Cleanup: Remove interface region files to C++

Moves all `interface_region*` files to C++ except for the tooptip region
which is slightly more complicated. Also move a few other files as well.
This helps to simplify and speed up code, especially through the use
of better C++ data structures. This change builds on all platforms on
the buildbot.

source/blender/editors/include/UI_interface.h

@@ -634,7 +634,7 @@ uiPopupMenu *UI_popup_menu_begin_ex(struct bContext *C,
  * Set the whole structure to work.
  */
 void UI_popup_menu_end(struct bContext *C, struct uiPopupMenu *pup);
-bool UI_popup_menu_end_or_cancel(struct bContext *C, struct uiPopupMenu *head);
+bool UI_popup_menu_end_or_cancel(struct bContext *C, struct uiPopupMenu *pup);
 struct uiLayout *UI_popup_menu_layout(uiPopupMenu *pup);
 
 void UI_popup_menu_reports(struct bContext *C, struct ReportList *reports) ATTR_NONNULL();
@@ -1595,13 +1595,15 @@ typedef enum {
 } eButLabelAlign;
 
 /* Return info for uiDefAutoButsRNA */
-typedef enum {
+typedef enum eAutoPropButsReturn {
   /* Returns when no buttons were added */
   UI_PROP_BUTS_NONE_ADDED = 1 << 0,
   /* Returned when any property failed the custom check callback (check_prop) */
   UI_PROP_BUTS_ANY_FAILED_CHECK = 1 << 1,
 } eAutoPropButsReturn;
 
+ENUM_OPERATORS(eAutoPropButsReturn, UI_PROP_BUTS_ANY_FAILED_CHECK);
+
 uiBut *uiDefAutoButR(uiBlock *block,
                      struct PointerRNA *ptr,
                      struct PropertyRNA *prop,

source/blender/editors/interface/CMakeLists.txt

@@ -46,25 +46,25 @@ set(SRC
   interface_layout.c
   interface_ops.c
   interface_panel.c
-  interface_query.c
-  interface_region_color_picker.c
-  interface_region_hud.c
-  interface_region_menu_pie.c
-  interface_region_menu_popup.c
-  interface_region_popover.c
-  interface_region_popup.c
+  interface_query.cc
+  interface_region_color_picker.cc
+  interface_region_hud.cc
+  interface_region_menu_pie.cc
+  interface_region_menu_popup.cc
+  interface_region_popover.cc
+  interface_region_popup.cc
   interface_region_search.cc
   interface_region_tooltip.c
-  interface_regions.c
-  interface_style.c
+  interface_regions.cc
+  interface_style.cc
   interface_template_asset_view.cc
   interface_template_attribute_search.cc
   interface_template_list.cc
   interface_template_search_menu.cc
   interface_template_search_operator.c
   interface_templates.c
   interface_undo.c
-  interface_utils.c
+  interface_utils.cc
   interface_view.cc
   interface_widgets.c
   resources.c

source/blender/editors/interface/interface_intern.h

@@ -214,8 +214,8 @@ struct uiBut {
   BIFIconID icon;
   /** Copied from the #uiBlock.emboss */
   eUIEmbossType emboss;
-  /** direction in a pie menu, used for collision detection (RadialDirection) */
-  signed char pie_dir;
+  /** direction in a pie menu, used for collision detection. */
+  RadialDirection pie_dir;
   /** could be made into a single flag */
   bool changed;
   /** so buttons can support unit systems which are not RNA */
@@ -954,7 +954,7 @@ void ui_pie_menu_level_create(uiBlock *block,
                               const EnumPropertyItem *items,
                               int totitem,
                               wmOperatorCallContext context,
-                              int flag);
+                              wmOperatorCallContext flag);
 
 /* interface_region_popup.c */