diff options
author | Sergey Sharybin <sergey.vfx@gmail.com> | 2016-05-22 14:41:55 +0300 |
---|---|---|
committer | Sergey Sharybin <sergey.vfx@gmail.com> | 2016-05-22 14:48:52 +0300 |
commit | 6115267a845a49bdf9a5d4c701fcf5b995fc499a (patch) | |
tree | 976e286d4ababadaaaa94775ea8d9ccc9b699ca2 /CMakeLists.txt | |
parent | e21af38f69577229c93cf46aab655384ee864948 (diff) |
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.
Diffstat (limited to 'CMakeLists.txt')
-rw-r--r-- | CMakeLists.txt | 24 |
1 files changed, 22 insertions, 2 deletions
diff --git a/CMakeLists.txt b/CMakeLists.txt index a950fc5d893..1539a55d74d 100644 --- a/CMakeLists.txt +++ b/CMakeLists.txt @@ -478,9 +478,19 @@ if(WIN32) endif() # Experimental support of C11 and C++11 -option(WITH_C11 "Build with C11 standard enabled, for development use only!" OFF) +# +# We default options to whatever default standard in the current compiler. +if(CMAKE_COMPILER_IS_GNUCC AND (NOT "${CMAKE_C_COMPILER_VERSION}" VERSION_LESS "6.0") AND (NOT WITH_CXX11)) + set(_c11_init ON) + set(_cxx11_init ON) +else() + set(_c11_init OFF) + set(_cxx11_init OFF) +endif() + +option(WITH_C11 "Build with C11 standard enabled, for development use only!" ${_c11_init}) mark_as_advanced(WITH_C11) -option(WITH_CXX11 "Build with C++11 standard enabled, for development use only!" OFF) +option(WITH_CXX11 "Build with C++11 standard enabled, for development use only!" ${_cxx11_init}) mark_as_advanced(WITH_CXX11) # Dependency graph @@ -3024,12 +3034,22 @@ endif() if(WITH_CXX11) if(CMAKE_COMPILER_IS_GNUCC OR CMAKE_C_COMPILER_ID MATCHES "Clang") + # TODO(sergey): Do we want c++11 or gnu-c++11 here? set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11") elseif(MSVC12) # Nothing special is needed, C++11 features are available by default. else() message(FATAL_ERROR "Compiler ${CMAKE_C_COMPILER_ID} is not supported for C++11 build yet") endif() +else() + # GCC-6 switched to C++11 by default, which would break linking with existing libraries + # by default. So we explicitly disable C++11 for a new GCC so no linking issues happens. + if(CMAKE_COMPILER_IS_GNUCC AND (NOT "${CMAKE_C_COMPILER_VERSION}" VERSION_LESS "6.0")) + set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=gnu++98") + # We also disable any of C++11 ABI from usage, so we wouldn't even try to + # link to stuff from std::__cxx11 namespace. + add_definitions("-D_GLIBCXX_USE_CXX11_ABI=0") + endif() endif() # Visual Studio has all standards it supports available by default |