[Bug c/79692] [7 Regression] -Wformat-overflow false positive with unknown width

[sirl at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79692

--- Comment #3 from Franz Sirl <sirl at gcc dot gnu.org> ---
I can confirm that the patch fixes both the submitted testcase and the original
code.
Thanks for your efforts.