%F in strftime() format gives an error

A minor bug, perhaps: When I use the %F format specifier in the format
string passed to strftime(), compiling in the IDE flags it as “unknown
conversion type character `F’ in format”.

This is because there is a pragma in the compiler that indicates that
the arguments to this function
should be validated by the compiler and there are some flags it
doesn’t know about.

What version of the compiler are you using (2.95 or 3.x or …)