644
--- a/vlib/v/builder/cbuilder/cbuilder.v
+++ b/vlib/v/builder/cbuilder/cbuilder.v
@@ -73,7 +73,7 @@ pub fn gen_c(mut b builder.Builder, v_files []string) string {
 	}
 
 	util.timing_start('C GEN')
-	header, res, out_str, out_fn_start_pos := c.gen(b.parsed_files, b.table, b.pref)
+	header, res, out_str, out_fn_start_pos := c.gen(b.parsed_files, mut b.table, b.pref)
 	util.timing_measure('C GEN')
 
 	if b.pref.parallel_cc {
diff --git a/vlib/v/builder/golangbuilder/golangbuilder.v b/vlib/v/builder/golangbuilder/golangbuilder.v
index 79cae393e..a6ab0c7b9 100644
--- a/vlib/v/builder/golangbuilder/golangbuilder.v
+++ b/vlib/v/builder/golangbuilder/golangbuilder.v
@@ -36,6 +36,6 @@ pub fn build_golang(mut b builder.Builder, v_files []string, out_file string) {
 	}
 	b.front_and_middle_stages(nvf) or { return }
 	util.timing_start('Golang GEN')
-	b.stats_lines, b.stats_bytes = golang.gen(b.parsed_files, b.table, out_file, b.pref)
+	b.stats_lines, b.stats_bytes = golang.gen(b.parsed_files, mut b.table, out_file, b.pref)
 	util.timing_measure('Golang GEN')
 }
diff --git a/vlib/v/builder/jsbuilder/jsbuilder.v b/vlib/v/builder/jsbuilder/jsbuilder.v
index 2b3941750..c37148d05 100644
--- a/vlib/v/builder/jsbuilder/jsbuilder.v
+++ b/vlib/v/builder/jsbuilder/jsbuilder.v
@@ -41,7 +41,7 @@ pub fn build_js(mut b builder.Builder, v_files []string, out_file string) {
 pub fn gen_js(mut b builder.Builder, v_files []string) string {
 	b.front_and_middle_stages(v_files) or { return '' }
 	util.timing_start('JS GEN')
-	res := js.gen(b.parsed_files, b.table, b.pref)
+	res := js.gen(b.parsed_files, mut b.table, b.pref)
 	util.timing_measure('JS GEN')
 	return res
 }
diff --git a/vlib/v/builder/nativebuilder/nativebuilder.v b/vlib/v/builder/nativebuilder/nativebuilder.v
index 790eea454..03c78da8a 100644
--- a/vlib/v/builder/nativebuilder/nativebuilder.v
+++ b/vlib/v/builder/nativebuilder/nativebuilder.v
@@ -58,6 +58,6 @@ pub fn build_native(mut b builder.Builder, v_files []string, out_file string) {
 			eprintln('Error: Only arm64 and amd64 are supported by V')
 		}
 	}
-	b.stats_lines, b.stats_bytes = native.gen(b.parsed_files, b.table, out_file, b.pref)
+	b.stats_lines, b.stats_bytes = native.gen(b.parsed_files, mut b.table, out_file, b.pref)
 	util.timing_measure('Native GEN')
 }
diff --git a/vlib/v/builder/wasmbuilder/wasmbuilder.v b/vlib/v/builder/wasmbuilder/wasmbuilder.v
index 95675a4a5..8518e43c4 100644
--- a/vlib/v/builder/wasmbuilder/wasmbuilder.v
+++ b/vlib/v/builder/wasmbuilder/wasmbuilder.v
@@ -31,6 +31,6 @@ pub fn compile_wasm(mut b builder.Builder) {
 pub fn build_wasm(mut b builder.Builder, v_files []string, out_file string) {
 	b.front_and_middle_stages(v_files) or { return }
 	util.timing_start('WebAssembly GEN')
-	wasm.gen(b.parsed_files, b.table, out_file, b.pref)
+	wasm.gen(b.parsed_files, mut b.table, out_file, b.pref)
 	util.timing_measure('WebAssembly GEN')
 }
diff --git a/vlib/v/checker/assign.v b/vlib/v/checker/assign.v
index f7aea8ca8..43311fe4c 100644
--- a/vlib/v/checker/assign.v
+++ b/vlib/v/checker/assign.v
@@ -223,11 +223,31 @@ fn (mut c Checker) assign_stmt(mut node ast.AssignStmt) {
 					}
 				}
 			}
-			if mut left is ast.Ident && mut right is ast.Ident {
-				if !c.inside_unsafe && left_type.is_ptr() && left.is_mut() && right_type.is_ptr()
-					&& !right.is_mut() {
+			if left is ast.Ident && left.is_mut() && !c.inside_unsafe {
+				if left_type.is_ptr() && mut right is ast.Ident && !right.is_mut()
+					&& right_type.is_ptr() {
 					c.error('`${right.name}` is immutable, cannot have a mutable reference to an immutable object',
 						right.pos)
+				} else if mut right is ast.StructInit {
+					typ_sym := c.table.sym(right.typ)
+					for init_field in right.init_fields {
+						if field_info := c.table.find_field_with_embeds(typ_sym, init_field.name) {
+							if field_info.is_mut {
+								if init_field.expr is ast.Ident && !init_field.expr.is_mut()
+									&& init_field.typ.is_ptr() {
+									c.note('`${init_field.expr.name}` is immutable, cannot have a mutable reference to an immutable object',
+										init_field.pos)
+								} else if init_field.expr is ast.PrefixExpr {
+									if init_field.expr.op == .amp
+										&& init_field.expr.right is ast.Ident
+										&& !init_field.expr.right.is_mut() {
+										c.note('`${init_field.expr.right.name}` is immutable, cannot have a mutable reference to an immutable object',
+											init_field.expr.right.pos)
+									}
+								}
+							}
+						}
+					}
 				}
 			}
 		} else {
diff --git a/vlib/v/checker/tests/assign_immutable_reference_struct_field_err.out b/vlib/v/checker/tests/assign_immutable_reference_struct_field_err.out
new file mode 100644
index 000000000..5c86a9172
--- /dev/null
+++ b/vlib/v/checker/tests/assign_immutable_reference_struct_field_err.out
@@ -0,0 +1,7 @@
+vlib/v/checker/tests/assign_immutable_reference_struct_field_err.vv:13:29: notice: `parent` is immutable, cannot have a mutable reference to an immutable object
+   11 |     }
+   12 |     // taking a reference of `parent` and putting it under a `mut:` struct field
+   13 |     mut child := Tree{parent: &parent}
+      |                                ~~~~~~
+   14 |
+   15 |     // unwrap the reference of `parent`, but declare it as `mut`
diff --git a/vlib/v/checker/tests/assign_immutable_reference_struct_field_err.vv b/vlib/v/checker/tests/assign_immutable_reference_struct_field_err.vv
new file mode 100644
index 000000000..7941226d9
--- /dev/null
+++ b/vlib/v/checker/tests/assign_immutable_reference_struct_field_err.vv
@@ -0,0 +1,19 @@
+struct Tree {
+mut:
+	garbage int
+	parent   ?&Tree
+}
+
+fn main() {
+	// `parent` is not declared as mutable!
+	parent := Tree{
+		garbage: 11
+	}
+	// taking a reference of `parent` and putting it under a `mut:` struct field
+	mut child := Tree{parent: &parent}
+
+	// unwrap the reference of `parent`, but declare it as `mut`
+	mut inner_parent := child.parent?
+	inner_parent.garbage = 777 // !we can mutate `parent` freely!
+	println(parent.garbage) // 777
+}
diff --git a/vlib/v/doc/doc.v b/vlib/v/doc/doc.v
index e76873f9c..0f0332ae4 100644
--- a/vlib/v/doc/doc.v
+++ b/vlib/v/doc/doc.v
@@ -453,7 +453,7 @@ pub fn (mut d Doc) generate() ! {
 		if i == 0 {
 			d.parent_mod_name = get_parent_mod(d.base_path) or { '' }
 		}
-		file_asts << parser.parse_file(file_path, d.table, comments_mode, d.prefs)
+		file_asts << parser.parse_file(file_path, mut d.table, comments_mode, d.prefs)
 	}
 	return d.file_asts(mut file_asts)
 }
diff --git a/vlib/v/doc/module.v b/vlib/v/doc/module.v
index 72176a0d9..cb41c097d 100644
--- a/vlib/v/doc/module.v
+++ b/vlib/v/doc/module.v
@@ -42,8 +42,8 @@ fn get_parent_mod(input_dir string) !string {
 		}
 		return error('No V files found.')
 	}
-	tbl := ast.new_table()
-	file_ast := parser.parse_file(v_files[0], tbl, .skip_comments, prefs)
+	mut tbl := ast.new_table()
+	file_ast := parser.parse_file(v_files[0], mut tbl, .skip_comments, prefs)
 	if file_ast.mod.name == 'main' {
 		return ''
 	}
diff --git a/vlib/v/fmt/fmt.v b/vlib/v/fmt/fmt.v
index 8c487398e..18140524c 100644
--- a/vlib/v/fmt/fmt.v
+++ b/vlib/v/fmt/fmt.v
@@ -16,10 +16,10 @@ const max_len = [0, 35, 60, 85, 93, 100]
 
 @[minify]
 pub struct Fmt {
+	pref &pref.Preferences = unsafe { nil }
 pub mut:
 	file               ast.File
-	table              &ast.Table        = unsafe { nil }
-	pref               &pref.Preferences = unsafe { nil }
+	table              &ast.Table = unsafe { nil }
 	is_debug           bool
 	out                strings.Builder
 	out_imports        strings.Builder
@@ -62,7 +62,7 @@ pub struct FmtOptions {
 	source_text string
 }
 
-pub fn fmt(file ast.File, table &ast.Table, pref_ &pref.Preferences, is_debug bool, options FmtOptions) string {
+pub fn fmt(file ast.File, mut table ast.Table, pref_ &pref.Preferences, is_debug bool, options FmtOptions) string {
 	mut f := Fmt{
 		file: file
 		table: table
diff --git a/vlib/v/fmt/fmt_bin2v_test.v b/vlib/v/fmt/fmt_bin2v_test.v
index de47d01c7..f36ace474 100644
--- a/vlib/v/fmt/fmt_bin2v_test.v
+++ b/vlib/v/fmt/fmt_bin2v_test.v
@@ -26,9 +26,9 @@ fn test_bin2v_formatting() {
 	}
 	prepare_bin2v_file()
 
-	table := ast.new_table()
-	file_ast := parser.parse_file(b2v_keep_path, table, .parse_comments, fpref)
-	result_ocontent := fmt.fmt(file_ast, table, fpref, false)
+	mut table := ast.new_table()
+	file_ast := parser.parse_file(b2v_keep_path, mut table, .parse_comments, fpref)
+	result_ocontent := fmt.fmt(file_ast, mut table, fpref, false)
 	eprintln('> the file ${b2v_keep_path} can be formatted.')
 	expected_ocontent := os.read_file(b2v_keep_path)!
 	if expected_ocontent != result_ocontent {
diff --git a/vlib/v/fmt/fmt_keep_test.v b/vlib/v/fmt/fmt_keep_test.v
index 33c1d22ec..a82875e1e 100644
--- a/vlib/v/fmt/fmt_keep_test.v
+++ b/vlib/v/fmt/fmt_keep_test.v
@@ -50,9 +50,9 @@ fn test_fmt() {
 			eprintln(fmt_bench.step_message_fail('cannot read from ${vrelpath}'))
 			continue
 		}
-		table := ast.new_table()
-		file_ast := parser.parse_file(ipath, table, .parse_comments, fpref)
-		result_ocontent := fmt.fmt(file_ast, table, fpref, false)
+		mut table := ast.new_table()
+		file_ast := parser.parse_file(ipath, mut table, .parse_comments, fpref)
+		result_ocontent := fmt.fmt(file_ast, mut table, fpref, false)
 		if expected_ocontent != result_ocontent {
 			fmt_bench.fail()
 			eprintln(fmt_bench.step_message_fail('file ${vrelpath} after formatting, does not look as expected.'))
diff --git a/vlib/v/fmt/fmt_test.v b/vlib/v/fmt/fmt_test.v
index 214192034..dfb4a33f0 100644
--- a/vlib/v/fmt/fmt_test.v
+++ b/vlib/v/fmt/fmt_test.v
@@ -46,9 +46,9 @@ fn test_fmt() {
 			eprintln(fmt_bench.step_message_fail('cannot read from ${opath}'))
 			continue
 		}
-		table := ast.new_table()
-		file_ast := parser.parse_file(ipath, table, .parse_comments, fpref)
-		result_ocontent := fmt.fmt(file_ast, table, fpref, false)
+		mut table := ast.new_table()
+		file_ast := parser.parse_file(ipath, mut table, .parse_comments, fpref)
+		result_ocontent := fmt.fmt(file_ast, mut table, fpref, false)
 		if expected_ocontent != result_ocontent {
 			fmt_bench.fail()
 			eprintln(fmt_bench.step_message_fail('file ${ipath} after formatting, does not look as expected.'))
diff --git a/vlib/v/fmt/fmt_vlib_test.v b/vlib/v/fmt/fmt_vlib_test.v
index 637ad91e6..341510ed1 100644
--- a/vlib/v/fmt/fmt_vlib_test.v
+++ b/vlib/v/fmt/fmt_vlib_test.v
@@ -44,9 +44,9 @@ fn test_vlib_fmt() {
 			eprintln(fmt_bench.step_message_fail('cannot read from ${opath}'))
 			continue
 		}
-		table := ast.new_table()
-		file_ast := parser.parse_file(ipath, table, .parse_comments, fpref)
-		result_ocontent := fmt.fmt(file_ast, table, fpref, false)
+		mut table := ast.new_table()
+		file_ast := parser.parse_file(ipath, mut table, .parse_comments, fpref)
+		result_ocontent := fmt.fmt(file_ast, mut table, fpref, false)
 		if expected_ocontent != result_ocontent {
 			fmt_bench.fail()
 			eprintln(fmt_bench.step_message_fail('file ${ipath} after formatting, does not look as expected.'))
diff --git a/vlib/v/gen/c/cgen.v b/vlib/v/gen/c/cgen.v
index c64b424a2..f2b13da2a 100644
--- a/vlib/v/gen/c/cgen.v
+++ b/vlib/v/gen/c/cgen.v
@@ -261,7 +261,7 @@ struct GlobalConstDef {
 	is_precomputed bool     // can be declared as a const in C: primitive, and a simple definition
 }
 
-pub fn gen(files []&ast.File, table &ast.Table, pref_ &pref.Preferences) (string, string, string, []int) {
+pub fn gen(files []&ast.File, mut table ast.Table, pref_ &pref.Preferences) (string, string, string, []int) {
 	mut module_built := ''
 	if pref_.build_mode == .build_module {
 		for file in files {
@@ -313,7 +313,7 @@ pub fn gen(files []&ast.File, table &ast.Table, pref_ &pref.Preferences) (string
 		module_built: module_built
 		timers_should_print: timers_should_print
 		timers: util.new_timers(should_print: timers_should_print, label: 'global_cgen')
-		inner_loop: &ast.empty_stmt
+		inner_loop: unsafe { &ast.empty_stmt }
 		field_data_type: ast.Type(table.find_type_idx('FieldData'))
 		enum_data_type: ast.Type(table.find_type_idx('EnumData'))
 		is_cc_msvc: pref_.ccompiler == 'msvc'
diff --git a/vlib/v/gen/golang/golang.v b/vlib/v/gen/golang/golang.v
index a163a14e0..5c5c68c3e 100644
--- a/vlib/v/gen/golang/golang.v
+++ b/vlib/v/gen/golang/golang.v
@@ -12,9 +12,9 @@ import os
 const bs = '\\'
 
 pub struct Gen {
+	pref &pref.Preferences = unsafe { nil }
 pub mut:
-	table &ast.Table        = unsafe { nil }
-	pref  &pref.Preferences = unsafe { nil }
+	table &ast.Table = unsafe { nil }
 	// is_debug           bool
 	out                strings.Builder
 	out_imports        strings.Builder
@@ -45,7 +45,7 @@ pub mut:
 	nlines             int
 }
 
-pub fn gen(files []&ast.File, table &ast.Table, out_file string, pref_ &pref.Preferences) (int, int) {
+pub fn gen(files []&ast.File, mut table ast.Table, out_file string, pref_ &pref.Preferences) (int, int) {
 	mut g := Gen{
 		table: table
 		pref: pref_
diff --git a/vlib/v/gen/js/js.v b/vlib/v/gen/js/js.v
index d0db5cfc0..a15e4dacf 100644
--- a/vlib/v/gen/js/js.v
+++ b/vlib/v/gen/js/js.v
@@ -97,7 +97,7 @@ fn (mut g JsGen) write_tests_definitions() {
 	g.definitions.writeln('globalThis.g_test_fails = 0;')
 }
 
-pub fn gen(files []&ast.File, table &ast.Table, pref_ &pref.Preferences) string {
+pub fn gen(files []&ast.File, mut table ast.Table, pref_ &pref.Preferences) string {
 	mut g := &JsGen{
 		definitions: strings.new_builder(100)
 		table: table
diff --git a/vlib/v/gen/native/gen.v b/vlib/v/gen/native/gen.v
index 593093098..f27e72196 100644
--- a/vlib/v/gen/native/gen.v
+++ b/vlib/v/gen/native/gen.v
@@ -327,7 +327,7 @@ fn get_backend(arch pref.Arch, target_os pref.OS) !CodeGen {
 	return error('unsupported architecture')
 }
 
-pub fn gen(files []&ast.File, table &ast.Table, out_name string, pref_ &pref.Preferences) (int, int) {
+pub fn gen(files []&ast.File, mut table ast.Table, out_name string, pref_ &pref.Preferences) (int, int) {
 	exe_name := if pref_.os == .windows && !out_name.ends_with('.exe') {
 		out_name + '.exe'
 	} else {
diff --git a/vlib/v/gen/wasm/gen.v b/vlib/v/gen/wasm/gen.v
index f4c825ae7..04e1d6fd1 100644
--- a/vlib/v/gen/wasm/gen.v
+++ b/vlib/v/gen/wasm/gen.v
@@ -1283,7 +1283,7 @@ pub fn (mut g Gen) calculate_enum_fields() {
 	}
 }
 
-pub fn gen(files []&ast.File, table &ast.Table, out_name string, w_pref &pref.Preferences) {
+pub fn gen(files []&ast.File, mut table ast.Table, out_name string, w_pref &pref.Preferences) {
 	stack_top := w_pref.wasm_stack_top
 	mut g := &Gen{
 		table: table
diff --git a/vlib/v/markused/markused.v b/vlib/v/markused/markused.v
index 831db7cad..8e53bae61 100644
--- a/vlib/v/markused/markused.v
+++ b/vlib/v/markused/markused.v
@@ -7,7 +7,7 @@ import v.util
 import v.pref
 
 // mark_used walks the AST, starting at main() and marks all used fns transitively
-pub fn mark_used(mut table ast.Table, pref_ &pref.Preferences, ast_files []&ast.File) {
+pub fn mark_used(mut table ast.Table, mut pref_ pref.Preferences, ast_files []&ast.File) {
 	mut all_fns, all_consts, all_globals := all_fn_const_and_global(ast_files)
 	util.timing_start(@METHOD)
 	defer {
diff --git a/vlib/v/parser/comptime.v b/vlib/v/parser/comptime.v
index aeea8dc79..2bf4f0d56 100644
--- a/vlib/v/parser/comptime.v
+++ b/vlib/v/parser/comptime.v
@@ -282,7 +282,7 @@ fn (mut p Parser) comptime_call() ast.ComptimeCall {
 	// the tmpl inherits all parent scopes. previous functionality was just to
 	// inherit the scope from which the comptime call was made and no parents.
 	// this is much simpler and allows access to globals. can be changed if needed.
-	mut file := parse_comptime(tmpl_path, v_code, p.table, p.pref, p.scope)
+	mut file := parse_comptime(tmpl_path, v_code, mut p.table, p.pref, mut p.scope)
 	file.path = tmpl_path
 	return ast.ComptimeCall{
 		scope: unsafe { nil }
diff --git a/vlib/v/parser/parser.v b/vlib/v/parser/parser.v
index 737d2b534..bc0393fc1 100644
--- a/vlib/v/parser/parser.v
+++ b/vlib/v/parser/parser.v
@@ -116,7 +116,7 @@ pub mut:
 __global codegen_files = unsafe { []&ast.File{} }
 
 // for tests
-pub fn parse_stmt(text string, table &ast.Table, scope &ast.Scope) ast.Stmt {
+pub fn parse_stmt(text string, mut table ast.Table, mut scope ast.Scope) ast.Stmt {
 	$if trace_parse_stmt ? {
 		eprintln('> ${@MOD}.${@FN} text: ${text}')
 	}
@@ -136,7 +136,7 @@ pub fn parse_stmt(text string, table &ast.Table, scope &ast.Scope) ast.Stmt {
 	return p.stmt(false)
 }
 
-pub fn parse_comptime(tmpl_path string, text string, table &ast.Table, pref_ &pref.Preferences, scope &ast.Scope) &ast.File {
+pub fn parse_comptime(tmpl_path string, text string, mut table ast.Table, pref_ &pref.Preferences, mut scope ast.Scope) &ast.File {
 	$if trace_parse_comptime ? {
 		eprintln('> ${@MOD}.${@FN} text: ${text}')
 	}
@@ -154,7 +154,7 @@ pub fn parse_comptime(tmpl_path string, text string, table &ast.Table, pref_ &pr
 	return res
 }
 
-pub fn parse_text(text string, path string, table &ast.Table, comments_mode scanner.CommentsMode, pref_ &pref.Preferences) &ast.File {
+pub fn parse_text(text string, path string, mut table ast.Table, comments_mode scanner.CommentsMode, pref_ &pref.Preferences) &ast.File {
 	$if trace_parse_text ? {
 		eprintln('> ${@MOD}.${@FN} comments_mode: ${comments_mode:-20} | path: ${path:-20} | text: ${text}')
 	}
@@ -232,7 +232,7 @@ pub fn (mut p Parser) set_path(path string) {
 	}
 }
 
-pub fn parse_file(path string, table &ast.Table, comments_mode scanner.CommentsMode, pref_ &pref.Preferences) &ast.File {
+pub fn parse_file(path string, mut table ast.Table, comments_mode scanner.CommentsMode, pref_ &pref.Preferences) &ast.File {
 	// Note: when comments_mode == .toplevel_comments,
 	// the parser gives feedback to the scanner about toplevel statements, so that the scanner can skip
 	// all the tricky inner comments. This is needed because we do not have a good general solution
@@ -258,7 +258,7 @@ pub fn parse_file(path string, table &ast.Table, comments_mode scanner.CommentsM
 	return res
 }
 
-pub fn parse_vet_file(path string, table_ &ast.Table, pref_ &pref.Preferences) (&ast.File, []vet.Error, []vet.Error) {
+pub fn parse_vet_file(path string, mut table_ ast.Table, pref_ &pref.Preferences) (&ast.File, []vet.Error, []vet.Error) {
 	$if trace_parse_vet_file ? {
 		eprintln('> ${@MOD}.${@FN} path: ${path}')
 	}
@@ -367,7 +367,8 @@ pub fn (mut p Parser) parse() &ast.File {
 	// codegen
 	if p.codegen_text.len > 0 && !p.pref.is_fmt {
 		ptext := 'module ' + p.mod.all_after_last('.') + '\n' + p.codegen_text
-		codegen_files << parse_text(ptext, p.file_name, p.table, p.comments_mode, p.pref)
+		codegen_files << parse_text(ptext, p.file_name, mut p.table, p.comments_mode,
+			p.pref)
 	}
 
 	return &ast.File{
@@ -427,7 +428,7 @@ fn (mut q Queue) run() {
 	}
 }
 */
-pub fn parse_files(paths []string, table &ast.Table, pref_ &pref.Preferences) []&ast.File {
+pub fn parse_files(paths []string, mut table ast.Table, pref_ &pref.Preferences) []&ast.File {
 	mut timers := util.new_timers(should_print: false, label: 'parse_files: ${paths}')
 	$if time_parsing ? {
 		timers.should_print = true
@@ -459,7 +460,7 @@ pub fn parse_files(paths []string, table &ast.Table, pref_ &pref.Preferences) []
 		mut files := []&ast.File{cap: paths.len}
 		for path in paths {
 			timers.start('parse_file ${path}')
-			files << parse_file(path, table, .skip_comments, pref_)
+			files << parse_file(path, mut table, .skip_comments, pref_)
 			timers.show('parse_file ${path}')
 		}
 		if codegen_files.len > 0 {
diff --git a/vlib/v/parser/v_parser_test.v b/vlib/v/parser/v_parser_test.v
index d35a58702..e9b4653e8 100644
--- a/vlib/v/parser/v_parser_test.v
+++ b/vlib/v/parser/v_parser_test.v
@@ -79,9 +79,9 @@ fn main() {
   ff(8+x)
 }
 '
-	table := ast.new_table()
+	mut table := ast.new_table()
 	vpref := &pref.Preferences{}
-	mut prog := parse_text(source_text, '', table, .skip_comments, vpref)
+	mut prog := parse_text(source_text, '', mut table, .skip_comments, vpref)
 	mut checker_ := checker.new_checker(table, vpref)
 	checker_.check(mut prog)
 }
@@ -93,14 +93,14 @@ fn test_one() {
 	println(@LOCATION)
 	input := ['a := 10', 'b := -a', 'c := 20']
 	expected := 'int a = 10;int b = -a;int c = 20;'
-	table := ast.new_table()
+	mut table := ast.new_table()
 	vpref := &pref.Preferences{}
-	scope := &ast.Scope{
+	mut scope := &ast.Scope{
 		start_pos: 0
 	}
 	mut e := []ast.Stmt{}
 	for line in input {
-		e << parse_stmt(line, table, scope)
+		e << parse_stmt(line, mut table, mut scope)
 	}
 	mut program := &ast.File{
 		stmts: e
@@ -109,7 +109,7 @@ fn test_one() {
 	}
 	mut checker_ := checker.new_checker(table, vpref)
 	checker_.check(mut program)
-	mut res, _, _, _ := c.gen([program], table, vpref)
+	mut res, _, _, _ := c.gen([program], mut table, vpref)
 	res = res.replace('\n', '').trim_space().after('#endif')
 	println(res)
 	ok := expected == res
@@ -136,15 +136,15 @@ fn test_parse_expr() {
 		'string s = tos3("hi");', 'x = 11;', 'a += 10;', '1.2 + 3.4;', '4 + 4;', '1 + 2 * 5;',
 		'-a + 1;', '2 + 2;']
 	mut e := []ast.Stmt{}
-	table := ast.new_table()
+	mut table := ast.new_table()
 	vpref := &pref.Preferences{}
 	mut chk := checker.new_checker(table, vpref)
-	scope := &ast.Scope{
+	mut scope := &ast.Scope{
 		start_pos: 0
 	}
 	for s in input {
 		println('\n\nst="${s}"')
-		e << parse_stmt(s, table, scope)
+		e << parse_stmt(s, mut table, mut scope)
 	}
 	mut program := &ast.File{
 		stmts: e
@@ -152,7 +152,7 @@ fn test_parse_expr() {
 		global_scope: scope
 	}
 	chk.check(mut program)
-	mut res, _, _, _ := c.gen([program], table, vpref)
+	mut res, _, _, _ := c.gen([program], mut table, vpref)
 	res = res.after('#endif')
 	println('========')
 	println(res)
@@ -185,13 +185,13 @@ fn test_num_literals() {
 		'c := -12.',
 		'd := -a',
 	]
-	table := ast.new_table()
+	mut table := ast.new_table()
 	mut scope := &ast.Scope{
 		start_pos: 0
 	}
 	mut rhs_types := []string{}
 	for input in inputs {
-		stmt := parse_stmt(input, table, scope)
+		stmt := parse_stmt(input, mut table, mut scope)
 		r := (stmt as ast.AssignStmt).right
 		match r[0] {
 			ast.IntegerLiteral { rhs_types << 'int literal' }
@@ -297,8 +297,8 @@ fn parse(output_mode pref.OutputMode) ! {
 	pref_.output_mode = output_mode
 	for idx, f in files {
 		// eprintln('> parsing in mode: ${output_mode}, ${idx+1:5}/${files.len} $f ...')
-		table := ast.new_table()
-		p := parse_file(f, table, .parse_comments, pref_)
+		mut table := ast.new_table()
+		p := parse_file(f, mut table, .parse_comments, pref_)
 		assert !isnil(p), 'failed to parse `${f}` in mode: ${output_mode}'
 		assert p.errors.len == 0, 'file ${f} should have been parsed with 0 errors'
 	}
diff --git a/vlib/v/tests/option_selector_assign_test.v b/vlib/v/tests/option_selector_assign_test.v
index 08d45dad5..bc0862295 100644
--- a/vlib/v/tests/option_selector_assign_test.v
+++ b/vlib/v/tests/option_selector_assign_test.v
@@ -13,7 +13,7 @@ fn test_main() {
 		nr_elems: 11
 	}
 	mut child := Tree{
-		parent: &parent
+		parent: unsafe { &parent }
 	}
 	child.set_nr_elems('Buzz', 123)
 	assert child.parent or { return }.nr_elems == 123
diff --git a/vlib/v/tests/parse_invalid_map_type_test.v b/vlib/v/tests/parse_invalid_map_type_test.v
index 1a562db02..c47597317 100644
--- a/vlib/v/tests/parse_invalid_map_type_test.v
+++ b/vlib/v/tests/parse_invalid_map_type_test.v
@@ -3,11 +3,13 @@ import v.parser
 import v.pref
 
 fn test_parser_map_type() {
-	result := parser.parse_text('a := map[*Node]bool', '', ast.new_table(), .parse_comments,
-		&pref.Preferences{
+	mut table := ast.new_table()
+	pref_ := pref.Preferences{
 		output_mode: .silent
 		is_fmt: true
-	})
+	}
+	result := parser.parse_text('a := map[*Node]bool', '', mut table, .parse_comments,
+		pref_)
 	println(result)
 	assert true
 }
-- 
2.39.5