[PATCH] D142196: [clang][Lex] Add back PPCallbacks::FileNotFound

[Jonas Hahnfeld via Phabricator via cfe-commits]

Hahnfeld created this revision.
Hahnfeld added reviewers: jansvoboda11, ahoppen.
Herald added subscribers: shchenz, kbarton, nemanjai.
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This callback was removed with commit rG7a124f4859 <https://reviews.llvm.org/rG7a124f4859d5c4093467abc2e734f8ab15e78cc6>, but we use it downstream in ROOT/Cling to implement handling of a special include syntax. Add back a "safe" version of the callback that only takes the file name and return a bool to silently skip the file.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D142196

Files:
  clang/include/clang/Lex/PPCallbacks.h
  clang/lib/Lex/PPDirectives.cpp


Index: clang/lib/Lex/PPDirectives.cpp
===================================================================
--- clang/lib/Lex/PPDirectives.cpp
+++ clang/lib/Lex/PPDirectives.cpp
@@ -2019,6 +2019,10 @@
   if (File)
     return File;
 
+  // Give the clients a chance to silently skip this include.
+  if (Callbacks && Callbacks->FileNotFound(Filename))
+    return std::nullopt;
+
   if (SuppressIncludeNotFoundError)
     return std::nullopt;
 
Index: clang/include/clang/Lex/PPCallbacks.h
===================================================================
--- clang/include/clang/Lex/PPCallbacks.h
+++ clang/include/clang/Lex/PPCallbacks.h
@@ -83,6 +83,16 @@
                            const Token &FilenameTok,
                            SrcMgr::CharacteristicKind FileType) {}
 
+  /// Callback invoked whenever an inclusion directive results in a
+  /// file-not-found error.
+  ///
+  /// \param FileName The name of the file being included, as written in the
+  /// source code.
+  ///
+  /// \returns true to indicate that the preprocessor should skip this file
+  /// and not issue any diagnostic.
+  virtual bool FileNotFound(StringRef FileName) { return false; }
+
   /// Callback invoked whenever an inclusion directive of
   /// any kind (\c \#include, \c \#import, etc.) has been processed, regardless
   /// of whether the inclusion will actually result in an inclusion.
@@ -451,6 +461,14 @@
     Second->FileSkipped(SkippedFile, FilenameTok, FileType);
   }
 
+  bool FileNotFound(StringRef FileName) override {
+    bool Skip = First->FileNotFound(FileName);
+    // Make sure to invoke the second callback, no matter if the first already
+    // returned true to skip the file.
+    Skip |= Second->FileNotFound(FileName);
+    return Skip;
+  }
+
   void InclusionDirective(SourceLocation HashLoc, const Token &IncludeTok,
                           StringRef FileName, bool IsAngled,
                           CharSourceRange FilenameRange,


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