[feature] Clarify expected format of tools.build:compiler_executables and make it consistent in all toolchains

[SpaceIm]

What is your suggestion?

Since #14676, MesonToolchain can accept that each key of tools.build:compiler_executables can be a string or a list. But when it's a string, it interprets each space as if it was a separated list of values, breaking compiler paths with spaces (see conan-io/conan-center-index#21848).
In the meantime, it doesn't work like this in CMakeToolchain, and paths with spaces won't be parsed, so that a compiler path with spaces works fine.

So it would be nice to get some consistency, so that user can expect consistent behavior of tools.build:compiler_executables irrespective of underlying build system used by recipe.

I would expect that if a key is just a string, spaces are interpreted as spaces in full path to compiler, nothing else, so it's passed as is if build system supports it, otherwise sanitized.
If someone wants to misuse tools.build:compiler_executables and extend compiler paths with compiler options and C/C++ flags, then he should use a list (or better pass these options to tools.build:c_flags or tools.build:cxx_flags).

Have you read the CONTRIBUTING guide?

• I've read the CONTRIBUTING guide