mizvekov added inline comments.
================ Comment at: clang/lib/Sema/SemaTemplateInstantiate.cpp:1872 QualType Result = getSema().Context.getTemplateTypeParmType( - T->getDepth() - TemplateArgs.getNumSubstitutedLevels(), T->getIndex(), - T->isParameterPack(), NewTTPDecl); + getNewDepth(T->getDepth()), T->getIndex(), T->isParameterPack(), + NewTTPDecl); ---------------- mizvekov wrote: > rsmith wrote: > > mizvekov wrote: > > > mark > > Instead of adding the new `EarlySubstitution` flag and wiring it through > > everywhere, can you use the existing > > `MultiLevelTemplateArgumentList::getNewDepth` function? That already > > handles the case of a depth that's within the number of retained outer > > levels. We might need to set the number of retained outer levels properly > > when doing alias template substitution; I'm not sure if we do so currently > > and I suspect we don't. > I think we do set the number of outer levels correctly when substituting > within the type of alias templates, circa SemaTemplate.cpp:3718: > ``` > // Only substitute for the innermost template argument list. > MultiLevelTemplateArgumentList TemplateArgLists; > TemplateArgLists.addOuterTemplateArguments(&StackTemplateArgs); > TemplateArgLists.addOuterRetainedLevels( > AliasTemplate->getTemplateParameters()->getDepth()); > ``` > > What the flag was done to deal with is what happens in > `TemplateDeclInstantiator::VisitTypeAliasTemplateDecl`, when replacing just > the inner level. We need to substitute there without changing any depths, > including the template parameters of the alias itself, and I could not find a > way to do that without extending it with the new flag. > > Anyway, I will think about this again. > I ended up finding another test case which this patch only partially helps, > so I have been back investigating this problem again: > https://godbolt.org/z/9fGb1KKvq > ``` > template <typename... As> struct Y; > template <typename ...Bs> using Z = Y<Bs...>; > template <typename ...Cs> struct foo { > template <typename ...Ds> using bind = Z<Ds..., Cs...>; > }; > using U = foo<int>::bind<char>; > ``` Though that last test case seems actually to be a wrong index problem, not wrong depth. Repository: rG LLVM Github Monorepo CHANGES SINCE LAST ACTION https://reviews.llvm.org/D127351/new/ https://reviews.llvm.org/D127351 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
