rsmith added a comment. In D111543#3067619 <https://reviews.llvm.org/D111543#3067619>, @rsmith wrote:
> In D111543#3066686 <https://reviews.llvm.org/D111543#3066686>, @jansvoboda11 > wrote: > >> My understanding is that `Preprocessor::getIdentifierInfo` may trigger AST >> deserialization. The problem here seems to be that we're calling >> `getIdentifierInfo` before the preprocessor's `IdentifierTable` is set up >> with "external identifier info lookup" (aka `ASTReader`). So the call to >> `IdentifierTable::get` creates new `IdentifierInfo` for `"Interface"` >> instead of looking it up in the AST. Further calls to `getIdentifierInfo` >> resolve to this new `IdentifierInfo` and the `ObjCInterfaceDecl` never gets >> deserialized. > > Interesting, that could explain what we're seeing. If that's it, then this is > an invalidation bug: changing the presence or behavior of the external > identifier resolver should trigger invalidation of all existing identifiers > so that we will properly query the external source. > > But I'm missing something from that explanation: the > `IdentifierTable::ExternalLookup` is set in the constructor and never changed > from that point onwards, I was wrong about that. Not sure how I missed the setter :) Nonetheless: `ASTReader::ReadAST` calls `ASTReader::ReadASTBlock`, which sets the `ASTReader` as the external identifier lookup source. Then, once the recursive deserialization is done, `ASTReader::ReadAST` marks any pre-existing identifiers as out-of-date. Perhaps the problem is that the identifiers attached to these attributes are somehow being loaded from within `ReadASTBlock`, before they get invalidated? That'd explain what's going wrong. If that's right, then I think this patch would not fully fix the bug: you'd see the same thing if you loaded a module that used the identifier `Interface`, then triggered deserialization of that identifier so it was marked up-to-date, then loaded the problematic module from your testcase. The fix for that would be to ensure that `ReadASTBlock` doesn't deserialize these (or any) identifiers. But I don't see where `ReadASTBlock` is triggering a load of any identifiers either... Repository: rG LLVM Github Monorepo CHANGES SINCE LAST ACTION https://reviews.llvm.org/D111543/new/ https://reviews.llvm.org/D111543 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
