Merge branch 'master' into bugfix/st-synthetic-named-expr-in-match

Author: sterliakov

.github/workflows/mypy_primer.yml

@@ -28,7 +28,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        shard-index: [0, 1, 2, 3, 4]
+        shard-index: [0, 1, 2, 3, 4, 5]
       fail-fast: false
     timeout-minutes: 60
     steps:
@@ -63,7 +63,7 @@ jobs:
             mypy_primer \
             --repo mypy_to_test \
             --new $GITHUB_SHA --old base_commit \
-            --num-shards 5 --shard-index ${{ matrix.shard-index }} \
+            --num-shards 6 --shard-index ${{ matrix.shard-index }} \
             --debug \
             --additional-flags="--debug-serialize" \
             --output concise \

docs/source/error_code_list.rst

@@ -215,6 +215,35 @@ You can use :py:class:`~collections.abc.Callable` as the type for callable objec
         for x in objs:
             f(x)
 
+.. _code-metaclass:
+
+Check the validity of a class's metaclass [metaclass]
+-----------------------------------------------------
+
+Mypy checks whether the metaclass of a class is valid. The metaclass
+must be a subclass of ``type``. Further, the class hierarchy must yield
+a consistent metaclass. For more details, see the
+`Python documentation <https://docs.python.org/3.13/reference/datamodel.html#determining-the-appropriate-metaclass>`_
+
+Note that mypy's metaclass checking is limited and may produce false-positives.
+See also :ref:`limitations`.
+
+Example with an error:
+
+.. code-block:: python
+
+    class GoodMeta(type):
+        pass
+
+    class BadMeta:
+        pass
+
+    class A1(metaclass=GoodMeta):  # OK
+        pass
+
+    class A2(metaclass=BadMeta):  # Error:  Metaclasses not inheriting from "type" are not supported  [metaclass]
+        pass
+
 .. _code-var-annotated:
 
 Require annotation if variable type is unclear [var-annotated]

docs/source/metaclasses.rst

@@ -90,3 +90,28 @@ so it's better not to combine metaclasses and class hierarchies:
 * ``Self`` is not allowed as annotation in metaclasses as per `PEP 673`_.
 
 .. _PEP 673: https://peps.python.org/pep-0673/#valid-locations-for-self
+
+For some builtin types, mypy may think their metaclass is :py:class:`abc.ABCMeta`
+even if it is :py:class:`type` at runtime. In those cases, you can either:
+
+* use :py:class:`abc.ABCMeta` instead of :py:class:`type` as the
+  superclass of your metaclass if that works in your use-case
+* mute the error with ``# type: ignore[metaclass]``
+
+.. code-block:: python
+
+    import abc
+
+    assert type(tuple) is type  # metaclass of tuple is type at runtime
+
+    # The problem:
+    class M0(type): pass
+    class A0(tuple, metaclass=M0): pass  # Mypy Error: metaclass conflict
+
+    # Option 1: use ABCMeta instead of type
+    class M1(abc.ABCMeta): pass
+    class A1(tuple, metaclass=M1): pass
+
+    # Option 2: mute the error
+    class M2(type): pass
+    class A2(tuple, metaclass=M2): pass  # type: ignore[metaclass]

misc/profile_self_check.py renamed to misc/profile_check.py

@@ -1,4 +1,6 @@
-"""Compile mypy using mypyc and profile self-check using perf.
+"""Compile mypy using mypyc and profile type checking using perf.
+
+By default does a self check.
 
 Notes:
  - Only Linux is supported for now (TODO: add support for other profilers)
@@ -23,6 +25,8 @@
       CFLAGS="-O2 -g -fno-omit-frame-pointer"
 """
 
+from __future__ import annotations
+
 import argparse
 import glob
 import os
@@ -41,24 +45,28 @@
 TARGET_DIR = "mypy.profile.tmpdir"
 
 
-def _profile_self_check(target_dir: str) -> None:
+def _profile_type_check(target_dir: str, code: str | None) -> None:
     cache_dir = os.path.join(target_dir, ".mypy_cache")
     if os.path.exists(cache_dir):
         shutil.rmtree(cache_dir)
-    files = []
-    for pat in "mypy/*.py", "mypy/*/*.py", "mypyc/*.py", "mypyc/test/*.py":
-        files.extend(glob.glob(pat))
-    self_check_cmd = ["python", "-m", "mypy", "--config-file", "mypy_self_check.ini"] + files
-    cmdline = ["perf", "record", "-g"] + self_check_cmd
+    args = []
+    if code is None:
+        args.extend(["--config-file", "mypy_self_check.ini"])
+        for pat in "mypy/*.py", "mypy/*/*.py", "mypyc/*.py", "mypyc/test/*.py":
+            args.extend(glob.glob(pat))
+    else:
+        args.extend(["-c", code])
+    check_cmd = ["python", "-m", "mypy"] + args
+    cmdline = ["perf", "record", "-g"] + check_cmd
     t0 = time.time()
     subprocess.run(cmdline, cwd=target_dir, check=True)
     elapsed = time.time() - t0
     print(f"{elapsed:.2f}s elapsed")
 
 
-def profile_self_check(target_dir: str) -> None:
+def profile_type_check(target_dir: str, code: str | None) -> None:
     try:
-        _profile_self_check(target_dir)
+        _profile_type_check(target_dir, code)
     except subprocess.CalledProcessError:
         print("\nProfiling failed! You may missing some permissions.")
         print("\nThis may help (note that it has security implications):")
@@ -92,7 +100,7 @@ def main() -> None:
     check_requirements()
 
     parser = argparse.ArgumentParser(
-        description="Compile mypy and profile self checking using 'perf'."
+        description="Compile mypy and profile type checking using 'perf' (by default, self check)."
     )
     parser.add_argument(
         "--multi-file",
@@ -102,9 +110,17 @@ def main() -> None:
     parser.add_argument(
         "--skip-compile", action="store_true", help="use compiled mypy from previous run"
     )
+    parser.add_argument(
+        "-c",
+        metavar="CODE",
+        default=None,
+        type=str,
+        help="profile type checking Python code fragment instead of mypy self-check",
+    )
     args = parser.parse_args()
     multi_file: bool = args.multi_file
     skip_compile: bool = args.skip_compile
+    code: str | None = args.c
 
     target_dir = TARGET_DIR
 
@@ -116,7 +132,7 @@ def main() -> None:
     elif not os.path.isdir(target_dir):
         sys.exit("error: Can't find compile mypy from previous run -- can't use --skip-compile")
 
-    profile_self_check(target_dir)
+    profile_type_check(target_dir, code)
 
     print()
     print('NOTE: Compile CPython using CFLAGS="-O2 -g -fno-omit-frame-pointer" for good results')

mypy/checker.py

@@ -623,7 +623,7 @@ def accept_loop(
                     if on_enter_body is not None:
                         on_enter_body()
 
-                    with IterationErrorWatcher(self.msg.errors, iter_errors) as watcher:
+                    with IterationErrorWatcher(self.msg.errors, iter_errors):
                         self.accept(body)
 
                 partials_new = sum(len(pts.map) for pts in self.partial_types)
@@ -646,10 +646,7 @@ def accept_loop(
                 if iter == 20:
                     raise RuntimeError("Too many iterations when checking a loop")
 
-            for error_info in watcher.yield_error_infos():
-                self.msg.fail(*error_info[:2], code=error_info[2])
-            for note_info in watcher.yield_note_infos(self.options):
-                self.note(*note_info)
+            self.msg.iteration_dependent_errors(iter_errors)
 
             # If exit_condition is set, assume it must be False on exit from the loop:
             if exit_condition:
@@ -2964,7 +2961,11 @@ def check_metaclass_compatibility(self, typ: TypeInfo) -> None:
                 "Metaclass conflict: the metaclass of a derived class must be "
                 "a (non-strict) subclass of the metaclasses of all its bases",
                 typ,
+                code=codes.METACLASS,
             )
+            explanation = typ.explain_metaclass_conflict()
+            if explanation:
+                self.note(explanation, typ, code=codes.METACLASS)
 
     def visit_import_from(self, node: ImportFrom) -> None:
         for name, _ in node.names:
@@ -3042,7 +3043,7 @@ def is_noop_for_reachability(self, s: Statement) -> bool:
             if isinstance(s.expr, EllipsisExpr):
                 return True
             elif isinstance(s.expr, CallExpr):
-                with self.expr_checker.msg.filter_errors():
+                with self.expr_checker.msg.filter_errors(filter_revealed_type=True):
                     typ = get_proper_type(
                         self.expr_checker.accept(
                             s.expr, allow_none_return=True, always_allow_any=True
@@ -3142,7 +3143,7 @@ def check_assignment(
                         else:
                             self.check_getattr_method(signature, lvalue, name)
 
-                if name == "__slots__":
+                if name == "__slots__" and self.scope.active_class() is not None:
                     typ = lvalue_type or self.expr_checker.accept(rvalue)
                     self.check_slots_definition(typ, lvalue)
                 if name == "__match_args__" and inferred is not None:
@@ -3321,6 +3322,12 @@ def get_variable_type_context(self, inferred: Var, rvalue: Expression) -> Type |
                     type_contexts.append(base_type)
         # Use most derived supertype as type context if available.
         if not type_contexts:
+            if inferred.name == "__slots__" and self.scope.active_class() is not None:
+                str_type = self.named_type("builtins.str")
+                return self.named_generic_type("typing.Iterable", [str_type])
+            if inferred.name == "__all__" and self.scope.is_top_level():
+                str_type = self.named_type("builtins.str")
+                return self.named_generic_type("typing.Sequence", [str_type])
             return None
         candidate = type_contexts[0]
         for other in type_contexts:
@@ -4970,7 +4977,7 @@ def visit_try_stmt(self, s: TryStmt) -> None:
             if s.finally_body:
                 # First we check finally_body is type safe on all abnormal exit paths
                 iter_errors = IterationDependentErrors()
-                with IterationErrorWatcher(self.msg.errors, iter_errors) as watcher:
+                with IterationErrorWatcher(self.msg.errors, iter_errors):
                     self.accept(s.finally_body)
 
         if s.finally_body:
@@ -4987,13 +4994,9 @@ def visit_try_stmt(self, s: TryStmt) -> None:
             # that follows the try statement.)
             assert iter_errors is not None
             if not self.binder.is_unreachable():
-                with IterationErrorWatcher(self.msg.errors, iter_errors) as watcher:
+                with IterationErrorWatcher(self.msg.errors, iter_errors):
                     self.accept(s.finally_body)
-
-            for error_info in watcher.yield_error_infos():
-                self.msg.fail(*error_info[:2], code=error_info[2])
-            for note_info in watcher.yield_note_infos(self.options):
-                self.msg.note(*note_info)
+            self.msg.iteration_dependent_errors(iter_errors)
 
     def visit_try_without_finally(self, s: TryStmt, try_frame: bool) -> None:
         """Type check a try statement, ignoring the finally block.
@@ -7303,7 +7306,7 @@ def named_type(self, name: str) -> Instance:
         if isinstance(node, TypeAlias):
             assert isinstance(node.target, Instance)  # type: ignore[misc]
             node = node.target.type
-        assert isinstance(node, TypeInfo)
+        assert isinstance(node, TypeInfo), node
         any_type = AnyType(TypeOfAny.from_omitted_generics)
         return Instance(node, [any_type] * len(node.defn.type_vars))
 
@@ -7322,7 +7325,7 @@ def lookup_typeinfo(self, fullname: str) -> TypeInfo:
         # Assume that the name refers to a class.
         sym = self.lookup_qualified(fullname)
         node = sym.node
-        assert isinstance(node, TypeInfo)
+        assert isinstance(node, TypeInfo), node
         return node
 
     def type_type(self) -> Instance:
@@ -7913,6 +7916,9 @@ def has_valid_attribute(self, typ: Type, name: str) -> bool:
     def get_expression_type(self, node: Expression, type_context: Type | None = None) -> Type:
         return self.expr_checker.accept(node, type_context=type_context)
 
+    def is_defined_in_stub(self, typ: Instance, /) -> bool:
+        return self.modules[typ.type.module_name].is_stub
+
     def check_deprecated(self, node: Node | None, context: Context) -> None:
         """Warn if deprecated and not directly imported with a `from` statement."""
         if isinstance(node, Decorator):

mypy/checker_shared.py

@@ -277,6 +277,10 @@ def checking_await_set(self) -> Iterator[None]:
     def get_precise_awaitable_type(self, typ: Type, local_errors: ErrorWatcher) -> Type | None:
         raise NotImplementedError
 
+    @abstractmethod
+    def is_defined_in_stub(self, typ: Instance, /) -> bool:
+        raise NotImplementedError
+
 
 class CheckerScope:
     # We keep two stacks combined, to maintain the relative order
@@ -334,6 +338,10 @@ def current_self_type(self) -> Instance | TupleType | None:
                 return fill_typevars(item)
         return None
 
+    def is_top_level(self) -> bool:
+        """Is current scope top-level (no classes or functions)?"""
+        return len(self.stack) == 1
+
     @contextmanager
     def push_function(self, item: FuncItem) -> Iterator[None]:
         self.stack.append(item)

mypy/checkexpr.py

@@ -2684,9 +2684,12 @@ def check_arg(
                 context=context,
                 outer_context=outer_context,
             )
-            self.msg.incompatible_argument_note(
-                original_caller_type, callee_type, context, parent_error=error
-            )
+            if not caller_kind.is_star():
+                # For *args and **kwargs this note would be incorrect - we're comparing
+                # iterable/mapping type with union of relevant arg types.
+                self.msg.incompatible_argument_note(
+                    original_caller_type, callee_type, context, parent_error=error
+                )
             if not self.msg.prefer_simple_messages():
                 self.chk.check_possible_missing_await(
                     caller_type, callee_type, context, error.code

mypy/checkmember.py

@@ -1477,23 +1477,18 @@ def bind_self_fast(method: F, original_type: Type | None = None) -> F:
         items = [bind_self_fast(c, original_type) for c in method.items]
         return cast(F, Overloaded(items))
     assert isinstance(method, CallableType)
-    func: CallableType = method
-    if not func.arg_types:
+    if not method.arg_types:
         # Invalid method, return something.
         return method
-    if func.arg_kinds[0] in (ARG_STAR, ARG_STAR2):
+    if method.arg_kinds[0] in (ARG_STAR, ARG_STAR2):
         # See typeops.py for details.
         return method
-    original_type = get_proper_type(original_type)
-    if isinstance(original_type, CallableType) and original_type.is_type_obj():
-        original_type = TypeType.make_normalized(original_type.ret_type)
-    res = func.copy_modified(
-        arg_types=func.arg_types[1:],
-        arg_kinds=func.arg_kinds[1:],
-        arg_names=func.arg_names[1:],
+    return method.copy_modified(
+        arg_types=method.arg_types[1:],
+        arg_kinds=method.arg_kinds[1:],
+        arg_names=method.arg_names[1:],
         is_bound=True,
     )
-    return cast(F, res)
 
 
 def has_operator(typ: Type, op_method: str, named_type: Callable[[str], Instance]) -> bool:

mypy/checkpattern.py

@@ -796,9 +796,9 @@ def get_var(expr: Expression) -> Var:
     Warning: this in only true for expressions captured by a match statement.
     Don't call it from anywhere else
     """
-    assert isinstance(expr, NameExpr)
+    assert isinstance(expr, NameExpr), expr
     node = expr.node
-    assert isinstance(node, Var)
+    assert isinstance(node, Var), node
     return node
 
 

mypy/errorcodes.py

@@ -270,6 +270,7 @@ def __hash__(self) -> int:
     "General",
     default_enabled=False,
 )
+METACLASS: Final[ErrorCode] = ErrorCode("metaclass", "Ensure that metaclass is valid", "General")
 
 # Syntax errors are often blocking.
 SYNTAX: Final[ErrorCode] = ErrorCode("syntax", "Report syntax errors", "General")