vcpkg/ports/paraview/external_vtk.patch

diff --git a/CMake/ParaViewOptions.cmake b/CMake/ParaViewOptions.cmake
index 70c771151..14df81490 100644
--- a/CMake/ParaViewOptions.cmake
+++ b/CMake/ParaViewOptions.cmake
@@ -99,7 +99,7 @@ endif()
 #========================================================================
 
 # XXX(VTK): External VTK is not yet actually supported.
-if (FALSE)
+if (TRUE)
 option(PARAVIEW_USE_EXTERNAL_VTK "Use an external VTK." OFF)
 mark_as_advanced(PARAVIEW_USE_EXTERNAL_VTK)
 else ()
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 6ee167322..628745584 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -73,7 +73,13 @@ if (NOT CMAKE_INSTALL_LICENSEDIR)
 endif ()
 
 set(paraview_cmake_dir "${CMAKE_CURRENT_SOURCE_DIR}/CMake")
-set(vtk_cmake_dir "${CMAKE_CURRENT_SOURCE_DIR}/VTK/CMake")
+if (PARAVIEW_USE_EXTERNAL_VTK)
+  find_package(VTK CONFIG REQUIRED)
+  get_filename_component(vtk_cmake_dir "${VTK_CONFIG}" DIRECTORY )
+else()
+  set(vtk_cmake_dir "${CMAKE_CURRENT_SOURCE_DIR}/VTK/CMake")
+endif()
+
 if (NOT IS_DIRECTORY "${vtk_cmake_dir}")
   message(FATAL_ERROR
     "Failed to find the VTK CMake directory. Did you forget to initialize the "
@@ -242,9 +246,7 @@ if (PARAVIEW_USE_FORTRAN)
   enable_language(Fortran OPTIONAL)
 endif ()
 
-if (PARAVIEW_USE_EXTERNAL_VTK)
-  find_package(VTK REQUIRED)
-else ()
+if (NOT PARAVIEW_USE_EXTERNAL_VTK)
   list(APPEND CMAKE_MODULE_PATH
     "${CMAKE_CURRENT_SOURCE_DIR}/VTK/CMake")
   include(vtkCMakeBackports)
@@ -423,9 +425,67 @@ endif ()
 
 if (PARAVIEW_USE_EXTERNAL_VTK)
   if (paraview_required_modules OR paraview_unrecognized_modules)
-    message(FATAL_ERROR
-      "The following modules were requested or required, but not found: "
-      "${paraview_required_modules};${paraview_unrecognized_modules}.")
+    foreach(mod ${paraview_required_modules})
+        if(NOT TARGET ${mod})
+            list(APPEND modules_notarget ${mod})
+        endif()
+        if(${mod} MATCHES "VTK::") # For better debugging
+            list(APPEND vtk_modules ${mod})
+        endif()
+    endforeach()
+    foreach(mod ${paraview_unrecognized_modules})
+        if(NOT TARGET ${mod})
+            list(FIND paraview_rejected_modules ${mod} _found_mod)
+            if(_found_mod GREATER_EQUAL 0)
+                list(APPEND _to_remove ${mod})
+            endif()
+        else()
+            list(APPEND _to_remove ${mod})
+            #list(APPEND vtk_modules ${mod}) #probably do not need to add unrecognized_modules to the wrapper
+        endif()
+    endforeach()
+    list(REMOVE_ITEM paraview_unrecognized_modules ${_to_remove})
+    message(STATUS "UNRECOGNIZED:${paraview_unrecognized_modules}")
+    message(STATUS "REJECTED MODULES: ${paraview_rejected_modules}")
+    message(STATUS "UNRECOGNIZED WITHOUT REJECTED AND KNOWN TARGETS: ${paraview_unrecognized_modules}")
+    message(STATUS "ALL PROVIDED MODULES: ${paraview_modules}")
+    set(_unnecessary_moduls ${paraview_modules})
+    list(REMOVE_ITEM _unnecessary_moduls ${paraview_required_modules})
+    if(modules_notarget)
+        message(FATAL_ERROR
+          "The following modules were requested or required, but not found: "
+          "${modules_notarget}")
+    endif()
+    list(REMOVE_DUPLICATES vtk_modules)
+    macro(search_dependent_targets)
+        set(vtk_mod_dep_list)
+        foreach(vtk_targ ${ARGN})
+            get_target_property(vtk_mod_dep ${vtk_targ} "INTERFACE_vtk_module_depends")
+            if(vtk_mod_dep)
+                list(APPEND vtk_mod_dep_list ${vtk_mod_dep})
+            endif()
+            get_target_property(vtk_mod_pdep ${vtk_targ} "INTERFACE_vtk_module_private_depends")
+            if(vtk_mod_pdep)
+                list(APPEND vtk_mod_dep_list ${vtk_mod_pdep})
+            endif()
+            get_target_property(vtk_mod_odep ${vtk_targ} "INTERFACE_vtk_module_opional_depends")
+            if(vtk_mod_odep)
+                list(APPEND vtk_mod_dep_list ${vtk_mod_odep})
+            endif()
+            if(vtk_mod_dep_list)
+                message(STATUS "Target ${vtk_targ} depends on ${vtk_mod_dep_list}")
+                list(REMOVE_ITEM vtk_mod_dep_list ${vtk_modules})
+                if(vtk_mod_dep_list)
+                    message(STATUS "Newly discovered modules: ${vtk_mod_dep_list}")
+                    list(APPEND vtk_modules ${vtk_mod_dep_list})
+                    search_dependent_targets(${vtk_mod_dep_list})
+                else()
+                    message(STATUS "No new modules discovered!")
+                endif()
+            endif()
+        endforeach()
+    endmacro()
+    search_dependent_targets(${vtk_modules})
   endif ()
 
   if (PARAVIEW_USE_PYTHON)
@@ -508,7 +574,7 @@ else ()
   endif()
 
   # Set up these variables now so that modules may acess them
-  if (NOT PARAVIEW_USE_EXTERNAL_VTK AND PARAVIEW_INSTALL_DEVELOPMENT_FILES)
+  if (PARAVIEW_INSTALL_DEVELOPMENT_FILES)
     set(vtk_cmake_dir
       "${CMAKE_CURRENT_SOURCE_DIR}/VTK/CMake")
     set(vtk_cmake_destination
@@ -642,6 +708,9 @@ set(_paraview_add_tests_default_data_directory
 set(_paraview_add_tests_default_test_data_target
   "ParaViewData")
 
+list(REMOVE_DUPLICATES vtk_modules) # Missed this somewhere
+list(REMOVE_DUPLICATES paraview_modules) # probably not needed
+
 vtk_module_build(
   MODULES             ${paraview_modules}
   KITS                ${paraview_kits}
@@ -703,9 +772,11 @@ if (PARAVIEW_ENABLE_CATALYST)
 endif ()
 
 include(vtkModuleJson)
-vtk_module_json(
-  MODULES ${vtk_modules}
-  OUTPUT "vtk-modules.json")
+if(NOT PARAVIEW_USE_EXTERNAL_VTK)
+    vtk_module_json(
+      MODULES ${vtk_modules}
+      OUTPUT "vtk-modules.json")
+endif()
 vtk_module_json(
   MODULES ${paraview_modules}
   OUTPUT "paraview-modules.json")