Move folly/Launder.h

Summary: [Folly] Move `folly/Launder.h` to `folly/lang/`.

Reviewed By: luciang

Differential Revision: D6182882

fbshipit-source-id: 97e46bd4e4d6f212d8234209ee90a41e7850ecb9

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

diff --git a/folly/Makefile.am b/folly/Makefile.am
index a35a4a946e5424b5d3b534a565e550add7b9c82c..337b1cd6d351c82155836f25f5a91e9c57f6d0c6 100644 (file)
--- a/folly/Makefile.am
+++ b/folly/Makefile.am
@@ -313,7 +313,7 @@ nobase_follyinclude_HEADERS = \
        io/async/test/Util.h \
        json.h \
        lang/Assume.h \
-       Launder.h \
+       lang/Launder.h \
        Lazy.h \
        LifoSem.h \
        Likely.h \

diff --git a/folly/Optional.h b/folly/Optional.h
index 39abcc1c6db900ddc5a4118c0335dec55e115b98..acd0b1267d0b51ecdb94c7f57a8b34e85f91efa6 100644 (file)
--- a/folly/Optional.h
+++ b/folly/Optional.h
@@ -61,10 +61,10 @@
 #include <type_traits>
 #include <utility>
 
-#include <folly/Launder.h>
 #include <folly/Portability.h>
 #include <folly/Traits.h>
 #include <folly/Utility.h>
+#include <folly/lang/Launder.h>
 
 namespace folly {
 

diff --git a/folly/Replaceable.h b/folly/Replaceable.h
index b786f8e8b15a207abf3a19888c6ef70389df2ad5..92d1ec6f6bc3d6402642bbc718dc833467c9a00a 100644 (file)
--- a/folly/Replaceable.h
+++ b/folly/Replaceable.h
@@ -21,10 +21,10 @@
 #include <type_traits>
 #include <utility>
 
-#include <folly/Launder.h>
 #include <folly/Portability.h>
 #include <folly/Traits.h>
 #include <folly/Utility.h>
+#include <folly/lang/Launder.h>
 
 /**
  * An instance of `Replaceable<T>` wraps an instance of `T`.

diff --git a/folly/lang/Launder.h b/folly/lang/Launder.h
new file mode 100644 (file)
index 0000000..fb0e5f7
--- /dev/null
+++ b/folly/lang/Launder.h
@@ -0,0 +1,56 @@
+/*
+ * 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

diff --git a/folly/lang/test/LaunderTest.cpp b/folly/lang/test/LaunderTest.cpp
new file mode 100644 (file)
index 0000000..df3b555
--- /dev/null
+++ b/folly/lang/test/LaunderTest.cpp
@@ -0,0 +1,28 @@
+/*
+ * 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.
+ */
+
+#include <folly/lang/Launder.h>
+#include <folly/portability/GTest.h>
+
+using namespace ::testing;
+using namespace folly;
+
+TEST(LaunderTest, Basics) {
+  int a;
+  int* pa = &a;
+  EXPECT_EQ(pa, launder(pa));
+  EXPECT_TRUE(noexcept(launder(pa)));
+}

diff --git a/folly/test/LaunderTest.cpp b/folly/test/LaunderTest.cpp
deleted file mode 100644 (file)
index fb33c98..0000000
--- a/folly/test/LaunderTest.cpp
+++ /dev/null
@@ -1,28 +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.
- */
-
-#include <folly/Launder.h>
-#include <folly/portability/GTest.h>
-
-using namespace ::testing;
-using namespace folly;
-
-TEST(LaunderTest, Basics) {
-  int a;
-  int* pa = &a;
-  EXPECT_EQ(pa, launder(pa));
-  EXPECT_TRUE(noexcept(launder(pa)));
-}