ENH: IOobject headerClassName now initialised to empty value

- was previously populated with "IOobject" (the typeName) but then
  cannot easily detect if the object was actually read.
  Also clear the headerClassName on a failed read

BUG: parallel inconsistency in regIOobject::readHeaderOk

- headerOk() checked with master, but possible parallel operations
  within it

applications/utilities/preProcessing/setExprFields/setExprFields.C

@@ -272,18 +272,18 @@ void evaluate
         );
         io.typeHeaderOk<IOobject>(false);
 
-        oldFieldType = io.headerClassName();
-
-        if (oldFieldType == IOobject::typeName)
+        if (!io.hasHeaderClass() || io.isHeaderClass<IOobject>())
         {
             FatalErrorInFunction
-                << "Field " << fieldName << "(type: " << oldFieldType
-                << ") seems to be missing. Use 'create'" << nl
+                << "Field '" << fieldName
+                << "' seems to be missing. Use 'create'" << nl
                 << exit(FatalError);
         }
 
+        oldFieldType = io.headerClassName();
+
         Info<< "Modify field: " << fieldName
-            << " (type " << oldFieldType << ')';
+            << " (type: " << oldFieldType << ')';
     }
 
 

src/OpenFOAM/db/IOobject/IOobject.C

@@ -321,7 +321,7 @@ Foam::IOobject::IOobject
     sizeofScalar_(static_cast<unsigned char>(sizeof(scalar))),
 
     name_(name),
-    headerClassName_(typeName),
+    headerClassName_(),
     note_(),
     instance_(instance),
     local_(),
@@ -331,8 +331,7 @@ Foam::IOobject::IOobject
     if (objectRegistry::debug)
     {
         InfoInFunction
-            << "Constructing IOobject called " << name_
-            << " of type " << headerClassName_ << endl;
+            << "Constructing IOobject: " << name_ << endl;
     }
 }
 
@@ -352,7 +351,7 @@ Foam::IOobject::IOobject
     sizeofScalar_(static_cast<unsigned char>(sizeof(scalar))),
 
     name_(name),
-    headerClassName_(typeName),
+    headerClassName_(),
     note_(),
     instance_(instance),
     local_(local),
@@ -362,8 +361,7 @@ Foam::IOobject::IOobject
     if (objectRegistry::debug)
     {
         InfoInFunction
-            << "Constructing IOobject called " << name_
-            << " of type " << headerClassName_ << endl;
+            << "Constructing IOobject: " << name_ << endl;
     }
 }
 
@@ -381,7 +379,7 @@ Foam::IOobject::IOobject
     sizeofScalar_(static_cast<unsigned char>(sizeof(scalar))),
 
     name_(),
-    headerClassName_(typeName),
+    headerClassName_(),
     note_(),
     instance_(),
     local_(),
@@ -398,8 +396,7 @@ Foam::IOobject::IOobject
     if (objectRegistry::debug)
     {
         InfoInFunction
-            << "Constructing IOobject called " << name_
-            << " of type " << headerClassName_ << endl;
+            << "Constructing IOobject: " << name_ << endl;
     }
 }
 

src/OpenFOAM/db/IOobject/IOobjectReadHeader.C

@@ -120,6 +120,9 @@ bool Foam::IOobject::readHeader(dictionary& headerDict, Istream& is)
 
         writeHeader(Info);
 
+        // Mark as not read
+        headerClassName_.clear();
+
         return false;
     }
 

src/OpenFOAM/db/regIOobject/regIOobjectRead.C

@@ -60,7 +60,9 @@ bool Foam::regIOobject::readHeaderOk
         {
             if (Pstream::master())
             {
+                const bool oldParRun = Pstream::parRun(false);
                 isHeaderOk = headerOk();
+                Pstream::parRun(oldParRun);
             }
             Pstream::broadcast(isHeaderOk);
         }