1include(CMakePushCheckState) 2include(CheckLibraryExists) 3include(CheckCCompilerFlag) 4include(CheckCXXCompilerFlag) 5include(CheckCSourceCompiles) 6 7if(WIN32 AND NOT MINGW) 8 # NOTE(compnerd) this is technically a lie, there is msvcrt, but for now, lets 9 # let the default linking take care of that. 10 set(LIBCXX_HAS_C_LIB NO) 11else() 12 check_library_exists(c fopen "" LIBCXX_HAS_C_LIB) 13endif() 14 15if (NOT LIBCXX_USE_COMPILER_RT) 16 if(WIN32 AND NOT MINGW) 17 set(LIBCXX_HAS_GCC_S_LIB NO) 18 else() 19 if(ANDROID) 20 check_library_exists(gcc __gcc_personality_v0 "" LIBCXX_HAS_GCC_LIB) 21 else() 22 check_library_exists(gcc_s __gcc_personality_v0 "" LIBCXX_HAS_GCC_S_LIB) 23 endif() 24 endif() 25endif() 26 27# libc++ is using -nostdlib++ at the link step when available, 28# otherwise -nodefaultlibs is used. We want all our checks to also 29# use one of these options, otherwise we may end up with an inconsistency between 30# the flags we think we require during configuration (if the checks are 31# performed without one of those options) and the flags that are actually 32# required during compilation (which has the -nostdlib++ or -nodefaultlibs). libc is 33# required for the link to go through. We remove sanitizers from the 34# configuration checks to avoid spurious link errors. 35 36check_c_compiler_flag(-nostdlib++ LIBCXX_SUPPORTS_NOSTDLIBXX_FLAG) 37if (LIBCXX_SUPPORTS_NOSTDLIBXX_FLAG) 38 set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} -nostdlib++") 39else() 40 check_c_compiler_flag(-nodefaultlibs LIBCXX_SUPPORTS_NODEFAULTLIBS_FLAG) 41 if (LIBCXX_SUPPORTS_NODEFAULTLIBS_FLAG) 42 set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} -nodefaultlibs") 43 endif() 44endif() 45 46if (LIBCXX_SUPPORTS_NOSTDLIBXX_FLAG OR LIBCXX_SUPPORTS_NODEFAULTLIBS_FLAG) 47 if (LIBCXX_HAS_C_LIB) 48 list(APPEND CMAKE_REQUIRED_LIBRARIES c) 49 endif () 50 if (LIBCXX_USE_COMPILER_RT) 51 list(APPEND CMAKE_REQUIRED_FLAGS -rtlib=compiler-rt) 52 find_compiler_rt_library(builtins LIBCXX_BUILTINS_LIBRARY) 53 list(APPEND CMAKE_REQUIRED_LIBRARIES "${LIBCXX_BUILTINS_LIBRARY}") 54 elseif (LIBCXX_HAS_GCC_LIB) 55 list(APPEND CMAKE_REQUIRED_LIBRARIES gcc) 56 elseif (LIBCXX_HAS_GCC_S_LIB) 57 list(APPEND CMAKE_REQUIRED_LIBRARIES gcc_s) 58 endif () 59 if (MINGW) 60 # Mingw64 requires quite a few "C" runtime libraries in order for basic 61 # programs to link successfully with -nodefaultlibs. 62 if (LIBCXX_USE_COMPILER_RT) 63 set(MINGW_RUNTIME ${LIBCXX_BUILTINS_LIBRARY}) 64 else () 65 set(MINGW_RUNTIME gcc_s gcc) 66 endif() 67 set(MINGW_LIBRARIES mingw32 ${MINGW_RUNTIME} moldname mingwex msvcrt advapi32 68 shell32 user32 kernel32 mingw32 ${MINGW_RUNTIME} 69 moldname mingwex msvcrt) 70 list(APPEND CMAKE_REQUIRED_LIBRARIES ${MINGW_LIBRARIES}) 71 endif() 72 if (CMAKE_C_FLAGS MATCHES -fsanitize OR CMAKE_CXX_FLAGS MATCHES -fsanitize) 73 set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} -fno-sanitize=all") 74 endif () 75 if (CMAKE_C_FLAGS MATCHES -fsanitize-coverage OR CMAKE_CXX_FLAGS MATCHES -fsanitize-coverage) 76 set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} -fno-sanitize-coverage=edge,trace-cmp,indirect-calls,8bit-counters") 77 endif () 78endif () 79 80# Check compiler pragmas 81if(CMAKE_CXX_COMPILER_ID MATCHES "Clang") 82 cmake_push_check_state() 83 set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} -Werror=unknown-pragmas") 84 check_c_source_compiles(" 85#pragma comment(lib, \"c\") 86int main() { return 0; } 87" LIBCXX_HAS_COMMENT_LIB_PRAGMA) 88 cmake_pop_check_state() 89endif() 90 91# Check libraries 92if(WIN32 AND NOT MINGW) 93 # TODO(compnerd) do we want to support an emulation layer that allows for the 94 # use of pthread-win32 or similar libraries to emulate pthreads on Windows? 95 set(LIBCXX_HAS_PTHREAD_LIB NO) 96 set(LIBCXX_HAS_M_LIB NO) 97 set(LIBCXX_HAS_RT_LIB NO) 98 set(LIBCXX_HAS_SYSTEM_LIB NO) 99 set(LIBCXX_HAS_ATOMIC_LIB NO) 100elseif(APPLE) 101 check_library_exists(System write "" LIBCXX_HAS_SYSTEM_LIB) 102 set(LIBCXX_HAS_PTHREAD_LIB NO) 103 set(LIBCXX_HAS_M_LIB NO) 104 set(LIBCXX_HAS_RT_LIB NO) 105 set(LIBCXX_HAS_ATOMIC_LIB NO) 106elseif(FUCHSIA) 107 set(LIBCXX_HAS_M_LIB NO) 108 set(LIBCXX_HAS_PTHREAD_LIB NO) 109 set(LIBCXX_HAS_RT_LIB NO) 110 set(LIBCXX_HAS_SYSTEM_LIB NO) 111 check_library_exists(atomic __atomic_fetch_add_8 "" LIBCXX_HAS_ATOMIC_LIB) 112else() 113 check_library_exists(pthread pthread_create "" LIBCXX_HAS_PTHREAD_LIB) 114 check_library_exists(m ccos "" LIBCXX_HAS_M_LIB) 115 check_library_exists(rt clock_gettime "" LIBCXX_HAS_RT_LIB) 116 set(LIBCXX_HAS_SYSTEM_LIB NO) 117 check_library_exists(atomic __atomic_fetch_add_8 "" LIBCXX_HAS_ATOMIC_LIB) 118endif() 119