Auto merge of #117819 - fmease:rustc_parse_format-stable-rustc, r=Nilstrieb

Make `rustc_parse_format` compile on stable again

Fixes [#115948 (review comment)](https://github.com/rust-lang/rust/pull/115948/files/822233559619e7e77d984f9020d05302b784cf50#r1385932710).
cc `@Veykril` `@notriddle`

r? compiler

Author: bors