cpp 17 / std::filesystem wip

[ofTheo]

This PR is for addressing the last things from #6585

The code changes needed for OF are all done from previous PRs.
This PR is to simplify the process of enabling cpp 17 ( or newer ) for a project.

One common theme is that we need to both set the cpp version to c++17 but also define OF_USING_STD_FS=1.
I am wondering maybe could we just detect c++17 in ofConstants.h and auto enable OF_USING_STD_FS if not defined
Edit: going with auto detect as it makes everything cleaner.

Status:

• macOS Xcode ( [see notes here](Discussion about supporting C++17 #6585 (comment) 1018168686) )
• macOS makefile ( see notes/questions here )
• windows visual studio
• windows msys2
• linux
• linux arm
• emscripten
• android
• iOS/tvOS

[dimitre]

Great work @ofTheo ! What do you think we could use to opt for different Project.xcconfig versions?
Maybe something in project generator or a duplicate template for osx?

[ofTheo]

Yeah I think maybe the default could be C++17 and then using the PG template system for macOS 10.14 which can't handle C++17 - that should be fairly easy.

I don't think there are other platforms which couldn't just be C++17 going forward ( will see as we get the rest of the platforms in this PR ).

[arturoc]

I think most platforms should support c++17 without problem. I would even remove boost at some point once we deprecate whatever version of macos is the latest that doesn't support c++17. boost was always a temporary thing to get rid of poco until there was support for std::fs

[ofTheo]

@arturoc great! sounds good.
Yeah, I think we could probably keep boost for one more release and then remove.
macOS 10.14 is now 4 versions behind, so maybe even by the time we get to the next release it could be safe to remove :)

[ofTheo]

Thanks @danoli3!
I think it can work without recompiling libs.
At least managed to do so for most platforms so far - now just trying to get all the platform changes in without breaking others. :P

[ofTheo]

seems to be working now!
going to look at android and arm next ( had to disable armv7 as there were some unrelated issues )

[chilina]

Hey Theo (and others) thank you so much for working on this! I'm always in awe of how the development team keeps oF current and relevant on so many different platforms. Looking forward to using the TBB library on macOS with c++17. I'd help if my skills were better; I'd be completely lost trying to do this. So many many thanks and excited to see these kinds of projects in process!

[ofTheo]

@chilina you're welcome - thanks for the note!
Hoping to get this finished and merged in soon so people can test with the nightly builds.

[ofTheo]

So looks like Android will have to wait till the NDK update from @danoli3
( see error message at bottom )

Everything else is working just need to clean it up a bit and do a couple more tests.

error: invalid value 'c++17' in '-std=c++17'
note: use 'c++98' for 'ISO C++ 1998 with amendments' standard
note: use 'c++03' for 'ISO C++ 1998 with amendments' standard
note: use 'gnu++98' for 'ISO C++ 1998 with amendments and GNU extensions' standard
note: use 'c++0x' for 'ISO C++ 2011 with amendments' standard
note: use 'c++11' for 'ISO C++ 2011 with amendments' standard
note: use 'gnu++0x' for 'ISO C++ 2011 with amendments and GNU extensions' standard
note: use 'gnu++11' for 'ISO C++ 2011 with amendments and GNU extensions' standard
note: use 'c++1y' for 'ISO C++ 2014 with amendments' standard
note: use 'c++14' for 'ISO C++ 2014 with amendments' standard
note: use 'gnu++1y' for 'ISO C++ 2014 with amendments and GNU extensions' standard
note: use 'gnu++14' for 'ISO C++ 2014 with amendments and GNU extensions' standard
note: use 'c++1z' for 'Working draft for ISO C++ 2017' standard
note: use 'gnu++1z' for 'Working draft for ISO C++ 2017 with GNU extensions' standard
note: use 'cuda' for 'NVIDIA CUDA(tm)' standard

[stungeye]

I've tested cpp17 and std::filesystem in the night build with Visual Studio 2022. Works great! Results here.