Print stack trace on assert() failure or when calling fatal_error()

Note: this uses the __sanitizer_print_stack_trace() function from the
AddressSanitizer runtime, so it only works when AddressSanitizer is
in use.

debug.h

@@ -0,0 +1,32 @@
+#pragma once
+
+#include "macros.h"
+
+#ifdef NDEBUG
+    #define BUG(...) UNREACHABLE()
+#else
+    #define BUG(...) bug(__FILE__, __LINE__, __func__, __VA_ARGS__)
+#endif
+
+#undef assert
+
+#define assert(x) do { \
+    IGNORE_WARNING("-Wtautological-compare") \
+    if (unlikely(!(x))) { \
+        BUG("assertion failed: '%s'", #x); \
+    } \
+    UNIGNORE_WARNINGS \
+} while (0)
+
+#ifndef static_assert
+    #if __STDC_VERSION__ >= 201112L
+        #define static_assert(x, msg) _Static_assert((x), msg)
+    #elif GNUC_AT_LEAST(4, 6) || HAS_EXTENSION(c_static_assert)
+        #define static_assert(x, msg) __extension__ _Static_assert((x), msg)
+    #else
+        #define static_assert(x, msg)
+    #endif
+#endif
+
+noreturn void fatal_error(const char *msg, int err) COLD;
+noreturn void bug(const char *file, int line, const char *func, const char *fmt, ...) PRINTF(4) COLD;