From a91f86f95f553e344da603080dcc760eaecd683f Mon Sep 17 00:00:00 2001
From: Alexander Medvednikov <alexander@medvednikov.com>
Date: Wed, 25 Mar 2026 23:22:14 +0300
Subject: [PATCH] parser: fix c functions do not warn for param named interface
 (fixes #25859)

---
 .../v/checker/tests/c_fn_param_named_interface_err.out |  8 ++++++++
 vlib/v/checker/tests/c_fn_param_named_interface_err.vv | 10 ++++++++++
 vlib/v/parser/fn.v                                     |  3 ++-
 3 files changed, 20 insertions(+), 1 deletion(-)
 create mode 100644 vlib/v/checker/tests/c_fn_param_named_interface_err.out
 create mode 100644 vlib/v/checker/tests/c_fn_param_named_interface_err.vv

diff --git a/vlib/v/checker/tests/c_fn_param_named_interface_err.out b/vlib/v/checker/tests/c_fn_param_named_interface_err.out
new file mode 100644
index 000000000..2a858b4da
--- /dev/null
+++ b/vlib/v/checker/tests/c_fn_param_named_interface_err.out
@@ -0,0 +1,8 @@
+vlib/v/checker/tests/c_fn_param_named_interface_err.vv:9:4: error: expected 4 arguments, but got 3
+    7 | fn main() {
+    8 |     registry := C.wl_registry{}
+    9 |     C.wl_registry_bind(&registry, u32(0), u32(0))
+      |       ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+   10 | }
+Details: have (&C.wl_registry, u32, u32)
+         want (&C.wl_registry, u32, &C.wl_interface, u32)
diff --git a/vlib/v/checker/tests/c_fn_param_named_interface_err.vv b/vlib/v/checker/tests/c_fn_param_named_interface_err.vv
new file mode 100644
index 000000000..367dc3c1f
--- /dev/null
+++ b/vlib/v/checker/tests/c_fn_param_named_interface_err.vv
@@ -0,0 +1,10 @@
+pub struct C.wl_interface {}
+
+pub struct C.wl_registry {}
+
+fn C.wl_registry_bind(wl_registry &C.wl_registry, name u32, interface &C.wl_interface, version u32) voidptr
+
+fn main() {
+	registry := C.wl_registry{}
+	C.wl_registry_bind(&registry, u32(0), u32(0))
+}
diff --git a/vlib/v/parser/fn.v b/vlib/v/parser/fn.v
index e2abaaddf..171144b6d 100644
--- a/vlib/v/parser/fn.v
+++ b/vlib/v/parser/fn.v
@@ -1332,7 +1332,8 @@ fn (mut p Parser) fn_params() ([]ast.Param, bool, bool, bool) {
 			if is_mut {
 				p.next()
 			}
-			if p.fn_language == .c && p.tok.kind == .name
+			if p.fn_language == .c && is_ident_name(p.tok.lit)
+				&& p.tok.kind !in [.key_fn, .key_struct]
 				&& p.peek_tok.kind !in [.comma, .rpar, .dot] {
 				name = p.tok.lit
 				p.next()
-- 
2.39.5