I'm trying to get the LLDB buildbot to run tests, and currently the issue is that many tests fail when trying to write the session log file. The build directory on the buildbot is already nested kind of deep, which means the path to clang.exe is also deep, and having this in the filename results in paths that are 400+ characters long, which don't work well in Windows.
To fix this, I'm allowing the specification of a custom file format, where you can specify various fields to be included in the filename. The default behavior of dotest is unchanged, it will still display everything it's always displayed. But if you're using CMake then the default will be to not include the compiler path. This is because by default CMake also uses only runs tests with one compiler anyway, so the compiler path is not needed to distinguish identical tests run with different compilers.