/*
- * Copyright 2017 Facebook, Inc.
+ * Copyright 2015-present Facebook, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
#pragma once
+#ifndef __has_attribute
+#define FOLLY_HAS_ATTRIBUTE(x) 0
+#else
+#define FOLLY_HAS_ATTRIBUTE(x) __has_attribute(x)
+#endif
+
#ifndef __has_cpp_attribute
#define FOLLY_HAS_CPP_ATTRIBUTE(x) 0
#else
* FOLLY_FALLTHROUGH; // no warning: annotated fall-through
* }
*/
-#if FOLLY_HAS_CPP_ATTRIBUTE(clang::fallthrough)
+#if FOLLY_HAS_CPP_ATTRIBUTE(fallthrough)
+#define FOLLY_FALLTHROUGH [[fallthrough]]
+#elif FOLLY_HAS_CPP_ATTRIBUTE(clang::fallthrough)
#define FOLLY_FALLTHROUGH [[clang::fallthrough]]
+#elif FOLLY_HAS_CPP_ATTRIBUTE(gnu::fallthrough)
+#define FOLLY_FALLTHROUGH [[gnu::fallthrough]]
#else
#define FOLLY_FALLTHROUGH
#endif
*/
#if FOLLY_HAS_CPP_ATTRIBUTE(maybe_unused)
#define FOLLY_MAYBE_UNUSED [[maybe_unused]]
-#elif FOLLY_HAS_CPP_ATTRIBUTE(gnu::unused)
-#define FOLLY_MAYBE_UNUSED [[gnu::unused]]
+#elif FOLLY_HAS_ATTRIBUTE(__unused__) || __GNUC__
+#define FOLLY_MAYBE_UNUSED __attribute__((__unused__))
#else
#define FOLLY_MAYBE_UNUSED
#endif
*/
#if FOLLY_HAS_EXTENSION(nullability)
#define FOLLY_NULLABLE _Nullable
+#define FOLLY_NONNULL _Nonnull
#else
#define FOLLY_NULLABLE
+#define FOLLY_NONNULL
+#endif
+
+/**
+ * "Cold" indicates to the compiler that a function is only expected to be
+ * called from unlikely code paths. It can affect decisions made by the
+ * optimizer both when processing the function body and when analyzing
+ * call-sites.
+ */
+#if __GNUC__
+#define FOLLY_COLD __attribute__((__cold__))
+#else
+#define FOLLY_COLD
#endif