[PATCH] D111543: [clang][modules] Stop creating `IdentifierInfo` for names of explicit modules

[Jan Svoboda via Phabricator via cfe-commits]

jansvoboda11 created this revision.
jansvoboda11 added reviewers: Bigcheese, dexonsmith, rsmith.
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When using explicit Clang modules, some declarations might unexpectedly become invisible.

This was noticed in the following scenario:

- module named `Interface` contains an ObjC interface declaration of the same name, and its PCM is passed to Clang via the `-fmodule-file=<path>` argument,
- another module referring to `Interface` within an attribute (`objc_bridge`) is passed to Clang (also via the `-fmodule-file=<path>` argument),
- the Clang invocation then can't find the `Interface` interface declaration.

This seems to be caused by the mechanism that loads PCM files passed via `-fmodule-file=<path>` which creates an `IdentifierInfo` for the module name. I'm not sure why exactly that trips up name resolution, but using `StringRef` for the module name resolves the error. Creating an `IdentifierInfo` with some prefix (e.g. `CI.getPreprocessor().getIdentifierInfo("LoadModuleCacheKey_" + ModuleName)`) also resolves the issue.

Note that the `-fmodule-file=<name>=<path>` form of the argument doesn't suffer from this issue, since it doesn't create `IdentifierInfo` for the module name.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D111543

Files:
  clang/include/clang/Lex/ModuleMap.h
  clang/lib/Frontend/CompilerInstance.cpp
  clang/test/Modules/Inputs/interface-visibility-2/Interface.h
  clang/test/Modules/Inputs/interface-visibility-2/InterfaceBridge.h
  clang/test/Modules/Inputs/interface-visibility-2/module.modulemap
  clang/test/Modules/interface-visibility-2.m

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