Tracking line numbers for warnings can be tricky. Sometimes it's neccessary to put little progress report warnings in the uncertain area, as in 
warn "before if";
        if ($_[$i] =~ /^(.+?)\.(zip|t?gz|tar|bz2?|tbz)$/i) {
warn "in if"
           ...
        elsif (...) {
warn "in elsif 1";
           ...
        else {
warn "in else";

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With these in place, you can tell where the "undefined" warning comes in the sequence of execution. It's messy, but you only have to look at it once, for a quick reality check. The debugger is another way to do this, which could be easier or harder, depending on your inclination to switch over to the debugger mindset.

In reply to Re: Warning gets the line number wrong? by rodion
in thread Warning gets the line number wrong? by Cap'n Steve

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