CMake provides "CrayClang" as a compiler ID for the C and CXX Cray compilers based on Clang:

https://cmake.org/cmake/help/latest/variable/CMAKE_LANG_COMPILER_ID.html

SetupCompilerOptions uses matches for Clang to match both Clang and AppleClang:

This causes BLT to erroneously classify CrayClang C and CrayClang CXX as Clang mainline rather than CrayClang.

This results in situations like this:

-- The Fortran compiler identification is Cray 18.0.0
-- The C compiler identification is Clang 18.1.6
-- The CXX compiler identification is Clang 18.1.6

When specifying the cray clang compilers in cmake for CMAKE_C_COMPILER and CMAKE_CXX_COMPILER.