[clang] [clang-tools-extra] [clangd] [C++20] [Modules] Build Database Support (PR #199384)

[Chuanqi Xu via cfe-commits]

ChuanqiXu9 wrote:

BTW, I just found I can infer the corresponding TU imported by a specific TU in current compilation database by looking at the compile flags. But this only works for clang now. We may still need this for GCC.

https://github.com/llvm/llvm-project/pull/199384