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  See also https://phabricator.kde.org/D16894 which (initially) aimed to tackle 
this in a more general fashion.
  
  IMHO the way forward (if my proposal is not acceptable) is to replace the 
existing clang version check with an actual test if the compiler supports the 
flac (CXXCompilerCheckFlag IIRC):
  
    if (CMAKE_CXX_COMPILER_ID MATCHES "Clang") 
      if (CXXCompilerCheckFlag("-foo")
        set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} foo")
      endif()
    endif()
  
  That avoids the overhead when GCC is used but also won't give false positives 
or negatives when clang is used because the compiler/version detection was just 
off.

INLINE COMMENTS

> KDEFrameworkCompilerSettings.cmake:75
> +# don't enable with apple clang
> +if (CMAKE_CXX_COMPILER_ID STREQUAL "Clang")
>     if (NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS "5.0.0")

I'm amazed that this works because CMake *may* detect Apple's clang as 
AppleClang depending on version and how policy 25 (IIRC) is set. Annoyingly 
that policy can only be set before the toplevel project statement, i.e. not in 
the ECM.

In addition, Apple's versioning is very hard if not impossible to match with 
upstream versioning.

REPOSITORY
  R240 Extra CMake Modules

REVISION DETAIL
  https://phabricator.kde.org/D18547

To: vonreth, aacid, apol, dfaure, rjvbb, bcooksley
Cc: aacid, kde-frameworks-devel, kde-buildsystem, michaelh, ngraham, bruns

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