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36bb134ac7
We support GCC 13, which supports the flag. This allows simplifying the CMake logic around the use of -nostdlib++. Note that there are other places where we don't assume -nostdlib++ yet in the build, but this patch is intentionally trying to be small because this part of our CMake is pretty tricky.
115 lines
4.5 KiB
CMake
115 lines
4.5 KiB
CMake
include(CMakePushCheckState)
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include(CheckLibraryExists)
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include(LLVMCheckCompilerLinkerFlag)
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include(CheckCCompilerFlag)
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include(CheckCXXCompilerFlag)
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include(CheckCSourceCompiles)
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# The compiler driver may be implicitly trying to link against libunwind.
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# This is normally ok (libcxx relies on an unwinder), but if libunwind is
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# built in the same cmake invocation as libcxx and we've got
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# LIBCXXABI_USE_LLVM_UNWINDER set, we'd be linking against the just-built
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# libunwind (and the compiler implicit -lunwind wouldn't succeed as the newly
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# built libunwind isn't installed yet). For those cases, it'd be good to
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# link with --uwnindlib=none. Check if that option works.
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llvm_check_compiler_linker_flag(C "--unwindlib=none" CXX_SUPPORTS_UNWINDLIB_EQ_NONE_FLAG)
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if (NOT LIBCXX_USE_COMPILER_RT)
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if(WIN32 AND NOT MINGW)
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set(LIBCXX_HAS_GCC_S_LIB NO)
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else()
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if(ANDROID)
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check_library_exists(gcc __gcc_personality_v0 "" LIBCXX_HAS_GCC_LIB)
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else()
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check_library_exists(gcc_s __gcc_personality_v0 "" LIBCXX_HAS_GCC_S_LIB)
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endif()
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endif()
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endif()
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# libc++ is using -nostdlib++ at the link step when available,
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# otherwise -nodefaultlibs is used. We want all our checks to also
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# use one of these options, otherwise we may end up with an inconsistency between
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# the flags we think we require during configuration (if the checks are
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# performed without one of those options) and the flags that are actually
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# required during compilation (which has the -nostdlib++ or -nodefaultlibs). libc is
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# required for the link to go through. We remove sanitizers from the
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# configuration checks to avoid spurious link errors.
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check_cxx_compiler_flag(-nostdlib++ CXX_SUPPORTS_NOSTDLIBXX_FLAG)
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if (CXX_SUPPORTS_NOSTDLIBXX_FLAG)
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set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} -nostdlib++")
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else()
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check_c_compiler_flag(-nodefaultlibs C_SUPPORTS_NODEFAULTLIBS_FLAG)
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if (C_SUPPORTS_NODEFAULTLIBS_FLAG)
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set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} -nodefaultlibs")
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endif()
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endif()
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if (CXX_SUPPORTS_NOSTDLIBXX_FLAG OR C_SUPPORTS_NODEFAULTLIBS_FLAG)
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if (LIBCXX_USE_COMPILER_RT)
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include(HandleCompilerRT)
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find_compiler_rt_library(builtins LIBCXX_BUILTINS_LIBRARY
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FLAGS ${LIBCXX_COMPILE_FLAGS})
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if (LIBCXX_BUILTINS_LIBRARY)
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list(APPEND CMAKE_REQUIRED_LIBRARIES "${LIBCXX_BUILTINS_LIBRARY}")
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else()
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message(WARNING "Could not find builtins library from libc++")
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endif()
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elseif (LIBCXX_HAS_GCC_LIB)
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list(APPEND CMAKE_REQUIRED_LIBRARIES gcc)
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elseif (LIBCXX_HAS_GCC_S_LIB)
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list(APPEND CMAKE_REQUIRED_LIBRARIES gcc_s)
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endif ()
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if (MINGW)
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# Mingw64 requires quite a few "C" runtime libraries in order for basic
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# programs to link successfully with -nodefaultlibs.
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if (LIBCXX_USE_COMPILER_RT)
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set(MINGW_RUNTIME ${LIBCXX_BUILTINS_LIBRARY})
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else ()
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set(MINGW_RUNTIME gcc_s gcc)
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endif()
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set(MINGW_LIBRARIES mingw32 ${MINGW_RUNTIME} moldname mingwex msvcrt advapi32
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shell32 user32 kernel32 mingw32 ${MINGW_RUNTIME}
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moldname mingwex msvcrt)
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list(APPEND CMAKE_REQUIRED_LIBRARIES ${MINGW_LIBRARIES})
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endif()
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if (CMAKE_C_FLAGS MATCHES -fsanitize OR CMAKE_CXX_FLAGS MATCHES -fsanitize)
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set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} -fno-sanitize=all")
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endif ()
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if (CMAKE_C_FLAGS MATCHES -fsanitize-coverage OR CMAKE_CXX_FLAGS MATCHES -fsanitize-coverage)
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set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} -fsanitize-coverage=0")
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endif ()
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endif ()
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# Check compiler pragmas
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if(CMAKE_CXX_COMPILER_ID MATCHES "Clang")
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cmake_push_check_state()
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set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} -Werror=unknown-pragmas")
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check_c_source_compiles("
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#pragma comment(lib, \"c\")
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int main(void) { return 0; }
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" C_SUPPORTS_COMMENT_LIB_PRAGMA)
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cmake_pop_check_state()
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endif()
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# Check libraries
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if(WIN32 AND NOT MINGW)
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# TODO(compnerd) do we want to support an emulation layer that allows for the
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# use of pthread-win32 or similar libraries to emulate pthreads on Windows?
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set(LIBCXX_HAS_PTHREAD_LIB NO)
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set(LIBCXX_HAS_RT_LIB NO)
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set(LIBCXX_HAS_ATOMIC_LIB NO)
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elseif(APPLE)
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set(LIBCXX_HAS_PTHREAD_LIB NO)
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set(LIBCXX_HAS_RT_LIB NO)
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set(LIBCXX_HAS_ATOMIC_LIB NO)
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elseif(FUCHSIA)
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set(LIBCXX_HAS_PTHREAD_LIB NO)
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set(LIBCXX_HAS_RT_LIB NO)
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check_library_exists(atomic __atomic_fetch_add_8 "" LIBCXX_HAS_ATOMIC_LIB)
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else()
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check_library_exists(pthread pthread_create "" LIBCXX_HAS_PTHREAD_LIB)
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check_library_exists(rt clock_gettime "" LIBCXX_HAS_RT_LIB)
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check_library_exists(atomic __atomic_fetch_add_8 "" LIBCXX_HAS_ATOMIC_LIB)
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endif()
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