improve `-ffile-prefix-map` detection

[timblechmann]

Description

the current implementation has two problems:

• clang-cl does not know -ffile-prefix-map, but it identifies as "Clang", so the compiler will warn about an unknown compiler option
• xcode's clang however does not identify as "Clang", but as "AppleClang". so -ffile-prefix-map is not passed although it is supported by the compiler

[codecov[bot]]

Codecov Report

Merging #2517 (2848c2c) into devel (32eae0e) will increase coverage by 0.03%. The diff coverage is n/a.

:exclamation: Current head 2848c2c differs from pull request most recent head 752743b. Consider uploading reports for the commit 752743b to get more accurate results

@@            Coverage Diff             @@
##            devel    #2517      +/-   ##
==========================================
+ Coverage   91.54%   91.56%   +0.03%     
==========================================
  Files         183      183              
  Lines        7561     7560       -1     
==========================================
+ Hits         6921     6922       +1     
+ Misses        640      638       -2     

[jbadwaik]

I think it's a bug with CMake if they identify two different compilers, clang and clang-cl, as the same.

https://gitlab.kitware.com/cmake/cmake/-/issues/22668

[horenmar]

This will need some fixes to the path normalization code in approval tests.

[timblechmann]

This will need some fixes to the path normalization code in approval tests.

do you have any pointers for the entry points to do these fixes?

[horenmar]

@timblechmann Approval tests run the SelfTest binary and compare the output to a known good one. The implementation is in tools/scripts/approvalTests.py, and the problematic part is in normalizePath function, which looks for the absolute path to the binary in the text output, and if it finds it, it removes prefix.

-ffile-prefix-map also removes the prefix, but uses a slightly different prefix than the approval test normalization. This leads me to an idea; we could instead change the mapping used by -ffile-prefix-map to ${CATCH_DIR}/=, so that the resulting path is the same as what the approval tests want.