Consistently use type-abstract error code (#14619)

Ref #4717

Although function use case is much more important, the variable
assignment should use the same error code, otherwise this may cause
confusion.

Author: ilevkivskyi

mypy/errors.py

@@ -24,7 +24,7 @@
 
 # Keep track of the original error code when the error code of a message is changed.
 # This is used to give notes about out-of-date "type: ignore" comments.
-original_error_codes: Final = {codes.LITERAL_REQ: codes.MISC}
+original_error_codes: Final = {codes.LITERAL_REQ: codes.MISC, codes.TYPE_ABSTRACT: codes.MISC}
 
 
 class ErrorInfo:

mypy/messages.py

@@ -1787,7 +1787,9 @@ def bad_proto_variance(
 
     def concrete_only_assign(self, typ: Type, context: Context) -> None:
         self.fail(
-            f"Can only assign concrete classes to a variable of type {format_type(typ)}", context
+            f"Can only assign concrete classes to a variable of type {format_type(typ)}",
+            context,
+            code=codes.TYPE_ABSTRACT,
         )
 
     def concrete_only_call(self, typ: Type, context: Context) -> None:

test-data/unit/check-errorcodes.test

@@ -998,6 +998,11 @@ T = TypeVar("T")
 def test(tp: Type[T]) -> T: ...
 test(C)  # E: Only concrete class can be given where "Type[C]" is expected  [type-abstract]
 
+class D(C):
+    @abc.abstractmethod
+    def bar(self) -> None: ...
+cls: Type[C] = D  # E: Can only assign concrete classes to a variable of type "Type[C]"  [type-abstract]
+
 [case testUncheckedAnnotationCodeShown]
 def f():
     x: int = "no"  # N: By default the bodies of untyped functions are not checked, consider using --check-untyped-defs  [annotation-unchecked]