From 6115267a845a49bdf9a5d4c701fcf5b995fc499a Mon Sep 17 00:00:00 2001 From: Sergey Sharybin Date: Sun, 22 May 2016 13:41:55 +0200 Subject: CMake: Solve compilation error with pre-compiled libraries and new GCC-6 Since version 6 G++ switched to C++11 by default, which breaks some logic around WITH_CXX11 checks in out CMake files, leading to compilation errors. This is easy to solve by explicitly enabling older C++ standard when C++11 was not explicitly enabled by CMake options. However, G++-6 will also use new ABI by default even if older standard was specified in the compiler options. This is being addressed by a special define flag. This tricks made it possible to use new G++-6 without need to recompile any of pre-compiled libraries. However, this might break compilation with existing system libraries, which might already be using new ABI. We can't address this automatically, so now we simply default WITH_C11 and WITH_CXX11 options to whatever defaults of the current compiler are. This means, for G++-6 we'll set WITH_CXX11 to truth. This should make linking with system libraries working just fine, but to make pre-compiled libraries we still might need to disable CXX11. This should work fine work for a new environments with G++-6 and install_deps script run from scratch there, because C++ standard will be the same for both Blender dependencies and Blender itself. --- build_files/cmake/macros.cmake | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) (limited to 'build_files') diff --git a/build_files/cmake/macros.cmake b/build_files/cmake/macros.cmake index 239371c227c..08d26e55ed4 100644 --- a/build_files/cmake/macros.cmake +++ b/build_files/cmake/macros.cmake @@ -803,7 +803,15 @@ macro(TEST_UNORDERED_MAP_SUPPORT) # UNORDERED_MAP_NAMESPACE, namespace for unordered_map, if found include(CheckIncludeFileCXX) - CHECK_INCLUDE_FILE_CXX("unordered_map" HAVE_STD_UNORDERED_MAP_HEADER) + + # Workaround for newer GCC (6.x+) where C++11 was enabled by default, which lead us + # to a situation when there is include but which can't be used uless + # C++11 is enabled. + if(CMAKE_COMPILER_IS_GNUCC AND (NOT "${CMAKE_C_COMPILER_VERSION}" VERSION_LESS "6.0") AND (NOT WITH_CXX11)) + set(HAVE_STD_UNORDERED_MAP_HEADER False) + else() + CHECK_INCLUDE_FILE_CXX("unordered_map" HAVE_STD_UNORDERED_MAP_HEADER) + endif() if(HAVE_STD_UNORDERED_MAP_HEADER) # Even so we've found unordered_map header file it doesn't # mean unordered_map and unordered_set will be declared in -- cgit v1.2.3