Core: Add hints to run with --verbose when leaking nodes/resources at exit

(cherry picked from commit 2b5545270a60a1a60f57c91bb565131dc03de74d)

core/object.cpp

@@ -2132,7 +2132,7 @@ void ObjectDB::cleanup() {
 	rw_lock->write_lock();
 	if (instances.size()) {
 
-		WARN_PRINT("ObjectDB Instances still exist!");
+		WARN_PRINT("ObjectDB instances leaked at exit (run with --verbose for details).");
 		if (OS::get_singleton()->is_stdout_verbose()) {
 			const ObjectID *K = NULL;
 			while ((K = instances.next(K))) {
@@ -2141,9 +2141,10 @@ void ObjectDB::cleanup() {
 				if (instances[*K]->is_class("Node"))
 					node_name = " - Node name: " + String(instances[*K]->call("get_name"));
 				if (instances[*K]->is_class("Resource"))
-					node_name = " - Resource name: " + String(instances[*K]->call("get_name")) + " Path: " + String(instances[*K]->call("get_path"));
+					node_name = " - Resource path: " + String(instances[*K]->call("get_path"));
 				print_line("Leaked instance: " + String(instances[*K]->get_class()) + ":" + itos(*K) + node_name);
 			}
+			print_line("Hint: Leaked instances typically happen when nodes are removed from the scene tree (with `remove_child()`) but not freed (with `free()` or `queue_free()`).");
 		}
 	}
 	instances.clear();

core/resource.cpp

@@ -33,6 +33,7 @@
 #include "core/core_string_names.h"
 #include "core/io/resource_loader.h"
 #include "core/os/file_access.h"
+#include "core/os/os.h"
 #include "core/script_language.h"
 #include "scene/main/node.h" //only so casting works
 
@@ -472,21 +473,22 @@ void ResourceCache::setup() {
 }
 
 void ResourceCache::clear() {
-	if (resources.size())
-		ERR_PRINT("Resources Still in use at Exit!");
+	if (resources.size()) {
+		ERR_PRINT("Resources still in use at exit (run with --verbose for details).");
+		if (OS::get_singleton()->is_stdout_verbose()) {
+			const String *K = nullptr;
+			while ((K = resources.next(K))) {
+				Resource *r = resources[*K];
+				print_line(vformat("Resource still in use: %s (%s)", *K, r->get_class()));
+			}
+		}
+	}
 
 	resources.clear();
 	memdelete(lock);
 }
 
 void ResourceCache::reload_externals() {
-
-	/*
-	const String *K=NULL;
-	while ((K=resources.next(K))) {
-		resources[*K]->reload_external_data();
-	}
-	*/
 }
 
 bool ResourceCache::has(const String &p_path) {
@@ -573,6 +575,5 @@ void ResourceCache::dump(const char *p_file, bool p_short) {
 	}
 
 	lock->read_unlock();
-
 #endif
 }