https://gcc.gnu.org/bugzilla/show_bug.cgi?id=43319
David <gccbugzilla at limegreensocks dot com> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |gccbugzilla@limegreensocks. | |com --- Comment #3 from David <gccbugzilla at limegreensocks dot com> --- This is a duplicate of 30527. A subset of the most commonly needed/used modifiers have been added to the docs as of 5.x (including the %c1 referenced above). %P (also mentioned above) is not currently documented, and I see no reason that it should be. An examination of glibc suggests that instead of using the undocumented/unsupported %P1, they can accomplish what they need with the already documented %c1.