rsmith added inline comments.
================
Comment at: clang/lib/Sema/SemaConcept.cpp:775-776
+static bool IsInsideImplicitFullTemplateSpecialization(const DeclContext *DC) {
+ auto *CTSDecl = dyn_cast_or_null<ClassTemplateSpecializationDecl>(
+ DC->getOuterLexicalRecordContext());
+ return CTSDecl && !isa<ClassTemplatePartialSpecializationDecl>(CTSDecl) &&
----------------
rsmith wrote:
> This doesn't look right to me; there could be a class template nested inside
> a non-templated class, so I think you would need to walk up the enclosing
> `DeclContext`s one by one checking each in turn. But, we might be inside a
> function template specialization or variable template specialization instead,
> in some weird cases:
>
> ```
> template<typename T> concept C = true;
> template<typename T> auto L = []<C<T> U>() {};
> struct Q {
> template<C<int> U> friend constexpr auto decltype(L<int>)::operator()()
> const;
> };
> ```
>
> ... so I think we want a different approach than looking for an enclosing
> class template specialization declaration.
>
> Can we skip this check entirely, and instead always compute and substitute
> the template instantiation arguments as is done below? That computation will
> walk the enclosing contexts for us in a careful way that properly handles
> cases like this lambda-in-variable-template situation. If we find we get zero
> levels of template argument list, we can skip doing the actual substitution
> as an optimization.
Sorry, that should be:
```
template<typename T, typename U> concept C = true;
```
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D146178/new/
https://reviews.llvm.org/D146178
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