checker: fix struct update expr checking, when an alias is used (fix #24581) (#24582)

Author: felipensp

vlib/v/checker/struct.v

@@ -916,8 +916,8 @@ or use an explicit `unsafe{ a[..] }`, if you do not want a copy of the slice.',
 			s := c.table.type_to_str(update_type)
 			c.error('expected struct, found `${s}`', node.update_expr.pos())
 		} else if update_type != node.typ {
-			from_sym := c.table.sym(update_type)
-			to_sym := c.table.sym(node.typ)
+			from_sym := c.table.final_sym(update_type)
+			to_sym := c.table.final_sym(node.typ)
 			from_info := from_sym.info as ast.Struct
 			to_info := to_sym.info as ast.Struct
 			// TODO: this check is too strict

vlib/v/tests/aliases/alias_updated_expr_test.v

@@ -0,0 +1,21 @@
+module main
+
+struct Cfg {
+	item string
+}
+
+type AliasCfg = Cfg
+
+fn foo(cfg &AliasCfg) {
+	var := &AliasCfg{
+		...cfg
+		item: 'foo'
+	}
+	assert var.item == 'foo'
+}
+
+fn test_main() {
+	foo(AliasCfg{
+		item: 'bar'
+	})
+}