unix: add UNREACHABLE() macro

Asserts and aborts when program flow reaches a place it shouldn't.

src/unix/error.c

@@ -86,7 +86,5 @@ uv_err_code uv_translate_sys_error(int sys_errno) {
     case ETIMEDOUT: return UV_ETIMEDOUT;
     default: return UV_UNKNOWN;
   }
-
-  assert(0 && "unreachable");
-  return -1;
+  UNREACHABLE();
 }

src/unix/internal.h

@@ -25,6 +25,8 @@
 #include "uv-common.h"
 #include "uv-eio.h"
 
+#include <assert.h>
+#include <stdlib.h> /* abort */
 #include <stddef.h> /* offsetof */
 
 #if __STRICT_ANSI__
@@ -133,13 +135,20 @@ inline static int sys_accept4(int fd,
 #define container_of(ptr, type, member) \
   ((type *) ((char *) (ptr) - offsetof(type, member)))
 
-#define SAVE_ERRNO(block) \
-  do { \
-    int _saved_errno = errno; \
-    do { block; } while (0); \
-    errno = _saved_errno; \
-  } \
-  while (0);
+#define UNREACHABLE()                                                         \
+  do {                                                                        \
+    assert(0 && "unreachable code");                                          \
+    abort();                                                                  \
+  }                                                                           \
+  while (0)
+
+#define SAVE_ERRNO(block)                                                     \
+  do {                                                                        \
+    int _saved_errno = errno;                                                 \
+    do { block; } while (0);                                                  \
+    errno = _saved_errno;                                                     \
+  }                                                                           \
+  while (0)
 
 /* flags */
 enum {

src/unix/kqueue.c

@@ -141,13 +141,13 @@ int uv_fs_event_init(uv_loop_t* loop,
 
 
 void uv__fs_event_destroy(uv_fs_event_t* handle) {
-  assert(0 && "unreachable");
+  UNREACHABLE();
 }
 
 
 /* Called by libev, don't touch. */
 void uv__kqueue_hack(EV_P_ int fflags, ev_io *w) {
-  assert(0 && "unreachable");
+  UNREACHABLE();
 }
 
 #endif /* HAVE_KQUEUE */

src/unix/linux.c

@@ -679,8 +679,7 @@ int uv_fs_event_init(uv_loop_t* loop,
 
 
 void uv__fs_event_destroy(uv_fs_event_t* handle) {
-  assert(0 && "unreachable");
-  abort();
+  UNREACHABLE();
 }
 
 #endif /* HAVE_INOTIFY_INIT || HAVE_INOTIFY_INIT1 */

src/unix/sunos.c

@@ -214,7 +214,7 @@ int uv_fs_event_init(uv_loop_t* loop,
 
 
 void uv__fs_event_destroy(uv_fs_event_t* handle) {
-  assert(0 && "unreachable"); /* should never be called */
+  UNREACHABLE();
 }
 
 #endif /* HAVE_PORTS_FS */