C++20: Support "concepts" syntax

[Zingam]

Support the "concepts" syntax, which is not yet supported.

[michelleangela]

The extension's C++ standard features are inherited from Visual Studio. Please upvote this feedback ticket https://developercommunity.visualstudio.com/idea/549930/add-standard-concepts-libary-support.html on Visual Studio to support C++ 20 concepts library.

[sean-mcmanus]

Michelle -- that issue is for the cl.exe compiler...there might be another issue tracking IntelliSense, but we usually keep the issues open on our side until we get the fix from VS.

[tloka]

Any news on this?

[sean-mcmanus]

C++ IntelliSense concepts support is still being worked on. I found a related VS bug at https://developercommunity.visualstudio.com/content/problem/745318/-cpp-lib-concepts-isnt-defined-in-vs-2019-1630-rel.html .

[elijaharita]

Concepts Intellisense support is now available with Visual Studio 16.6 Preview 2

[sean-mcmanus]

@elijahseedarita Yes, we plan to integrate those changes for our 1.0 release (our soon-to-be-released 0.27.0 won't have those changes yet). Also, it sounded like the support for concepts was not 100% yet.

[elijaharita]

@sean-mcmanus Thanks for all your work! =)

[sean-mcmanus]

Fixed with https://github.com/microsoft/vscode-cpptools/releases/tag/0.28.0-insiders2 in regards to IntelliSense parsing, but support for the global symbol (tag) parser (i.e. outline view, workspace symbol search, find all references, etc.) hasn't been checked in yet (it should be available in 0.29.0-insiders)...not sure if we need another issue to track that or if we should just keep this issue open until then.

[sean-mcmanus]

Actually, it looks like concepts support is still not 100% finished in Intellisense. We'll track the remaining work in #5444 .

[elahehrashedi]

This issue is fixed in 0.28.0.
0.28.0 release: https://github.com/microsoft/vscode-cpptools/releases/tag/0.28.0

[OleksandrKvl]

Not sure whether it's related to this particular issue, I have 1.45.1 VSC and 0.28.1 C++ extension and concept/requires keywords are not highlighted even though VSC clearly knows(they're suggested) that they're C++ keywords.