[CMake] Colored diagnostic output for GCC 4.9 through Ninja

[Robert Dailey]

On Wed, Oct 28, 2015 at 11:19 AM, Robert Dailey
<rcdailey.lists at gmail.com> wrote:
> On Wed, Oct 28, 2015 at 9:03 AM, Miller Henry <MillerHenry at johndeere.com> wrote:
>>
>> I do something like this, which works for clang and should work for gcc 4.9 though I haven't tested it.   I haven't wrote the right way to do this which is to check if the terminal supports color before passing the flag in. I don't know what will happen on our e.g. CI system which doesn't support color.
>>
>> macro(AddCXXFlagIfSupported flag test)
>>    CHECK_CXX_COMPILER_FLAG(${flag} ${test})
>>    if( ${${test}} )
>>       message("adding ${flag}")
>>       set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${flag}")
>>    endif()
>> endmacro()
>>
>> if("Ninja" STREQUAL ${CMAKE_GENERATOR})
>>    AddCXXFlagIfSupported(-fcolor-diagnostics COMPILER_SUPPORTS_fcolor-diagnostics)
>> endif()
>>
>> P.s. AddCXXFlagIfSupported ought to be in the default cmake distribution along with a lot or similar things
>
> Unfortunately your solution doesn't seem to work. I get the following output:
>
> [1/1] Re-running CMake...
> -- Performing Test COMPILER_SUPPORTS_fcolor-diagnostics
> -- Performing Test COMPILER_SUPPORTS_fcolor-diagnostics - Failed
>
> GCC 4.9 supports this I thought?

I found the issue, the flag is diagnostics-color, not color-diagnostics.