functionObjects::fieldExpression: Correct and improve warning messages

postProcess -func MachNo

previously generated the warning

Executing functionObjects
--> FOAM Warning :     functionObjects::MachNo MachNo cannot find required field U

which is incorrect; the field 'U' is available but the
thermophysicalProperties is not.  Now 'postProcess' generates the
warning:

Executing functionObjects
--> FOAM Warning :     functionObjects::MachNo MachNo cannot find required object thermophysicalProperties of type fluidThermo
--> FOAM Warning :     functionObjects::MachNo MachNo failed to execute.

Resolves bug-report http://bugs.openfoam.org/view.php?id=2352

src/functionObjects/field/MachNo/MachNo.C

@@ -52,11 +52,11 @@ bool Foam::functionObjects::MachNo::calc()
     if
     (
         foundObject<volVectorField>(fieldName_)
-     && mesh_.foundObject<fluidThermo>(fluidThermo::dictName)
+     && foundObject<fluidThermo>(fluidThermo::dictName)
     )
     {
         const fluidThermo& thermo =
-            mesh_.lookupObject<fluidThermo>(fluidThermo::dictName);
+            lookupObject<fluidThermo>(fluidThermo::dictName);
 
         const volVectorField& U = lookupObject<volVectorField>(fieldName_);
 

src/functionObjects/field/fieldExpression/fieldExpression.C

@@ -115,7 +115,7 @@ bool Foam::functionObjects::fieldExpression::execute()
     {
         Warning
             << "    functionObjects::" << type() << " " << name()
-            << " cannot find required field " << fieldName_ << endl;
+            << " failed to execute." << endl;
 
         // Clear the result field from the objectRegistry if present
         clear();

src/functionObjects/field/fieldExpression/fieldExpression.H

@@ -75,6 +75,9 @@ protected:
 
         void setResultName(const word& typeName, const word& defaultArg);
 
+        template<class Type>
+        bool foundObject(const word& name);
+
 
 private:
 
@@ -133,6 +136,12 @@ public:
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
+#ifdef NoRepository
+    #include "fieldExpressionTemplates.C"
+#endif
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
 #endif
 
 // ************************************************************************* //

src/functionObjects/field/fieldExpression/fieldExpressionTemplates.C

@@ -0,0 +1,52 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | Copyright (C) 2016 OpenFOAM Foundation
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+License
+    This file is part of OpenFOAM.
+
+    OpenFOAM is free software: you can redistribute it and/or modify it
+    under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
+    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+    for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.
+
+\*---------------------------------------------------------------------------*/
+
+#include "fieldExpression.H"
+
+// * * * * * * * * * * * * * Protected Member Functions  * * * * * * * * * * //
+
+template<class Type>
+bool Foam::functionObjects::fieldExpression::foundObject
+(
+    const word& name
+)
+{
+    if (fvMeshFunctionObject::foundObject<Type>(name))
+    {
+        return true;
+    }
+    else
+    {
+        Warning
+            << "    functionObjects::" << type() << " " << this->name()
+            << " cannot find required object " << name << " of type "
+            << Type::typeName << endl;
+
+        return false;
+    }
+}
+
+
+// ************************************************************************* //