There are three related problems:

• An explicit declaration of a function and its definition don't match:

  >perl -we"sub trim(@); sub trim($) {}"
  Prototype mismatch: sub main::trim (@) vs ($) at -e line 1.
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  There's no problem if the declaration has no prototype, so this isn't the cause of your problem.

• An implicit declaration of a function and its definition don't match:

  >perl -we"trim('abc'); sub trim($) {}"
  main::trim() called too early to check prototype at -e line 1.
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• A function's is defined twice with different prototypes:

  >perl -we"sub trim {} sub trim($) {}"
  Prototype mismatch: sub main::trim: none vs ($) at -e line 1.
  Subroutine trim redefined at -e line 1.
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  If so, you'll also get a "Subroutine trim redefined" warning. (You do have warnings turned on, right?)

The last problem is the only one I can get to result in "none vs ($)". The solution, of course, is to get rid of the trim you don't want. Note that you might be importing one (or both) from a module.