Fix typo in Function.h

[folly.git] / folly / Launder.h

diff --git a/folly/Launder.h b/folly/Launder.h
index 2f9c47b8788e1aead9066186c9e9c349b83e9cbb..6a3b976dee649d7fadd38220370039f44c202752 100644 (file)
--- a/folly/Launder.h
+++ b/folly/Launder.h
@@ -16,44 +16,31 @@
 
 #pragma once
 
+#include <folly/CPortability.h>
 #include <folly/Portability.h>
 
 namespace folly {
 
-#ifdef __GNUC__
-#ifdef __has_builtin
-#if __has_builtin(__builtin_launder)
-#define FOLLY_USE_BUILTIN_LAUNDER 1
-#endif
-#endif
-#endif
-
 /**
  * Approximate backport from C++17 of std::launder. It should be `constexpr`
  * but that can't be done without specific support from the compiler.
  */
 template <typename T>
 FOLLY_NODISCARD inline T* launder(T* in) noexcept {
-#ifdef __GNUC__
-#ifdef FOLLY_USE_BUILTIN_LAUNDER
-  // Newer GCC versions have a builtin for this with no unwanted side-effects
+#if FOLLY_HAS_BUILTIN(__builtin_launder) || __GNUC__ >= 7
+  // The builtin has no unwanted side-effects.
   return __builtin_launder(in);
-#else
+#elif __GNUC__
   // This inline assembler block declares that `in` is an input and an output,
   // so the compiler has to assume that it has been changed inside the block.
   __asm__("" : "+r"(in));
   return in;
-#endif
 #else
   static_assert(
       false, "folly::launder is not implemented for this environment");
 #endif
 }
 
-#ifdef FOLLY_USE_BUILTIN_LAUNDER
-#undef FOLLY_USE_BUILTIN_LAUNDER
-#endif
-
 /* The standard explicitly forbids laundering these */
 void launder(void*) = delete;
 void launder(void const*) = delete;