From afd16eac09d8178d47d2e39ba8fe87c765369fc7 Mon Sep 17 00:00:00 2001
From: Dmitry Olshansky <dmitry.olsh@gmail.com>
Date: Wed, 6 Apr 2016 16:52:12 +0300
Subject: [PATCH] Fix issue 7551 - Regex parsing bug for right bracket in
 character class

---
 std/regex/internal/parser.d | 17 ++++++++++++++---
 std/regex/internal/tests.d  |  9 +++++++++
 2 files changed, 23 insertions(+), 3 deletions(-)

diff --git a/std/regex/internal/parser.d b/std/regex/internal/parser.d
index 32889131ed1..f8387490922 100644
--- a/std/regex/internal/parser.d
+++ b/std/regex/internal/parser.d
@@ -1143,9 +1143,20 @@ struct Parser(R)
                     opstack.push(Operator.Negate);
                     enforce(next(), "unexpected end of character class");
                 }
-                //[] is prohibited
-                enforce(current != ']', "wrong character class");
-                goto default;
+                else if (current == ']') // []...] is special cased
+                {
+                    enforce(next(), "wrong character set");
+                    auto pair = parseCharTerm();
+                    pair[0].add(']', ']'+1);
+                    if(pair[1] != Operator.None)
+                    {
+                        if(opstack.top == Operator.Union)
+                            unrollWhile!(unaryFun!"a == a.Union")(vstack, opstack);
+                        opstack.push(pair[1]);
+                    }
+                    vstack.push(pair[0]);
+                }
+                break;
             case ']':
                 enforce(unrollWhile!(unaryFun!"a != a.Open")(vstack, opstack),
                     "character class syntax error");
diff --git a/std/regex/internal/tests.d b/std/regex/internal/tests.d
index e5d61300003..88bc0a6eac1 100644
--- a/std/regex/internal/tests.d
+++ b/std/regex/internal/tests.d
@@ -968,3 +968,12 @@ unittest
         assert(matchAll(v, ctPat2).front.hit == v);
 }
 
+// bugzilla 7551
+unittest
+{
+    auto r = regex("[]abc]*");
+    assert("]ab".matchFirst(r).hit == "]ab");
+    assertThrown(regex("[]"));
+    auto r2 = regex("[]abc--ab]*");
+    assert("]ac".matchFirst(r2).hit == "]");
+}