checker: fix references for alias type, that could still be uninitalized (fix #15935) (#15940)

vlib/v/checker/struct.v

@@ -522,6 +522,12 @@ pub fn (mut c Checker) struct_init(mut node ast.StructInit) ast.Type {
 				if sym.kind == .struct_ && !(sym.info as ast.Struct).is_typedef {
 					c.check_ref_fields_initialized(sym, mut checked_structs, '${type_sym.name}.$field.name',
 						node)
+				} else if sym.kind == .alias {
+					parent_sym := c.table.sym((sym.info as ast.Alias).parent_type)
+					if parent_sym.kind == .struct_ {
+						c.check_ref_fields_initialized(parent_sym, mut checked_structs,
+							'${type_sym.name}.$field.name', node)
+					}
 				}
 				// Do not allow empty uninitialized interfaces
 				mut has_noinit := false
@@ -608,6 +614,13 @@ fn (mut c Checker) check_ref_fields_initialized(struct_sym &ast.TypeSymbol, mut
 			checked_structs << field.typ
 			c.check_ref_fields_initialized(sym, mut checked_structs, '${linked_name}.$field.name',
 				node)
+		} else if sym.kind == .alias {
+			parent_sym := c.table.sym((sym.info as ast.Alias).parent_type)
+			if parent_sym.kind == .struct_ {
+				checked_structs << field.typ
+				c.check_ref_fields_initialized(parent_sym, mut checked_structs, '${linked_name}.$field.name',
+					node)
+			}
 		}
 	}
 }

vlib/v/checker/tests/struct_ref_fields_uninitialized_err.out

@@ -1,13 +1,20 @@
-vlib/v/checker/tests/struct_ref_fields_uninitialized_err.vv:22:7: warning: reference field `Outer.c.b` must be initialized
+vlib/v/checker/tests/struct_ref_fields_uninitialized_err.vv:25:7: warning: reference field `Outer.c1.b` must be initialized
-   20 | 
+   23 | 
-   21 | fn main() {
+   24 | fn main() {
-   22 |     _ := Outer{}
+   25 |     _ := Outer{}
       |          ~~~~~~~
-   23 |     _ := Struct{}
+   26 |     _ := Struct{}
-   24 | }
+   27 | }
-vlib/v/checker/tests/struct_ref_fields_uninitialized_err.vv:23:7: warning: reference field `Struct.ref2` must be initialized
+vlib/v/checker/tests/struct_ref_fields_uninitialized_err.vv:25:7: warning: reference field `Outer.c2.b` must be initialized
-   21 | fn main() {
+   23 | 
-   22 |     _ := Outer{}
+   24 | fn main() {
-   23 |     _ := Struct{}
+   25 |     _ := Outer{}
+      |          ~~~~~~~
+   26 |     _ := Struct{}
+   27 | }
+vlib/v/checker/tests/struct_ref_fields_uninitialized_err.vv:26:7: warning: reference field `Struct.ref2` must be initialized
+   24 | fn main() {
+   25 |     _ := Outer{}
+   26 |     _ := Struct{}
       |          ~~~~~~~~
-   24 | }
+   27 | }

vlib/v/checker/tests/struct_ref_fields_uninitialized_err.vv

@@ -3,8 +3,11 @@ struct ContainsRef {
 	b &int
 }
 
+type TypeForContainsRef = ContainsRef
+
 struct Outer {
-	c ContainsRef
+	c1 ContainsRef
+	c2 TypeForContainsRef
 }
 
 struct Ref {}