Improved cmake compiler check message

[madduci]

Changelog: Fix: Improved cmake compiler check message to explain the problem with different compiler versions when installing dependencies
Docs: Omit

• Refer to the issue that supports this Pull Request.
• If the issue has missing info, explain the purpose/use case/pain/need that covers this Pull Request.
• I've read the Contributing guide.
• I've followed the PEP8 style guides for Python code.
• I've opened another PR in the Conan docs repo to the develop branch, documenting this one.

^{Note: By default this PR will skip the slower tests and will use a limited set of python versions. Check here how to increase the testing level by writing some tags in the current PR body text.}

[memsharded]

This is good, but the error will also appear if not using the default profile but a custom profile, and the compiler doesn't match. Could you please put it in a generic way? Thanks!

[madduci]

Yeah sure.
Actually, do you have any suggestion for the message?

I've thought something like:

Detected error in your Conan profile: compiler type or compiler version differs from the one detected by CMake

Or something like that

[memsharded]

I think this is not necessary, the file already has a check for compiler mistmach, and and error message, before getting to the version one. Check:

if (NOT CMAKE_CXX_COMPILER_ID MATCHES ${EXPECTED_CMAKE_CXX_COMPILER_ID})
            message(FATAL_ERROR "Incorrect '${CONAN_COMPILER}'. Toolset specifies compiler as '${EXPECTED_CMAKE_CXX_COMPILER_ID}' "
                                "but CMake detected '${CMAKE_CXX_COMPILER_ID}'")
        endif()

The error message is perfect now, thanks!

[madduci]

But if we don't check here again against CONAN_COMPILER, than the error happens in case of profile mismatch, as you commented previously in the other commit. I can remove that part of not required and not desired

[memsharded]

I am not sure if I follow. CONAN_COMPILER is checked before calling check_compiler_version(), so in theory, inside check_compiler_version() it is not possible that there is a compiler mismatch. What am I missing here? There is probably something that I dont see.

[memsharded]

Thanks! These UX improvements are great, they might help to a few users!