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);
----------------
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>;
```
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
