src/test/ui/fmt/issue-91556.stderr

   1 error: invalid format string: expected `'}'` but string was terminated
   2   --> $DIR/issue-91556.rs:2:19
   3    |
   4 LL |   let _ = format!(concat!("{0}𝖳𝖾𝗌𝗍{"), i);
   5    |                   ^^^^^^^^^^^^^^^^^^^ expected `'}'` in format string
   6    |
   7    = note: if you intended to print `{`, you can escape it using `{{`
   8    = note: this error originates in the macro `concat` (in Nightly builds, run with -Z macro-backtrace for more info)
   9
  10 error: aborting due to previous error
  11