The "hint" in the error message provides a big clue.

The arguments to use if are evaluated in list context. Therefore the match expressions are being evaluated in list context.

From the Perl documentation: "When there are no parentheses in the pattern, the return value is the list (1) for success. With or without parentheses, an empty list is returned upon failure."

So, on a non-MSwindows platform, $^O =~ /MSWin/ is returning an empty list.

Of course, on MSwindows, $^O !~ /MSWin/ is failing, but because it has an implied not, it is equivalent to not ($^O =~ /MSWin/) so is returning a non-empty false value.

In reply to Re: Problem with ``use if COND, Some::Module'' on Linux by RonW
in thread Problem with ``use if COND, Some::Module'' on Linux by stevieb

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