Merge pull request #3032 from mgreter/bugfix/edge-case-crashes

Fix various edge case crashes

Author: mgreter

src/extender.cpp

@@ -142,6 +142,7 @@ namespace Sass {
   // ##########################################################################
   bool Extender::checkForUnsatisfiedExtends(Extension& unsatisfied) const
   {
+    if (selectors.empty()) return false;
     ExtSmplSelSet originals = getSimpleSelectors();
     for (auto target : extensions) {
       SimpleSelector* key = target.first;

src/parser.cpp

@@ -2247,15 +2247,17 @@ namespace Sass {
     if (lex < kwd_not >()) { media_query->is_negated(true); lex < css_comments >(false); }
     else if (lex < kwd_only >()) { media_query->is_restricted(true); lex < css_comments >(false); }
 
-    if (lex < identifier_schema >())  media_query->media_type(parse_identifier_schema());
-    else if (lex < identifier >())    media_query->media_type(parse_interpolated_chunk(lexed));
+    if (lex < identifier_schema >()) media_query->media_type(parse_identifier_schema());
+    else if (lex < identifier >())   media_query->media_type(parse_interpolated_chunk(lexed));
     else                             media_query->append(parse_media_expression());
 
     while (lex_css < kwd_and >()) media_query->append(parse_media_expression());
     if (lex < identifier_schema >()) {
       String_Schema* schema = SASS_MEMORY_NEW(String_Schema, pstate);
-      schema->append(media_query->media_type());
-      schema->append(SASS_MEMORY_NEW(String_Constant, pstate, " "));
+      if (media_query->media_type()) {
+        schema->append(media_query->media_type());
+        schema->append(SASS_MEMORY_NEW(String_Constant, pstate, " "));
+      }
       schema->append(parse_identifier_schema());
       media_query->media_type(schema);
     }

src/permutate.hpp

@@ -24,6 +24,7 @@ namespace Sass {
 
     size_t L = in.size(), n = 0;
 
+    if (L == 0) return {};
     // Exit early if any entry is empty
     for (size_t i = 0; i < L; i += 1) {
       if (in[i].size() == 0) return {};
@@ -80,12 +81,18 @@ namespace Sass {
 
     size_t L = in.size();
     size_t n = in.size() - 1;
+
+    if (L == 0) return {};
+    // Exit early if any entry is empty
+    for (size_t i = 0; i < L; i += 1) {
+      if (in[i].size() == 0) return {};
+    }
+
     size_t* state = new size_t[L];
     std::vector< std::vector<T>> out;
 
     // First initialize all states for every permutation group
     for (size_t i = 0; i < L; i += 1) {
-      if (in[i].size() == 0) return {};
       state[i] = in[i].size() - 1;
     }
 
@@ -104,10 +111,8 @@ namespace Sass {
       // Current group finished
       if (state[n] == 0) {
         // Find position of next decrement
-        while (n > 0 && state[--n] == 0)
-        {
+        while (n > 0 && state[--n] == 0) {}
 
-        }
         // Check for end condition
         if (state[n] != 0) {
           // Decrease next on the left side