Fix #19552.

This also forces all inclusions of the `Singleton.h` header
to use angle brackets (since in theory third-party libraries
may be in system paths and even when provided by VTK should
use `-isystem` instead of `-I`).

Common/DataModel/vtkCellMetadata.cxx

@@ -5,8 +5,6 @@
 #include "vtkCellGrid.h"
 #include "vtkDebugLeaks.h"
 
-#include <token/Singletons.h>
-
 VTK_ABI_NAMESPACE_BEGIN
 
 using namespace vtk::literals;

Common/DataModel/vtkCellMetadata.h

@@ -30,6 +30,8 @@
 #include "vtkStringToken.h"  // for vtkStringToken::Hash
 #include "vtkTypeName.h"     // for vtk::TypeName<>()
 
+#include <token/Singletons.h> // Increment Schwarz counter for initialization.
+
 #include <functional>
 #include <set>
 #include <unordered_map>

Common/ExecutionModel/vtkFilteringInformationKeyManager.h

@@ -16,9 +16,10 @@
 #include "vtkCommonExecutionModelModule.h" // For export macro
 #include "vtkSystemIncludes.h"
 
-#include "token/Singletons.h"     // to increment its Schwarz counter
 #include "vtkDebugLeaksManager.h" // DebugLeaks exists longer than info keys.
 
+#include <token/Singletons.h> // to increment its Schwarz counter
+
 #include <functional> // for finalizers
 #include <vector>     // for finalizers
 

Documentation/release/dev/cell-grid-initialization.md

+# Fix cell-grid initialization
+
+Static debug builds on Windows could crash at initialization as
+the Schwarz counter to prepare the singleton container used to
+register cell-grid cell metadata subclasses was not incremented
+in time. See [#19552](https://gitlab.kitware.com/vtk/vtk/-/issues/19552)
+for more information.