[CMake] CHECK_CXX_COMPILER_FLAG doesn't give correct result for -fsanitize=address

[Michael Ellery]

I’ve dealt with that using something like this:

  set (_saved_CRL ${CMAKE_REQUIRED_LIBRARIES})
  set (CMAKE_REQUIRED_LIBRARIES “-fsanitize=address;asan")
  check_cxx_compiler_flag (-fsanitize=address COMPILER_SUPPORTS_SAN)
  set (CMAKE_REQUIRED_LIBRARIES ${_saved_CRL})

the second item in CMAKE_REQUIRED_LIBRARIES is only needed when using gcc which also requires a -lasan when linking (clang does not need this)

> On Oct 24, 2019, at 12:47 PM, Turner, Adrian Keith via CMake <cmake at cmake.org> wrote:
> 
> Hi CMake Mailing List,
> 
> I am using the CHECK_CXX_COMPILER_FLAG directive in a CMake file to detect whether the compiler uses the "-fsanitize=address" compiler flag. I'm using the g++ 7.3.0 compiler which supports this flag but the CHECK_CXX_COMPILER_FLAG directive incorrectly determines that this flag is not supported.
> 
> To test this I tried compiling the following program:
> int main() {};
> 
> This compiled with the following commands:
> > g++ -fsanitize=address -c test.cpp
> > g++ -fsanitize=address test.o -o test.exe
> 
> And fails with the same error message as CHECK_CXX_COMPILER_FLAG when I compile with:
> > g++ -fsanitize=address -c test.cpp
> > g++ test.o -o test.exe
> 
> producing the following message:
> Undefined symbols for architecture x86_64:
>   "___asan_init", referenced from:
>       __GLOBAL__sub_I_00099_0_test.cpp in test.o
>   "___asan_version_mismatch_check_v8", referenced from:
>       __GLOBAL__sub_I_00099_0_test.cpp in test.o
> ld: symbol(s) not found for architecture x86_64
> collect2: error: ld returned 1 exit status
> 
> It seems that CHECK_CXX_COMPILER_FLAG doesn't add the flag to the linking command when it tests compilation. Is this a bug with CHECK_CXX_COMPILER_FLAG or is there something I'm missing?
> 
> Many thanks
> Adrian Turner
> 
> 
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