Operators: add a new flag stating that operator needs access to evaluated data.

For now, that flag is only used in redo code, since after undo step
depsgraph is totally empty... We *may* want to add at least an assert in
op calling code too, though?

source/blender/editors/undo/ed_undo.c

@@ -48,6 +48,7 @@
 #include "BKE_context.h"
 #include "BKE_global.h"
 #include "BKE_main.h"
+#include "BKE_scene.h"
 #include "BKE_screen.h"
 #include "BKE_layer.h"
 #include "BKE_undo_system.h"
@@ -414,6 +415,15 @@ int ED_undo_operator_repeat(bContext *C, wmOperator *op)
 				}
 			}
 
+			if (op->type->flag & OPTYPE_USE_EVAL_DATA) {
+				/* We need to force refresh of depsgraph after undo step,
+				 * redoing the operator *may* rely on some valid evaluated data. */
+				Main *bmain = CTX_data_main(C);
+				scene = CTX_data_scene(C);
+				ViewLayer *view_layer = CTX_data_view_layer(C);
+				BKE_scene_view_layer_graph_evaluated_ensure(bmain, scene, view_layer);
+			}
+
 			retval = WM_operator_repeat(C, op);
 			if ((retval & OPERATOR_FINISHED) == 0) {
 				if (G.debug & G_DEBUG)

source/blender/makesrna/intern/rna_wm.c

@@ -432,6 +432,8 @@ static const EnumPropertyItem operator_flag_items[] = {
 	                      "is enabled"},
 	{OPTYPE_PRESET, "PRESET", 0, "Preset", "Display a preset button with the operators settings"},
 	{OPTYPE_INTERNAL, "INTERNAL", 0, "Internal", "Removes the operator from search results"},
+	{OPTYPE_USE_EVAL_DATA, "USE_EVAL_DATA", 0, "Use Evaluated Data",
+	                       "Uses evaluated data (i.e. needs a valid depsgraph for current context)"},
 	{0, NULL, 0, NULL, NULL}
 };
 #endif

source/blender/windowmanager/WM_types.h

@@ -145,6 +145,7 @@ enum {
 
 	OPTYPE_LOCK_BYPASS  = (1 << 7),  /* Allow operator to run when interface is locked */
 	OPTYPE_UNDO_GROUPED = (1 << 8),  /* Special type of undo which doesn't store itself multiple times */
+	OPTYPE_USE_EVAL_DATA = (1 << 9),  /* Need evaluated data (i.e. a valid, up-to-date depsgraph for current context) */
 };
 
 /* context to call operator in for WM_operator_name_call */