erichkeane added inline comments.
================
Comment at: clang/lib/Sema/SemaTemplateInstantiate.cpp:322
+ // they mean.
+ R = Response::UseNextDecl(PartialClassTemplSpec);
} else if (const auto *ClassTemplSpec =
----------------
erichkeane wrote:
> rsmith wrote:
> > Can we produce a "done" response instead here? It doesn't seem right to
> > carry on to the next level here without adding a level of template
> > arguments -- if any further arguments were somehow collected, they would be
> > collected at the wrong template depth. But, as far as I can determine, we
> > should never encounter a partial specialization declaration except in cases
> > where there is nothing remaining to be substituted (all outer substitutions
> > would be identity substitutions). I think the same thing applies when we
> > reach a class template declaration (the first branch in `HandleRecordDecl`)
> > -- we should just be able to stop in that case too, rather than collecting
> > some identity template arguments and carrying on to an outer level.
> >
> > If we can't produce a "done" response here for some reason, then we should
> > collect a level of identity template arguments instead.
> For constraints, the arguments are relative to namespace scope as far as I
> can tell. If we ended up 'stopping' we would miss references to the outer
> template, so something like:
>
> ```
> template<typename T>
> struct Outer {
>
> template<typename U>
> struct Inner {
> void foo() requires (is_same<T, U>){}
> };
>
> };
>
> ```
>
> Right? The substitution fo 'T' would be invalid at that point?
>
> Also, what do you mean by 'identity' template arguments? I'm not sure I
> follow.
Er, I meant something like (since it needs to be a partial spec):
```
1 template<typename T>
2 concept C = true;
3
4 template<typename T>
5 struct Outer {
6 template<typename U, typename V>
7 struct Inner {};
8 template<typename U>
9 struct Inner<U, U> {
10 void foo() requires C<U> && C<T>{}
11 void foo() requires true{}
12 };
13 };
```
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D147722/new/
https://reviews.llvm.org/D147722
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