Here is a way to do it that I have used before for finding tokens in C files

use strict;

my $param_rx      = '[^),]+';  
my $list_start_rx = '\s*\(\s*'; 
my $list_end_rx   = '\s*\)\s*'; 


my @regexes=(
         qr/^\s*/,
         qr/(\S+)/,
         qr/\s+/,
         qr/(\S+)/,
         qr/$list_start_rx/,
         qr/($param_rx(?:\s*,\s*$param_rx)*)?/,
         qr/$list_end_rx/,
         qr/=\s*/,
         qr/(?:0x)?\d+/,
         qr/\s*;\s*$/
         );

PARSER:
while (<DATA>) {
  foreach my $regex (@regexes) {
    if ( not /\G$regex/gc ) {
      print "^<-- Parse failed on line $. at (column " . pos()  . " of
+ " . length($_) . ")\n";
     print '"'.substr($_,0,pos())." HERE>>".substr($_,pos(),-1)."\"\n"
+;
      last PARSER;
    }
  }
}

__DATA__
some list (one, two three) = 5;
another list (one, two three) = 5;
a bad list (one two (three))
[download]

This outputs:

^<-- Parse failed on line 3 at (column 5 of 29)
"a bad HERE>> list (one two (three))"
[download]