ENH: replace autoPtr<bool> with Switch (#2777)

- initialise with Switch::INVALID and then test if good() to
  trigger the initial update.

  This avoids some overhead, but primarily avoids ambiguity with
  implicit casting to a 'bool' that autoPtr<bool> has.

src/optimisation/adjointOptimisation/adjoint/adjointBoundaryConditions/adjointBoundaryCondition/adjointBoundaryCondition.C

@@ -172,11 +172,11 @@ adjointBoundaryCondition<Type>::computePatchGrad(word name)
 template<class Type>
 bool adjointBoundaryCondition<Type>::addATCUaGradUTerm()
 {
-    if (!addATCUaGradUTerm_)
+    if (!addATCUaGradUTerm_.good())
     {
-        addATCUaGradUTerm_.reset(new bool(isA<ATCUaGradU>(getATC())));
+        addATCUaGradUTerm_ = bool(isA<ATCUaGradU>(getATC()));
     }
-    return addATCUaGradUTerm_();
+    return addATCUaGradUTerm_;
 }
 
 
@@ -202,7 +202,7 @@ adjointBoundaryCondition<Type>::adjointBoundaryCondition
             adjointBC.patch_
         )
     ),
-    addATCUaGradUTerm_(adjointBC.addATCUaGradUTerm_)
+    addATCUaGradUTerm_(Switch::INVALID)
 {}
 
 
@@ -221,7 +221,7 @@ adjointBoundaryCondition<Type>::adjointBoundaryCondition
     adjointSolverName_(solverName),
     simulationType_("incompressible"),
     boundaryContrPtr_(nullptr),
-    addATCUaGradUTerm_(nullptr)
+    addATCUaGradUTerm_(Switch::INVALID)
 {
     // Set the boundaryContribution pointer
     setBoundaryContributionPtr();

src/optimisation/adjointOptimisation/adjoint/adjointBoundaryConditions/adjointBoundaryCondition/adjointBoundaryCondition.H

@@ -39,6 +39,7 @@ Description
 
 #include "boundaryAdjointContribution.H"
 #include "ATCModel.H"
+#include "Switch.H"
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
@@ -73,11 +74,10 @@ protected:
         //- to the adjoint boundary conditions
         autoPtr<boundaryAdjointContribution> boundaryContrPtr_;
 
-
-        //- Whether to add the extra term from the UaGradU formulation
-        //  autoPtr since ATCModel has not been allocated at the time
-        //  adjointBoundaryConditions are constructed
-        autoPtr<bool> addATCUaGradUTerm_;
+        //- Whether to add the extra term from the UaGradU formulation.
+        //  As a Switch with delayed evaluation since ATCModel
+        //  has not been allocated at the time of construction
+        Switch addATCUaGradUTerm_;
 
 
     // Protected Member Functions