Merge pull request #3095 from mgreter/bugfix/unordered-map-usage

Fix issue with some std::unordered_map implementations

src/ast.hpp

@@ -358,7 +358,7 @@ namespace Sass {
   class Hashed {
   private:
     std::unordered_map<
-      K, T, ObjHash, ObjEquality
+      K, T, ObjHash, ObjHashEquality
     > elements_;
 
     sass::vector<K> _keys;
@@ -396,7 +396,7 @@ namespace Sass {
     bool has_duplicate_key() const         { return duplicate_key_ != nullptr; }
     K get_duplicate_key() const  { return duplicate_key_; }
     const std::unordered_map<
-      K, T, ObjHash, ObjEquality
+      K, T, ObjHash, ObjHashEquality
     >& elements() { return elements_; }
     Hashed& operator<<(std::pair<K, T> p)
     {
@@ -432,7 +432,7 @@ namespace Sass {
       return *this;
     }
     const std::unordered_map<
-      K, T, ObjHash, ObjEquality
+      K, T, ObjHash, ObjHashEquality
     >& pairs() const { return elements_; }
 
     const sass::vector<K>& keys() const { return _keys; }

src/ast_helpers.hpp

@@ -149,6 +149,30 @@ namespace Sass {
     }
   };
 
+  // ###########################################################################
+  // Special compare function only for hashes.
+  // We need to make sure to not have objects equal that 
+  // have different hashes. This is currently an issue,
+  // since `1px` is equal to `1` but have different hashes.
+  // This goes away once we remove unitless equality.
+  // ###########################################################################
+
+  template <class T>
+  // Compare the objects and its hashes
+  bool ObjHashEqualityFn(const T& lhs, const T& rhs) {
+    if (lhs == nullptr) return rhs == nullptr;
+    else if (rhs == nullptr) return false;
+    else return lhs->hash() == rhs->hash();
+  }
+  struct ObjHashEquality {
+    template <class T>
+    // Compare the objects and its contents and hashes
+    bool operator() (const T& lhs, const T& rhs) const {
+      return ObjEqualityFn<T>(lhs, rhs) &&
+        ObjHashEqualityFn(lhs, rhs);
+    }
+  };
+
   // ###########################################################################
   // Implement ordering operations for AST Nodes
   // ###########################################################################