[clang] [Clang][Sema] Error message refers to `__begin1` with `constexpr` variable in range-based for loop (PR #218145)

[Shengxin Pei via cfe-commits]

TPPPP72 wrote:

I took a quick look and didn't spot any obvious issues with the implementation. Of course, I don't have time for a full review right now, so if any other reviewers have the time, please take a look.

https://github.com/llvm/llvm-project/pull/218145