CMakeLists.txt update c++ standard to 20

[leleftheriades]

CMakeLists.txt update c++ standard to 20

[tt4g]

The current minimum required C++ version is C++17.
The default C++ version cannot be changed to C++20.

You can build with C++20 by defining CMAKE_CXX_STANDARD when you run the cmake command (e.g. cmake -DCMAKE_CXX_STANDARD=20).

[jtv]

Exactly. I plan to stop supporting C++17 soon, but then the whole game will just start over again with C++20 vs. C++23.

[leleftheriades]

I tried to link the library which got built with default options to a c++20 project and got linker errors in msvc, so i assumed the support for c++17 was dropped that was why i raised an issue. Thank u, i will use the cmake command line argument to ensure i get the version i want

[jtv]

Yes, it's a thorny issue that the package managers are totally ignoring: you can't reliably link code compiled in one C++ version to code compiled in another.

Perhaps the worst part is that it sometimes works. At least when it breaks consistently you will know when it needs fixing.