rsmith added a comment.
I think that the bugs that this was aiming to fix were fixed by
rG1e43349e321694d7fee3d77cb691887ad67fb5d7
<https://reviews.llvm.org/rG1e43349e321694d7fee3d77cb691887ad67fb5d7>, which
means that we should not ask whether the constraints of an inherited
constructor are satisfied any more. Instead, overload resolution will look at
whether the constraints of the original constructors are satisfied. (More
broadly, I wonder whether `DiagnoseUseOfDecl` should be considering constraints
at all -- the model in the standard is that any time you name a function, you
go through overload resolution, which considers constraints, so
`DiagnoseUseOfDecl` should only ever be duplicating work that's already been
done by overload resolution, but it's possible we're not entirely following
that model. Still, we should be able to avoid redoing the constraint
satisfaction checks in the common case where overload resolution already did
them.)
That said, I think this change would still be correct if for whatever reason we
started reaching this codepath for inheriting constructors again.
================
Comment at: clang/lib/Sema/SemaTemplateInstantiate.cpp:138-144
+ bool SkipForSpecialization,
+ bool ForConstraintInstantiation) {
if (!ClassTemplSpec->isClassScopeExplicitSpecialization()) {
// We're done when we hit an explicit specialization.
if (ClassTemplSpec->getSpecializationKind() == TSK_ExplicitSpecialization
&&
- !isa<ClassTemplatePartialSpecializationDecl>(ClassTemplSpec))
+ !isa<ClassTemplatePartialSpecializationDecl>(ClassTemplSpec) &&
+ !ForConstraintInstantiation)
----------------
It seems to me that a namespace-scope explicit specialization shouldn't pick up
template arguments, even during constraint checking:
```
template<typename T> struct A {};
template<> struct A<int> {
template<typename U> void f() requires U::value;
};
```
Constraint checking for `A<X>::f<Y>` should produce a single level of template
arguments, `<Y>`, not two layers `<X>, <Y>`, because `U` in `U::value` is a
depth-0 index-0 parameter.
================
Comment at: clang/lib/Sema/SemaTemplateInstantiate.cpp:217-219
+ if (Ctor->isImplicit() && Ctor->isInheritingConstructor() &&
+ Ctor->getInheritedConstructor().getConstructor())
+ Ctor = Ctor->getInheritedConstructor().getConstructor();
----------------
These checks can be simplified.
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D149264/new/
https://reviews.llvm.org/D149264
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