Tom Wyant

The redundant and missing warnings were added in Perl 5.22 to cover the case where a call to the printf or sprintf had more (redundant) or fewer (missing) arguments than the format calls for. The documentation says that they may be extended to other built-ins (pack and unpack being named specifically) but as of Perl 5.34.0 only the printf() built-ins are covered.

I have (very occasionally) found myself writing a subroutine taking a printf-style format and some arguments, and letting the format specify which (if any) of the arguments actually appear in the output. If I just throw all the arguments after the format into the printf(), one of these warnings is very likely to be thrown, starting with 5.22, since use warnings; enables them by default.

Getting such code to work silently under versions of Perl both before and after the warnings were introduced puzzled me for a bit. Eventially I realized the solution was another pragma: if, which has been in core since Perl 5.6.2. To wit:

sub my_printf {
    no if "$]" >= 5.022, qw{ warnings redundant missing };
    return printf @_;
}

This is the second entry in a desultory series of blogs on the warnings pragma.