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      1 include(CheckLibraryExists)
      2 include(CheckCCompilerFlag)
      3 include(CheckCXXCompilerFlag)
      4 
      5 if(WIN32 AND NOT MINGW)
      6   # NOTE(compnerd) this is technically a lie, there is msvcrt, but for now, lets
      7   # let the default linking take care of that.
      8   set(LIBCXX_HAS_C_LIB NO)
      9 else()
     10   check_library_exists(c fopen "" LIBCXX_HAS_C_LIB)
     11 endif()
     12 
     13 if (NOT LIBCXX_USE_COMPILER_RT)
     14   if(WIN32 AND NOT MINGW)
     15     set(LIBCXX_HAS_GCC_S_LIB NO)
     16   else()
     17     check_library_exists(gcc_s __gcc_personality_v0 "" LIBCXX_HAS_GCC_S_LIB)
     18   endif()
     19 endif()
     20 
     21 # libc++ is built with -nodefaultlibs, so we want all our checks to also
     22 # use this option, otherwise we may end up with an inconsistency between
     23 # the flags we think we require during configuration (if the checks are
     24 # performed without -nodefaultlibs) and the flags that are actually
     25 # required during compilation (which has the -nodefaultlibs). libc is
     26 # required for the link to go through. We remove sanitizers from the
     27 # configuration checks to avoid spurious link errors.
     28 check_c_compiler_flag(-nodefaultlibs LIBCXX_SUPPORTS_NODEFAULTLIBS_FLAG)
     29 if (LIBCXX_SUPPORTS_NODEFAULTLIBS_FLAG)
     30   set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} -nodefaultlibs")
     31   if (LIBCXX_HAS_C_LIB)
     32     list(APPEND CMAKE_REQUIRED_LIBRARIES c)
     33   endif ()
     34   if (LIBCXX_USE_COMPILER_RT)
     35     list(APPEND CMAKE_REQUIRED_FLAGS -rtlib=compiler-rt)
     36     find_compiler_rt_library(builtins LIBCXX_BUILTINS_LIBRARY)
     37     list(APPEND CMAKE_REQUIRED_LIBRARIES "${LIBCXX_BUILTINS_LIBRARY}")
     38   elseif (LIBCXX_HAS_GCC_S_LIB)
     39     list(APPEND CMAKE_REQUIRED_LIBRARIES gcc_s)
     40   endif ()
     41   if (MINGW)
     42     # Mingw64 requires quite a few "C" runtime libraries in order for basic
     43     # programs to link successfully with -nodefaultlibs.
     44     if (LIBCXX_USE_COMPILER_RT)
     45       set(MINGW_RUNTIME ${LIBCXX_BUILTINS_LIBRARY})
     46     else ()
     47       set(MINGW_RUNTIME gcc_s gcc)
     48     endif()
     49     set(MINGW_LIBRARIES mingw32 ${MINGW_RUNTIME} moldname mingwex msvcrt advapi32
     50                         shell32 user32 kernel32 mingw32 ${MINGW_RUNTIME}
     51                         moldname mingwex msvcrt)
     52     list(APPEND CMAKE_REQUIRED_LIBRARIES ${MINGW_LIBRARIES})
     53   endif()
     54   if (CMAKE_C_FLAGS MATCHES -fsanitize OR CMAKE_CXX_FLAGS MATCHES -fsanitize)
     55     set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} -fno-sanitize=all")
     56   endif ()
     57   if (CMAKE_C_FLAGS MATCHES -fsanitize-coverage OR CMAKE_CXX_FLAGS MATCHES -fsanitize-coverage)
     58     set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} -fno-sanitize-coverage=edge,trace-cmp,indirect-calls,8bit-counters")
     59   endif ()
     60 endif ()
     61 
     62 if(NOT WIN32 OR MINGW)
     63   include(CheckLibcxxAtomic)
     64 endif()
     65 
     66 # Check compiler flags
     67 
     68 check_cxx_compiler_flag(/WX                     LIBCXX_HAS_WX_FLAG)
     69 check_cxx_compiler_flag(/WX-                    LIBCXX_HAS_NO_WX_FLAG)
     70 check_cxx_compiler_flag(/EHsc                   LIBCXX_HAS_EHSC_FLAG)
     71 check_cxx_compiler_flag(/EHs-                   LIBCXX_HAS_NO_EHS_FLAG)
     72 check_cxx_compiler_flag(/EHa-                   LIBCXX_HAS_NO_EHA_FLAG)
     73 check_cxx_compiler_flag(/GR-                    LIBCXX_HAS_NO_GR_FLAG)
     74 
     75 
     76 # Check libraries
     77 if(WIN32 AND NOT MINGW)
     78   # TODO(compnerd) do we want to support an emulation layer that allows for the
     79   # use of pthread-win32 or similar libraries to emulate pthreads on Windows?
     80   set(LIBCXX_HAS_PTHREAD_LIB NO)
     81   set(LIBCXX_HAS_M_LIB NO)
     82   set(LIBCXX_HAS_RT_LIB NO)
     83 else()
     84   check_library_exists(pthread pthread_create "" LIBCXX_HAS_PTHREAD_LIB)
     85   check_library_exists(m ccos "" LIBCXX_HAS_M_LIB)
     86   check_library_exists(rt clock_gettime "" LIBCXX_HAS_RT_LIB)
     87 endif()
     88