Cray PE can select from multiple compilers as backends for better language standard support while maintaining performance of Cray frontend optimizations. Compilers such as Intel oneAPI themselves use GCC as a backend on Linux. Manual configuration may be required as the default system GCC may be too old for the desired language standard features. Or, the libstdc++ can be too old in the system default GCC. These issues are remediated by purposeful specification of the Cray-Intel-GCC toolchain in a CMake toolchain file.

This toolchain file can be copied to a common location like ~ and used among many projects, such as our cray.cmake.

For CMake project that have ExternalProject inside them, there must be a CMAKE_TOOLCHAIN_FILE parameter to ExternalProject_Add like:

set(cmake_args ...)

if(CMAKE_TOOLCHAIN_FILE)
  list(APPEND cmake_args -DCMAKE_TOOLCHAIN_FILE:FILEPATH=${CMAKE_TOOLCHAIN_FILE})
endif()


ExternalProject_Add(...
CMAKE_ARGS ${cmake_args}
)

The CMake project is configured like:

cmake --toolchain ~/cray.cmake -B build