glibc strftime extensions

[Joseph S. Myers]

glibc's strftime flags and widths are documented to apply only to numeric
formats; but they also affect the formatting of other formats made up of
multiple numeric formats, such as %F (e.g., %20F and %020F are interpreted
by glibc, and the padding applies to the leftmost number).  Is this a
feature, which GCC should allow when checking the formats, or a
side-effect of the implementation, which GCC should complain about when
checking the formats?

-- 
Joseph S. Myers
jsm28@cam.ac.uk