Support script global resource name in EditorFileSystem

* Works for binary and text files.
* Makes EditorQuickOpen work with custom resources again.
* Information is cached and easily accessible.

Properly fixes #66179. Supersedes #66215 and supersedes #62417

**WARNING**: This required breaking backwards binary compatibility (.res and .scn files). Files saved after this PR is merged will no longer open in any earlier versions of Godot.

4 files changed, 119 insertions, 1 deletions

diff --git a/core/io/resource_format_binary.cpp b/core/io/resource_format_binary.cpp
index 45e1301930..3dc1e98a21 100644
--- a/core/io/resource_format_binary.cpp
+++ b/core/io/resource_format_binary.cpp
@@ -91,7 +91,8 @@ enum {
 	// Version 2: added 64 bits support for float and int.
 	// Version 3: changed nodepath encoding.
 	// Version 4: new string ID for ext/subresources, breaks forward compat.
-	FORMAT_VERSION = 4,
+	// Version 5: Ability to store script class in the header.
+	FORMAT_VERSION = 5,
 	FORMAT_VERSION_CAN_RENAME_DEPS = 1,
 	FORMAT_VERSION_NO_NODEPATH_PROPERTY = 3,
 };
@@ -1013,6 +1014,10 @@ void ResourceLoaderBinary::open(Ref<FileAccess> p_f, bool p_no_resources, bool p
 		uid = ResourceUID::INVALID_ID;
 	}
 
+	if (flags & ResourceFormatSaverBinaryInstance::FORMAT_FLAG_HAS_SCRIPT_CLASS) {
+		script_class = get_unicode_string();
+	}
+
 	for (int i = 0; i < ResourceFormatSaverBinaryInstance::RESERVED_FIELDS; i++) {
 		f->get_32(); //skip a few reserved fields
 	}
@@ -1117,6 +1122,57 @@ String ResourceLoaderBinary::recognize(Ref<FileAccess> p_f) {
 	return get_unicode_string();
 }
 
+String ResourceLoaderBinary::recognize_script_class(Ref<FileAccess> p_f) {
+	error = OK;
+
+	f = p_f;
+	uint8_t header[4];
+	f->get_buffer(header, 4);
+	if (header[0] == 'R' && header[1] == 'S' && header[2] == 'C' && header[3] == 'C') {
+		// Compressed.
+		Ref<FileAccessCompressed> fac;
+		fac.instantiate();
+		error = fac->open_after_magic(f);
+		if (error != OK) {
+			f.unref();
+			return "";
+		}
+		f = fac;
+
+	} else if (header[0] != 'R' || header[1] != 'S' || header[2] != 'R' || header[3] != 'C') {
+		// Not normal.
+		error = ERR_FILE_UNRECOGNIZED;
+		f.unref();
+		return "";
+	}
+
+	bool big_endian = f->get_32();
+	f->get_32(); // use_real64
+
+	f->set_big_endian(big_endian != 0); //read big endian if saved as big endian
+
+	uint32_t ver_major = f->get_32();
+	f->get_32(); // ver_minor
+	uint32_t ver_fmt = f->get_32();
+
+	if (ver_fmt > FORMAT_VERSION || ver_major > VERSION_MAJOR) {
+		f.unref();
+		return "";
+	}
+
+	get_unicode_string(); // type
+
+	f->get_64(); // Metadata offset
+	uint32_t flags = f->get_32();
+	f->get_64(); // UID
+
+	if (flags & ResourceFormatSaverBinaryInstance::FORMAT_FLAG_HAS_SCRIPT_CLASS) {
+		return get_unicode_string();
+	} else {
+		return String();
+	}
+}
+
 Ref<Resource> ResourceFormatLoaderBinary::load(const String &p_path, const String &p_original_path, Error *r_error, bool p_use_sub_threads, float *r_progress, CacheMode p_cache_mode) {
 	if (r_error) {
 		*r_error = ERR_FILE_CANT_OPEN;
@@ -1299,6 +1355,9 @@ Error ResourceFormatLoaderBinary::rename_dependencies(const String &p_path, cons
 
 	fw->store_32(flags);
 	fw->store_64(uid_data);
+	if (flags & ResourceFormatSaverBinaryInstance::FORMAT_FLAG_HAS_SCRIPT_CLASS) {
+		save_ustring(fw, get_ustring(f));
+	}
 
 	for (int i = 0; i < ResourceFormatSaverBinaryInstance::RESERVED_FIELDS; i++) {
 		fw->store_32(0); // reserved
@@ -1420,6 +1479,18 @@ String ResourceFormatLoaderBinary::get_resource_type(const String &p_path) const
 	return ClassDB::get_compatibility_remapped_class(r);
 }
 
+String ResourceFormatLoaderBinary::get_resource_script_class(const String &p_path) const {
+	Ref<FileAccess> f = FileAccess::open(p_path, FileAccess::READ);
+	if (f.is_null()) {
+		return ""; //could not read
+	}
+
+	ResourceLoaderBinary loader;
+	loader.local_path = ProjectSettings::get_singleton()->localize_path(p_path);
+	loader.res_path = loader.local_path;
+	return loader.recognize_script_class(f);
+}
+
 ResourceUID::ID ResourceFormatLoaderBinary::get_resource_uid(const String &p_path) const {
 	String ext = p_path.get_extension().to_lower();
 	if (!ClassDB::is_resource_extension(ext)) {
@@ -2037,15 +2108,31 @@ Error ResourceFormatSaverBinaryInstance::save(const String &p_path, const Ref<Re
 
 	save_unicode_string(f, _resource_get_class(p_resource));
 	f->store_64(0); //offset to import metadata
+
+	String script_class;
 	{
 		uint32_t format_flags = FORMAT_FLAG_NAMED_SCENE_IDS | FORMAT_FLAG_UIDS;
 #ifdef REAL_T_IS_DOUBLE
 		format_flags |= FORMAT_FLAG_REAL_T_IS_DOUBLE;
 #endif
+		if (!p_resource->is_class("PackedScene")) {
+			Ref<Script> s = p_resource->get_script();
+			if (s.is_valid()) {
+				script_class = s->get_global_name();
+				if (!script_class.is_empty()) {
+					format_flags |= ResourceFormatSaverBinaryInstance::FORMAT_FLAG_HAS_SCRIPT_CLASS;
+				}
+			}
+		}
+
 		f->store_32(format_flags);
 	}
 	ResourceUID::ID uid = ResourceSaver::get_resource_id_for_path(p_path, true);
 	f->store_64(uid);
+	if (!script_class.is_empty()) {
+		save_unicode_string(f, script_class);
+	}
+
 	for (int i = 0; i < ResourceFormatSaverBinaryInstance::RESERVED_FIELDS; i++) {
 		f->store_32(0); // reserved
 	}
@@ -2298,6 +2385,10 @@ Error ResourceFormatSaverBinaryInstance::set_uid(const String &p_path, ResourceU
 	fw->store_32(flags);
 	fw->store_64(p_uid);
 
+	if (flags & ResourceFormatSaverBinaryInstance::FORMAT_FLAG_HAS_SCRIPT_CLASS) {
+		save_ustring(fw, get_ustring(f));
+	}
+
 	//rest of file
 	uint8_t b = f->get_8();
 	while (!f->eof_reached()) {
diff --git a/core/io/resource_format_binary.h b/core/io/resource_format_binary.h
index 2e8988005f..41536491a2 100644
--- a/core/io/resource_format_binary.h
+++ b/core/io/resource_format_binary.h
@@ -65,6 +65,7 @@ class ResourceLoaderBinary {
 
 	bool using_named_scene_ids = false;
 	bool using_uids = false;
+	String script_class;
 	bool use_sub_threads = false;
 	float *progress = nullptr;
 	Vector<ExtResource> external_resources;
@@ -100,6 +101,7 @@ public:
 	void set_remaps(const HashMap<String, String> &p_remaps) { remaps = p_remaps; }
 	void open(Ref<FileAccess> p_f, bool p_no_resources = false, bool p_keep_uuid_paths = false);
 	String recognize(Ref<FileAccess> p_f);
+	String recognize_script_class(Ref<FileAccess> p_f);
 	void get_dependencies(Ref<FileAccess> p_f, List<String> *p_dependencies, bool p_add_types);
 	void get_classes_used(Ref<FileAccess> p_f, HashSet<StringName> *p_classes);
 
@@ -113,6 +115,7 @@ public:
 	virtual void get_recognized_extensions(List<String> *p_extensions) const;
 	virtual bool handles_type(const String &p_type) const;
 	virtual String get_resource_type(const String &p_path) const;
+	virtual String get_resource_script_class(const String &p_path) const;
 	virtual void get_classes_used(const String &p_path, HashSet<StringName> *r_classes);
 	virtual ResourceUID::ID get_resource_uid(const String &p_path) const;
 	virtual void get_dependencies(const String &p_path, List<String> *p_dependencies, bool p_add_types = false);
@@ -165,6 +168,7 @@ public:
 		FORMAT_FLAG_NAMED_SCENE_IDS = 1,
 		FORMAT_FLAG_UIDS = 2,
 		FORMAT_FLAG_REAL_T_IS_DOUBLE = 4,
+		FORMAT_FLAG_HAS_SCRIPT_CLASS = 8,
 
 		// Amount of reserved 32-bit fields in resource header
 		RESERVED_FIELDS = 11
diff --git a/core/io/resource_loader.cpp b/core/io/resource_loader.cpp
index 946c31cf0d..05acbf0e2e 100644
--- a/core/io/resource_loader.cpp
+++ b/core/io/resource_loader.cpp
@@ -99,6 +99,12 @@ String ResourceFormatLoader::get_resource_type(const String &p_path) const {
 	return ret;
 }
 
+String ResourceFormatLoader::get_resource_script_class(const String &p_path) const {
+	String ret;
+	GDVIRTUAL_CALL(_get_resource_script_class, p_path, ret);
+	return ret;
+}
+
 ResourceUID::ID ResourceFormatLoader::get_resource_uid(const String &p_path) const {
 	int64_t uid = ResourceUID::INVALID_ID;
 	GDVIRTUAL_CALL(_get_resource_uid, p_path, uid);
@@ -184,6 +190,7 @@ void ResourceFormatLoader::_bind_methods() {
 	GDVIRTUAL_BIND(_recognize_path, "path", "type");
 	GDVIRTUAL_BIND(_handles_type, "type");
 	GDVIRTUAL_BIND(_get_resource_type, "path");
+	GDVIRTUAL_BIND(_get_resource_script_class, "path");
 	GDVIRTUAL_BIND(_get_resource_uid, "path");
 	GDVIRTUAL_BIND(_get_dependencies, "path", "add_types");
 	GDVIRTUAL_BIND(_rename_dependencies, "path", "renames");
@@ -764,6 +771,19 @@ String ResourceLoader::get_resource_type(const String &p_path) {
 	return "";
 }
 
+String ResourceLoader::get_resource_script_class(const String &p_path) {
+	String local_path = _validate_local_path(p_path);
+
+	for (int i = 0; i < loader_count; i++) {
+		String result = loader[i]->get_resource_script_class(local_path);
+		if (!result.is_empty()) {
+			return result;
+		}
+	}
+
+	return "";
+}
+
 ResourceUID::ID ResourceLoader::get_resource_uid(const String &p_path) {
 	String local_path = _validate_local_path(p_path);
 
diff --git a/core/io/resource_loader.h b/core/io/resource_loader.h
index 41ba0dc6e6..4f308e3d65 100644
--- a/core/io/resource_loader.h
+++ b/core/io/resource_loader.h
@@ -54,6 +54,7 @@ protected:
 	GDVIRTUAL2RC(bool, _recognize_path, String, StringName)
 	GDVIRTUAL1RC(bool, _handles_type, StringName)
 	GDVIRTUAL1RC(String, _get_resource_type, String)
+	GDVIRTUAL1RC(String, _get_resource_script_class, String)
 	GDVIRTUAL1RC(ResourceUID::ID, _get_resource_uid, String)
 	GDVIRTUAL2RC(Vector<String>, _get_dependencies, String, bool)
 	GDVIRTUAL1RC(Vector<String>, _get_classes_used, String)
@@ -71,6 +72,7 @@ public:
 	virtual bool handles_type(const String &p_type) const;
 	virtual void get_classes_used(const String &p_path, HashSet<StringName> *r_classes);
 	virtual String get_resource_type(const String &p_path) const;
+	virtual String get_resource_script_class(const String &p_path) const;
 	virtual ResourceUID::ID get_resource_uid(const String &p_path) const;
 	virtual void get_dependencies(const String &p_path, List<String> *p_dependencies, bool p_add_types = false);
 	virtual Error rename_dependencies(const String &p_path, const HashMap<String, String> &p_map);
@@ -175,6 +177,7 @@ public:
 	static void remove_resource_format_loader(Ref<ResourceFormatLoader> p_format_loader);
 	static void get_classes_used(const String &p_path, HashSet<StringName> *r_classes);
 	static String get_resource_type(const String &p_path);
+	static String get_resource_script_class(const String &p_path);
 	static ResourceUID::ID get_resource_uid(const String &p_path);
 	static void get_dependencies(const String &p_path, List<String> *p_dependencies, bool p_add_types = false);
 	static Error rename_dependencies(const String &p_path, const HashMap<String, String> &p_map);