[clang] [Sema] Don't call isNonConstantStorage on incomplete variable types (PR #161590)

[Eli Friedman via cfe-commits]

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

LGTM... but it would be nice to get a second opinion on whether `var->getDeclContext()->isDependentContext()` is the right way to check this.

https://github.com/llvm/llvm-project/pull/161590