ENH: ensure that content changes in coded objects are noticed (#1293)

- for codedFunctionObject and CodedSource the main code snippets
  were not included in the SHA1 calculation, which meant that many
  changes would not be noticed and no new library would be compiled.

  As a workaround, a dummy 'code' entry could be used solely for the
  purposes of generating a SHA1, but this is easily forgotten.

  We now allow tracking of the dynamicCodeContext for the coded
  objects and append to the SHA1 hasher with specific entries.
  This should solve the previous misbehaviour.

  We additionally add information about the ordering of the code
  sections. Suppose we have a coded function object (all code
  segments are optional) with the following:

      codeExecute "";
      codeWrite   #{ Info<< "Called\n"; #};

  which we subsequently change to this:

      codeExecute #{ Info<< "Called\n"; #};
      codeWrite   "";

  If the code strings are simply concatenated together, the SHA1 hashes
  will be identical. We thus 'salt' with their semantic locations,
  choosing tags that are unlikely to occur within the code strings
  themselves.

- simplify the coded templates with constexpr for the SHA1sum
  information.

- Correct the CodedSource to use 'codeConstrain' instead of
  'codeSetValue' for consistency with the underlying functions.

etc/codeTemplates/dynamicCode/codedFvOptionTemplate.H

@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     |
-    \\  /    A nd           |
+    \\  /    A nd           | Copyright (C) 2019 OpenCFD Ltd.
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
                             | Copyright (C) YEAR AUTHOR,AFFILIATION
@@ -27,6 +27,7 @@ Description
     Template for use with dynamic code generation of a source.
     The hook functions take the following arguments:
 
+    \verbatim
     codeCorrect
     (
         GeometricField<Type, fvPatchField, volMesh>& fld
@@ -38,16 +39,18 @@ Description
         const label fieldi
     )
 
-    constrain
+    codeConstrain
     (
         fvMatrix<Type>& eqn,
         const label fieldi
     )
+    \endverbatim
 
     where :
         fieldi is the index in the fields entry
         eqn is the fvMatrix
 
+    \verbatim
     energySource
     {
         type            scalarCodedSource;
@@ -62,7 +65,6 @@ Description
 
             codeInclude
             #{
-
             #};
 
             codeCorrect
@@ -78,18 +80,9 @@ Description
                 heSource -= 0.1*sqr(time.value())*V;
             #};
 
-            codeSetValue
+            codeConstrain
             #{
-                Pout<< "**codeSetValue**" << endl;
-            #};
-
-            // Dummy entry. Make dependent on above to trigger recompilation
-            code
-            #{
-                $codeInclude
-                $codeCorrect
-                $codeAddSup
-                $codeSetValue
+                Pout<< "**codeConstrain**" << endl;
             #};
         }
 
@@ -98,6 +91,7 @@ Description
             // Dummy entry
         }
     }
+    \endverbatim
 
 SourceFiles
     codedFvOptionTemplate.C
@@ -113,7 +107,6 @@ SourceFiles
 
 namespace Foam
 {
-
 namespace fv
 {
 
@@ -125,10 +118,18 @@ class ${typeName}FvOption${SourceType}
 :
     public cellSetOption
 {
+    // Private Member Functions
+
+        //- Report a message with the SHA1sum
+        inline static void printMessage(const char* message)
+        {
+            Info<< message << " sha1: " << SHA1sum << '\n';
+        }
+
 public:
 
-    //- Information about the SHA1 of the code itself
-    static const char* const SHA1sum;
+    //- SHA1 representation of the code content
+    static constexpr const char* const SHA1sum = "${SHA1sum}";
 
     //- Runtime type information
     TypeName("${typeName}");
@@ -149,44 +150,42 @@ public:
     virtual ~${typeName}FvOption${SourceType}();
 
 
-    // Member functions
+    // Member Functions
 
-            //- Correct field
-            virtual void correct
-            (
-                GeometricField<${TemplateType}, fvPatchField, volMesh>&
-            );
+        //- Correct field
+        virtual void correct
+        (
+            GeometricField<${TemplateType}, fvPatchField, volMesh>& fld
+        );
 
-            //- Explicit and implicit matrix contributions
-            virtual void addSup
-            (
-                fvMatrix<${TemplateType}>& eqn,
-                const label fieldi
-            );
+        //- Explicit/implicit matrix contributions
+        virtual void addSup
+        (
+            fvMatrix<${TemplateType}>& eqn,
+            const label fieldi
+        );
 
-            //- Explicit and implicit matrix contributions for compressible
-            //  equations
-            virtual void addSup
-            (
-                const volScalarField& rho,
-                fvMatrix<${TemplateType}>& eqn,
-                const label fieldi
-            );
+        //- Explicit/implicit matrix contributions for compressible equations
+        virtual void addSup
+        (
+            const volScalarField& rho,
+            fvMatrix<${TemplateType}>& eqn,
+            const label fieldi
+        );
 
-            //- Set value
-            virtual void constrain
-            (
-                fvMatrix<${TemplateType}>& eqn,
-                const label fieldi
-            );
+        //- Set value
+        virtual void constrain
+        (
+            fvMatrix<${TemplateType}>& eqn,
+            const label fieldi
+        );
 };
 
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
-} // End namespace Foam
-
 } // End namespace fv
+} // End namespace Foam
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //