[llvm-branch-commits] [clang] release/21.x: [clang] Allow trivial pp-directives before C++ module directive (#153641) (PR #154077)

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yronglin wrote:

> > I don't think this really meets our requirements for a backport? It isn't really fixing a regression/etc, right? This is just a general bug-fix? Or am I missing something?
> 
> Ah, I see on the original that @ChuanqiXu9 said we need to do so? I'd like to see the reasoning.

Yes, @boris-kolpackov also report an issue: "BTW, the linked https://github.com/llvm/llvm-project/issues/151985 show that this issue precludes Clang from compiling its own -frewrite-includes output".

https://github.com/llvm/llvm-project/pull/154077