[PATCH] D86048: [AST][RecoveryExpr] Popagate the error-bit from a VarDecl's initializer to DeclRefExpr.

[Richard Smith - zygoloid via Phabricator via cfe-commits]

rsmith added a comment.

In D86048#2254607 <https://reviews.llvm.org/D86048#2254607>, @sammccall wrote:

> The crux is we're forcing `decltype(N)` to be a (unique) dependent type, which feels wrong.
> [...]
> There are three behaviors:
>
> - standard up to C++14: traversing the expr looking for a template param to be lexically included (this is my reading of the standard)

FWIW, "involves a template parameter" is exactly the same phrasing that [temp.over.link] uses to refer to instantiation-dependence; that's why Clang uses instantiation-dependence in this case at the moment.

> - what clang actually does: check instantiation dependence, which I think pulls in too many cases
> - standard after http://wg21.link/cwg2064: check type dependence
>
> I think it's probably OK to adopt the C++17 behavior for all versions (if I'm right that the current behavior is a bug).
> @rsmith It's your DR, what do you think :-)

Let's try it and see what happens. I think this will reveal a collection of cases where we don't properly handle instantiation-dependent-but-not-type-dependent constructs (such as, if I remember correctly, the types of non-type template parameters), but we should be fixing those bugs anyway :)


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