Never.
An ellipsis (anapodoton) of if pigs had wings, they would fly.
if only
I wish that; would (that) (archaic). Signifies a wish or desire for th…
if it's all the same
If it makes no difference; if nobody minds; if it doesn't bother anyon…
if the shoe fits
Ellipsis of if the shoe fits, wear it.
if need be
If necessary; if there is a need.
if needs be
If need be; if there is a need.
if anything
Used to suggest or state tentatively that something may be the case (o…