GDScript: Replace abstract keyword with @abstract annotation

Co-authored-by: Danil Alexeev <dalexeev12@yandex.ru>

modules/gdscript/tests/scripts/analyzer/errors/abstract_methods.gd

@@ -1,15 +1,15 @@
-abstract class AbstractClass:
-	abstract func some_func()
+@abstract class AbstractClass:
+	@abstract func some_func()
 
 class ImplementedClass extends AbstractClass:
 	func some_func():
 		pass
 
-abstract class AbstractClassAgain extends ImplementedClass:
-	abstract func some_func()
+@abstract class AbstractClassAgain extends ImplementedClass:
+	@abstract func some_func()
 
 class Test1:
-	abstract func some_func()
+	@abstract func some_func()
 
 class Test2 extends AbstractClass:
 	pass
@@ -24,5 +24,18 @@ class Test4 extends AbstractClass:
 	func other_func():
 		super.some_func()
 
+@abstract class A:
+	@abstract @abstract func abstract_dup()
+
+	# An abstract function cannot have a body.
+	@abstract func abstract_bodyful():
+		pass
+
+	# A static function cannot be marked as `@abstract`.
+	@abstract static func abstract_stat()
+
+@abstract @abstract class DuplicateAbstract:
+	pass
+
 func test():
 	pass

modules/gdscript/tests/scripts/analyzer/errors/abstract_methods.out

@@ -1,6 +1,11 @@
 GDTEST_ANALYZER_ERROR
->> ERROR at line 11: Class "Test1" is not abstract but contains abstract methods. Mark the class as abstract or remove "abstract" from all methods in this class.
->> ERROR at line 14: Class "Test2" must implement "AbstractClass.some_func()" and other inherited abstract methods or be marked as abstract.
->> ERROR at line 17: Class "Test3" must implement "AbstractClassAgain.some_func()" and other inherited abstract methods or be marked as abstract.
+>> ERROR at line 37: "@abstract" annotation can only be used once per class.
+>> ERROR at line 28: "@abstract" annotation can only be used once per function.
+>> ERROR at line 35: "@abstract" annotation cannot be applied to static functions.
+>> ERROR at line 11: Class "Test1" is not abstract but contains abstract methods. Mark the class as "@abstract" or remove "@abstract" from all methods in this class.
+>> ERROR at line 14: Class "Test2" must implement "AbstractClass.some_func()" and other inherited abstract methods or be marked as "@abstract".
+>> ERROR at line 17: Class "Test3" must implement "AbstractClassAgain.some_func()" and other inherited abstract methods or be marked as "@abstract".
 >> ERROR at line 22: Cannot call the parent class' abstract function "some_func()" because it hasn't been defined.
 >> ERROR at line 25: Cannot call the parent class' abstract function "some_func()" because it hasn't been defined.
+>> ERROR at line 32: Abstract function cannot have a body.
+>> ERROR at line 35: A function must either have a ":" followed by a body, or be marked as "@abstract".

modules/gdscript/tests/scripts/analyzer/errors/construct_abstract_class.gd

@@ -2,7 +2,7 @@ extends RefCounted
 
 const AbstractScript = preload("./construct_abstract_script.notest.gd")
 
-abstract class AbstractClass:
+@abstract class AbstractClass:
 	pass
 
 func test():

modules/gdscript/tests/scripts/analyzer/errors/construct_abstract_script.notest.gd

@@ -1 +1 @@
-abstract class_name AbstractScript
+@abstract class_name AbstractScript

modules/gdscript/tests/scripts/analyzer/features/extend_abstract_class.gd

@@ -8,7 +8,7 @@ class B extends A:
 class C extends CanvasItem:
 	pass
 
-abstract class X:
+@abstract class X:
 	pass
 
 class Y extends X:

modules/gdscript/tests/scripts/completion/common/override_function_abstract.gd

@@ -1,5 +1,5 @@
-abstract class A:
-	abstract func test(x: int) -> void
+@abstract class A:
+	@abstract func test(x: int) -> void
 
 class B extends A:
 	func ➡

modules/gdscript/tests/scripts/parser/errors/abstract_func_with_body.gd

@@ -1,8 +0,0 @@
-extends RefCounted
-
-abstract class A:
-	abstract func f():
-		pass
-
-func test():
-	pass

modules/gdscript/tests/scripts/parser/errors/abstract_func_with_body.out

@@ -1,2 +0,0 @@
-GDTEST_PARSER_ERROR
-Expected end of statement after abstract function declaration, found ":" instead.

modules/gdscript/tests/scripts/parser/errors/abstract_static_func.gd

@@ -1,8 +0,0 @@
-extends RefCounted
-
-abstract class A:
-	# Currently, an abstract function cannot be static.
-	abstract static func f()
-
-func test():
-	pass

modules/gdscript/tests/scripts/parser/errors/abstract_static_func.out

@@ -1,2 +0,0 @@
-GDTEST_PARSER_ERROR
-Expected "class" or "func" after "abstract".

modules/gdscript/tests/scripts/parser/errors/brace_syntax.out

@@ -1,2 +1,2 @@
 GDTEST_PARSER_ERROR
-Expected ":" after function declaration.
+Expected end of statement after bodyless function declaration, found "{" instead.

modules/gdscript/tests/scripts/parser/errors/duplicate_abstract_class.gd

@@ -1,7 +0,0 @@
-extends RefCounted
-
-abstract abstract class A:
-	pass
-
-func test():
-	pass

modules/gdscript/tests/scripts/parser/errors/duplicate_abstract_class.out

@@ -1,2 +0,0 @@
-GDTEST_PARSER_ERROR
-Expected "class_name", "extends", "class", or "func" after "abstract".

modules/gdscript/tests/scripts/parser/errors/duplicate_abstract_func.gd

@@ -1,7 +0,0 @@
-extends RefCounted
-
-abstract class A:
-	abstract abstract func f()
-
-func test():
-	pass

modules/gdscript/tests/scripts/parser/errors/duplicate_abstract_func.out

@@ -1,2 +0,0 @@
-GDTEST_PARSER_ERROR
-Expected "class" or "func" after "abstract".

modules/gdscript/tests/scripts/parser/errors/lambda_without_colon.gd

@@ -0,0 +1,3 @@
+#           No colon --v
+var f = func () -> void
+	pass

modules/gdscript/tests/scripts/parser/errors/lambda_without_colon.out

@@ -0,0 +1,2 @@
+GDTEST_PARSER_ERROR
+Expected ":" after lambda declaration.

modules/gdscript/tests/scripts/parser/errors/static_abstract_func.gd

@@ -1,8 +0,0 @@
-extends RefCounted
-
-abstract class A:
-	# Currently, an abstract function cannot be static.
-	static abstract func f()
-
-func test():
-	pass

modules/gdscript/tests/scripts/parser/errors/static_abstract_func.out

@@ -1,2 +0,0 @@
-GDTEST_PARSER_ERROR
-Expected "func" or "var" after "static".

modules/gdscript/tests/scripts/runtime/features/abstract_methods.gd

@@ -1,18 +1,18 @@
-abstract class A:
-	abstract func get_text_1() -> String
-	abstract func get_text_2() -> String
+@abstract class A:
+	@abstract func get_text_1() -> String
+	@abstract func get_text_2() -> String
 
 	# No `UNUSED_PARAMETER` warning.
-	abstract func func_with_param(param: int) -> int
-	abstract func func_with_rest_param(...args: Array) -> int
-	abstract func func_with_semicolon() -> int;
-	abstract func func_1() -> int; abstract func func_2() -> int
-	abstract func func_without_return_type()
+	@abstract func func_with_param(param: int) -> int
+	@abstract func func_with_rest_param(...args: Array) -> int
+	@abstract func func_with_semicolon() -> int;
+	@abstract func func_1() -> int; @abstract func func_2() -> int
+	@abstract func func_without_return_type()
 
 	func print_text_1() -> void:
 		print(get_text_1())
 
-abstract class B extends A:
+@abstract class B extends A:
 	func get_text_1() -> String:
 		return "text_1b"
 
@@ -30,8 +30,8 @@ class C extends B:
 	func func_2() -> int: return 0
 	func func_without_return_type(): pass
 
-abstract class D extends C:
-	abstract func get_text_1() -> String
+@abstract class D extends C:
+	@abstract func get_text_1() -> String
 
 	func get_text_2() -> String:
 		return super() + " text_2d"

modules/gdscript/tests/scripts/runtime/features/member_info_inheritance.gd

@@ -2,9 +2,9 @@
 
 @warning_ignore_start("unused_signal")
 
-abstract class A:
-	abstract func test_abstract_func_1()
-	abstract func test_abstract_func_2()
+@abstract class A:
+	@abstract func test_abstract_func_1()
+	@abstract func test_abstract_func_2()
 	func test_override_func_1(): pass
 	func test_override_func_2(): pass
 

modules/gdscript/tests/scripts/runtime/features/member_info_inheritance.out

@@ -32,8 +32,8 @@ func test_override_func_1() -> void
 func test_override_func_2() -> void
 func test_func_b1() -> void
 func test_func_b2() -> void
-abstract func test_abstract_func_1() -> void
-abstract func test_abstract_func_2() -> void
+@abstract func test_abstract_func_1() -> void
+@abstract func test_abstract_func_2() -> void
 func test_override_func_1() -> void
 func test_override_func_2() -> void
 --- C ---
@@ -53,8 +53,8 @@ func test_override_func_1() -> void
 func test_override_func_2() -> void
 func test_func_b1() -> void
 func test_func_b2() -> void
-abstract func test_abstract_func_1() -> void
-abstract func test_abstract_func_2() -> void
+@abstract func test_abstract_func_1() -> void
+@abstract func test_abstract_func_2() -> void
 func test_override_func_1() -> void
 func test_override_func_2() -> void
 === Signals ===

modules/gdscript/tests/scripts/utils.notest.gd

@@ -101,7 +101,7 @@ static func print_property_extended_info(property: Dictionary, base: Object = nu
 static func get_method_signature(method: Dictionary, is_signal: bool = false) -> String:
 	var result: String = ""
 	if method.flags & METHOD_FLAG_VIRTUAL_REQUIRED:
-		result += "abstract "
+		result += "@abstract "
 	if method.flags & METHOD_FLAG_STATIC:
 		result += "static "
 	result += ("signal " if is_signal else "func ") + method.name + "("