Clang C++20 Feature: P1857R3 - Modules Dependency Discovery

[tstellar]

---

id: P1857R3
paper: https://wg21.link/p1857r3

[llvmbot]

@llvm/issue-subscribers-c-20

[erichkeane]

Note what is left is 'Part B', which has a review here (though work need to be done to see if this is sufficient): https://reviews.llvm.org/D110641

[llvmbot]

@llvm/issue-subscribers-clang-frontend

[royjacobson]

@ChuanqiXu9 @Bigcheese do you know if anybody is planning to work on this? The paper says that a Clang implementation was available at the time, but it seems it was never upstreamed.

[ChuanqiXu9]

@ChuanqiXu9 @Bigcheese do you know if anybody is planning to work on this? The paper says that a Clang implementation was available at the time, but it seems it was never upstreamed.

I'm planning to complete it.