GDScript: Add static typing for for loop variable

modules/gdscript/tests/scripts/runtime/errors/for_loop_iterator_type_not_match_specified.gd

@@ -0,0 +1,4 @@
+func test():
+	var a: Array = [Resource.new()]
+	for node: Node in a:
+		print(node)

modules/gdscript/tests/scripts/runtime/errors/for_loop_iterator_type_not_match_specified.out

@@ -0,0 +1,6 @@
+GDTEST_RUNTIME_ERROR
+>> SCRIPT ERROR
+>> on function: test()
+>> runtime/errors/for_loop_iterator_type_not_match_specified.gd
+>> 3
+>> Trying to assign value of type 'Resource' to a variable of type 'Node'.

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

@@ -0,0 +1,34 @@
+func test():
+	print("Test range.")
+	for e: float in range(2, 5):
+		var elem := e
+		prints(var_to_str(e), var_to_str(elem))
+
+	print("Test int.")
+	for e: float in 3:
+		var elem := e
+		prints(var_to_str(e), var_to_str(elem))
+
+	print("Test untyped int array.")
+	var a1 := [10, 20, 30]
+	for e: float in a1:
+		var elem := e
+		prints(var_to_str(e), var_to_str(elem))
+
+	print("Test typed int array.")
+	var a2: Array[int] = [10, 20, 30]
+	for e: float in a2:
+		var elem := e
+		prints(var_to_str(e), var_to_str(elem))
+
+	print("Test String-keys dictionary.")
+	var d1 := {a = 1, b = 2, c = 3}
+	for k: StringName in d1:
+		var key := k
+		prints(var_to_str(k), var_to_str(key))
+
+	print("Test RefCounted-keys dictionary.")
+	var d2 := {RefCounted.new(): 1, Resource.new(): 2, ConfigFile.new(): 3}
+	for k: RefCounted in d2:
+		var key := k
+		prints(k.get_class(), key.get_class())

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

@@ -0,0 +1,25 @@
+GDTEST_OK
+Test range.
+2.0 2.0
+3.0 3.0
+4.0 4.0
+Test int.
+0.0 0.0
+1.0 1.0
+2.0 2.0
+Test untyped int array.
+10.0 10.0
+20.0 20.0
+30.0 30.0
+Test typed int array.
+10.0 10.0
+20.0 20.0
+30.0 30.0
+Test String-keys dictionary.
+&"a" &"a"
+&"b" &"b"
+&"c" &"c"
+Test RefCounted-keys dictionary.
+RefCounted RefCounted
+Resource Resource
+ConfigFile ConfigFile