[clang] Fix incorrect array initialization with string literal (fixes #112189) (PR #156846)

[via cfe-commits]

awson wrote:

> Thanks for working on this.
> 
> I have some concerns that we do that transformation even in non template contexts, it seems a fairly big hammer. Can you try to find ways to limit how often the cloning is done? id you explore the other suggestion made by @zygoloid at all ? (to do it in TreeTransform)

I'm (almost) absolutely new to the clang codebase, and the second option seemed much more approachable to me to implement.

I've looked into TreeTransform, but, while understanding (in principle) its purpose, I don't quite understand what should I do and where.

But well, I'll look if I can limit the cloning.

https://github.com/llvm/llvm-project/pull/156846