[PATCH] D123104: [Modules] Use looked-up filename when looking for module maps

[Ben Barham via Phabricator via cfe-commits]

bnbarham created this revision.
bnbarham added a reviewer: dexonsmith.
Herald added a project: All.
bnbarham requested review of this revision.
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Prevent possible modulemap collisions by making sure to always use the
looked-up filename, regardless of any possible overlays.

Upstreamed from apple#llvm-project
72cf785051fb1b3ef22eee4dd33366e41a275981. As well as preventing the
collisions as above, it also highlighted an issue with the recent change
to narrow the FileManager hack of setting the `DirectoryEntry` in
`FileEntry` to the most recently looked up directory
(3fda0edc51fd68192a30e302d45db081bb02d7f9 <https://reviews.llvm.org/rG3fda0edc51fd68192a30e302d45db081bb02d7f9>). Specifically, it would cause
the incorrect path to be used in `DoFrameworkLookup` in a crash
reproducer:

- Crash reproducers have `use-external-names` set to false
- `File->getFileEntry().getDir()->getName()` would then be the *cached* path, not the just looked up one
- `crash-vfs-umbrella-frameworks.m` fails with this change since the correct path is now looked up and causes B to be loaded twice


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D123104

Files:
  clang/include/clang/Lex/HeaderSearch.h
  clang/lib/Lex/HeaderSearch.cpp
  clang/test/Modules/Inputs/all-product-headers.yaml
  clang/test/Modules/modulemap-collision.m

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