[Bug c/85949] __attribute__ ((format (printf,1,1))); improve error messages

[jg at jguk dot org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85949

--- Comment #6 from Jonny Grant <jg at jguk dot org> ---
Created attachment 45435
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=45435&action=edit
Could these be detected as errors?