checker: fix multi types generic struct init (#10201)

vlib/v/checker/checker.v

@@ -3241,7 +3241,7 @@ pub fn (mut c Checker) assign_stmt(mut assign_stmt ast.AssignStmt) {
 		}
 		return
 	}
-	//
+
 	is_decl := assign_stmt.op == .decl_assign
 	for i, left in assign_stmt.left {
 		if left is ast.CallExpr {
@@ -3283,6 +3283,13 @@ pub fn (mut c Checker) assign_stmt(mut assign_stmt ast.AssignStmt) {
 		right := if i < assign_stmt.right.len { assign_stmt.right[i] } else { assign_stmt.right[0] }
 		mut right_type := assign_stmt.right_types[i]
 		if is_decl {
+			// check generic struct init and return unwrap generic struct type
+			if right is ast.StructInit {
+				if right.typ.has_flag(.generic) {
+					c.expr(right)
+					right_type = right.typ
+				}
+			}
 			if right.is_auto_deref_var() {
 				left_type = c.table.mktyp(right_type.deref())
 			} else {

vlib/v/tests/generics_multi_types_struct_init_test.v

@@ -0,0 +1,41 @@
+struct Response<T> {
+	result T
+}
+
+pub fn send<T>(res T) string {
+	msg := Response<T>{
+		result: res
+	}
+	return '$msg'
+}
+
+struct Foo {}
+
+struct Bar {}
+
+fn test_generics_multi_types_struct_init() {
+	mut ret := send(Foo{})
+	println(ret)
+	assert ret.contains('Response<Foo>{')
+	assert ret.contains('result: Foo{}')
+
+	ret = send(Bar{})
+	println(ret)
+	assert ret.contains('Response<Bar>{')
+	assert ret.contains('result: Bar{}')
+
+	ret = send(123)
+	println(ret)
+	assert ret.contains('Response<int>{')
+	assert ret.contains('result: 123')
+
+	ret = send('abc')
+	println(ret)
+	assert ret.contains('Response<string>{')
+	assert ret.contains("result: 'abc'")
+
+	ret = send(2.22)
+	println(ret)
+	assert ret.contains('Response<f64>{')
+	assert ret.contains('result: 2.22')
+}