[clang] Consider aggregate bases when checking if an InitListExpr is constant (PR #80519)

[Shafik Yaghmour via cfe-commits]

https://github.com/shafik commented:

Also in the issue: https://github.com/llvm/llvm-project/issues/80510 you pointed out a crash bug. We should have the bug covered in the test case as well.

https://github.com/llvm/llvm-project/pull/80519