CMake 3.15.4 can not detect C++14 support with GCC 7.2.0
CC: @brad.king
I think that I have determined that CMake 3.15.4 has a regression where it cannot detect C++14 support with GCC 7.2.0. Through a lot of experimentation with Spack packages (see https://github.com/spack/spack/issues/13550) I have determined that CMake 3.15.4 does not correctly detect C++14 support with GCC 7.2.0 when using the command:
target_compile_features(${DETECTION_LIBRARY} INTERFACE cxx_std_14)
and put -std=gnu++14
on the compile line. When using CMake 3.14.5, it does correctly put -std=gnu++14
on the compile line.
This is very bad for ATDM at Sandia as the EMPIRE code uses this feature to turn on C++14 support. Therefore, we are stuck with CMake 3.14 and can't upgrade to CMake 3.15.