STYLE: Add in-class {} member initializers to objects created by New()

For an object created by `New()`, the performance cost of adding a `{}` default
member initializer to each of its non-static data members should be neglectable
compared to the cost of allocating the object itself, as it is allocated on the
heap.

In-class default member initialization effectively prevents Valgrind/Memcheck
warnings like "Conditional jump or move depends on uninitialised value(s)", and
Visual C++ Code Analysis warnings like "warning C26495: Variable is
uninitialized. Always initialize a member variable (type.6)"

These cases are found using the regular expression `  \w.* m_\w[^{}=]+;`,
excluding `static` data members and data members of a reference (`&`) type.

`Octree::m_ColorTable` was excluded, to avoid GCC warnings saying "const/copy
propagation disabled" and "GCSE disabled" [-Wdisabled-optimization].

Modules/Bridge/VTK/include/itkVTKImageExport.h

@@ -128,14 +128,14 @@ class ITK_TEMPLATE_EXPORT VTKImageExport : public VTKImageExportBase
   BufferPointerCallback() override;
 
 private:
-  std::string m_ScalarTypeName;
-  int         m_WholeExtent[6];
-  int         m_DataExtent[6];
-  double      m_DataSpacing[3];
-  double      m_DataOrigin[3];
-  double      m_DataDirection[9];
-  float       m_FloatDataSpacing[3];
-  float       m_FloatDataOrigin[3];
+  std::string m_ScalarTypeName{};
+  int         m_WholeExtent[6]{};
+  int         m_DataExtent[6]{};
+  double      m_DataSpacing[3]{};
+  double      m_DataOrigin[3]{};
+  double      m_DataDirection[9]{};
+  float       m_FloatDataSpacing[3]{};
+  float       m_FloatDataOrigin[3]{};
 };
 } // end namespace itk
 

Modules/Bridge/VTK/include/itkVTKImageImport.h

@@ -201,7 +201,7 @@ class ITK_TEMPLATE_EXPORT VTKImageImport : public ImageSource<TOutputImage>
   DataExtentCallbackType            m_DataExtentCallback{ nullptr };
   BufferPointerCallbackType         m_BufferPointerCallback{ nullptr };
 
-  std::string m_ScalarTypeName;
+  std::string m_ScalarTypeName{};
 };
 } // namespace itk
 

Modules/Bridge/VtkGlue/include/itkImageToVTKImageFilter.h

@@ -105,8 +105,8 @@ class ITK_TEMPLATE_EXPORT ImageToVTKImageFilter : public ProcessObject
   ~ImageToVTKImageFilter() override;
 
 private:
-  ExporterFilterPointer m_Exporter;
-  vtkImageImport *      m_Importer;
+  ExporterFilterPointer m_Exporter{};
+  vtkImageImport *      m_Importer{};
 };
 
 } // end namespace itk

Modules/Bridge/VtkGlue/include/itkVTKImageToImageFilter.h

@@ -93,7 +93,7 @@ class ITK_TEMPLATE_EXPORT VTKImageToImageFilter : public VTKImageImport<TOutputI
 
 private:
   using ImageExportPointer = vtkSmartPointer<vtkImageExport>;
-  ImageExportPointer m_Exporter;
+  ImageExportPointer m_Exporter{};
 };
 
 } // end namespace itk

Modules/Compatibility/Deprecated/include/itkBarrier.h

@@ -79,8 +79,8 @@ class ITKDeprecated_EXPORT Barrier : public LightObject
   unsigned int            m_NumberArrived{ 0 };
   unsigned int            m_NumberExpected{ 0 };
   unsigned int            m_Generation{ 0 }; // Allows successive waits
-  std::condition_variable m_ConditionVariable;
-  std::mutex              m_Mutex;
+  std::condition_variable m_ConditionVariable{};
+  std::mutex              m_Mutex{};
 };
 } // end namespace itk
 

Modules/Compatibility/Deprecated/include/itkConditionVariable.h

@@ -92,7 +92,7 @@ class ITKDeprecated_EXPORT ConditionVariable : public LightObject
   ~ConditionVariable() override;
 
 private:
-  ConditionVariableType m_ConditionVariable;
+  ConditionVariableType m_ConditionVariable{};
 };
 } // end namespace itk
 

Modules/Compatibility/Deprecated/include/itkFastMutexLock.h

@@ -92,7 +92,7 @@ class ITKDeprecated_EXPORT FastMutexLock : public Object
   FastMutexLock() = default;
   ~FastMutexLock() override = default;
 
-  SimpleFastMutexLock m_SimpleFastMutexLock;
+  SimpleFastMutexLock m_SimpleFastMutexLock{};
   void
   PrintSelf(std::ostream & os, Indent indent) const override;
 };

Modules/Compatibility/Deprecated/include/itkMutexLock.h

@@ -151,7 +151,7 @@ class ITKDeprecated_EXPORT MutexLock : public Object
   MutexLock() = default;
   ~MutexLock() override = default;
 
-  SimpleMutexLock m_SimpleMutexLock;
+  SimpleMutexLock m_SimpleMutexLock{};
   void
   PrintSelf(std::ostream & os, Indent indent) const override;
 };

Modules/Compatibility/Deprecated/include/itkTreeContainer.h

@@ -121,9 +121,9 @@ class ITK_TEMPLATE_EXPORT TreeContainer : public TreeContainerBase<TValue>
   TreeContainer();
   ~TreeContainer() override = default;
 
-  typename TreeNodeType::Pointer m_Root;
+  typename TreeNodeType::Pointer m_Root{};
 
-  int m_DefaultChildrenCount;
+  int m_DefaultChildrenCount{};
 
   void
   PrintSelf(std::ostream & os, Indent indent) const override;

Modules/Compatibility/Deprecated/include/itkTreeNode.h

@@ -142,10 +142,10 @@ class ITK_TEMPLATE_EXPORT TreeNode : public Object
   TreeNode() = default;
   ~TreeNode() override;
 
-  TValue m_Data;
+  TValue m_Data{};
   Self * m_Parent{ nullptr };
 
-  ChildrenListType m_Children;
+  ChildrenListType m_Children{};
 };
 } // end namespace itk
 

Modules/Compatibility/Deprecated/include/itkVectorCentralDifferenceImageFunction.h

@@ -147,7 +147,7 @@ class ITK_TEMPLATE_EXPORT VectorCentralDifferenceImageFunction
 private:
   // flag to take or not the image direction into account
   // when computing the derivatives.
-  bool m_UseImageDirection;
+  bool m_UseImageDirection{};
 };
 } // end namespace itk
 

Modules/Compatibility/Deprecated/include/itkVectorResampleImageFilter.h

@@ -233,14 +233,14 @@ class ITK_TEMPLATE_EXPORT VectorResampleImageFilter : public ImageToImageFilter<
 
 
 private:
-  SizeType                m_Size;
-  TransformPointerType    m_Transform;
-  InterpolatorPointerType m_Interpolator;
-  PixelType               m_DefaultPixelValue;
-  SpacingType             m_OutputSpacing;
-  OriginPointType         m_OutputOrigin;
-  DirectionType           m_OutputDirection;
-  IndexType               m_OutputStartIndex;
+  SizeType                m_Size{};
+  TransformPointerType    m_Transform{};
+  InterpolatorPointerType m_Interpolator{};
+  PixelType               m_DefaultPixelValue{};
+  SpacingType             m_OutputSpacing{};
+  OriginPointType         m_OutputOrigin{};
+  DirectionType           m_OutputDirection{};
+  IndexType               m_OutputStartIndex{};
 };
 } // end namespace itk
 

Modules/Core/Common/include/itkAutoPointerDataObjectDecorator.h

@@ -103,7 +103,7 @@ class ITK_TEMPLATE_EXPORT AutoPointerDataObjectDecorator : public DataObject
 
 protected:
 private:
-  ComponentPointer m_Component;
+  ComponentPointer m_Component{};
 };
 } // end namespace itk
 

Modules/Core/Common/include/itkBinaryThresholdSpatialFunction.h

@@ -92,10 +92,10 @@ class ITK_TEMPLATE_EXPORT BinaryThresholdSpatialFunction
   void
   PrintSelf(std::ostream & os, Indent indent) const override;
 
-  FunctionOutputType m_LowerThreshold;
-  FunctionOutputType m_UpperThreshold;
+  FunctionOutputType m_LowerThreshold{};
+  FunctionOutputType m_UpperThreshold{};
 
-  typename FunctionType::Pointer m_Function;
+  typename FunctionType::Pointer m_Function{};
 };
 } // end namespace itk
 

Modules/Core/Common/include/itkBoundingBox.h

@@ -197,11 +197,11 @@ class ITK_TEMPLATE_EXPORT BoundingBox : public Object
   using ConstIterator = typename PointsContainer::ConstIterator;
 
 private:
-  PointsContainerConstPointer m_PointsContainer;
+  PointsContainerConstPointer m_PointsContainer{};
 #if !defined(ITK_LEGACY_REMOVE)
   PointsContainerPointer m_CornersContainer{ PointsContainer::New() };
 #endif
-  mutable BoundsArrayType m_Bounds;
+  mutable BoundsArrayType m_Bounds{};
   mutable TimeStamp       m_BoundsMTime; // The last time the bounds
                                          // were computed.
 };

Modules/Core/Common/include/itkColorTable.h

@@ -130,8 +130,8 @@ class ITK_TEMPLATE_EXPORT ColorTable : public Object
 
   unsigned int m_NumberOfColors{ 0 };
 
-  ColorNameVectorType m_ColorName;
-  ColorVectorType     m_Color;
+  ColorNameVectorType m_ColorName{};
+  ColorVectorType     m_Color{};
 };
 } // namespace itk
 

Modules/Core/Common/include/itkCommand.h

@@ -447,7 +447,7 @@ class ITKCommon_EXPORT FunctionCommand : public Command
   ~FunctionCommand() override;
 
 
-  FunctionObjectType m_FunctionObject;
+  FunctionObjectType m_FunctionObject{};
 };
 
 } // end namespace itk

Modules/Core/Common/include/itkConicShellInteriorExteriorSpatialFunction.h

@@ -127,8 +127,8 @@ class ITK_TEMPLATE_EXPORT ConicShellInteriorExteriorSpatialFunction
   PrintSelf(std::ostream & os, Indent indent) const override;
 
 private:
-  InputType    m_Origin;
-  GradientType m_OriginGradient;
+  InputType    m_Origin{};
+  GradientType m_OriginGradient{};
   double       m_DistanceMin{ 0.0 };
   double       m_DistanceMax{ 0.0 };
   double       m_Epsilon{ 0.0 };

Modules/Core/Common/include/itkDataObjectDecorator.h

@@ -141,7 +141,7 @@ class ITK_TEMPLATE_EXPORT DataObjectDecorator : public DataObject
 
 protected:
 private:
-  ComponentPointer m_Component;
+  ComponentPointer m_Component{};
 };
 } // end namespace itk
 

Modules/Core/Common/include/itkEllipsoidInteriorExteriorSpatialFunction.h

@@ -89,10 +89,10 @@ class ITK_TEMPLATE_EXPORT EllipsoidInteriorExteriorSpatialFunction
 
 private:
   /** The center of the ellipsoid. */
-  InputType m_Center;
+  InputType m_Center{};
 
   /** The axes lengths of the ellipsoid. */
-  InputType m_Axes;
+  InputType m_Axes{};
 
   /** The orientation vectors (must be orthogonal) of the ellipsoid axes. */
   OrientationType m_Orientations{};

Modules/Core/Common/include/itkEquivalencyTable.h

@@ -179,7 +179,7 @@ class ITKCommon_EXPORT EquivalencyTable : public DataObject
   void
   PrintSelf(std::ostream & os, Indent indent) const override;
 
-  HashTableType m_HashMap;
+  HashTableType m_HashMap{};
 };
 } // end namespace itk
 

Modules/Core/Common/include/itkExtractImageFilter.h

@@ -314,9 +314,9 @@ class ITK_TEMPLATE_EXPORT ExtractImageFilter : public InPlaceImageFilter<TInputI
   void
   GenerateData() override;
 
-  InputImageRegionType m_ExtractionRegion;
+  InputImageRegionType m_ExtractionRegion{};
 
-  OutputImageRegionType m_OutputImageRegion;
+  OutputImageRegionType m_OutputImageRegion{};
 
 private:
   DirectionCollapseStrategyEnum m_DirectionCollapseStrategy{ DirectionCollapseStrategyEnum::DIRECTIONCOLLAPSETOUNKOWN };

Modules/Core/Common/include/itkFileOutputWindow.h

@@ -88,12 +88,12 @@ class ITKCommon_EXPORT FileOutputWindow : public OutputWindow
   void
   Initialize();
 
-  std::ofstream * m_Stream;
+  std::ofstream * m_Stream{};
 
-  std::string m_FileName;
+  std::string m_FileName{};
 
-  bool m_Flush;
-  bool m_Append;
+  bool m_Flush{};
+  bool m_Append{};
 };
 } // end namespace itk
 

Modules/Core/Common/include/itkFiniteCylinderSpatialFunction.h

@@ -97,17 +97,17 @@ class ITK_TEMPLATE_EXPORT FiniteCylinderSpatialFunction : public InteriorExterio
 
 private:
   /** The center of the cylinder. */
-  InputType m_Center;
+  InputType m_Center{};
 
   /** The medial axis length of the cylinder. */
-  double m_AxisLength;
+  double m_AxisLength{};
 
   /** The radius length of the cylinder. */
-  double m_Radius;
+  double m_Radius{};
 
   /** The orientation vectors (must be orthogonal) of the ellipsoid axes. */
-  InputType m_Orientation;
-  InputType m_NormalizedOrientation;
+  InputType m_Orientation{};
+  InputType m_NormalizedOrientation{};
 };
 } // end namespace itk
 

Modules/Core/Common/include/itkFrustumSpatialFunction.h

@@ -132,7 +132,7 @@ class ITK_TEMPLATE_EXPORT FrustumSpatialFunction : public InteriorExteriorSpatia
   PrintSelf(std::ostream & os, Indent indent) const override;
 
 private:
-  InputType                m_Apex;
+  InputType                m_Apex{};
   double                   m_AngleZ{ 0.0f };
   double                   m_ApertureAngleX{ 0.0f };
   double                   m_ApertureAngleY{ 0.0f };

Modules/Core/Common/include/itkGaussianDerivativeSpatialFunction.h

@@ -98,19 +98,19 @@ class ITK_TEMPLATE_EXPORT GaussianDerivativeSpatialFunction : public SpatialFunc
 
 private:
   /** Current direction */
-  mutable unsigned int m_Direction;
+  mutable unsigned int m_Direction{};
 
   /** The standard deviation in each direction. */
-  ArrayType m_Sigma;
+  ArrayType m_Sigma{};
 
   /** The mean in each direction. */
-  ArrayType m_Mean;
+  ArrayType m_Mean{};
 
   /** A scale factor multiplied by the true value of the Gaussian. */
-  double m_Scale;
+  double m_Scale{};
 
   /** Whether or not to normalize the Gaussian. */
-  bool m_Normalized;
+  bool m_Normalized{};
 };
 } // end namespace itk
 

Modules/Core/Common/include/itkGaussianKernelFunction.h

@@ -73,7 +73,7 @@ class ITK_TEMPLATE_EXPORT GaussianKernelFunction : public KernelFunctionBase<TRe
   }
 
 private:
-  const TRealValueType m_Factor;
+  const TRealValueType m_Factor{};
 };
 } // end namespace itk
 

Modules/Core/Common/include/itkGaussianSpatialFunction.h

@@ -95,9 +95,9 @@ class ITK_TEMPLATE_EXPORT GaussianSpatialFunction : public SpatialFunction<TOutp
   PrintSelf(std::ostream & os, Indent indent) const override;
 
 private:
-  ArrayType m_Sigma;
+  ArrayType m_Sigma{};
 
-  ArrayType m_Mean;
+  ArrayType m_Mean{};
 
   double m_Scale{ 1.0 };
 

Modules/Core/Common/include/itkImage.h

@@ -393,7 +393,7 @@ class ITK_TEMPLATE_EXPORT Image : public ImageBase<VImageDimension>
 
 private:
   /** Memory for the current buffer. */
-  PixelContainerPointer m_Buffer;
+  PixelContainerPointer m_Buffer{};
 };
 } // end namespace itk
 

Modules/Core/Common/include/itkImageBase.h

@@ -870,9 +870,9 @@ class ITK_TEMPLATE_EXPORT ImageBase : public DataObject
 private:
   OffsetValueType m_OffsetTable[VImageDimension + 1]{};
 
-  RegionType m_LargestPossibleRegion;
-  RegionType m_RequestedRegion;
-  RegionType m_BufferedRegion;
+  RegionType m_LargestPossibleRegion{};
+  RegionType m_RequestedRegion{};
+  RegionType m_BufferedRegion{};
 };
 } // end namespace itk
 

Modules/Core/Common/include/itkImageDuplicator.h

@@ -121,9 +121,9 @@ class ITK_TEMPLATE_EXPORT ImageDuplicator : public Object
   PrintSelf(std::ostream & os, Indent indent) const override;
 
 private:
-  ImageConstPointer m_InputImage;
-  ImagePointer      m_DuplicateImage;
-  ModifiedTimeType  m_InternalImageTime;
+  ImageConstPointer m_InputImage{};
+  ImagePointer      m_DuplicateImage{};
+  ModifiedTimeType  m_InternalImageTime{};
 };
 } // end namespace itk
 

Modules/Core/Common/include/itkImageRegionSplitterDirection.h

@@ -77,7 +77,7 @@ class ITKCommon_EXPORT ImageRegionSplitterDirection : public ImageRegionSplitter
   PrintSelf(std::ostream & os, Indent indent) const override;
 
 private:
-  unsigned int m_Direction;
+  unsigned int m_Direction{};
 };
 } // end namespace itk