detect choice of stdlib

Summary: The stdlibs export ways to detect which are in use. Cut the unnecessary preprocessor names for detecting/overriding.

Differential Revision: D32515501

fbshipit-source-id: 2bc85cda30ebbdfa0163e3fe287aceb8df923303

CMake/FollyConfigChecks.cmake

@@ -167,24 +167,6 @@ check_cxx_source_compiles("
   FOLLY_HAVE_EXTRANDOM_SFMT19937
 )
 
-check_cxx_source_compiles("
-  #include <type_traits>
-  #if !_LIBCPP_VERSION
-  #error No libc++
-  #endif
-  int main() { return 0; }"
-  FOLLY_USE_LIBCPP
-)
-
-check_cxx_source_compiles("
-  #include <type_traits>
-  #if !__GLIBCXX__
-  #error No libstdc++
-  #endif
-  int main() { return 0; }"
-  FOLLY_USE_LIBSTDCPP
-)
-
 check_cxx_source_runs("
   #include <stdarg.h>
   #include <stdio.h>

CMake/folly-config.h.cmake

@@ -36,7 +36,6 @@
 #cmakedefine FOLLY_HAVE_LIBGLOG 1
 
 #cmakedefine FOLLY_USE_JEMALLOC 1
-#cmakedefine FOLLY_USE_LIBSTDCPP 1
 
 #if __has_include(<features.h>)
 #include <features.h>
@@ -62,7 +61,6 @@
 #cmakedefine FOLLY_HAVE_INT128_T 1
 #cmakedefine FOLLY_HAVE_WCHAR_SUPPORT 1
 #cmakedefine FOLLY_HAVE_EXTRANDOM_SFMT19937 1
-#cmakedefine FOLLY_USE_LIBCPP 1
 #cmakedefine HAVE_VSNPRINTF_ERRORS 1
 
 #cmakedefine FOLLY_HAVE_LIBUNWIND 1

folly/Portability.h

@@ -220,8 +220,7 @@ constexpr bool kIsSanitize = false;
 // It turns out that GNU libstdc++ and LLVM libc++ differ on how they implement
 // the 'std' namespace; the latter uses inline namespaces. Wrap this decision
 // up in a macro to make forward-declarations easier.
-#if FOLLY_USE_LIBCPP
-#include <__config> // @manual
+#if defined(_LIBCPP_VERSION)
 #define FOLLY_NAMESPACE_STD_BEGIN _LIBCPP_BEGIN_NAMESPACE_STD
 #define FOLLY_NAMESPACE_STD_END _LIBCPP_END_NAMESPACE_STD
 #else

folly/concurrency/test/AtomicSharedPtrPerformance.cpp

@@ -18,7 +18,7 @@
 
 // AtomicSharedPtr-detail.h only works with libstdc++, so skip these tests for
 // other vendors
-#if FOLLY_USE_LIBSTDCPP
+#if defined(__GLIBCXX__)
 
 #include <folly/concurrency/AtomicSharedPtr.h>
 
@@ -236,10 +236,10 @@ int main(int, char**) {
   return 0;
 }
 
-#else // #if FOLLY_USE_LIBSTDCPP
+#else // defined(__GLIBCXX__)
 
 int main(int, char**) {
   return 1;
 }
 
-#endif // #if FOLLY_USE_LIBSTDCPP
+#endif // defined(__GLIBCXX__)

folly/concurrency/test/AtomicSharedPtrTest.cpp

@@ -18,7 +18,7 @@
 
 // AtomicSharedPtr-detail.h only works with libstdc++, so skip these tests for
 // other vendors
-#if FOLLY_USE_LIBSTDCPP
+#if defined(__GLIBCXX__)
 
 #include <folly/concurrency/test/AtomicSharedPtrCounted.h>
 
@@ -187,4 +187,4 @@ TEST(AtomicSharedPtr, DeterministicTest) {
     DSched::join(t);
   }
 }
-#endif // #if FOLLY_USE_LIBSTDCPP
+#endif // defined(__GLIBCXX__)

folly/concurrency/test/CoreCachedSharedPtrTest.cpp

@@ -18,7 +18,7 @@
 
 // AtomicSharedPtr-detail.h only works with libstdc++, so skip these tests for
 // other vendors
-#if FOLLY_USE_LIBSTDCPP
+#if defined(__GLIBCXX__)
 
 #include <atomic>
 #include <memory>
@@ -318,7 +318,7 @@ int main(int argc, char** argv) {
   return ret;
 }
 
-#endif // #if FOLLY_USE_LIBSTDCPP
+#endif // defined(__GLIBCXX__)
 
 #if 0
 // On Intel(R) Xeon(R) CPU E5-2680 v4 @ 2.40GHz, 2 sockets, 28 cores, 56 threads.

folly/experimental/exception_tracer/ExceptionTracer.cpp

@@ -205,7 +205,6 @@ std::vector<ExceptionInfo> getCurrentExceptions() {
   return exceptions;
 }
 
-#if FOLLY_USE_LIBSTDCPP
 namespace {
 
 std::terminate_handler origTerminate = abort;
@@ -244,7 +243,6 @@ void installHandlers() {
   };
   static Once once;
 }
-#endif // FOLLY_USE_LIBSTDCPP
 
 } // namespace exception_tracer
 } // namespace folly

folly/experimental/symbolizer/SymbolizePrinter.cpp

@@ -183,7 +183,7 @@ void SymbolizePrinter::println(
 namespace {
 
 int getFD(const std::ios& stream) {
-#if FOLLY_USE_LIBSTDCPP && FOLLY_HAS_RTTI
+#if defined(__GLIBCXX__) && FOLLY_HAS_RTTI
   std::streambuf* buf = stream.rdbuf();
   using namespace __gnu_cxx;
 
@@ -201,7 +201,7 @@ int getFD(const std::ios& stream) {
   }
 #else
   (void)stream;
-#endif // __GNUC__
+#endif
   return -1;
 }
 

folly/portability/Config.h

@@ -28,6 +28,10 @@
 #include <bits/c++config.h> // @manual
 #endif
 
+#if __has_include(<__config>)
+#include <__config> // @manual
+#endif
+
 #ifdef __ANDROID__
 #include <android/api-level.h> // @manual
 #endif