unix: clean up __attribute__((quux)) usage

Macro-ify __attribute__((destructor)) and __attribute__((unused)).

The macros are no-ops when the compiler does not support function
attributes.

src/unix/internal.h

@@ -67,6 +67,21 @@
   }                                                                           \
   while (0)
 
+/* The __clang__ and __INTEL_COMPILER checks are superfluous because they
+ * define __GNUC__. They are here to convey to you, dear reader, that these
+ * macros are enabled when compiling with clang or icc.
+ */
+#if defined(__clang__) ||                                                     \
+    defined(__GNUC__) ||                                                      \
+    defined(__INTEL_COMPILER) ||                                              \
+    defined(__SUNPRO_C)
+# define UV_DESTRUCTOR(declaration) __attribute__((destructor)) declaration
+# define UV_UNUSED(declaration)     __attribute__((unused)) declaration
+#else
+# define UV_DESTRUCTOR(declaration) declaration
+# define UV_UNUSED(declaration)     declaration
+#endif
+
 #if defined(__linux__)
 # define UV__POLLIN   UV__EPOLLIN
 # define UV__POLLOUT  UV__EPOLLOUT
@@ -242,21 +257,20 @@ static const int kFSEventStreamEventFlagItemIsSymlink = 0x00040000;
 
 #endif /* defined(__APPLE__) */
 
-__attribute__((unused))
-static void uv__req_init(uv_loop_t* loop, uv_req_t* req, uv_req_type type) {
+UV_UNUSED(static void uv__req_init(uv_loop_t* loop,
+                                   uv_req_t* req,
+                                   uv_req_type type)) {
   req->type = type;
   uv__req_register(loop, req);
 }
 #define uv__req_init(loop, req, type) \
   uv__req_init((loop), (uv_req_t*)(req), (type))
 
-__attribute__((unused))
-static void uv__update_time(uv_loop_t* loop) {
+UV_UNUSED(static void uv__update_time(uv_loop_t* loop)) {
   loop->time = uv__hrtime() / 1000000;
 }
 
-__attribute__((unused))
-static char* uv__basename_r(const char* path) {
+UV_UNUSED(static char* uv__basename_r(const char* path)) {
   char* s;
 
   s = strrchr(path, '/');

src/unix/proctitle.c

@@ -96,8 +96,7 @@ int uv_get_process_title(char* buffer, size_t size) {
 }
 
 
-__attribute__((destructor))
-static void free_args_mem(void) {
+UV_DESTRUCTOR(static void free_args_mem(void)) {
   free(args_mem);  /* Keep valgrind happy. */
   args_mem = NULL;
 }

src/unix/threadpool.c

@@ -129,9 +129,7 @@ static void init_once(void) {
 }
 
 
-#if defined(__GNUC__)
-__attribute__((destructor))
-static void cleanup(void) {
+UV_DESTRUCTOR(static void cleanup(void)) {
   unsigned int i;
 
   if (initialized == 0)
@@ -153,7 +151,6 @@ static void cleanup(void) {
   nthreads = 0;
   initialized = 0;
 }
-#endif
 
 
 void uv__work_submit(uv_loop_t* loop,