Apparently, CMake now stores its config.log as YAML...

What was "The C compiler identification is GNU" is now

-
kind: "message-v1"
backtrace:
- "/usr/share/cmake/Modules/CMakeDetermineCompilerId.cmake:17 (message)"
- "/usr/share/cmake/Modules/CMakeDetermineCompilerId.cmake:64 (__determine_compiler_id_test)"
- "/usr/share/cmake/Modules/CMakeDetermineCCompiler.cmake:123 (CMAKE_DETERMINE_COMPILER_ID)"
message: |
The C compiler identification is GNU