Move folly/Launder.h

[folly.git] / folly / Launder.h

diff --git a/folly/Launder.h b/folly/Launder.h
deleted file mode 100644 (file)
index fb0e5f7..0000000
--- a/folly/Launder.h
+++ /dev/null
@@ -1,56 +0,0 @@
-/*
- * Copyright 2017-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.
- * You may obtain a copy of the License at
- *
- *   http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#pragma once
-
-#include <folly/CPortability.h>
-#include <folly/Portability.h>
-
-namespace folly {
-
-/**
- * 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 {
-#if FOLLY_HAS_BUILTIN(__builtin_launder) || __GNUC__ >= 7
-  // The builtin has no unwanted side-effects.
-  return __builtin_launder(in);
-#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;
-#elif defined(_WIN32)
-  // MSVC does not currently have optimizations around const members of structs.
-  // _ReadWriteBarrier() will prevent compiler reordering memory accesses.
-  _ReadWriteBarrier();
-  return in;
-#else
-  static_assert(
-      false, "folly::launder is not implemented for this environment");
-#endif
-}
-
-/* The standard explicitly forbids laundering these */
-void launder(void*) = delete;
-void launder(void const*) = delete;
-void launder(void volatile*) = delete;
-void launder(void const volatile*) = delete;
-template <typename T, typename... Args>
-void launder(T (*)(Args...)) = delete;
-} // namespace folly