From 45b7a0e6e2c9d12405819fdde486750101e13ccb Mon Sep 17 00:00:00 2001
From: Felipe Pena <felipensp@gmail.com>
Date: Sat, 2 Nov 2024 05:53:08 -0300
Subject: [PATCH] checker, cgen: fix comptime `T.methods`  with generic types
 and interface checking with `is` operator (fix #22721) (#22724)

---
 vlib/v/ast/table.v                            | 12 +++
 vlib/v/ast/types.v                            | 25 ++++++
 vlib/v/checker/comptime.v                     |  8 +-
 vlib/v/gen/c/comptime.v                       |  4 +-
 .../comptime_methods_generic_struct_test.v    | 80 +++++++++++++++++++
 5 files changed, 122 insertions(+), 7 deletions(-)
 create mode 100644 vlib/v/tests/comptime/comptime_methods_generic_struct_test.v

diff --git a/vlib/v/ast/table.v b/vlib/v/ast/table.v
index fdf08d2e8..f45f55896 100644
--- a/vlib/v/ast/table.v
+++ b/vlib/v/ast/table.v
@@ -1564,6 +1564,18 @@ pub fn (t &Table) does_type_implement_interface(typ Type, inter_typ Type) bool {
 				}
 				continue
 			}
+			match sym.info {
+				SumType, Struct, Interface {
+					if method := sym.find_method_with_generic_parent(imethod.name) {
+						msg := t.is_same_method(imethod, method)
+						if msg.len > 0 {
+							return false
+						}
+						continue
+					}
+				}
+				else {}
+			}
 			return false
 		}
 		// verify fields
diff --git a/vlib/v/ast/types.v b/vlib/v/ast/types.v
index a780a1c61..f6ed74087 100644
--- a/vlib/v/ast/types.v
+++ b/vlib/v/ast/types.v
@@ -1942,3 +1942,28 @@ pub fn (i Interface) get_methods() []string {
 	}
 	return []
 }
+
+pub fn (t &TypeSymbol) get_methods() []Fn {
+	mut methods := t.methods.filter(it.attrs.len == 0) // methods without attrs first
+	mut methods_with_attrs := t.methods.filter(it.attrs.len > 0) // methods with attrs second
+	match t.info {
+		Struct, Interface, SumType {
+			if t.info.parent_type.has_flag(.generic) {
+				parent_sym := global_table.sym(t.info.parent_type)
+				match parent_sym.info {
+					Struct, Interface, SumType {
+						parent_methods := parent_sym.methods
+						if parent_methods.len > 0 {
+							methods << parent_methods.filter(it.attrs.len == 0)
+							methods_with_attrs << parent_methods.filter(it.attrs.len > 0)
+						}
+					}
+					else {}
+				}
+			}
+		}
+		else {}
+	}
+	methods << methods_with_attrs
+	return methods
+}
diff --git a/vlib/v/checker/comptime.v b/vlib/v/checker/comptime.v
index cbbccb886..986d54d22 100644
--- a/vlib/v/checker/comptime.v
+++ b/vlib/v/checker/comptime.v
@@ -311,10 +311,7 @@ fn (mut c Checker) comptime_for(mut node ast.ComptimeFor) {
 			return
 		}
 	} else if node.kind == .methods {
-		mut methods := sym.methods.filter(it.attrs.len == 0) // methods without attrs first
-		methods_with_attrs := sym.methods.filter(it.attrs.len > 0) // methods with attrs second
-		methods << methods_with_attrs
-
+		methods := sym.get_methods()
 		for method in methods {
 			c.push_new_comptime_info()
 			c.comptime.inside_comptime_for = true
@@ -774,6 +771,9 @@ fn (mut c Checker) comptime_if_cond(mut cond ast.Expr, pos token.Pos) ComptimeBr
 						sym := c.table.sym(cond.right.typ)
 						if sym.kind != .interface {
 							c.expr(mut cond.left)
+						} else {
+							return c.check_compatible_types((cond.left as ast.TypeNode).typ,
+								cond.right)
 						}
 						return .unknown
 					} else if cond.left is ast.TypeNode && mut cond.right is ast.ComptimeType {
diff --git a/vlib/v/gen/c/comptime.v b/vlib/v/gen/c/comptime.v
index ac7bcf99c..b22057bd5 100644
--- a/vlib/v/gen/c/comptime.v
+++ b/vlib/v/gen/c/comptime.v
@@ -825,9 +825,7 @@ fn (mut g Gen) comptime_for(node ast.ComptimeFor) {
 	mut i := 0
 
 	if node.kind == .methods {
-		mut methods := sym.methods.filter(it.attrs.len == 0) // methods without attrs first
-		methods_with_attrs := sym.methods.filter(it.attrs.len > 0) // methods with attrs second
-		methods << methods_with_attrs
+		methods := sym.get_methods()
 		if methods.len > 0 {
 			g.writeln('FunctionData ${node.val_var} = {0};')
 		}
diff --git a/vlib/v/tests/comptime/comptime_methods_generic_struct_test.v b/vlib/v/tests/comptime/comptime_methods_generic_struct_test.v
new file mode 100644
index 000000000..1cc64c27c
--- /dev/null
+++ b/vlib/v/tests/comptime/comptime_methods_generic_struct_test.v
@@ -0,0 +1,80 @@
+interface El {
+	tag() string
+	content() ![]u8
+}
+
+struct Aa {
+	a string
+}
+
+fn (a Aa) tag() string {
+	return 'a'
+}
+
+fn (a Aa) content() ![]u8 {
+	return a.a.bytes()
+}
+
+struct Bb {
+	b string
+}
+
+fn (b Bb) tag() string {
+	return 'b'
+}
+
+fn (b Bb) content() ![]u8 {
+	return b.b.bytes()
+}
+
+struct Choi[T] implements El {
+	src []T
+}
+
+fn (c Choi[T]) tag() string {
+	return 'seq'
+}
+
+fn (c Choi[T]) content() ![]u8 {
+	mut out := []u8{}
+	for el in c.src {
+		out << el.tag().bytes()
+		out << el.content()!
+	}
+	return out
+}
+
+fn is_gelement[T]() int {
+	mut val := 0
+	$for meth in T.methods {
+		$if meth.name == 'tag' {
+			val += 1
+		}
+		$if meth.name == 'content' {
+			val += 1
+		}
+	}
+	return val
+}
+
+fn is_element[T]() bool {
+	$if T is El {
+		return true
+	}
+	return false
+}
+
+struct Per {
+	a Aa
+	b Bb
+	c Choi[Aa]
+	d string
+}
+
+fn test_main() {
+	assert dump(is_element[Aa]()) == true
+	assert dump(is_element[Bb]()) == true
+	assert dump(is_gelement[Bb]()) == 2
+	assert dump(is_element[Choi[Aa]]()) == true
+	assert dump(is_gelement[Choi[Bb]]()) == 2
+}
-- 
2.39.5