checker: check sumtype argument mismatch in generic methods (fix #16340 part2) (#16403)

vlib/v/checker/check_types.v

@@ -267,7 +267,10 @@ pub fn (mut c Checker) check_expected_call_arg(got ast.Type, expected_ ast.Type,
 		if got_typ_sym.symbol_name_except_generic() == expected_typ_sym.symbol_name_except_generic() {
 			// Check if we are making a comparison between two different types of
 			// the same type like `Type<int> and &Type<>`
-			if (got.is_ptr() != expected.is_ptr()) || !c.check_same_module(got, expected) {
+			if (got.is_ptr() != expected.is_ptr())
+				|| !c.check_same_module(got, expected)
+				|| (!got.is_ptr() && !expected.is_ptr()
+				&& got_typ_sym.name != expected_typ_sym.name) {
 				got_typ_str, expected_typ_str := c.get_string_names_of(got, expected)
 				return error('cannot use `$got_typ_str` as `$expected_typ_str`')
 			}

vlib/v/checker/fn.v

@@ -1428,18 +1428,21 @@ pub fn (mut c Checker) method_call(mut node ast.CallExpr) ast.Type {
 		rec_sym := c.table.final_sym(node.left_type)
 		rec_is_generic := left_type.has_flag(.generic)
 		mut rec_concrete_types := []ast.Type{}
-		if rec_sym.info is ast.Struct {
-			rec_concrete_types = rec_sym.info.concrete_types.clone()
-			if rec_is_generic && node.concrete_types.len == 0
-				&& method.generic_names.len == rec_sym.info.generic_types.len {
-				node.concrete_types = rec_sym.info.generic_types
-			} else if !rec_is_generic && rec_sym.info.concrete_types.len > 0
-				&& node.concrete_types.len > 0
-				&& rec_sym.info.concrete_types.len + node.concrete_types.len == method.generic_names.len {
-				t_concrete_types := node.concrete_types.clone()
-				node.concrete_types = rec_sym.info.concrete_types
-				node.concrete_types << t_concrete_types
+		match rec_sym.info {
+			ast.Struct, ast.SumType, ast.Interface {
+				rec_concrete_types = rec_sym.info.concrete_types.clone()
+				if rec_is_generic && node.concrete_types.len == 0
+					&& method.generic_names.len == rec_sym.info.generic_types.len {
+					node.concrete_types = rec_sym.info.generic_types
+				} else if !rec_is_generic && rec_sym.info.concrete_types.len > 0
+					&& node.concrete_types.len > 0
+					&& rec_sym.info.concrete_types.len + node.concrete_types.len == method.generic_names.len {
+					t_concrete_types := node.concrete_types.clone()
+					node.concrete_types = rec_sym.info.concrete_types
+					node.concrete_types << t_concrete_types
+				}
 			}
+			else {}
 		}
 		mut concrete_types := []ast.Type{}
 		for concrete_type in node.concrete_types {
@@ -1644,12 +1647,16 @@ pub fn (mut c Checker) method_call(mut node ast.CallExpr) ast.Type {
 				}
 
 				if got_arg_typ.has_flag(.generic) {
-					if got_utyp := c.table.resolve_generic_to_concrete(got_arg_typ, method.generic_names,
-						method_concrete_types)
-					{
-						got_arg_typ = got_utyp
+					if c.table.cur_fn != unsafe { nil } && c.table.cur_concrete_types.len > 0 {
+						got_arg_typ = c.unwrap_generic(got_arg_typ)
 					} else {
-						continue
+						if got_utyp := c.table.resolve_generic_to_concrete(got_arg_typ,
+							method.generic_names, method_concrete_types)
+						{
+							got_arg_typ = got_utyp
+						} else {
+							continue
+						}
 					}
 				}
 			}

vlib/v/checker/tests/generics_method_sumtype_arg_mismatch.out

@@ -0,0 +1,7 @@
+vlib/v/checker/tests/generics_method_sumtype_arg_mismatch.vv:56:13: error: cannot use `Maybe<string>` as `Maybe<int>` in argument 1 to `Maybe<int>.or`
+   54 |     b := some('abc')
+   55 |
+   56 |     c := a.@or(b)
+      |                ^
+   57 |     println(c)
+   58 | }

vlib/v/checker/tests/generics_method_sumtype_arg_mismatch.vv

@@ -0,0 +1,58 @@
+module main
+
+struct None {}
+
+pub type Maybe<T> = None | T
+
+pub fn (m Maybe<T>) str<T>() string {
+	return if m is T {
+		x := m as T
+		'Some($x)'
+	} else {
+		'Noth'
+	}
+}
+
+pub fn some<T>(v T) Maybe<T> {
+	return Maybe<T>(v)
+}
+
+pub fn noth<T>() Maybe<T> {
+	return Maybe<T>(None{})
+}
+
+pub fn (m Maybe<T>) is_some<T>() bool {
+	return match m {
+		None { false }
+		T { true }
+	}
+}
+
+pub fn (m Maybe<T>) is_noth<T>() bool {
+	return match m {
+		None { true }
+		T { false }
+	}
+}
+
+pub fn (m Maybe<T>) @or<T>(m2 Maybe<T>) Maybe<T> {
+	return match m {
+		None {
+			match m2 {
+				None { None{} }
+				T { m2 }
+			}
+		}
+		T {
+			m
+		}
+	}
+}
+
+fn main() {
+	a := some(123)
+	b := some('abc')
+
+	c := a.@or(b)
+	println(c)
+}