[PATCH] D80263: [HeaderSearch] Fix processing #import-ed headers multiple times with modules enabled.

[Volodymyr Sapsai via Phabricator via cfe-commits]

vsapsai created this revision.
vsapsai added reviewers: rsmith, bruno, Bigcheese.
Herald added subscribers: ributzka, dexonsmith, jkorous.
Herald added a project: clang.

HeaderSearch was marking requested HeaderFileInfo as Resolved only based on
the presence of ExternalSource. As the result, using any module was enough
to set ExternalSource and headers unknown to this module would have
HeaderFileInfo with empty fields, including `isImport = 0`, `NumIncludes = 0`.
Such HeaderFileInfo was preserved without changes regardless of how the
header was used in other modules and caused incorrect result in
`HeaderSearch::ShouldEnterIncludeFile`.

Fix by marking HeaderFileInfo as Resolved only if ExternalSource knows
about this header.

rdar://problem/62126911


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D80263

Files:
  clang/lib/Lex/HeaderSearch.cpp
  clang/test/Modules/Inputs/import-once/ImportOnce.framework/Headers/ImportOnce.h
  clang/test/Modules/Inputs/import-once/ImportOnce.framework/Modules/module.modulemap
  clang/test/Modules/Inputs/import-once/IndirectImporter.framework/Headers/IndirectImporter.h
  clang/test/Modules/Inputs/import-once/IndirectImporter.framework/Modules/module.modulemap
  clang/test/Modules/Inputs/import-once/Unrelated.framework/Headers/Unrelated.h
  clang/test/Modules/Inputs/import-once/Unrelated.framework/Modules/module.modulemap
  clang/test/Modules/import-once.m

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