STYLE: ensure that emptyLabelList is known from List.H

- treat as a List constant without requiring inclusion of ListOps.H

- replace use of emptyList<label>() with emptyLabelList directly.
  The emptyList<T>() casting is disallowed with many modern compilers
  and now marked as deprecated (expect early removal).

- relocate labelList typedef to List.H for more general access.
  Similar reasoning to having labelUList defined in UList.H

src/OpenFOAM/algorithms/dynamicIndexedOctree/dynamicIndexedOctree.C

@@ -2398,7 +2398,7 @@ const Foam::labelList& Foam::dynamicIndexedOctree<Type>::findIndices
         return *(contents_[getContent(contentIndex)]);
     }
 
-    return emptyList<label>();
+    return Foam::emptyLabelList;
 }
 
 

src/OpenFOAM/algorithms/indexedOctree/indexedOctree.C

@@ -2660,7 +2660,7 @@ const Foam::labelList& Foam::indexedOctree<Type>::findIndices
 {
     if (nodes_.empty())
     {
-        return emptyList<label>();
+        return Foam::emptyLabelList;
     }
 
     labelBits index = findNode(0, sample);
@@ -2675,7 +2675,7 @@ const Foam::labelList& Foam::indexedOctree<Type>::findIndices
         return contents_[getContent(contentIndex)];
     }
 
-    return emptyList<label>();
+    return Foam::emptyLabelList;
 }
 
 

src/OpenFOAM/containers/Lists/List/List.H

@@ -69,8 +69,12 @@ template<class T> class BiIndirectList;
 
 template<class T> Istream& operator>>(Istream& is, List<T>& list);
 
-// Commonly required list types
+// Common list types
 typedef List<char> charList;
+typedef List<label> labelList;
+
+//- A zero-sized list of labels
+extern const labelList emptyLabelList;
 
 
 /*---------------------------------------------------------------------------*\

src/OpenFOAM/containers/Lists/ListOps/ListOps.C

@@ -26,7 +26,7 @@ License
 #include "ListOps.H"
 #include <numeric>
 
-// * * * * * * * * * * * * * * Static Data Members * * * * * * * * * * * * * //
+// * * * * * * * * * * * * * * Global Data Members * * * * * * * * * * * * * //
 
 const Foam::labelList Foam::emptyLabelList;
 

src/OpenFOAM/containers/Lists/ListOps/ListOps.H

@@ -54,10 +54,10 @@ SourceFiles
 namespace Foam
 {
 
-extern const labelList emptyLabelList;
+//- Return reference to zero-sized list.
-
+//  Compare to List::null() which returns null pointer cast as list reference.
-//- Return reference to zero-sized list. Compare to List::null() which returns
+//
-//  null pointer cast as list reference.
+//  \deprecated This cast is disallowed with many modern compilers (JUL-2018)
 template<class Type>
 static const List<Type>& emptyList()
 {

src/OpenFOAM/containers/Lists/SubList/SubList.H

@@ -47,6 +47,13 @@ SourceFiles
 namespace Foam
 {
 
+// Forward declarations
+template<class T> class SubList;
+
+// Common list types
+typedef SubList<label> labelSubList;
+
+
 /*---------------------------------------------------------------------------*\
                            Class SubList Declaration
 \*---------------------------------------------------------------------------*/

src/OpenFOAM/containers/Lists/UList/UList.H

@@ -67,10 +67,11 @@ template<class T> class UList;
 template<class T> Ostream& operator<<(Ostream&, const UList<T>&);
 template<class T> Istream& operator>>(Istream&, UList<T>&);
 
-// Commonly required list types
+// Common list types
 typedef UList<char> charUList;
 typedef UList<label> labelUList;
 
+
 /*---------------------------------------------------------------------------*\
                            Class UList Declaration
 \*---------------------------------------------------------------------------*/

src/OpenFOAM/primitives/ints/lists/labelList.H

@@ -64,9 +64,10 @@ Description
 
 namespace Foam
 {
-    // NB: labelUList is defined in UList itself
+    // labelUList   = defined in UList.H
-    typedef List<label> labelList;
+    // labelList    = defined in List.H
-    typedef SubList<label> labelSubList;
+    // labelSubList = defined in SubList.H
+
     typedef List<labelList> labelListList;
     typedef List<labelListList> labelListListList;
 }