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

Author: sterliakov

CHANGELOG.md

@@ -4,7 +4,10 @@
 
 ### Performance improvements
 
-TODO
+Mypy may be 5-30% faster. This improvement comes largely from tuning the performance of the
+garbage collector.
+
+Contributed by Jukka Lehtosalo (PR [18306](https://github.com/python/mypy/pull/18306)).
 
 ### Drop Support for Python 3.8
 
@@ -33,13 +36,14 @@ Use this flag to disable this behavior. `--strict-bytes` will be enabled by defa
 Contributed by Ali Hamdan (PR [18137](https://github.com/python/mypy/pull/18263/)) and
 Shantanu Jain (PR [13952](https://github.com/python/mypy/pull/13952)).
 
-### Improvements to partial type handling in loops
+### Improvements to reachability analysis and partial type handling in loops
 
 This change results in mypy better modelling control flow within loops and hence detecting several
 issues it previously did not detect. In some cases, this change may require use of an additional
 explicit annotation of a variable.
 
-Contributed by Christoph Tyralla (PR [18180](https://github.com/python/mypy/pull/18180)).
+Contributed by Christoph Tyralla (PR [18180](https://github.com/python/mypy/pull/18180),
+[PR](https://github.com/python/mypy/pull/18433)).
 
 (Speaking of partial types, another reminder that mypy plans on enabling `--local-partial-types`
 by default in **mypy 2.0**).

docs/source/common_issues.rst

@@ -427,8 +427,8 @@ More specifically, mypy will understand the use of :py:data:`sys.version_info` a
    import sys
 
    # Distinguishing between different versions of Python:
-   if sys.version_info >= (3, 8):
-       # Python 3.8+ specific definitions and imports
+   if sys.version_info >= (3, 13):
+       # Python 3.13+ specific definitions and imports
    else:
        # Other definitions and imports
 

docs/source/runtime_troubles.rst

@@ -335,29 +335,25 @@ Using new additions to the typing module
 ----------------------------------------
 
 You may find yourself wanting to use features added to the :py:mod:`typing`
-module in earlier versions of Python than the addition, for example, using any
-of ``Literal``, ``Protocol``, ``TypedDict`` with Python 3.6.
+module in earlier versions of Python than the addition.
 
 The easiest way to do this is to install and use the ``typing_extensions``
 package from PyPI for the relevant imports, for example:
 
 .. code-block:: python
 
-   from typing_extensions import Literal
-   x: Literal["open", "close"]
+   from typing_extensions import TypeIs
 
 If you don't want to rely on ``typing_extensions`` being installed on newer
 Pythons, you could alternatively use:
 
 .. code-block:: python
 
    import sys
-   if sys.version_info >= (3, 8):
-       from typing import Literal
+   if sys.version_info >= (3, 13):
+       from typing import TypeIs
    else:
-       from typing_extensions import Literal
-
-   x: Literal["open", "close"]
+       from typing_extensions import TypeIs
 
 This plays nicely well with following :pep:`508` dependency specification:
-``typing_extensions; python_version<"3.8"``
+``typing_extensions; python_version<"3.13"``

mypy/checker.py

@@ -591,24 +591,43 @@ def accept_loop(
         *,
         exit_condition: Expression | None = None,
     ) -> None:
-        """Repeatedly type check a loop body until the frame doesn't change.
-        If exit_condition is set, assume it must be False on exit from the loop.
+        """Repeatedly type check a loop body until the frame doesn't change."""
 
-        Then check the else_body.
-        """
-        # The outer frame accumulates the results of all iterations
+        # The outer frame accumulates the results of all iterations:
         with self.binder.frame_context(can_skip=False, conditional_frame=True):
+
+            # Check for potential decreases in the number of partial types so as not to stop the
+            # iteration too early:
             partials_old = sum(len(pts.map) for pts in self.partial_types)
+
+            # 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)
+
             while True:
                 with self.binder.frame_context(can_skip=True, break_frame=2, continue_frame=1):
                     self.accept(body)
                 partials_new = sum(len(pts.map) for pts in self.partial_types)
                 if (partials_new == partials_old) and not self.binder.last_pop_changed:
                     break
                 partials_old = partials_new
+
+            # 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):
+                    self.accept(body)
+
+            # If exit_condition is set, assume it must be False on exit from the loop:
             if exit_condition:
                 _, else_map = self.find_isinstance_check(exit_condition)
                 self.push_type_map(else_map)
+
+            # Check the else body:
             if else_body:
                 self.accept(else_body)
 
@@ -2102,6 +2121,13 @@ def check_method_override_for_base_with_name(
                 if original_node and is_property(original_node):
                     original_type = get_property_type(original_type)
 
+            if isinstance(original_node, Var):
+                expanded_type = map_type_from_supertype(original_type, defn.info, base)
+                expanded_type = expand_self_type(
+                    original_node, expanded_type, fill_typevars(defn.info)
+                )
+                original_type = get_proper_type(expanded_type)
+
             if is_property(defn):
                 inner: FunctionLike | None
                 if isinstance(typ, FunctionLike):

mypy/checkpattern.py

@@ -713,6 +713,8 @@ def should_self_match(self, typ: Type) -> bool:
         return False
 
     def can_match_sequence(self, typ: ProperType) -> bool:
+        if isinstance(typ, AnyType):
+            return True
         if isinstance(typ, UnionType):
             return any(self.can_match_sequence(get_proper_type(item)) for item in typ.items)
         for other in self.non_sequence_match_types:
@@ -763,6 +765,8 @@ def construct_sequence_child(self, outer_type: Type, inner_type: Type) -> Type:
         or class T(Sequence[Tuple[T, T]]), there is no way any of those can map to Sequence[str].
         """
         proper_type = get_proper_type(outer_type)
+        if isinstance(proper_type, AnyType):
+            return outer_type
         if isinstance(proper_type, UnionType):
             types = [
                 self.construct_sequence_child(item, inner_type)
@@ -772,7 +776,6 @@ def construct_sequence_child(self, outer_type: Type, inner_type: Type) -> Type:
             return make_simplified_union(types)
         sequence = self.chk.named_generic_type("typing.Sequence", [inner_type])
         if is_subtype(outer_type, self.chk.named_type("typing.Sequence")):
-            proper_type = get_proper_type(outer_type)
             if isinstance(proper_type, TupleType):
                 proper_type = tuple_fallback(proper_type)
             assert isinstance(proper_type, Instance)