[PATCH] D82568: [clang][CrossTU] Invalidate parent map after get cross TU definition.

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gamesh411 accepted this revision.
gamesh411 added a comment.
This revision is now accepted and ready to land.

I have found this in ASTContext.h:

  // A traversal scope limits the parts of the AST visible to certain analyses.
     // RecursiveASTVisitor::TraverseAST will only visit reachable nodes, and
     // getParents() will only observe reachable parent edges.
     //
     // The scope is defined by a set of "top-level" declarations.
     // Initially, it is the entire TU: {getTranslationUnitDecl()}.
     // Changing the scope clears the parent cache, which is expensive to rebuild.
     std::vector<Decl *> getTraversalScope() const { return TraversalScope; }

The setTraversalScope resets the parentmap in ASTContext.cpp:

  void ASTContext::setTraversalScope(const std::vector<Decl *> &TopLevelDecls) {
     TraversalScope = TopLevelDecls;
     getParentMapContext().clear();
   }

It seems to me that not resetting this cache could very well cause a bad AST being available.
Just curious: Is there an example that you are aware of, where this caused an actual problem?


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  https://reviews.llvm.org/D82568/new/

https://reviews.llvm.org/D82568