clang-tidy: fix `modernize-use-equals-default` lints

Common/Core/SMP/TBB/vtkSMPThreadLocalImpl.h

@@ -49,7 +49,7 @@ class vtkSMPThreadLocalImpl<BackendType::TBB, T> : public vtkSMPThreadLocalImplA
   typedef typename vtkSMPThreadLocalImplAbstract<T>::ItImpl ItImplAbstract;
 
 public:
-  vtkSMPThreadLocalImpl() {}
+  vtkSMPThreadLocalImpl() = default;
 
   explicit vtkSMPThreadLocalImpl(const T& exemplar)
     : Internal(exemplar)

Common/ImplicitArrays/vtkIndexedImplicitBackend.txx

@@ -191,9 +191,7 @@ vtkIndexedImplicitBackend<ValueType>::vtkIndexedImplicitBackend(
 
 //-----------------------------------------------------------------------
 template <typename ValueType>
-vtkIndexedImplicitBackend<ValueType>::~vtkIndexedImplicitBackend()
-{
-}
+vtkIndexedImplicitBackend<ValueType>::~vtkIndexedImplicitBackend() = default;
 
 //-----------------------------------------------------------------------
 template <typename ValueType>

Domains/Microscopy/vtkOpenSlideReader.h

@@ -66,7 +66,7 @@ public:
   const char* GetDescriptiveName() override { return "Openslide::WholeSlideImage"; }
 
 protected:
-  vtkOpenSlideReader() {}
+  vtkOpenSlideReader() = default;
   ~vtkOpenSlideReader() override;
   ///@}
 

Rendering/CellGrid/vtkOpenGLCellGridRenderRequest.h

@@ -48,7 +48,7 @@ public:
   class StateBase
   {
   public:
-    virtual ~StateBase() {}
+    virtual ~StateBase() = default;
   };
 
   /// An enumeration of which shapes to render.

Testing/DataModel/vtkMappedUnstructuredGridGenerator.h

@@ -55,7 +55,7 @@ public:
   static void GenerateUnstructuredGrid(vtkUnstructuredGrid** grid);
 
 protected:
-  vtkMappedUnstructuredGridGenerator() {}
+  vtkMappedUnstructuredGridGenerator() = default;
   vtkMappedUnstructuredGridGenerator(const vtkMappedUnstructuredGridGenerator&) = delete;
 
   void operator=(const vtkMappedUnstructuredGridGenerator&) = delete;

Utilities/Benchmarks/vtkRenderTimings.h

@@ -74,7 +74,7 @@ public:
     RenderWidth = RenderHeight = 600;
   }
 
-  virtual ~vtkRTTest() {}
+  virtual ~vtkRTTest() = default;
 
 protected:
   float TargetTime;
@@ -132,7 +132,7 @@ public:
     this->ChartResults = true;
   }
 
-  virtual ~vtkRTTestSequence() {}
+  virtual ~vtkRTTestSequence() = default;
 
 protected:
   std::vector<vtkRTTestResult> TestResults;

Utilities/DICOMParser/DICOMCallback.h

@@ -44,7 +44,7 @@ VTK_ABI_NAMESPACE_BEGIN
 class DICOM_EXPORT DICOMCallback
 {
 public:
-  virtual ~DICOMCallback() {}
+  virtual ~DICOMCallback() = default;
   virtual void Execute(DICOMParser* parser, doublebyte group, doublebyte element,
     DICOMParser::VRTypes type, unsigned char* val, quadbyte len) = 0;
 };

Utilities/octree/octree/octree_cursor.txx

@@ -60,9 +60,7 @@
  */
 VTK_ABI_NAMESPACE_BEGIN
 template <typename T_, typename R_, typename P_, typename O_, typename OP_, int d_>
-octree_cursor<T_, R_, P_, O_, OP_, d_>::octree_cursor()
-{
-}
+octree_cursor<T_, R_, P_, O_, OP_, d_>::octree_cursor() = default;
 
 /**\brief Constructor you should generally use.
  *