[cmake-developers] COMPILE_FEATURES, Mac and non-Apple clang versions

[Robert Maynard]

The problem that was reported in that other thread was due to having
policy CMP0025 set to a false value, once that policy was enabled
compiler detection worked properly.

I would make sure the same isn't happening for you.

I have attached a simple CMakeList.txt file you can use to determine
if potentially you are seeing the same policy issue.



On Tue, Jan 3, 2017 at 9:21 AM, René J.V. Bertin <rjvbertin at gmail.com> wrote:
> Hi,
>
> I just had a run-in with a CMake file from Qt5 in a project I've been building with a locally built Clang 3.9 version, affectionately called clang-mp-3.9 . I got the cryptic message
>
>  CMake Error in src/platformtheme/CMakeLists.txt:
>    No known features for CXX compiler
>
>    "Clang"
>
>    version 3.9.0.
>
>
> Would you consider adding support for non-Apple clang versions on Mac too, and who would best request that, a Qt dev who considers the cxx_decltype test crucial, or the 1st user for whom that breaks his builds (i.e. me)?
>
> I see this has already come up for HB:
> https://cmake.org/pipermail/cmake/2016-December/064719.html
>
>
> Thanks,
> René Bertin
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cmake_minimum_required(VERSION 2.8.12 FATAL_ERROR)
cmake_policy(SET CMP0025 NEW)

project(t C CXX)

cmake_policy(GET CMP0025 appleClangPolicy)
if(NOT appleClangPolicy STREQUAL NEW)
  message(STATUS "cmake_determine_compile_features was not enabled as policy 0025 needs to be set to NEW")
endif()

message(STATUS "CMAKE_CXX_COMPILE_FEATURES: ${CMAKE_CXX_COMPILE_FEATURES}")