Let CMake autodetect Apple arch on M1 processor

[pparuzel]

Description

With the introduction of Apple M1 processor the architecture for SFML build need not be imposed unless specified explicitly. It feels more intuitive to let CMake decide on what the default architecture should be for a specified Apple processor.

Tasks

Changes affect only Apple systems

• Tested on macOS
• Tested on iOS

How to test this PR?

Simply assert that this finishes successfully on Apple M1:

# On Apple M1 processor natively
cmake -B build-native
cmake --build build-native -j12

# On Apple M1 processor with arch x86_64
cmake -B build-x86 -DCMAKE_OSX_ARCHITECTURES=x86_64
cmake --build build-x86 -j12

echo "Test results:"
[[ ! -z $(otool -hv build-native/lib/libsfml-system.dylib | grep -io arm64) ]] && echo "SUCCESS ARM64" || echo "FAILED ARM64"
[[ ! -z $(otool -hv build-x86/lib/libsfml-system.dylib | grep -io x86_64) ]] && echo "SUCCESS x86_64" || echo "FAILED x86_64"

[eXpl0it3r]

Yeah, I've ran into this as well and it makes sense to not enforce it anymore.

Could you rebase this onto 2.6.x and change the target branch to 2.6.x?

[pparuzel]

Rebased and had to force-push to drop commits from 3.0

[eXpl0it3r]

Thanks for this fix! 🙂
As we don't have (m)any macOS developers, feel free to open or PRs or start discussions on the forum, if you see something the could improve the macOS experience.

[pparuzel]

Glad I could be of help!

I'm excited to see the library expand into the Modern C++ world and I independently came back here after a couple of years to realize the transition is just starting :)