Attempt to instantiate invalid nested class declaration crashes clang

[RealLitb]

Bugzilla Link	9573
Resolution	FIXED
Resolved on	Dec 07, 2020 18:11
Version	trunk
OS	Linux
CC	@DougGregor

Extended Description

Clang crashes on this code:

template
struct A {
struct A; // should probably diagnose this.
};

template struct A::A; // crashes here.

[llvmbot]

this is an old bug and not reproducible in trunk (and probably not for a while) - so am closing it for now.

Thanks!