[clang] [clang][Sema] Fix crash on designated initializer of union member in subobject (PR #167171)

[Naveen Seth Hanig via cfe-commits]

naveen-seth wrote:

I tried a different approach earlier in afcda23927bb79dfd7446aa90bfc741d5254c2e2, which I believed was the correct fix. However, it caused test failures in `clang/test/AST/ast-dump-stmt.cpp` and `clang/test/AST/ast-dump-stmt-json.cpp` ([see CI run](https://github.com/llvm/llvm-project/actions/runs/19197400180/job/54880367454)).
Does this approach make more sense?

I think I should have updated the failing tests instead of reverting to this workaround. My apologies, I will do that now.

https://github.com/llvm/llvm-project/pull/167171