ENH: work with processors with 0 cells. polyMesh::directions, checkMesh.

applications/utilities/mesh/manipulation/checkMesh/checkTopology.C

@@ -12,6 +12,7 @@ bool Foam::checkSync(const wordList& names)
     List<wordList> allNames(Pstream::nProcs());
     allNames[Pstream::myProcNo()] = names;
     Pstream::gatherList(allNames);
+    Pstream::scatterList(allNames);
 
     bool hasError = false;
 
@@ -72,8 +73,8 @@ Foam::label Foam::checkTopology
                 Info<< " ***FaceZone " << mesh.faceZones()[zoneI].name()
                     << " is not correctly synchronised"
                     << " across coupled boundaries."
-                    << " (coupled faces both"
-                    << " present in set but with opposite flipmap)" << endl;
+                    << " (coupled faces are either not both "
+                    << " present in set or have same flipmap)" << endl;
                 noFailedChecks++;
             }
         }

src/OpenFOAM/meshes/polyMesh/polyMesh.C

@@ -85,6 +85,9 @@ void Foam::polyMesh::calcDirections() const
         }
     }
 
+    reduce(nEmptyPatches, maxOp<label>());
+    reduce(nWedgePatches, maxOp<label>());
+
     if (nEmptyPatches)
     {
         reduce(emptyDirVec, sumOp<vector>());

src/OpenFOAM/meshes/polyMesh/zones/faceZone/faceZone.C

@@ -498,10 +498,9 @@ bool Foam::faceZone::checkParallelSync(const bool report) const
                         break;
                     }
                 }
-
-                // Flip state should be opposite.
-                if (myZoneFlip[bFaceI] == neiZoneFlip[bFaceI])
+                else if (myZoneFlip[bFaceI] == neiZoneFlip[bFaceI])
                 {
+                    // Flip state should be opposite.
                     hasError = true;
 
                     if (report)