Merge branch 'master' into patch-2

Author: BobTheBuidler

.github/workflows/mypy_primer.yml

@@ -67,7 +67,6 @@ jobs:
             --debug \
             --additional-flags="--debug-serialize" \
             --output concise \
-            --show-speed-regression \
             | tee diff_${{ matrix.shard-index }}.txt
           ) || [ $? -eq 1 ]
       - if: ${{ matrix.shard-index == 0 }}

CHANGELOG.md

@@ -2,6 +2,33 @@
 
 ## Next Release
 
+### Remove Support for targeting Python 3.8
+
+Mypy now requires `--python-version 3.9` or greater. Support for only Python 3.8 is
+fully removed now. Given an unsupported version, mypy will default to the oldest
+supported one, currently 3.9.
+
+This change is necessary because typeshed stopped supporting Python 3.8 after it
+reached its End of Life in October 2024.
+
+Contributed by Marc Mueller
+(PR [19157](https://github.com/python/mypy/pull/19157), PR [19162](https://github.com/python/mypy/pull/19162)).
+
+### Initial Support for Python 3.14
+
+Mypy is now tested on 3.14 and mypyc works with 3.14.0b3 and later.
+Mypyc compiled wheels of mypy itself will be available for new versions after 3.14.0rc1 is released.
+
+Note that not all new features might be supported just yet.
+
+Contributed by Marc Mueller (PR [19164](https://github.com/python/mypy/pull/19164))
+
+### Deprecated Flag: \--force-uppercase-builtins
+
+Mypy only supports Python 3.9+. The \--force-uppercase-builtins flag is now deprecated and a no-op. It will be removed in a future version.
+
+Contributed by Marc Mueller (PR [19176](https://github.com/python/mypy/pull/19176))
+
 ## Mypy 1.16
 
 We’ve just uploaded mypy 1.16 to the Python Package Index ([PyPI](https://pypi.org/project/mypy/)).

docs/source/command_line.rst

@@ -845,6 +845,7 @@ of the above sections.
         x = 'a string'
         x.trim()  # error: "str" has no attribute "trim"  [attr-defined]
 
+
 .. _configuring-error-messages:
 
 Configuring error messages
@@ -936,11 +937,6 @@ in error messages.
     useful or they may be overly noisy. If ``N`` is negative, there is
     no limit. The default limit is -1.
 
-.. option:: --force-uppercase-builtins
-
-    Always use ``List`` instead of ``list`` in error messages,
-    even on Python 3.9+.
-
 .. option:: --force-union-syntax
 
     Always use ``Union[]`` and ``Optional[]`` for union types

docs/source/config_file.rst

@@ -922,14 +922,6 @@ These options may only be set in the global section (``[mypy]``).
 
     Show absolute paths to files.
 
-.. confval:: force_uppercase_builtins
-
-    :type: boolean
-    :default: False
-
-    Always use ``List`` instead of ``list`` in error messages,
-    even on Python 3.9+.
-
 .. confval:: force_union_syntax
 
     :type: boolean

docs/source/error_code_list2.rst

@@ -612,3 +612,44 @@ Example:
     # mypy: disallow-any-explicit
     from typing import Any
     x: Any = 1  # Error: Explicit "Any" type annotation  [explicit-any]
+
+
+.. _code-exhaustive-match:
+
+Check that match statements match exhaustively [match-exhaustive]
+-----------------------------------------------------------------------
+
+If enabled with :option:`--enable-error-code exhaustive-match <mypy --enable-error-code>`,
+mypy generates an error if a match statement does not match all possible cases/types.
+
+
+Example:
+
+.. code-block:: python
+
+        import enum
+
+
+        class Color(enum.Enum):
+            RED = 1
+            BLUE = 2
+
+        val: Color = Color.RED
+
+        # OK without --enable-error-code exhaustive-match
+        match val:
+            case Color.RED:
+                print("red")
+
+        # With --enable-error-code exhaustive-match
+        # Error: Match statement has unhandled case for values of type "Literal[Color.BLUE]"
+        match val:
+            case Color.RED:
+                print("red")
+
+        # OK with or without --enable-error-code exhaustive-match, since all cases are handled
+        match val:
+            case Color.RED:
+                print("red")
+            case _:
+                print("other")

docs/source/literal_types.rst

@@ -468,6 +468,10 @@ If we forget to handle one of the cases, mypy will generate an error:
       assert_never(direction)  # E: Argument 1 to "assert_never" has incompatible type "Direction"; expected "NoReturn"
 
 Exhaustiveness checking is also supported for match statements (Python 3.10 and later).
+For match statements specifically, inexhaustive matches can be caught
+without needing to use ``assert_never`` by using
+:option:`--enable-error-code exhaustive-match <mypy --enable-error-code>`.
+
 
 Extra Enum checks
 *****************

mypy/checker.py

@@ -25,7 +25,7 @@
 from mypy.constraints import SUPERTYPE_OF
 from mypy.erasetype import erase_type, erase_typevars, remove_instance_last_known_values
 from mypy.errorcodes import TYPE_VAR, UNUSED_AWAITABLE, UNUSED_COROUTINE, ErrorCode
-from mypy.errors import Errors, ErrorWatcher, report_internal_error
+from mypy.errors import Errors, ErrorWatcher, LoopErrorWatcher, report_internal_error
 from mypy.expandtype import expand_type
 from mypy.literals import Key, extract_var_from_literal_hash, literal, literal_hash
 from mypy.maptype import map_instance_to_supertype
@@ -599,19 +599,27 @@ def accept_loop(
             # on without bound otherwise)
             widened_old = len(self.widened_vars)
 
-            # Disable error types that we cannot safely identify in intermediate iteration steps:
-            warn_unreachable = self.options.warn_unreachable
-            warn_redundant = codes.REDUNDANT_EXPR in self.options.enabled_error_codes
-            self.options.warn_unreachable = False
-            self.options.enabled_error_codes.discard(codes.REDUNDANT_EXPR)
-
+            # one set of `unreachable`, `redundant-expr`, and `redundant-casts` errors
+            # per iteration step:
+            uselessness_errors = []
+            # one set of unreachable line numbers per iteration step:
+            unreachable_lines = []
+            # one set of revealed types per line where `reveal_type` is used (each
+            # created set can grow during the iteration):
+            revealed_types = defaultdict(set)
             iter = 1
             while True:
                 with self.binder.frame_context(can_skip=True, break_frame=2, continue_frame=1):
                     if on_enter_body is not None:
                         on_enter_body()
 
-                    self.accept(body)
+                    with LoopErrorWatcher(self.msg.errors) as watcher:
+                        self.accept(body)
+                    uselessness_errors.append(watcher.uselessness_errors)
+                    unreachable_lines.append(watcher.unreachable_lines)
+                    for key, values in watcher.revealed_types.items():
+                        revealed_types[key].update(values)
+
                 partials_new = sum(len(pts.map) for pts in self.partial_types)
                 widened_new = len(self.widened_vars)
                 # Perform multiple iterations if something changed that might affect
@@ -632,16 +640,29 @@ def accept_loop(
                 if iter == 20:
                     raise RuntimeError("Too many iterations when checking a loop")
 
-            # If necessary, reset the modified options and make up for the postponed error checks:
-            self.options.warn_unreachable = warn_unreachable
-            if warn_redundant:
-                self.options.enabled_error_codes.add(codes.REDUNDANT_EXPR)
-            if warn_unreachable or warn_redundant:
-                with self.binder.frame_context(can_skip=True, break_frame=2, continue_frame=1):
-                    if on_enter_body is not None:
-                        on_enter_body()
-
-                    self.accept(body)
+            # Report only those `unreachable`, `redundant-expr`, and `redundant-casts`
+            # errors that could not be ruled out in any iteration step:
+            persistent_uselessness_errors = set()
+            for candidate in set(itertools.chain(*uselessness_errors)):
+                if all(
+                    (candidate in errors) or (candidate[2] in lines)
+                    for errors, lines in zip(uselessness_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]
+                self.msg.fail(error_info[1], context, code=error_info[0])
+
+            #  Report all types revealed in at least one iteration step:
+            for note_info, types in revealed_types.items():
+                sorted_ = sorted(types, key=lambda typ: typ.lower())
+                revealed = sorted_[0] if len(types) == 1 else 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]
+                self.note(f'Revealed type is "{revealed}"', context)
 
             # If exit_condition is set, assume it must be False on exit from the loop:
             if exit_condition:
@@ -2264,7 +2285,7 @@ def check_method_override_for_base_with_name(
                 original_type,
                 defn.name,
                 name,
-                base.name,
+                base.name if base.module_name == self.tree.fullname else base.fullname,
                 original_class_or_static,
                 override_class_or_static,
                 context,
@@ -2449,7 +2470,7 @@ def erase_override(t: Type) -> Type:
                     if not is_subtype(original_arg_type, erase_override(override_arg_type)):
                         context: Context = node
                         if isinstance(node, FuncDef) and not node.is_property:
-                            arg_node = node.arguments[i + len(override.bound_args)]
+                            arg_node = node.arguments[i + override.bound()]
                             if arg_node.line != -1:
                                 context = arg_node
                         self.msg.argument_incompatible_with_supertype(
@@ -2664,7 +2685,7 @@ def check_typevar_defaults(self, tvars: Sequence[TypeVarLikeType]) -> None:
                 continue
             if not is_subtype(tv.default, tv.upper_bound):
                 self.fail("TypeVar default must be a subtype of the bound type", tv)
-            if tv.values and not any(tv.default == value for value in tv.values):
+            if tv.values and not any(is_same_type(tv.default, value) for value in tv.values):
                 self.fail("TypeVar default must be one of the constraint types", tv)
 
     def check_enum(self, defn: ClassDef) -> None:
@@ -3427,7 +3448,9 @@ def check_compatibility_all_supers(self, lvalue: RefExpr, rvalue: Expression) ->
             # store the rvalue type on the variable.
             actual_lvalue_type = None
             if lvalue_node.is_inferred and not lvalue_node.explicit_self_type:
-                rvalue_type = self.expr_checker.accept(rvalue, lvalue_node.type)
+                # Don't use partial types as context, similar to regular code path.
+                ctx = lvalue_node.type if not isinstance(lvalue_node.type, PartialType) else None
+                rvalue_type = self.expr_checker.accept(rvalue, ctx)
                 actual_lvalue_type = lvalue_node.type
                 lvalue_node.type = rvalue_type
             lvalue_type, _ = self.node_type_from_base(lvalue_node.name, lvalue_node.info, lvalue)
@@ -5453,6 +5476,7 @@ def visit_match_stmt(self, s: MatchStmt) -> None:
             inferred_types = self.infer_variable_types_from_type_maps(type_maps)
 
             # The second pass narrows down the types and type checks bodies.
+            unmatched_types: TypeMap = None
             for p, g, b in zip(s.patterns, s.guards, s.bodies):
                 current_subject_type = self.expr_checker.narrow_type_from_binder(
                     named_subject, subject_type
@@ -5509,6 +5533,11 @@ def visit_match_stmt(self, s: MatchStmt) -> None:
                     else:
                         self.accept(b)
                 self.push_type_map(else_map, from_assignment=False)
+                unmatched_types = else_map
+
+            if unmatched_types is not None:
+                for typ in list(unmatched_types.values()):
+                    self.msg.match_statement_inexhaustive_match(typ, s)
 
             # This is needed due to a quirk in frame_context. Without it types will stay narrowed
             # after the match.
@@ -7689,9 +7718,13 @@ def get_isinstance_type(self, expr: Expression) -> list[TypeRange] | None:
         types: list[TypeRange] = []
         for typ in all_types:
             if isinstance(typ, FunctionLike) and typ.is_type_obj():
-                # Type variables may be present -- erase them, which is the best
-                # we can do (outside disallowing them here).
-                erased_type = erase_typevars(typ.items[0].ret_type)
+                # If a type is generic, `isinstance` can only narrow its variables to Any.
+                any_parameterized = fill_typevars_with_any(typ.type_object())
+                # Tuples may have unattended type variables among their items
+                if isinstance(any_parameterized, TupleType):
+                    erased_type = erase_typevars(any_parameterized)
+                else:
+                    erased_type = any_parameterized
                 types.append(TypeRange(erased_type, is_upper_bound=False))
             elif isinstance(typ, TypeType):
                 # Type[A] means "any type that is a subtype of A" rather than "precisely type A"

mypy/checkexpr.py

@@ -4975,7 +4975,7 @@ def apply_type_arguments_to_callable(
                         tp.fallback,
                         name="tuple",
                         definition=tp.definition,
-                        bound_args=tp.bound_args,
+                        is_bound=tp.is_bound,
                     )
                 self.msg.incompatible_type_application(
                     min_arg_count, len(type_vars), len(args), ctx
@@ -6171,7 +6171,7 @@ def visit_type_var_expr(self, e: TypeVarExpr) -> Type:
         ):
             if not is_subtype(p_default, e.upper_bound):
                 self.chk.fail("TypeVar default must be a subtype of the bound type", e)
-            if e.values and not any(p_default == value for value in e.values):
+            if e.values and not any(is_same_type(p_default, value) for value in e.values):
                 self.chk.fail("TypeVar default must be one of the constraint types", e)
         return AnyType(TypeOfAny.special_form)
 

mypy/checkmember.py

@@ -921,7 +921,7 @@ def analyze_var(
             bound_items = []
             for ct in call_type.items if isinstance(call_type, UnionType) else [call_type]:
                 p_ct = get_proper_type(ct)
-                if isinstance(p_ct, FunctionLike) and not p_ct.is_type_obj():
+                if isinstance(p_ct, FunctionLike) and (not p_ct.bound() or var.is_property):
                     item = expand_and_bind_callable(p_ct, var, itype, name, mx, is_trivial_self)
                 else:
                     item = expand_without_binding(ct, var, itype, original_itype, mx)
@@ -981,6 +981,10 @@ def expand_and_bind_callable(
     assert isinstance(expanded, CallableType)
     if var.is_settable_property and mx.is_lvalue and var.setter_type is not None:
         # TODO: use check_call() to infer better type, same as for __set__().
+        if not expanded.arg_types:
+            # This can happen when accessing invalid property from its own body,
+            # error will be reported elsewhere.
+            return AnyType(TypeOfAny.from_error)
         return expanded.arg_types[0]
     else:
         return expanded.ret_type
@@ -1480,19 +1484,20 @@ 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)
-    if not method.arg_types:
+    func: CallableType = method
+    if not func.arg_types:
         # Invalid method, return something.
-        return cast(F, method)
-    if method.arg_kinds[0] in (ARG_STAR, ARG_STAR2):
+        return method
+    if func.arg_kinds[0] in (ARG_STAR, ARG_STAR2):
         # See typeops.py for details.
-        return cast(F, method)
+        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 = method.copy_modified(
-        arg_types=method.arg_types[1:],
-        arg_kinds=method.arg_kinds[1:],
-        arg_names=method.arg_names[1:],
-        bound_args=[original_type],
+    res = func.copy_modified(
+        arg_types=func.arg_types[1:],
+        arg_kinds=func.arg_kinds[1:],
+        arg_names=func.arg_names[1:],
+        is_bound=True,
     )
     return cast(F, res)

mypy/config_parser.py

@@ -28,6 +28,14 @@
 _INI_PARSER_CALLABLE: _TypeAlias = Callable[[Any], _CONFIG_VALUE_TYPES]
 
 
+class VersionTypeError(argparse.ArgumentTypeError):
+    """Provide a fallback value if the Python version is unsupported."""
+
+    def __init__(self, *args: Any, fallback: tuple[int, int]) -> None:
+        self.fallback = fallback
+        super().__init__(*args)
+
+
 def parse_version(v: str | float) -> tuple[int, int]:
     m = re.match(r"\A(\d)\.(\d+)\Z", str(v))
     if not m:
@@ -44,7 +52,7 @@ def parse_version(v: str | float) -> tuple[int, int]:
             if isinstance(v, float):
                 msg += ". You may need to put quotes around your Python version"
 
-            raise argparse.ArgumentTypeError(msg)
+            raise VersionTypeError(msg, fallback=defaults.PYTHON3_VERSION_MIN)
     else:
         raise argparse.ArgumentTypeError(
             f"Python major version '{major}' out of range (must be 3)"
@@ -548,6 +556,9 @@ def parse_section(
                     continue
                 try:
                     v = ct(section.get(key))
+                except VersionTypeError as err_version:
+                    print(f"{prefix}{key}: {err_version}", file=stderr)
+                    v = err_version.fallback
                 except argparse.ArgumentTypeError as err:
                     print(f"{prefix}{key}: {err}", file=stderr)
                     continue