[clang] [clang][constexpr] Fix assertion failure in C++26 constexpr structured binding pack evaluation (#170991) (PR #213534)

[Yanzuo Liu via cfe-commits]

https://github.com/zwuis commented:

> Question:
> How are the vector and complex decomposition extensions intended to behave? Is there any documentation for them?
> Specifically, should Clang treat them analogous to the standard(e.g., ODR-use) or are they different?

We don't have documentation of structured bindings about these types. We can just treat them like arrays.

https://github.com/llvm/llvm-project/pull/213534