Update language standard for C and C++

[avitase]

By now, most compilers support C++23, and even C23.

See

• Compiler support C23 and CMAKE_C_KNOWN_FEATURES
• Compiler support C++23 and CMAKE_CXX_KNOWN_FEATURES

For this to work the CMake version has to be bumped to at least 3.21, though.

[friendlyanon]

For this to work the CMake version has to be bumped to at least 3.21, though.

But also, I want the C++23 template to be using modules and import std;, so that still has to wait a little.

If you still wish to work on a PR for C23, then you'd also have to make sure that project-is-top-level.cmake is not used nor generated, since 3.21 is where the variable was introduced to CMake. For cmake_minimum_required, a new boolean variable c23 ought to work with {% if c23 %}3.21{% else %}3.14{% end %}.

[avitase]

make sure that project-is-top-level.cmake is not used nor generated, since 3.21 is where the variable was introduced to CMake

does it hurt to still set this variable manually for 3.21+ ?

[friendlyanon]

No, but the whole point of that file is to "polyfill" that feature. If the feature is already there, then there is no purpose to that file anymore.

[avitase]

That's true. This was my lame excuse to avoid adding branches that will become obsolete once the global 3.14 requirement for CMake gets bumped ;)

[friendlyanon]

Are you interested in working further on this PR?

[friendlyanon]

Please open a new PR if you wish to work on the C project generation.