operator== on result of operator[] behaves weird

src/OpenFOAM/containers/Lists/PackedList/PackedList.H

@@ -148,9 +148,11 @@ public:
         //- Masking for all bits below the offset
         inline static unsigned int maskLower(unsigned offset);
 
-    // Forward declaration of iteratorBase
+    // Forward declaration of iterators
 
         class iteratorBase;
+        class iterator;
+        class const_iterator;
 
     // Constructors
 
@@ -328,7 +330,7 @@ public:
 
             // Member Operators
 
-                //- Compare positions
+                //- Compare values (not positions)
                 inline bool operator==(const iteratorBase&) const;
                 inline bool operator!=(const iteratorBase&) const;
 
@@ -355,7 +357,10 @@ public:
             public iteratorBase
         {
 
-            //- Should never violate const-ness!
+            //- Disallow copy constructor from const_iterator - violates const-ness!
+            iterator(const const_iterator&);
+
+            //- Disallow assignment from const_iterator - violates const-ness!
             void operator=(const const_iterator&);
 
         public:
@@ -375,6 +380,10 @@ public:
 
             // Member Operators
 
+                //- Compare positions (not values)
+                inline bool operator==(const iteratorBase&) const;
+                inline bool operator!=(const iteratorBase&) const;
+
                 //- Assign from iteratorBase, eg iter = packedlist[i]
                 //  An out-of-range iterator is assigned end()
                 inline iterator& operator=(const iteratorBase&);
@@ -420,17 +429,21 @@ public:
 
                 //- Construct from iterator base, eg iter(packedlist[i])
                 //  but also  "const_iterator iter = packedlist[i];"
-                //  An out-of-range iterator is assigned end()
+                //  An out-of-range iterator is assigned cend()
                 inline const_iterator(const iteratorBase&);
 
                 //- Construct from base list and position index
                 inline const_iterator(const PackedList*, const label);
 
-                //- Construct from non-const iterator
+                //- Construct from iterator
                 inline const_iterator(const iterator&);
 
             // Member operators
 
+                //- Compare positions (not values)
+                inline bool operator==(const iteratorBase&) const;
+                inline bool operator!=(const iteratorBase&) const;
+
                 //- Assign from iteratorBase or derived
                 //  eg, iter = packedlist[i] or even iter = list.begin()
                 inline const_iterator& operator=(const iteratorBase&);

src/OpenFOAM/containers/Lists/PackedList/PackedListI.H

@@ -176,7 +176,7 @@ inline bool Foam::PackedList<nBits>::iteratorBase::operator==
     const iteratorBase& iter
 ) const
 {
-    return this->index_ == iter.index_;
+    return this->get() == iter.get();
 }
 
 
@@ -186,7 +186,7 @@ inline bool Foam::PackedList<nBits>::iteratorBase::operator!=
     const iteratorBase& iter
 ) const
 {
-    return this->index_ != iter.index_;
+    return this->get() != iter.get();
 }
 
 
@@ -311,6 +311,48 @@ inline Foam::PackedList<nBits>::const_iterator::const_iterator
 {}
 
 
+template<unsigned nBits>
+inline bool Foam::PackedList<nBits>::iterator::operator==
+(
+    const iteratorBase& iter
+) const
+{
+    return this->index_ == iter.index_;
+}
+
+
+template<unsigned nBits>
+inline bool Foam::PackedList<nBits>::iterator::operator!=
+(
+    const iteratorBase& iter
+) const
+{
+    return this->index_ != iter.index_;
+}
+
+
+
+template<unsigned nBits>
+inline bool Foam::PackedList<nBits>::const_iterator::operator==
+(
+    const iteratorBase& iter
+) const
+{
+    return this->index_ == iter.index_;
+}
+
+
+template<unsigned nBits>
+inline bool Foam::PackedList<nBits>::const_iterator::operator!=
+(
+    const iteratorBase& iter
+) const
+{
+    return this->index_ != iter.index_;
+}
+
+
+
 template<unsigned nBits>
 inline typename Foam::PackedList<nBits>::iterator&
 Foam::PackedList<nBits>::iterator::operator=(const iteratorBase& iter)