From a186e445c73d3005220c440df35cc0c47d9cec12 Mon Sep 17 00:00:00 2001
From: Felipe Pena <felipensp@gmail.com>
Date: Mon, 20 Oct 2025 08:16:43 -0300
Subject: [PATCH] cgen: fix empty struct initializer for clang (fix #25467)
 (#25526)

---
 vlib/v/gen/c/auto_eq_methods.v                  |  6 ++++--
 .../v/tests/structs/struct_empty_auto_eq_test.v | 17 +++++++++++++++++
 2 files changed, 21 insertions(+), 2 deletions(-)
 create mode 100644 vlib/v/tests/structs/struct_empty_auto_eq_test.v

diff --git a/vlib/v/gen/c/auto_eq_methods.v b/vlib/v/gen/c/auto_eq_methods.v
index bcd87cac8..3f1aae526 100644
--- a/vlib/v/gen/c/auto_eq_methods.v
+++ b/vlib/v/gen/c/auto_eq_methods.v
@@ -542,14 +542,16 @@ fn (mut g Gen) gen_map_equality_fn(left_type ast.Type) string {
 	fn_builder.writeln('\t\tif (!builtin__DenseArray_has_index(&${key_values}, i)) continue;')
 	fn_builder.writeln('\t\tvoidptr k = builtin__DenseArray_key(&${key_values}, i);')
 	fn_builder.writeln('\t\tif (!builtin__map_exists(${b}, k)) return false;')
+	sym := g.table.sym(value.typ)
 	kind := g.table.type_kind(value.typ)
+	initializer := if !(sym.info is ast.Struct && sym.info.is_empty_struct()) { '0' } else { '' }
 	if kind == .function {
 		info := value.sym.info as ast.FnType
 		sig := g.fn_var_signature(info.func.return_type, info.func.params.map(it.typ),
 			'v')
 		fn_builder.writeln('\t\t${sig} = *(voidptr*)builtin__map_get(${a}, k, &(voidptr[]){ 0 });')
 	} else {
-		fn_builder.writeln('\t\t${ptr_value_styp} v = *(${ptr_value_styp}*)builtin__map_get(${a}, k, &(${ptr_value_styp}[]){ 0 });')
+		fn_builder.writeln('\t\t${ptr_value_styp} v = *(${ptr_value_styp}*)builtin__map_get(${a}, k, &(${ptr_value_styp}[]){ ${initializer} });')
 	}
 	match kind {
 		.string {
@@ -561,7 +563,7 @@ fn (mut g Gen) gen_map_equality_fn(left_type ast.Type) string {
 		}
 		.struct {
 			eq_fn := g.gen_struct_equality_fn(value.typ)
-			fn_builder.writeln('\t\tif (!${eq_fn}_struct_eq(*(${ptr_value_styp}*)builtin__map_get(${b}, k, &(${ptr_value_styp}[]){ 0 }), v)) {')
+			fn_builder.writeln('\t\tif (!${eq_fn}_struct_eq(*(${ptr_value_styp}*)builtin__map_get(${b}, k, &(${ptr_value_styp}[]){ ${initializer} }), v)) {')
 		}
 		.interface {
 			eq_fn := g.gen_interface_equality_fn(value.typ)
diff --git a/vlib/v/tests/structs/struct_empty_auto_eq_test.v b/vlib/v/tests/structs/struct_empty_auto_eq_test.v
new file mode 100644
index 000000000..15220b5a3
--- /dev/null
+++ b/vlib/v/tests/structs/struct_empty_auto_eq_test.v
@@ -0,0 +1,17 @@
+module main
+
+struct Example {}
+
+struct Components {
+	example map[string]Example
+}
+
+fn test_main() {
+	a := Components{}
+	b := Components{}
+	if a == b {
+		assert true
+	} else {
+		assert false
+	}
+}
-- 
2.39.5