GDScript: Fix PROPERTY_USAGE_SCRIPT_VARIABLE is not set for placeholder instance properties

Author: dalexeev

editor/animation/animation_track_editor.cpp

@@ -4892,7 +4892,16 @@ PropertyInfo AnimationTrackEditor::_find_hint_for_track(int p_idx, NodePath &r_b
 
 	for (const PropertyInfo &E : pinfo) {
 		if (E.name == leftover_path[leftover_path.size() - 1]) {
-			return E;
+			PropertyInfo pi = E;
+
+			// See `PropertySelector::_update_search()`. `PropertySelector` makes an exception for script variables,
+			// displaying them even if `PROPERTY_USAGE_EDITOR` is not set. So, we need to compensate for this here
+			// to ensure the property is visible in the Inspector.
+			if (pi.usage & PROPERTY_USAGE_SCRIPT_VARIABLE) {
+				pi.usage |= PROPERTY_USAGE_EDITOR;
+			}
+
+			return pi;
 		}
 	}
 

modules/gdscript/gdscript.cpp

@@ -560,8 +560,15 @@ bool GDScript::_update_exports(bool *r_err, bool p_recursive_call, PlaceHolderSc
 							continue;
 						}
 
-						members_cache.push_back(member.variable->export_info);
+						// See `GDScriptCompiler::_prepare_compilation()`. The `PROPERTY_USAGE_SCRIPT_VARIABLE` flag
+						// isn't stored in `export_info`, but is set separately in the compiler. We need to replicate
+						// the same logic for placeholders.
+						PropertyInfo property_info = member.variable->export_info;
+						property_info.usage |= PROPERTY_USAGE_SCRIPT_VARIABLE;
+
 						Variant default_value = analyzer.make_variable_default_value(member.variable);
+
+						members_cache.push_back(property_info);
 						member_default_values_cache[member.variable->identifier->name] = default_value;
 					} break;
 					case GDScriptParser::ClassNode::Member::SIGNAL: {