[PATCH] D102923: [clang][lex] Remark for used header search paths

[Jan Svoboda via Phabricator via cfe-commits]

jansvoboda11 created this revision.
jansvoboda11 added reviewers: Bigcheese, dexonsmith.
jansvoboda11 requested review of this revision.
Herald added a project: clang.
Herald added a subscriber: cfe-commits.

For dependency scanning, it would be useful to collect header search paths (provided on command-line via `-I` and friends) that were actually used during preprocessing. This patch adds that feature to `HeaderSearch` along with a new remark that reports such paths as they get used.

Previous version of this patch tried to use the existing `LookupFileCache` to report used paths via `HitIdx`. That doesn't work for `ComputeUserEntryUsage` (which is intended to be called *after* preprocessing), because it indexes used search paths by the file name. This means the values get overwritten when the code contains `#include_next`.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D102923

Files:
  clang/include/clang/Basic/DiagnosticLexKinds.td
  clang/include/clang/Lex/HeaderSearch.h
  clang/lib/Frontend/InitHeaderSearch.cpp
  clang/lib/Lex/HeaderSearch.cpp
  clang/test/Preprocessor/Inputs/header-search-user-entries/a/a.h
  clang/test/Preprocessor/Inputs/header-search-user-entries/a_next/a.h
  clang/test/Preprocessor/Inputs/header-search-user-entries/b/b.h
  clang/test/Preprocessor/Inputs/header-search-user-entries/d/d.h
  clang/test/Preprocessor/header-search-user-entries.c

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