[clang] Added partial support for compiling C++20 modules and header-units without scanning. (PR #147682)

[Michael Spencer via cfe-commits]

https://github.com/Bigcheese commented:

This really needs to start with an RFC on https://discourse.llvm.org/ first that covers what you want to do. See https://llvm.org/docs/DeveloperPolicy.html#discuss-the-change-gather-consensus, and you can see examples of other RFCs on discourse for how that generally works.

As a start the code would need a lot of changes to land in Clang. It doesn't follow https://llvm.org/docs/CodingStandards.html and https://llvm.org/docs/ProgrammersManual.html, and doesn't make use of existing code in ADT and Support.

https://github.com/llvm/llvm-project/pull/147682