From 70f694f72e9d0e12f1c0effbbff927806f22cb43 Mon Sep 17 00:00:00 2001
From: CreeperFace <165158232+dy-tea@users.noreply.github.com>
Date: Mon, 25 Aug 2025 19:39:42 +0100
Subject: [PATCH] cgen: fix generic_fn_name generating incorrect names for C
 structs (#25164)

---
 vlib/v/gen/c/cgen.v                                |  3 ++-
 vlib/v/tests/generics/foo.h                        |  9 +++++++++
 .../v/tests/generics/generic_struct_cstruct_test.v | 14 ++++++++++++++
 vlib/v/tests/generics/v.mod                        |  0
 4 files changed, 25 insertions(+), 1 deletion(-)
 create mode 100644 vlib/v/tests/generics/foo.h
 create mode 100644 vlib/v/tests/generics/generic_struct_cstruct_test.v
 create mode 100644 vlib/v/tests/generics/v.mod

diff --git a/vlib/v/gen/c/cgen.v b/vlib/v/gen/c/cgen.v
index 5fa5de541..9868fac16 100644
--- a/vlib/v/gen/c/cgen.v
+++ b/vlib/v/gen/c/cgen.v
@@ -1271,7 +1271,8 @@ fn (mut g Gen) generic_fn_name(types []ast.Type, before string) string {
 	// `foo[int]()` => `foo_T_int()`
 	mut name := before + '_T'
 	for typ in types {
-		name += '_' + strings.repeat_string('__ptr__', typ.nr_muls()) + g.styp(typ.set_nr_muls(0))
+		name += '_' + strings.repeat_string('__ptr__', typ.nr_muls()) +
+			g.styp(typ.set_nr_muls(0)).replace(' ', '_')
 	}
 	return name
 }
diff --git a/vlib/v/tests/generics/foo.h b/vlib/v/tests/generics/foo.h
new file mode 100644
index 000000000..9db679bfc
--- /dev/null
+++ b/vlib/v/tests/generics/foo.h
@@ -0,0 +1,9 @@
+// foo.h
+#ifndef TEST_H
+#define TEST_H
+
+struct foo {
+  int a;
+};
+
+#endif
diff --git a/vlib/v/tests/generics/generic_struct_cstruct_test.v b/vlib/v/tests/generics/generic_struct_cstruct_test.v
new file mode 100644
index 000000000..a4d606767
--- /dev/null
+++ b/vlib/v/tests/generics/generic_struct_cstruct_test.v
@@ -0,0 +1,14 @@
+#insert "@VMODROOT/foo.h"
+
+struct C.foo {
+	a int
+}
+
+fn ref[T](x T) &T {
+	return &x
+}
+
+fn test_main() {
+	a := C.foo{}
+	b := ref(a)
+}
diff --git a/vlib/v/tests/generics/v.mod b/vlib/v/tests/generics/v.mod
new file mode 100644
index 000000000..e69de29bb
-- 
2.39.5