Implement check for invalid extends

src/ast.cpp

@@ -1168,6 +1168,7 @@ namespace Sass {
   Complex_Selector* Complex_Selector::clone(Context& ctx) const
   {
     Complex_Selector* cpy = SASS_MEMORY_NEW(ctx.mem, Complex_Selector, *this);
+    cpy->is_optional(this->is_optional());
     cpy->media_block(this->media_block());
     if (tail()) cpy->tail(tail()->clone(ctx));
     return cpy;
@@ -1176,7 +1177,8 @@ namespace Sass {
   Complex_Selector* Complex_Selector::cloneFully(Context& ctx) const
   {
     Complex_Selector* cpy = SASS_MEMORY_NEW(ctx.mem, Complex_Selector, *this);
-
+    cpy->is_optional(this->is_optional());
+    cpy->media_block(this->media_block());
     if (head()) {
       cpy->head(head()->clone(ctx));
     }
@@ -1191,20 +1193,25 @@ namespace Sass {
   Compound_Selector* Compound_Selector::clone(Context& ctx) const
   {
     Compound_Selector* cpy = SASS_MEMORY_NEW(ctx.mem, Compound_Selector, *this);
+    cpy->is_optional(this->is_optional());
     cpy->media_block(this->media_block());
+    cpy->extended(this->extended());
     return cpy;
   }
 
   Selector_List* Selector_List::clone(Context& ctx) const
   {
     Selector_List* cpy = SASS_MEMORY_NEW(ctx.mem, Selector_List, *this);
+    cpy->is_optional(this->is_optional());
     cpy->media_block(this->media_block());
     return cpy;
   }
 
   Selector_List* Selector_List::cloneFully(Context& ctx) const
   {
     Selector_List* cpy = SASS_MEMORY_NEW(ctx.mem, Selector_List, pstate());
+    cpy->is_optional(this->is_optional());
+    cpy->media_block(this->media_block());
     for (size_t i = 0, L = length(); i < L; ++i) {
       *cpy << (*this)[i]->cloneFully(ctx);
     }

src/ast.hpp

@@ -2177,6 +2177,7 @@ namespace Sass {
   class Compound_Selector : public Selector, public Vectorized<Simple_Selector*> {
   private:
     SourcesSet sources_;
+    ADD_PROPERTY(bool, extended);
     ADD_PROPERTY(bool, has_parent_reference);
   protected:
     void adjust_after_pushing(Simple_Selector* s)
@@ -2188,6 +2189,7 @@ namespace Sass {
     Compound_Selector(ParserState pstate, size_t s = 0)
     : Selector(pstate),
       Vectorized<Simple_Selector*>(s),
+      extended_(false),
       has_parent_reference_(false)
     { }
     bool contains_placeholder() {

src/debugger.hpp

@@ -137,6 +137,7 @@ inline void debug_ast(AST_Node* node, std::string ind, Env* env)
     std::cerr << " <" << selector->hash() << ">";
     std::cerr << " [weight:" << longToHex(selector->specificity()) << "]";
     std::cerr << " [@media:" << selector->media_block() << "]";
+    std::cerr << (selector->extended() ? " [extended]": " -");
     std::cerr << (selector->is_optional() ? " [is_optional]": " -");
     std::cerr << (selector->has_parent_ref() ? " [has-parent]": " -");
     std::cerr << (selector->has_line_break() ? " [line-break]": " -");

src/extend.cpp

@@ -1591,6 +1591,7 @@ namespace Sass {
         for (size_t index = 0; index < pCompound->length(); index++) {
           Simple_Selector* pSimpleSelector = (*pCompound)[index];
           (*pSels) << pSimpleSelector;
+          pCompound->extended(true);
         }
       }
 
@@ -1779,29 +1780,6 @@ namespace Sass {
       pIter = pIter->tail();
     }
 
-    if (!hasExtension) {
-      /* ToDo: don't break stuff
-      std::stringstream err;
-      To_String to_string(&ctx);
-      std::string cwd(Sass::File::get_cwd());
-      std::string sel1(pComplexSelector->perform(&to_string));
-      Compound_Selector* pExtendSelector = 0;
-      for (auto i : subset_map.values()) {
-        if (i.first == pComplexSelector) {
-          pExtendSelector = i.second;
-          break;
-        }
-      }
-      if (!pExtendSelector || !pExtendSelector->is_optional()) {
-        std::string sel2(pExtendSelector ? pExtendSelector->perform(&to_string) : "[unknown]");
-        err << "\"" << sel1 << "\" failed to @extend \"" << sel2 << "\"\n";
-        err << "The selector \"" << sel2 << "\" was not found.\n";
-        err << "Use \"@extend " << sel2 << " !optional\" if the extend should be able to fail.";
-        error(err.str(), pExtendSelector ? pExtendSelector->pstate() : pComplexSelector->pstate());
-      }
-      */
-    }
-
     return hasExtension;
   }
 
@@ -2071,6 +2049,25 @@ namespace Sass {
     for (size_t i = 0, L = b->length(); i < L; ++i) {
       (*b)[i]->perform(this);
     }
+    // do final check if everything was extended
+    // we set `extended` flag on extended selectors
+    if (b->is_root()) {
+      // debug_subset_map(subset_map);
+      for(auto const &it : subset_map.values()) {
+        Complex_Selector* sel = it.first ? it.first->first() : NULL;
+        Compound_Selector* ext = it.second ? it.second : NULL;
+        if (ext && (ext->extended() || ext->is_optional())) continue;
+        std::string str_sel(sel->to_string());
+        std::string str_ext(ext->to_string());
+        // debug_ast(sel, "sel: ");
+        // debug_ast(ext, "ext: ");
+        error("\"" + str_sel + "\" failed to @extend \"" + str_ext + "\".\n"
+              "The selector \"" + str_ext + "\" was not found.\n"
+              "Use \"@extend " + str_ext + " !optional\" if the"
+                " extend should be able to fail.", ext->pstate());
+      }
+    }
+
   }
 
   void Extend::operator()(Ruleset* pRuleset)