Error messages point to wrong line number in if-elsif construct

[Sandy]

This really isn't a question, and I'm not sure if it is the correct place to post, but nonetheless...

While looking at node Resetting variables I was mislead by the line number of the error message.

It appears that when there is an if(){...}elsif(){...} construct that contains an error with the elsif part, the line number points to the line of the if statement.

Examples are better than words:

use strict;
use warnings;

# demonstration of error message
my $test = "";
my $abc = "abc";
if ($abc =~ /xyz/) {       # <- LINE 7
    print "nothing\n";
}
#elsif ($abc =~ /[$test]/) {
if ($abc =~ /[$test]/) {   # <- LINE 11
    print "passed 1st condition\n";
}

Result ... error is at line 11 ...

Unmatched [ before HERE mark in regex m/[ << HERE ]/ at D:\try3.pl lin
+e 11.

But

use strict;
use warnings;

# demonstration of error message
my $test = "";
my $abc = "abc";
if ($abc =~ /xyz/) {    # <- LINE 7
    print "nothing\n";
}
elsif ($abc =~ /[$test]/) {
#if ($abc =~ /[$test]/) {   # <- LINE 11
    print "passed 1st condition\n";
}

Result ... error is at line 7 ...

Unmatched [ before HERE mark in regex m/[ << HERE ]/ at D:\try3.pl lin
+e 7.

Very confusing. I haven't seen any documentation on this behaviour.

Sandy

[cchampion]

Have a look at if-elsif weirdness (and the explanation at Re: if-elsif weirdness) where the same issue was addressed some time ago.

It looks like it's either a well known bug or a behavior which most of the people are happy living with. :)

[gaal]

See No Pause on Elsif in Debugger for a discussion.

[ikegami]

elsif doesn't start a statement. It's part of an if statement. In this case, it's telling you that the error is in the statement that started at line 7. I don't know why it's not more precise, but I'm sure changing it would involve extreme changes to perl's guts.