From ebc05132095766ab0c1406f4c859f4dc0e9913df Mon Sep 17 00:00:00 2001
From: Simon Ruderich <simon@ruderich.org>
Date: Sat, 23 Jan 2016 21:18:03 +0100
Subject: [PATCH 1/1] fix match drawing if match group doesn't start at the
 beginning

Also display an error message if a regex doesn't contain a match group.
---
 bin/fcscs | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/bin/fcscs b/bin/fcscs
index 0033af8..abe9712 100755
--- a/bin/fcscs
+++ b/bin/fcscs
@@ -385,8 +385,11 @@ sub get_regex_matches {
 
     my @matches;
     while ($input->{string} =~ /$regex/g) {
+        my $offset = $-[1];
+        die "Match group required in regex '$regex'" if not defined $offset;
+
         my ($x, $y) = input_match_offset_to_coordinates($input->{width},
-                                                        $-[0]);
+                                                        $offset);
         push @matches, { x => $x, y => $y, string => $1 };
     }
     return @matches;
-- 
2.43.2