From @masak

<masak`> rakudo​: /<[..b]>/
<p6eval> rakudo 7d9cd9​: OUTPUT«Cannot get character of empty string [...]
* masak` submits rakudobug

The error looks like some piece of code internal to PGE is assuming
that there'll be something before the '..' in the regex.

From @kyleha

This is an automatically generated mail to inform you that tests are now available in t/spec/S05-metasyntax/regex.t

commit f5dc1ad05d028848c9c30182166125a1db470604
Author​: kyle <kyle@​c213334d-75ef-0310-aa23-eaa082d1ae64>
Date​: Thu Jul 30 03​:37​:49 2009 +0000

  [t/spec] Test for RT #​64220
 
  git-svn-id​: http://svn.pugscode.org/pugs@&#8203;27811 c213334d-75ef-0310-aa23-eaa082d1ae64

diff --git a/t/spec/S05-metasyntax/regex.t b/t/spec/S05-metasyntax/regex.t
index d332d75..979bcff 100644
--- a/t/spec/S05-metasyntax/regex.t
+++ b/t/spec/S05-metasyntax/regex.t
@@ -1,7 +1,7 @@
 use v6;
 use Test;
 
-plan 26;
+plan 27;
 
 # L<S05/Regexes are now first-class language, not strings>
 
@@ -94,3 +94,6 @@ ok ';' ~~ /\;/,             'escaped ";" in m// works';
     ok  $!  ~~ Exception, 'use of missing named rule dies';
     ok "$!" ~~ /nosuchrule/, 'error message mentions the missing rule';
 }
+
+#?rakudo todo 'RT #64220'
+eval_lives_ok '/<[..b]>/', '/<[..b]>/ lives';

The RT System itself - Status changed from 'new' to 'open'

From @moritz

Now passes tests

@moritz - Status changed from 'open' to 'resolved'