COMP: Adopt VXL private vnl_vector ivars via protected_set_data

Switch itk::Array<T> to vnl_vector::protected_set_data and turn off
VXL_USE_HISTORICAL_PROTECTED_IVARS so ITK builds against VXL >= 7.0.0
(where vnl_vector::data and num_elmts are private).

Bumps Modules/ThirdParty/VNL/CMakeLists.txt find_package floor 3.0.0
to 4.0.0 (protected_set_data first shipped in VXL v3.3.0).

Author: hjmjohnson

Modules/Core/Common/include/itkArray.hxx

@@ -54,8 +54,7 @@ template <typename TValue>
 Array<TValue>::Array(ValueType * datain, SizeValueType sz, bool LetArrayManageMemory)
   : m_LetArrayManageMemory(LetArrayManageMemory)
 {
-  vnl_vector<TValue>::data = datain;
-  vnl_vector<TValue>::num_elmts = sz;
+  vnl_vector<TValue>::protected_set_data(datain, sz, false);
 }
 
 #if defined(ITK_LEGACY_REMOVE)
@@ -82,7 +81,7 @@ Array<TValue>::~Array()
 {
   if (!m_LetArrayManageMemory)
   {
-    vnl_vector<TValue>::data = nullptr;
+    vnl_vector<TValue>::protected_set_data(nullptr, 0, false);
   }
 }
 
@@ -94,8 +93,7 @@ Array<TValue>::SetDataSameSize(TValue * datain, bool LetArrayManageMemory)
   {
     vnl_vector<TValue>::destroy();
   }
-  vnl_vector<TValue>::data = datain;
-  // NOTE: Required to have same size vnl_vector< TValue >::num_elmts = sz;
+  vnl_vector<TValue>::protected_set_data(datain, this->size(), false);
   m_LetArrayManageMemory = LetArrayManageMemory;
 }
 
@@ -107,8 +105,7 @@ Array<TValue>::SetData(TValue * datain, SizeValueType sz, bool LetArrayManageMem
   {
     vnl_vector<TValue>::destroy();
   }
-  vnl_vector<TValue>::data = datain;
-  vnl_vector<TValue>::num_elmts = sz;
+  vnl_vector<TValue>::protected_set_data(datain, sz, false);
   m_LetArrayManageMemory = LetArrayManageMemory;
 }
 
@@ -122,7 +119,7 @@ Array<TValue>::SetSize(SizeValueType sz)
     // on a resize
     if (!m_LetArrayManageMemory)
     {
-      vnl_vector<TValue>::data = nullptr;
+      vnl_vector<TValue>::protected_set_data(nullptr, 0, false);
     }
 
     // Call the superclass's set_size

Modules/ThirdParty/VNL/CMakeLists.txt

@@ -5,10 +5,7 @@ option(ITK_USE_SYSTEM_VXL "Use an outside build of VXL." OFF)
 mark_as_advanced(ITK_USE_SYSTEM_VXL)
 
 if(ITK_USE_SYSTEM_VXL)
-  find_package(VXL 3.0.0 REQUIRED)
-  # 3.0.0 is the first version of VXL that supports
-  # the requirement of front() and back() members
-  # in the vnl_vector and vnl_vector_fixed.
+  find_package(VXL 4.0.0 REQUIRED)
   set(
     ITKVNL_SYSTEM_INCLUDE_DIRS
     ${VXL_NETLIB_INCLUDE_DIR}
@@ -103,27 +100,16 @@ else()
   # set(VXL_USE_DCMTK                    OFF CACHE BOOL "VXL configuration for ITK" FORCE) # <- Not visible in itk extracted code
   # set(VXL_USE_ECW                      OFF CACHE BOOL "VXL configuration for ITK" FORCE) # <- Visible, but unreachable in itk extracted code
   set(VXL_USE_GEOTIFF OFF CACHE BOOL "VXL configuration for ITK" FORCE)
-  if(ITK_LEGACY_REMOVE OR ITK_FUTURE_LEGACY_REMOVE)
-    set(
-      VXL_USE_HISTORICAL_IMPLICIT_CONVERSIONS
-      OFF
-      CACHE BOOL
-      "Allow default deprecated implicit conversions."
-      FORCE
-    )
-  else()
-    set(
-      VXL_USE_HISTORICAL_IMPLICIT_CONVERSIONS
-      ON
-      CACHE BOOL
-      "Allow default deprecated implicit conversions."
-      FORCE
-    )
-  endif()
-  # MUST ALWAYS BE ON currently
+  set(
+    VXL_USE_HISTORICAL_IMPLICIT_CONVERSIONS
+    OFF
+    CACHE BOOL
+    "Allow default deprecated implicit conversions."
+    FORCE
+  )
   set(
     VXL_USE_HISTORICAL_PROTECTED_IVARS
-    ON
+    OFF
     CACHE BOOL
     "VXL configuration for ITK"
     FORCE