davrec added a comment. > There are already two way more sophisticated (forgive me my bias) > implementations in Clang that are for checking if two statements or decls are > the same. > > 1. ODRHash, used in modules to discover ODR violations > 2. ASTStructuralEquivalenceContext, used in ASTImporter to discover if two > AST nodes are the same or not (as a side effect we diagnose ODR violations as > well). > > It is not the first time, when such a similarity check is needed (see > https://reviews.llvm.org/D75041). Of course reusing the before mentioned > components would require some architectural changes, but it might be > beneficial.
I do not quite see the overlap. This patch addresses the structural equivalence of DeclRefExprs: as the `std::is_same` (or any type trait example) demonstrates, two declarations may be the "same" (e.g. they are both `std::false_type::value`), but two DeclRefExprs referring to those declarations should not necessarily be considered the "same": the qualifier, specifying the path that was taken to look them up, can matter to a user. It's not a matter of the sophistication of the similarity check, it's a matter of what we mean by similarity. I do not see DeclRefExprs handled in ODRHash or ASTStructuralEquivalence. I do see NestedNameSpecifiers handled in both, but I don't think the implementation quite matches what is needed here (e.g. in ASTStructuralEquivalence check, if one NNS is a NamespaceAlias, the other one is assumed to be a NamespaceAlias: not what we want). It's probably not worth the trouble to factor something common out of those; though they should certainly be used as a guide to make sure no cases have been missed. CHANGES SINCE LAST ACTION https://reviews.llvm.org/D114622/new/ https://reviews.llvm.org/D114622 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
