750a2d57bd
Fixes #9351. Note that this commit reworks that fix for #9317. The change is to check that the type implements `AsRef<str>` before regarding `to_string` as an equivalent of `to_owned`. This was suggested by Jarcho in the #9317 issue comments. The benefit of this is that it moves some complexity out of `check_other_call_arg` and simplifies the module as a whole.