A strange problem here. Perl is telling me 
"Use of uninitialized value $_[2] in pattern match (m//) at Plugin/Syn
+tax.pm line 39."

[download]
But there is no reference to $_[2] in the code. I stripped out most of the module to hit the function: (Line 39 is the first line of parse_rvalue()) 
package Plugin::Syntax;

use strict;
use warnings;

use Data::Dump;

my $code;
my $kw = qr/[A-Za-z_][A-Za-z0-9_-]*/;

my %directives = map { $_ => 1 } (qw|
    !some !data !snipped| );

my %commands = map { $_ => 1 } (qw|
    some data snipped| );

sub parse_command {
    return unless $_[0] =~ /\G\s*($kw)\s*=\s*/cg;  # not 'ident ='
    my $id = $1;
    my ($s,$e) = ($-[1],$+[1]);
    if( $id =~ /^(?:ok|e[0-9A-Fa-f]{2})$/ ) {
        $code->tagAdd( 'special', "$_[1] +${s}c", "$_[1] +${e}c" );
    }

    if( $_[0] =~ /\G($kw)\s*\(/cg ) {           # parse that command
        pos( $_[0] )--;                         # give back the paren
        if( exists $commands{lc $1} ) {         # Check if command exi
+sts
            $code->tagAdd( 'command', "$_[1] +$-[1]c", "$_[1] +$+[1]c"
+ );
        }
        return lc $1;
    }

    # This must be an immediate value
    &parse_rvalue;
    return 'none';
}

sub parse_rvalue {
    if( $_[0] =~ /\G[CS]?\d\d-\d\d(?:\s+var\s+[0-9A-Fa-f]{1,2})?/cg ) 
+{
        $code->tagAdd('constant', "$_[1] +$-[0]c", "$_[1] +$+[0]c");
    }
    elsif( $_[0] =~ /\G[CS]?[#][0-9A-Fa-f]{3}/cg ) {
        $code->tagAdd('constant', "$_[1] +$-[0]c", "$_[1] +$+[0]c");
    }
    elsif( $_[0] =~ /\G\$?[0-9A-Fa-f][0-9A-Fa-f ]*(?!\w)/cg ) {
        $code->tagAdd('constant', "$_[1] +$-[0]c", "$_[1] +$+[0]c");
    }
    elsif( $_[0] =~ /\G\$?$kw/cg ) {
        # indentifier, no highlight
    }
    elsif( $_[0] =~ /\G".*?"/cg ) {
        $code->tagAdd('constant', "$_[1] +$-[0]c +1c", "$_[1] +$+[0]c 
+-1c");
    }
    elsif( $_[0] =~ /\G\@[^\s,)]*/cg ) {
        $code->tagAdd('constant', "$_[1] +$-[0]c +1c", "$_[1] +$+[0]c"
+);
    }
    elsif( $_[2] =~ /^(?: hsm | cat | cat8 )$/x and $_[0] =~ /\G[<>;]/
+cg ) {
    }
    else {
        return;
    }
    return 1;
}

1;

[download]
And the test script: 
use strict;
use warnings;

use Plugin::Syntax;

Plugin::Syntax::parse_command( "xx = ", "" );

[download]

In reply to Weird undefined variable warning by JStrom

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