use warnings 'wtf'

[Paul Makepeace]

Is there any documentation for what all the various use warnings 'foo'
are? perldoc perllexwarn at least lists them but doesn't explain what
each one does, as far as my cursory glance suggested.

Specifically I wanted to turn off a "used only once" warning triggered
by List::MoreUtils::pairwise which aliases $a and $b. Bit surprised
the module doesn't document this as it seems like it'd end up warning
more often than not for the common case.

(The answer is "no warnings 'once'")

Paul