Panic when given empty character class

jstuder-gh · Mar 23, 2018 · 7c41dfa · 7c41dfa
1 parent 820c214
commit 7c41dfa
Showing 1 changed file with 5 additions and 0 deletions.
diff --git a/src/QRegex/P6Regex/Actions.nqp b/src/QRegex/P6Regex/Actions.nqp
@@ -621,6 +621,11 @@ class QRegex::P6Regex::Actions is HLL::Actions {
     method assertion:sym<[>($/) {
         my $clist := $<cclass_elem>;
         my $qast  := $clist[0].ast;
+        if +@($qast) == 0 {
+            $/.panic('Cannot have an empty character class. If you intended to include '
+                ~ 'whitespace within this character class, escape it with \\'
+            );
+        }
         if $qast.negate && $qast.rxtype eq 'subrule' {
             $qast.subtype('zerowidth');
             $qast := QAST::Regex.new(:rxtype<concat>, :node($/),