[refactor] Update errorcodes.py: harmonize all of the type annotations (#19880)

This completes an in-line todo from 3 years ago relating to a weakness
that mypy no longer has (edit: I did not read carefully enough. But I
did eventually stumble upon a sufficient workaround for
mypyc/mypyc#1142), and removes code with no
downside.

Author: wyattscarpenter

mypy/errorcodes.py

@@ -52,32 +52,28 @@ def __hash__(self) -> int:
 
 ATTR_DEFINED: Final = ErrorCode("attr-defined", "Check that attribute exists", "General")
 NAME_DEFINED: Final = ErrorCode("name-defined", "Check that name is defined", "General")
-CALL_ARG: Final[ErrorCode] = ErrorCode(
+CALL_ARG: Final = ErrorCode(
     "call-arg", "Check number, names and kinds of arguments in calls", "General"
 )
 ARG_TYPE: Final = ErrorCode("arg-type", "Check argument types in calls", "General")
 CALL_OVERLOAD: Final = ErrorCode(
     "call-overload", "Check that an overload variant matches arguments", "General"
 )
-VALID_TYPE: Final[ErrorCode] = ErrorCode(
-    "valid-type", "Check that type (annotation) is valid", "General"
-)
+VALID_TYPE: Final = ErrorCode("valid-type", "Check that type (annotation) is valid", "General")
 VAR_ANNOTATED: Final = ErrorCode(
     "var-annotated", "Require variable annotation if type can't be inferred", "General"
 )
 OVERRIDE: Final = ErrorCode(
     "override", "Check that method override is compatible with base class", "General"
 )
-RETURN: Final[ErrorCode] = ErrorCode(
-    "return", "Check that function always returns a value", "General"
-)
-RETURN_VALUE: Final[ErrorCode] = ErrorCode(
+RETURN: Final = ErrorCode("return", "Check that function always returns a value", "General")
+RETURN_VALUE: Final = ErrorCode(
     "return-value", "Check that return value is compatible with signature", "General"
 )
-ASSIGNMENT: Final[ErrorCode] = ErrorCode(
+ASSIGNMENT: Final = ErrorCode(
     "assignment", "Check that assigned value is compatible with target", "General"
 )
-METHOD_ASSIGN: Final[ErrorCode] = ErrorCode(
+METHOD_ASSIGN: Final = ErrorCode(
     "method-assign",
     "Check that assignment target is not a method",
     "General",
@@ -143,9 +139,7 @@ def __hash__(self) -> int:
 UNUSED_COROUTINE: Final = ErrorCode(
     "unused-coroutine", "Ensure that all coroutines are used", "General"
 )
-# TODO: why do we need the explicit type here? Without it mypyc CI builds fail with
-# mypy/message_registry.py:37: error: Cannot determine type of "EMPTY_BODY"  [has-type]
-EMPTY_BODY: Final[ErrorCode] = ErrorCode(
+EMPTY_BODY: Final = ErrorCode(
     "empty-body",
     "A dedicated error code to opt out return errors for empty/trivial bodies",
     "General",
@@ -160,7 +154,7 @@ def __hash__(self) -> int:
     "await-not-async", 'Warn about "await" outside coroutine ("async def")', "General"
 )
 # These error codes aren't enabled by default.
-NO_UNTYPED_DEF: Final[ErrorCode] = ErrorCode(
+NO_UNTYPED_DEF: Final = ErrorCode(
     "no-untyped-def", "Check that every function has an annotation", "General"
 )
 NO_UNTYPED_CALL: Final = ErrorCode(
@@ -186,13 +180,13 @@ def __hash__(self) -> int:
 UNREACHABLE: Final = ErrorCode(
     "unreachable", "Warn about unreachable statements or expressions", "General"
 )
-ANNOTATION_UNCHECKED = ErrorCode(
+ANNOTATION_UNCHECKED: Final = ErrorCode(
     "annotation-unchecked", "Notify about type annotations in unchecked functions", "General"
 )
-TYPEDDICT_READONLY_MUTATED = ErrorCode(
+TYPEDDICT_READONLY_MUTATED: Final = ErrorCode(
     "typeddict-readonly-mutated", "TypedDict's ReadOnly key is mutated", "General"
 )
-POSSIBLY_UNDEFINED: Final[ErrorCode] = ErrorCode(
+POSSIBLY_UNDEFINED: Final = ErrorCode(
     "possibly-undefined",
     "Warn about variables that are defined only in some execution paths",
     "General",
@@ -201,18 +195,18 @@ def __hash__(self) -> int:
 REDUNDANT_EXPR: Final = ErrorCode(
     "redundant-expr", "Warn about redundant expressions", "General", default_enabled=False
 )
-TRUTHY_BOOL: Final[ErrorCode] = ErrorCode(
+TRUTHY_BOOL: Final = ErrorCode(
     "truthy-bool",
     "Warn about expressions that could always evaluate to true in boolean contexts",
     "General",
     default_enabled=False,
 )
-TRUTHY_FUNCTION: Final[ErrorCode] = ErrorCode(
+TRUTHY_FUNCTION: Final = ErrorCode(
     "truthy-function",
     "Warn about function that always evaluate to true in boolean contexts",
     "General",
 )
-TRUTHY_ITERABLE: Final[ErrorCode] = ErrorCode(
+TRUTHY_ITERABLE: Final = ErrorCode(
     "truthy-iterable",
     "Warn about Iterable expressions that could always evaluate to true in boolean contexts",
     "General",
@@ -238,13 +232,13 @@ def __hash__(self) -> int:
     "General",
     default_enabled=False,
 )
-REDUNDANT_SELF_TYPE = ErrorCode(
+REDUNDANT_SELF_TYPE: Final = ErrorCode(
     "redundant-self",
     "Warn about redundant Self type annotations on method first argument",
     "General",
     default_enabled=False,
 )
-USED_BEFORE_DEF: Final[ErrorCode] = ErrorCode(
+USED_BEFORE_DEF: Final = ErrorCode(
     "used-before-def", "Warn about variables that are used before they are defined", "General"
 )
 UNUSED_IGNORE: Final = ErrorCode(
@@ -262,7 +256,7 @@ def __hash__(self) -> int:
     "General",
     default_enabled=False,
 )
-MUTABLE_OVERRIDE: Final[ErrorCode] = ErrorCode(
+MUTABLE_OVERRIDE: Final = ErrorCode(
     "mutable-override",
     "Reject covariant overrides for mutable attributes",
     "General",
@@ -274,42 +268,41 @@ def __hash__(self) -> int:
     "General",
     default_enabled=False,
 )
-METACLASS: Final[ErrorCode] = ErrorCode("metaclass", "Ensure that metaclass is valid", "General")
+METACLASS: Final = ErrorCode("metaclass", "Ensure that metaclass is valid", "General")
 
 # Syntax errors are often blocking.
-SYNTAX: Final[ErrorCode] = ErrorCode("syntax", "Report syntax errors", "General")
+SYNTAX: Final = ErrorCode("syntax", "Report syntax errors", "General")
 
 # This is an internal marker code for a whole-file ignore. It is not intended to
 # be user-visible.
 FILE: Final = ErrorCode("file", "Internal marker for a whole file being ignored", "General")
 del error_codes[FILE.code]
 
 # This is a catch-all for remaining uncategorized errors.
-MISC: Final[ErrorCode] = ErrorCode("misc", "Miscellaneous other checks", "General")
+MISC: Final = ErrorCode("misc", "Miscellaneous other checks", "General")
 
-OVERLOAD_CANNOT_MATCH: Final[ErrorCode] = ErrorCode(
+OVERLOAD_CANNOT_MATCH: Final = ErrorCode(
     "overload-cannot-match",
     "Warn if an @overload signature can never be matched",
     "General",
     sub_code_of=MISC,
 )
 
-
-OVERLOAD_OVERLAP: Final[ErrorCode] = ErrorCode(
+OVERLOAD_OVERLAP: Final = ErrorCode(
     "overload-overlap",
     "Warn if multiple @overload variants overlap in unsafe ways",
     "General",
     sub_code_of=MISC,
 )
 
-PROPERTY_DECORATOR = ErrorCode(
+PROPERTY_DECORATOR: Final = ErrorCode(
     "prop-decorator",
     "Decorators on top of @property are not supported",
     "General",
     sub_code_of=MISC,
 )
 
-NARROWED_TYPE_NOT_SUBTYPE: Final[ErrorCode] = ErrorCode(
+NARROWED_TYPE_NOT_SUBTYPE: Final = ErrorCode(
     "narrowed-type-not-subtype",
     "Warn if a TypeIs function's narrowed type is not a subtype of the original type",
     "General",

mypy/message_registry.py

@@ -11,11 +11,12 @@
 from typing import Final, NamedTuple
 
 from mypy import errorcodes as codes
+from mypy.errorcodes import ErrorCode
 
 
 class ErrorMessage(NamedTuple):
     value: str
-    code: codes.ErrorCode | None = None
+    code: ErrorCode | None = None
 
     def format(self, *args: object, **kwargs: object) -> ErrorMessage:
         return ErrorMessage(self.value.format(*args, **kwargs), code=self.code)