[release-branch.go1.24] runtime/cgo: avoid errors from -Wdeclaration-after-statement

It's used by the SWIG CI build, at least, and it's an easy fix.

Fixes #71963
For #71961

Change-Id: Id21071a5aef216b35ecf0e9cd3e05d08972d92fe
Reviewed-on: https://go-review.googlesource.com/c/go/+/652181
Reviewed-by: Cherry Mui <[email protected]>
Reviewed-by: Michael Pratt <[email protected]>
LUCI-TryBot-Result: Go LUCI <[email protected]>
Auto-Submit: Michael Pratt <[email protected]>
(cherry picked from commit 76c7028)
Reviewed-on: https://go-review.googlesource.com/c/go/+/652936
Reviewed-by: Michael Knyszek <[email protected]>

Author: ianlancetaylor

src/runtime/cgo/cgo.go

@@ -25,7 +25,8 @@ package cgo
 
 // Use -fno-stack-protector to avoid problems locating the
 // proper support functions. See issues #52919, #54313, #58385.
-#cgo CFLAGS: -Wall -Werror -fno-stack-protector
+// Use -Wdeclaration-after-statement because some CI builds use it.
+#cgo CFLAGS: -Wall -Werror -fno-stack-protector -Wdeclaration-after-statement
 
 #cgo solaris CPPFLAGS: -D_POSIX_PTHREAD_SEMANTICS
 

src/runtime/cgo/gcc_libinit.c

@@ -39,10 +39,11 @@ void
 x_cgo_sys_thread_create(void* (*func)(void*), void* arg) {
 	pthread_attr_t attr;
 	pthread_t p;
+	int err;
 
 	pthread_attr_init(&attr);
 	pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
-	int err = _cgo_try_pthread_create(&p, &attr, func, arg);
+	err = _cgo_try_pthread_create(&p, &attr, func, arg);
 	if (err != 0) {
 		fprintf(stderr, "pthread_create failed: %s", strerror(err));
 		abort();
@@ -52,9 +53,11 @@ x_cgo_sys_thread_create(void* (*func)(void*), void* arg) {
 uintptr_t
 _cgo_wait_runtime_init_done(void) {
 	void (*pfn)(struct context_arg*);
+	int done;
+
 	pfn = __atomic_load_n(&cgo_context_function, __ATOMIC_CONSUME);
 
-	int done = 2;
+	done = 2;
 	if (__atomic_load_n(&runtime_init_done, __ATOMIC_CONSUME) != done) {
 		pthread_mutex_lock(&runtime_init_mu);
 		while (__atomic_load_n(&runtime_init_done, __ATOMIC_CONSUME) == 0) {

src/runtime/cgo/gcc_libinit_windows.c

@@ -75,8 +75,10 @@ x_cgo_sys_thread_create(void (*func)(void*), void* arg) {
 
 int
 _cgo_is_runtime_initialized() {
+	 int status;
+
 	 EnterCriticalSection(&runtime_init_cs);
-	 int status = runtime_init_done;
+	 status = runtime_init_done;
 	 LeaveCriticalSection(&runtime_init_cs);
 	 return status;
 }