Merge branch 'master' into patch-3

Author: BobTheBuidler

mypy/checker.py

@@ -2338,10 +2338,10 @@ def apply_inferred_arguments(
         # Report error if some of the variables could not be solved. In that
         # case assume that all variables have type Any to avoid extra
         # bogus error messages.
-        for i, inferred_type in enumerate(inferred_args):
+        for inferred_type, tv in zip(inferred_args, callee_type.variables):
             if not inferred_type or has_erased_component(inferred_type):
                 # Could not infer a non-trivial type for a type variable.
-                self.msg.could_not_infer_type_arguments(callee_type, i + 1, context)
+                self.msg.could_not_infer_type_arguments(callee_type, tv, context)
                 inferred_args = [AnyType(TypeOfAny.from_error)] * len(inferred_args)
         # Apply the inferred types to the function type. In this case the
         # return type must be CallableType, since we give the right number of type

mypy/checkexpr.py

@@ -45,7 +45,6 @@
     freeze_all_type_vars,
     function_type,
     get_all_type_vars,
-    get_type_vars,
     make_simplified_union,
     supported_self_type,
     tuple_fallback,
@@ -371,8 +370,6 @@ def analyze_instance_member_access(
                     signature, mx.self_type, method.is_class, mx.context, name, mx.msg
                 )
                 signature = bind_self(signature, mx.self_type, is_classmethod=method.is_class)
-        # TODO: should we skip these steps for static methods as well?
-        # Since generic static methods should not be allowed.
         typ = map_instance_to_supertype(typ, method.info)
         member_type = expand_type_by_instance(signature, typ)
         freeze_all_type_vars(member_type)
@@ -1198,34 +1195,42 @@ def analyze_class_attribute_access(
 
         if isinstance(node.node, Var):
             assert isuper is not None
+            object_type = get_proper_type(mx.self_type)
             # Check if original variable type has type variables. For example:
             #     class C(Generic[T]):
             #         x: T
             #     C.x  # Error, ambiguous access
             #     C[int].x  # Also an error, since C[int] is same as C at runtime
             # Exception is Self type wrapped in ClassVar, that is safe.
+            prohibit_self = not node.node.is_classvar
             def_vars = set(node.node.info.defn.type_vars)
-            if not node.node.is_classvar and node.node.info.self_type:
+            if prohibit_self and node.node.info.self_type:
                 def_vars.add(node.node.info.self_type)
-            # TODO: should we include ParamSpec etc. here (i.e. use get_all_type_vars)?
-            typ_vars = set(get_type_vars(t))
-            if def_vars & typ_vars:
-                # Exception: access on Type[...], including first argument of class methods is OK.
-                if not isinstance(get_proper_type(mx.original_type), TypeType) or node.implicit:
-                    if node.node.is_classvar:
-                        message = message_registry.GENERIC_CLASS_VAR_ACCESS
-                    else:
-                        message = message_registry.GENERIC_INSTANCE_VAR_CLASS_ACCESS
-                    mx.fail(message)
+            # Exception: access on Type[...], including first argument of class methods is OK.
+            prohibit_generic = not isinstance(object_type, TypeType) or node.implicit
+            if prohibit_generic and def_vars & set(get_all_type_vars(t)):
+                if node.node.is_classvar:
+                    message = message_registry.GENERIC_CLASS_VAR_ACCESS
+                else:
+                    message = message_registry.GENERIC_INSTANCE_VAR_CLASS_ACCESS
+                mx.fail(message)
             t = expand_self_type_if_needed(t, mx, node.node, itype, is_class=True)
+            t = expand_type_by_instance(t, isuper)
             # Erase non-mapped variables, but keep mapped ones, even if there is an error.
             # In the above example this means that we infer following types:
             #     C.x -> Any
             #     C[int].x -> int
-            t = erase_typevars(expand_type_by_instance(t, isuper), {tv.id for tv in def_vars})
-
-        is_classmethod = (is_decorated and cast(Decorator, node.node).func.is_class) or (
-            isinstance(node.node, SYMBOL_FUNCBASE_TYPES) and node.node.is_class
+            if prohibit_generic:
+                erase_vars = set(itype.type.defn.type_vars)
+                if prohibit_self and itype.type.self_type:
+                    erase_vars.add(itype.type.self_type)
+                t = erase_typevars(t, {tv.id for tv in erase_vars})
+
+        is_classmethod = (
+            (is_decorated and cast(Decorator, node.node).func.is_class)
+            or (isinstance(node.node, SYMBOL_FUNCBASE_TYPES) and node.node.is_class)
+            or isinstance(node.node, Var)
+            and node.node.is_classmethod
         )
         is_staticmethod = (is_decorated and cast(Decorator, node.node).func.is_static) or (
             isinstance(node.node, SYMBOL_FUNCBASE_TYPES) and node.node.is_static
@@ -1237,7 +1242,12 @@ def analyze_class_attribute_access(
             is_trivial_self = node.node.func.is_trivial_self and not node.node.decorators
         elif isinstance(node.node, (FuncDef, OverloadedFuncDef)):
             is_trivial_self = node.node.is_trivial_self
-        if isinstance(t, FunctionLike) and is_classmethod and not is_trivial_self:
+        if (
+            isinstance(t, FunctionLike)
+            and is_classmethod
+            and not is_trivial_self
+            and not t.bound()
+        ):
             t = check_self_arg(t, mx.self_type, False, mx.context, name, mx.msg)
         t = add_class_tvars(
             t,
@@ -1406,7 +1416,7 @@ class B(A[str]): pass
         tvars = original_vars if original_vars is not None else []
         if not mx.preserve_type_var_ids:
             t = freshen_all_functions_type_vars(t)
-        if is_classmethod:
+        if is_classmethod and not t.is_bound:
             if is_trivial_self:
                 t = bind_self_fast(t, mx.self_type)
             else:

mypy/checkmember.py

@@ -1335,6 +1335,11 @@ def visit_tuple_type(self, template: TupleType) -> list[Constraint]:
                     res.extend(
                         infer_constraints(template_items[i], actual_items[i], self.direction)
                     )
+            res.extend(
+                infer_constraints(
+                    template.partial_fallback, actual.partial_fallback, self.direction
+                )
+            )
             return res
         elif isinstance(actual, AnyType):
             return self.infer_against_any(template.items, actual)

mypy/constraints.py

@@ -4,13 +4,15 @@
 import sys
 import traceback
 from collections import defaultdict
-from collections.abc import Iterable
+from collections.abc import Iterable, Iterator
+from itertools import chain
 from typing import Callable, Final, NoReturn, Optional, TextIO, TypeVar
 from typing_extensions import Literal, Self, TypeAlias as _TypeAlias
 
 from mypy import errorcodes as codes
 from mypy.error_formatter import ErrorFormatter
 from mypy.errorcodes import IMPORT, IMPORT_NOT_FOUND, IMPORT_UNTYPED, ErrorCode, mypy_error_codes
+from mypy.nodes import Context
 from mypy.options import Options
 from mypy.scope import Scope
 from mypy.util import DEFAULT_SOURCE_OFFSET, is_typeshed_file
@@ -219,23 +221,43 @@ def filtered_errors(self) -> list[ErrorInfo]:
         return self._filtered
 
 
-class LoopErrorWatcher(ErrorWatcher):
-    """Error watcher that filters and separately collects `unreachable` errors,
-    `redundant-expr` and `redundant-casts` errors, and revealed types when analysing
-    loops iteratively to help avoid making too-hasty reports."""
+class IterationDependentErrors:
+    """An `IterationDependentErrors` instance serves to collect the `unreachable`,
+    `redundant-expr`, and `redundant-casts` errors, as well as the revealed types,
+    handled by the individual `IterationErrorWatcher` instances sequentially applied to
+    the same code section."""
 
-    # Meaning of the tuple items: ErrorCode, message, line, column, end_line, end_column:
-    uselessness_errors: set[tuple[ErrorCode, str, int, int, int, int]]
+    # One set of `unreachable`, `redundant-expr`, and `redundant-casts` errors per
+    # iteration step.  Meaning of the tuple items: ErrorCode, message, line, column,
+    # end_line, end_column.
+    uselessness_errors: list[set[tuple[ErrorCode, str, int, int, int, int]]]
 
-    # Meaning of the tuple items: function_or_member, line, column, end_line, end_column:
+    # One set of unreachable line numbers per iteration step.  Not only the lines where
+    # the error report occurs but really all unreachable lines.
+    unreachable_lines: list[set[int]]
+
+    # One set of revealed types for each `reveal_type` statement.  Each created set can
+    # grow during the iteration.  Meaning of the tuple items: function_or_member, line,
+    # column, end_line, end_column:
     revealed_types: dict[tuple[str | None, int, int, int, int], set[str]]
 
-    # Not only the lines where the error report occurs but really all unreachable lines:
-    unreachable_lines: set[int]
+    def __init__(self) -> None:
+        self.uselessness_errors = []
+        self.unreachable_lines = []
+        self.revealed_types = defaultdict(set)
+
+
+class IterationErrorWatcher(ErrorWatcher):
+    """Error watcher that filters and separately collects `unreachable` errors,
+    `redundant-expr` and `redundant-casts` errors, and revealed types when analysing
+    code sections iteratively to help avoid making too-hasty reports."""
+
+    iteration_dependent_errors: IterationDependentErrors
 
     def __init__(
         self,
         errors: Errors,
+        iteration_dependent_errors: IterationDependentErrors,
         *,
         filter_errors: bool | Callable[[str, ErrorInfo], bool] = False,
         save_filtered_errors: bool = False,
@@ -247,31 +269,71 @@ def __init__(
             save_filtered_errors=save_filtered_errors,
             filter_deprecated=filter_deprecated,
         )
-        self.uselessness_errors = set()
-        self.unreachable_lines = set()
-        self.revealed_types = defaultdict(set)
+        self.iteration_dependent_errors = iteration_dependent_errors
+        iteration_dependent_errors.uselessness_errors.append(set())
+        iteration_dependent_errors.unreachable_lines.append(set())
 
     def on_error(self, file: str, info: ErrorInfo) -> bool:
+        """Filter out the "iteration-dependent" errors and notes and store their
+        information to handle them after iteration is completed."""
+
+        iter_errors = self.iteration_dependent_errors
 
         if info.code in (codes.UNREACHABLE, codes.REDUNDANT_EXPR, codes.REDUNDANT_CAST):
-            self.uselessness_errors.add(
+            iter_errors.uselessness_errors[-1].add(
                 (info.code, info.message, info.line, info.column, info.end_line, info.end_column)
             )
             if info.code == codes.UNREACHABLE:
-                self.unreachable_lines.update(range(info.line, info.end_line + 1))
+                iter_errors.unreachable_lines[-1].update(range(info.line, info.end_line + 1))
             return True
 
         if info.code == codes.MISC and info.message.startswith("Revealed type is "):
             key = info.function_or_member, info.line, info.column, info.end_line, info.end_column
             types = info.message.split('"')[1]
             if types.startswith("Union["):
-                self.revealed_types[key].update(types[6:-1].split(", "))
+                iter_errors.revealed_types[key].update(types[6:-1].split(", "))
             else:
-                self.revealed_types[key].add(types)
+                iter_errors.revealed_types[key].add(types)
             return True
 
         return super().on_error(file, info)
 
+    def yield_error_infos(self) -> Iterator[tuple[str, Context, ErrorCode]]:
+        """Report only those `unreachable`, `redundant-expr`, and `redundant-casts`
+        errors that could not be ruled out in any iteration step."""
+
+        persistent_uselessness_errors = set()
+        iter_errors = self.iteration_dependent_errors
+        for candidate in set(chain(*iter_errors.uselessness_errors)):
+            if all(
+                (candidate in errors) or (candidate[2] in lines)
+                for errors, lines in zip(
+                    iter_errors.uselessness_errors, iter_errors.unreachable_lines
+                )
+            ):
+                persistent_uselessness_errors.add(candidate)
+        for error_info in persistent_uselessness_errors:
+            context = Context(line=error_info[2], column=error_info[3])
+            context.end_line = error_info[4]
+            context.end_column = error_info[5]
+            yield error_info[1], context, error_info[0]
+
+    def yield_note_infos(self, options: Options) -> Iterator[tuple[str, Context]]:
+        """Yield all types revealed in at least one iteration step."""
+
+        for note_info, types in self.iteration_dependent_errors.revealed_types.items():
+            sorted_ = sorted(types, key=lambda typ: typ.lower())
+            if len(types) == 1:
+                revealed = sorted_[0]
+            elif options.use_or_syntax():
+                revealed = " | ".join(sorted_)
+            else:
+                revealed = f"Union[{', '.join(sorted_)}]"
+            context = Context(line=note_info[1], column=note_info[2])
+            context.end_line = note_info[3]
+            context.end_column = note_info[4]
+            yield f'Revealed type is "{revealed}"', context
+
 
 class Errors:
     """Container for compile errors.
@@ -786,6 +848,8 @@ def generate_unused_ignore_errors(self, file: str) -> None:
                 code=codes.UNUSED_IGNORE,
                 blocker=False,
                 only_once=False,
+                origin=(self.file, [line]),
+                target=self.target_module,
             )
             self._add_error_info(file, info)
 
@@ -837,6 +901,8 @@ def generate_ignore_without_code_errors(
                 code=codes.IGNORE_WITHOUT_CODE,
                 blocker=False,
                 only_once=False,
+                origin=(self.file, [line]),
+                target=self.target_module,
             )
             self._add_error_info(file, info)
 

mypy/errors.py

@@ -253,7 +253,6 @@ def with_additional_msg(self, info: str) -> ErrorMessage:
     'Cannot override class variable (previously declared on base class "{}") with instance '
     "variable"
 )
-CLASS_VAR_WITH_TYPEVARS: Final = "ClassVar cannot contain type variables"
 CLASS_VAR_WITH_GENERIC_SELF: Final = "ClassVar cannot contain Self type in generic classes"
 CLASS_VAR_OUTSIDE_OF_CLASS: Final = "ClassVar can only be used for assignments in class body"
 
@@ -353,6 +352,10 @@ def with_additional_msg(self, info: str) -> ErrorMessage:
     "TypeVar constraint type cannot be parametrized by type variables", codes.MISC
 )
 
+TYPE_VAR_REDECLARED_IN_NESTED_CLASS: Final = ErrorMessage(
+    'Type variable "{}" is bound by an outer class', codes.VALID_TYPE
+)
+
 TYPE_ALIAS_WITH_YIELD_EXPRESSION: Final = ErrorMessage(
     "Yield expression cannot be used within a type alias", codes.SYNTAX
 )

mypy/message_registry.py

@@ -1370,11 +1370,14 @@ def incompatible_type_application(
             self.fail(f"Type application has too few types ({s})", context)
 
     def could_not_infer_type_arguments(
-        self, callee_type: CallableType, n: int, context: Context
+        self, callee_type: CallableType, tv: TypeVarLikeType, context: Context
     ) -> None:
         callee_name = callable_name(callee_type)
-        if callee_name is not None and n > 0:
-            self.fail(f"Cannot infer type argument {n} of {callee_name}", context)
+        if callee_name is not None:
+            self.fail(
+                f"Cannot infer value of type parameter {format_type(tv, self.options)} of {callee_name}",
+                context,
+            )
             if callee_name == "<dict>":
                 # Invariance in key type causes more of these errors than we would want.
                 self.note(

mypy/messages.py

@@ -508,6 +508,8 @@ def __init__(self) -> None:
         self.info = FUNC_NO_INFO
         self.is_property = False
         self.is_class = False
+        # Is this a `@staticmethod` (explicit or implicit)?
+        # Note: use has_self_or_cls_argument to check if there is `self` or `cls` argument
         self.is_static = False
         self.is_final = False
         self.is_explicit_override = False
@@ -524,6 +526,15 @@ def name(self) -> str:
     def fullname(self) -> str:
         return self._fullname
 
+    @property
+    def has_self_or_cls_argument(self) -> bool:
+        """If used as a method, does it have an argument for method binding (`self`, `cls`)?
+
+        This is true for `__new__` even though `__new__` does not undergo method binding,
+        because we still usually assume that `cls` corresponds to the enclosing class.
+        """
+        return not self.is_static or self.name == "__new__"
+
 
 OverloadPart: _TypeAlias = Union["FuncDef", "Decorator"]
 
@@ -3371,15 +3382,25 @@ def calculate_metaclass_type(self) -> mypy.types.Instance | None:
             return declared
         if self._fullname == "builtins.type":
             return mypy.types.Instance(self, [])
-        candidates = [
-            s.declared_metaclass
-            for s in self.mro
-            if s.declared_metaclass is not None and s.declared_metaclass.type is not None
-        ]
-        for c in candidates:
-            if all(other.type in c.type.mro for other in candidates):
-                return c
-        return None
+
+        winner = declared
+        for super_class in self.mro[1:]:
+            super_meta = super_class.declared_metaclass
+            if super_meta is None or super_meta.type is None:
+                continue
+            if winner is None:
+                winner = super_meta
+                continue
+            if winner.type.has_base(super_meta.type.fullname):
+                continue
+            if super_meta.type.has_base(winner.type.fullname):
+                winner = super_meta
+                continue
+            # metaclass conflict
+            winner = None
+            break
+
+        return winner
 
     def is_metaclass(self, *, precise: bool = False) -> bool:
         return (