[clang] [C++20][Modules] Implement P1857R3 Modules Dependency Discovery (PR #107168)

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h-vetinari wrote:

> Why is that hard to believe?

Because there's no need to mix a completely new directive with fundamentally different instructions (and parsing) on the same line. All the complexity required to support this (much less the mental stumbling blocks for readers of the code) stand in contrast to the trivial alternative of "add a newline". The putative burden of doing so doesn't even come close to justifying the resulting complexity -- it's entirely self-defeating of the standard to allow this IMO.

https://github.com/llvm/llvm-project/pull/107168