[CMake] Pass -nostdlib if supported

[Hahnfeld]

Summary

The sanitizers use C++ but don't require linking with the library.

[beanz]

LGTM.

[Hahnfeld]

Apparently this hasn't worked that good: It seems my local linker just magically adds -lc. We could manually add it to the flags but I don't quite like that because that should be the compiler's job...

compiler-rt/trunk/CMakeLists.txt

else()
   append_string_if(COMPILER_RT_HAS_WALL_FLAG -Wall CMAKE_C_FLAGS CMAKE_CXX_FLAGS)
 endif()
 if(COMPILER_RT_ENABLE_WERROR)
   append_string_if(COMPILER_RT_HAS_WERROR_FLAG -Werror CMAKE_C_FLAGS CMAKE_CXX_FLAGS)
   append_string_if(COMPILER_RT_HAS_WX_FLAG /WX CMAKE_C_FLAGS CMAKE_CXX_FLAGS)
 endif()
 
 append_string_if(COMPILER_RT_HAS_STD_CXX11_FLAG -std=c++11 CMAKE_CXX_FLAGS)
+# we don't need to link with the C++ library
+append_string_if(COMPILER_RT_HAS_NOSTDLIB_FLAG -nostdlib CMAKE_CXX_FLAGS)
 
 # Emulate C99 and C++11's __func__ for MSVC prior to 2013 CTP.
 if(NOT COMPILER_RT_HAS_FUNC_SYMBOL)
   add_definitions(-D__func__=__FUNCTION__)
 endif()
 
 # Provide some common commmandline flags for Sanitizer runtimes.
 append_list_if(COMPILER_RT_HAS_FPIC_FLAG -fPIC SANITIZER_COMMON_CFLAGS)

compiler-rt/trunk/cmake/config-ix.cmake

 check_cxx_compiler_flag(-fno-stack-protector COMPILER_RT_HAS_FNO_STACK_PROTECTOR_FLAG)
 check_cxx_compiler_flag(-fno-sanitize=safe-stack COMPILER_RT_HAS_FNO_SANITIZE_SAFE_STACK_FLAG)
 check_cxx_compiler_flag(-fvisibility=hidden  COMPILER_RT_HAS_FVISIBILITY_HIDDEN_FLAG)
 check_cxx_compiler_flag(-frtti               COMPILER_RT_HAS_FRTTI_FLAG)
 check_cxx_compiler_flag(-fno-rtti            COMPILER_RT_HAS_FNO_RTTI_FLAG)
 check_cxx_compiler_flag(-ffreestanding       COMPILER_RT_HAS_FFREESTANDING_FLAG)
 check_cxx_compiler_flag("-Werror -fno-function-sections" COMPILER_RT_HAS_FNO_FUNCTION_SECTIONS_FLAG)
 check_cxx_compiler_flag(-std=c++11           COMPILER_RT_HAS_STD_CXX11_FLAG)
+check_cxx_compiler_flag(-nostdlib            COMPILER_RT_HAS_NOSTDLIB_FLAG)
 check_cxx_compiler_flag(-ftls-model=initial-exec COMPILER_RT_HAS_FTLS_MODEL_INITIAL_EXEC)
 check_cxx_compiler_flag(-fno-lto             COMPILER_RT_HAS_FNO_LTO_FLAG)
 check_cxx_compiler_flag("-Werror -msse3" COMPILER_RT_HAS_MSSE3_FLAG)
 check_cxx_compiler_flag(--sysroot=.          COMPILER_RT_HAS_SYSROOT_FLAG)
 
 if(NOT WIN32 AND NOT CYGWIN)
   # MinGW warns if -fvisibility-inlines-hidden is used.
   check_cxx_compiler_flag("-fvisibility-inlines-hidden" COMPILER_RT_HAS_FVISIBILITY_INLINES_HIDDEN_FLAG)