[clang] [clang] Fix the StringRef assertion failure for non-narrow strings. (PR #212108)

[Shengxin Pei via cfe-commits]

TPPPP72 wrote:

I think you should update your pr description. The current description is too long and does not describe actual change. We just need
```
change reason

actual fix

fix #******
```

Thanks!

https://github.com/llvm/llvm-project/pull/212108