ENH: ITKv5 override consistency

Provide remove virtual and override

Use clang-tidy to add ITK_OVERRIDE, and to remove
redundant virtual on functions.

cd ../ITK;
clang-tidy -p ITK-clangtidy $find Modules/[A-J]*  -name *.cxx |fgrep -v ThirdParty) -checks=-*,modernize-use-override  -header-filter=.* -fix
clang-tidy -p ITK-clangtidy $(find Modules/[K-Z]*  -name *.cxx |fgrep -v ThirdParty) -checks=-*,modernize-use-override  -header-filter=.* -fix

https://stackoverflow.com/questions/39932391/virtual-override-or-both-c

When you override a function you don't technically need to write either virtual
or override.

The original base class declaration needs the keyword virtual to mark it as virtual.

In the derived class the function is virtual by way of having the ¹same type as
the base class function.

However, an override can help avoid bugs by producing a compilation error when
the intended override isn't technically an override. E.g. that the function
type isn't exactly like the base class function. Or that a maintenance of the
base class changes that function's type, e.g. adding a defaulted argument.

In the same way, a virtual keyword in the derived class can make such a bug
more subtle, by ensuring that the function is still is virtual in further
derived classes.

So the general advice is,

virtual for the base class function declaration.
This is technically necessary.

Use override (only) for a derived class' override.
This helps with maintenance.

Author: hjmjohnson

include/itkArrivalFunctionToPathFilter.h

@@ -79,7 +79,7 @@ class ArrivalFunctionToPathCommand : public itk::Command
 
 protected:
   ArrivalFunctionToPathCommand(){}
-  ~ArrivalFunctionToPathCommand(){}
+  ~ArrivalFunctionToPathCommand() ITK_OVERRIDE{}
 
 private:
   ITK_DISALLOW_COPY_AND_ASSIGN(ArrivalFunctionToPathCommand);
@@ -212,8 +212,8 @@ class ITK_EXPORT ArrivalFunctionToPathFilter :
 
 protected:
   ArrivalFunctionToPathFilter();
-  ~ArrivalFunctionToPathFilter();
-  virtual void PrintSelf(std::ostream& os, Indent indent) const ITK_OVERRIDE;
+  ~ArrivalFunctionToPathFilter() ITK_OVERRIDE;
+  void PrintSelf(std::ostream& os, Indent indent) const ITK_OVERRIDE;
 
   /** Override since the filter needs all the data for the algorithm */
   void GenerateInputRequestedRegion() ITK_OVERRIDE;

include/itkIterateNeighborhoodOptimizer.h

@@ -104,7 +104,7 @@ class MinimalPathExtraction_EXPORT IterateNeighborhoodOptimizer :
 
 protected:
   IterateNeighborhoodOptimizer();
-  virtual ~IterateNeighborhoodOptimizer() {};
+  ~IterateNeighborhoodOptimizer() ITK_OVERRIDE {};
   void PrintSelf(std::ostream& os, Indent indent) const ITK_OVERRIDE;
 
 private:

include/itkPhysicalCentralDifferenceImageFunction.h

@@ -89,7 +89,7 @@ class ITK_EXPORT PhysicalCentralDifferenceImageFunction :
    * \warning this method caches BufferedRegion information.
    * If the BufferedRegion has changed, user must call
    * SetInputImage again to update cached values. */
-  virtual void SetInputImage( const InputImageType * ptr ) ITK_OVERRIDE
+  void SetInputImage( const InputImageType * ptr ) ITK_OVERRIDE
     {
         this->Superclass::SetInputImage( ptr );
         if ( m_Interpolator.IsNotNull() )
@@ -103,7 +103,7 @@ class ITK_EXPORT PhysicalCentralDifferenceImageFunction :
    *  No bounds checking is done. The point is assume to lie within the
    *  image buffer. ImageFunction::IsInsideBuffer() can be used to check
    *  bounds before calling this method. */
-  virtual OutputType EvaluateAtIndex( const IndexType& index ) const ITK_OVERRIDE
+  OutputType EvaluateAtIndex( const IndexType& index ) const ITK_OVERRIDE
     {
     PointType point;
     m_Interpolator->GetInputImage()->TransformIndexToPhysicalPoint( index, point );
@@ -116,7 +116,7 @@ class ITK_EXPORT PhysicalCentralDifferenceImageFunction :
    *  No bounds checking is done. The point is assume to lie within the
    *  image buffer. ImageFunction::IsInsideBuffer() can be used to check
    *  bounds before calling this method. */
-  virtual OutputType EvaluateAtContinuousIndex(
+  OutputType EvaluateAtContinuousIndex(
     const ContinuousIndexType& cindex ) const ITK_OVERRIDE
     {
     PointType point;
@@ -130,11 +130,11 @@ class ITK_EXPORT PhysicalCentralDifferenceImageFunction :
    *  No bounds checking is done. The point is assume to lie within the
    *  image buffer. ImageFunction::IsInsideBuffer() can be used to check
    *  bounds before calling this method. */
-   virtual OutputType Evaluate( const PointType& point ) const ITK_OVERRIDE;
+   OutputType Evaluate( const PointType& point ) const ITK_OVERRIDE;
 
 protected:
   PhysicalCentralDifferenceImageFunction();
-  ~PhysicalCentralDifferenceImageFunction(){};
+  ~PhysicalCentralDifferenceImageFunction() ITK_OVERRIDE{};
   void PrintSelf(std::ostream& os, Indent indent) const ITK_OVERRIDE;
 
 private:

include/itkSingleImageCostFunction.h

@@ -121,11 +121,11 @@ class ITK_EXPORT SingleImageCostFunction :
 
   /** This method returns the value of the cost function corresponding
     * to the specified parameters. */
-  virtual MeasureType GetValue( const ParametersType & parameters ) const ITK_OVERRIDE;
+  MeasureType GetValue( const ParametersType & parameters ) const ITK_OVERRIDE;
 
   /** This method returns the derivative of the cost function corresponding
     * to the specified parameters. */
-  virtual void GetDerivative( const ParametersType & parameters,
+  void GetDerivative( const ParametersType & parameters,
                               DerivativeType & derivative ) const ITK_OVERRIDE;
 
   // Set these depending on whether you will be minimizing or maximizing.
@@ -142,7 +142,7 @@ class ITK_EXPORT SingleImageCostFunction :
 
 protected:
   SingleImageCostFunction();
-  virtual ~SingleImageCostFunction() {}
+  ~SingleImageCostFunction() ITK_OVERRIDE {}
   void PrintSelf(std::ostream& os, Indent indent) const ITK_OVERRIDE;
 
 private:

include/itkSpeedFunctionPathInformation.h

@@ -119,8 +119,8 @@ class SpeedFunctionPathInformation :
 
 protected:
   SpeedFunctionPathInformation( );
-  virtual ~SpeedFunctionPathInformation( );
-  virtual void PrintSelf( std::ostream& os, Indent indent ) const ITK_OVERRIDE;
+  ~SpeedFunctionPathInformation( ) ITK_OVERRIDE;
+  void PrintSelf( std::ostream& os, Indent indent ) const ITK_OVERRIDE;
 
   std::vector< PointsContainerType > m_Information;
   SizeValueType                      m_Front;

include/itkSpeedFunctionToPathFilter.h

@@ -147,27 +147,27 @@ class ITK_EXPORT SpeedFunctionToPathFilter :
   }
 
   /** Handle optimizer iteration events. */
-  virtual void Execute( const itk::Object * object, const itk::EventObject & event ) ITK_OVERRIDE;
+  void Execute( const itk::Object * object, const itk::EventObject & event ) ITK_OVERRIDE;
 
   /** access the arrival image for debugging purposes */
   itkGetConstMacro( CurrentArrivalFunction, InputImagePointer );
 
 protected:
   SpeedFunctionToPathFilter( );
-  ~SpeedFunctionToPathFilter( );
-  virtual void PrintSelf( std::ostream& os, Indent indent ) const ITK_OVERRIDE;
+  ~SpeedFunctionToPathFilter( ) ITK_OVERRIDE;
+  void PrintSelf( std::ostream& os, Indent indent ) const ITK_OVERRIDE;
 
   /** Implemention of algorithm. */
   void GenerateData( void ) ITK_OVERRIDE;
 
   /** Get the number of paths which the user has instructed to extracted. */
-  virtual unsigned int GetNumberOfPathsToExtract( ) const ITK_OVERRIDE;
+  unsigned int GetNumberOfPathsToExtract( ) const ITK_OVERRIDE;
 
   /** Compute the arrival function from which to extract the path. */
-  virtual InputImageType * ComputeArrivalFunction( ) ITK_OVERRIDE;
+  InputImageType * ComputeArrivalFunction( ) ITK_OVERRIDE;
 
   /** Override handling of optimizer iteration events to accomodate way points. */
-  virtual const PointsContainerType & GetNextEndPoint( ) ITK_OVERRIDE;
+  const PointsContainerType & GetNextEndPoint( ) ITK_OVERRIDE;
 
   std::vector< typename PathInformationType::Pointer > m_Information;
   InputImagePointer                                    m_CurrentArrivalFunction;