C:\>perl -Mwarnings=FATAL,all -e"print 1 if shift == shift" foo foo
Argument "foo" isn't numeric in numeric eq (==) at -e line 1.

C:\>perl -we"print 1 if shift == shift" foo foo
Argument "foo" isn't numeric in numeric eq (==) at -e line 1.
Argument "foo" isn't numeric in numeric eq (==) at -e line 1.
1