[clang] [clang] Diagnose VLA types from an enclosing function in local classes and blocks (PR #229697)

[Eli Friedman via cfe-commits]

https://github.com/efriedma-quic commented:

I don't think it makes sense to have "captureVariablyModifiedType()" as a separate concept from "CheckVariablyModifiedTypeUse()"; we should be doing both checks in one unified function.  If a variably modified type is defined in the same context as the use, we don't need to do anything special.  If a use is in a lambda, and the variably modified type is defined in the parent of the lambda (or more generally, lambda x N ->definition context), we capture.  Otherwise, it's an error.

https://github.com/llvm/llvm-project/pull/229697