From e16ee9d4d8b9aadd1eb5c4f5550291c82ddfc19f Mon Sep 17 00:00:00 2001
From: Alexander Medvednikov <alexander@medvednikov.com>
Date: Tue, 21 Apr 2026 16:05:02 +0300
Subject: [PATCH] checker: fix c error when reference field improperly
 initialized (fixes #25980)

---
 vlib/v/checker/struct.v                              |  4 +++-
 .../tests/struct_ref_field_const_default_err.out     |  6 ++++++
 .../tests/struct_ref_field_const_default_err.vv      | 12 ++++++++++++
 3 files changed, 21 insertions(+), 1 deletion(-)
 create mode 100644 vlib/v/checker/tests/struct_ref_field_const_default_err.out
 create mode 100644 vlib/v/checker/tests/struct_ref_field_const_default_err.vv

diff --git a/vlib/v/checker/struct.v b/vlib/v/checker/struct.v
index 86291e5f0..66e4d9cec 100644
--- a/vlib/v/checker/struct.v
+++ b/vlib/v/checker/struct.v
@@ -136,7 +136,9 @@ fn (mut c Checker) struct_decl(mut node ast.StructDecl) {
 						val_desc := if field.default_expr_typ.is_ptr() { 'is' } else { 'is not' }
 						c.error('field ${err_desc} reference but default value ${val_desc} reference',
 							default_pos)
-					} else if field.default_expr is ast.StructInit {
+					} else if field.default_expr is ast.StructInit
+						|| (field.typ.is_ptr()
+						&& (field.default_expr is ast.Ident || field.default_expr is ast.SelectorExpr)) {
 						c.error('reference field must be initialized with reference', default_pos)
 					}
 				}
diff --git a/vlib/v/checker/tests/struct_ref_field_const_default_err.out b/vlib/v/checker/tests/struct_ref_field_const_default_err.out
new file mode 100644
index 000000000..d6e381d05
--- /dev/null
+++ b/vlib/v/checker/tests/struct_ref_field_const_default_err.out
@@ -0,0 +1,6 @@
+vlib/v/checker/tests/struct_ref_field_const_default_err.vv:11:13: error: reference field must be initialized with reference
+    9 |     a int
+   10 | pub mut:
+   11 |     tag &Tag = null_tag
+      |                ~~~~~~~~
+   12 | }
diff --git a/vlib/v/checker/tests/struct_ref_field_const_default_err.vv b/vlib/v/checker/tests/struct_ref_field_const_default_err.vv
new file mode 100644
index 000000000..03196451e
--- /dev/null
+++ b/vlib/v/checker/tests/struct_ref_field_const_default_err.vv
@@ -0,0 +1,12 @@
+struct Tag {
+	name string
+}
+
+const null_tag = Tag{}
+
+struct Thing {
+pub:
+	a int
+pub mut:
+	tag &Tag = null_tag
+}
-- 
2.39.5