From 6c18db1ae142c173cceaa32491b4da49c96e667e Mon Sep 17 00:00:00 2001
From: Marcel Greter <marcel.greter@ocbnet.ch>
Date: Tue, 23 Feb 2016 00:57:47 +0100
Subject: [PATCH] Fix segfault with non existing extend and parent selector

Cherry-picked from #1925.

Fixes #1916
Spec sass/sass-spec#732
---
 src/ast.cpp | 12 +++++-------
 1 file changed, 5 insertions(+), 7 deletions(-)

diff --git a/src/ast.cpp b/src/ast.cpp
index 0b6248d4b6..ed8db07b61 100644
--- a/src/ast.cpp
+++ b/src/ast.cpp
@@ -1085,18 +1085,16 @@ namespace Sass {
   Complex_Selector* Complex_Selector::first()
   {
     // declare variables used in loop
-    Complex_Selector* cur = this->tail_;
-    const Compound_Selector* head = head_;
+    Complex_Selector* cur = this;
+    const Compound_Selector* head;
     // processing loop
     while (cur)
     {
       // get the head
       head = cur->head_;
-      // check for single parent ref
-      if (head && head->length() == 1)
-      {
-        // abort (and return) if it is not a parent selector
-        if (!dynamic_cast<Parent_Selector*>((*head)[0])) break;
+      // abort (and return) if it is not a parent selector
+      if (!head || head->length() != 1 || !dynamic_cast<Parent_Selector*>((*head)[0])) {
+        break;
       }
       // advance to next
       cur = cur->tail_;