Refactor TypeState into a singleton class (#14327)

This helps mypyc, since accessing mutable attributes of singleton
instances is faster than accessing class variables. The implementation
is also arguably a bit cleaner.

This seems performance-neutral or a very minor optimization, but if we
continue to add attributes to TypeState, this can help.

mypy/build.py

@@ -100,7 +100,7 @@
     stub_package_name,
 )
 from mypy.types import Type
-from mypy.typestate import TypeState, reset_global_state
+from mypy.typestate import reset_global_state, type_state
 from mypy.version import __version__
 
 # Switch to True to produce debug output related to fine-grained incremental
@@ -276,7 +276,7 @@ def _build(
     try:
         graph = dispatch(sources, manager, stdout)
         if not options.fine_grained_incremental:
-            TypeState.reset_all_subtype_caches()
+            type_state.reset_all_subtype_caches()
         if options.timing_stats is not None:
             dump_timing_stats(options.timing_stats, graph)
         if options.line_checking_stats is not None:
@@ -2459,7 +2459,7 @@ def update_fine_grained_deps(self, deps: dict[str, set[str]]) -> None:
             from mypy.server.deps import merge_dependencies  # Lazy import to speed up startup
 
             merge_dependencies(self.compute_fine_grained_deps(), deps)
-            TypeState.update_protocol_deps(deps)
+            type_state.update_protocol_deps(deps)
 
     def valid_references(self) -> set[str]:
         assert self.ancestors is not None
@@ -2926,7 +2926,7 @@ def dispatch(sources: list[BuildSource], manager: BuildManager, stdout: TextIO)
             # then we need to collect fine grained protocol dependencies.
             # Since these are a global property of the program, they are calculated after we
             # processed the whole graph.
-            TypeState.add_all_protocol_deps(manager.fg_deps)
+            type_state.add_all_protocol_deps(manager.fg_deps)
             if not manager.options.fine_grained_incremental:
                 rdeps = generate_deps_for_cache(manager, graph)
                 write_deps_cache(rdeps, manager, graph)

mypy/checkexpr.py

@@ -162,7 +162,7 @@
     is_self_type_like,
     remove_optional,
 )
-from mypy.typestate import TypeState
+from mypy.typestate import type_state
 from mypy.typevars import fill_typevars
 from mypy.util import split_module_names
 from mypy.visitor import ExpressionVisitor
@@ -1591,13 +1591,13 @@ def allow_unions(self, type_context: Type) -> Iterator[None]:
         # of joins. This is a bit arbitrary, but in practice it works for most
         # cases. A cleaner alternative would be to switch to single bin type
         # inference, but this is a lot of work.
-        old = TypeState.infer_unions
+        old = type_state.infer_unions
         if has_recursive_types(type_context):
-            TypeState.infer_unions = True
+            type_state.infer_unions = True
         try:
             yield
         finally:
-            TypeState.infer_unions = old
+            type_state.infer_unions = old
 
     def infer_arg_types_in_context(
         self,

mypy/constraints.py

@@ -48,7 +48,7 @@
     is_named_instance,
     is_union_with_any,
 )
-from mypy.typestate import TypeState
+from mypy.typestate import type_state
 from mypy.typevartuples import (
     extract_unpack,
     find_unpack_in_list,
@@ -198,7 +198,7 @@ def infer_constraints(template: Type, actual: Type, direction: int) -> list[Cons
     if any(
         get_proper_type(template) == get_proper_type(t)
         and get_proper_type(actual) == get_proper_type(a)
-        for (t, a) in reversed(TypeState.inferring)
+        for (t, a) in reversed(type_state.inferring)
     ):
         return []
     if has_recursive_types(template) or isinstance(get_proper_type(template), Instance):
@@ -207,9 +207,9 @@ def infer_constraints(template: Type, actual: Type, direction: int) -> list[Cons
         if not has_type_vars(template):
             # Return early on an empty branch.
             return []
-        TypeState.inferring.append((template, actual))
+        type_state.inferring.append((template, actual))
         res = _infer_constraints(template, actual, direction)
-        TypeState.inferring.pop()
+        type_state.inferring.pop()
         return res
     return _infer_constraints(template, actual, direction)
 

mypy/mro.py

@@ -4,7 +4,7 @@
 
 from mypy.nodes import TypeInfo
 from mypy.types import Instance
-from mypy.typestate import TypeState
+from mypy.typestate import type_state
 
 
 def calculate_mro(info: TypeInfo, obj_type: Callable[[], Instance] | None = None) -> None:
@@ -17,7 +17,7 @@ def calculate_mro(info: TypeInfo, obj_type: Callable[[], Instance] | None = None
     info.mro = mro
     # The property of falling back to Any is inherited.
     info.fallback_to_any = any(baseinfo.fallback_to_any for baseinfo in info.mro)
-    TypeState.reset_all_subtype_caches_for(info)
+    type_state.reset_all_subtype_caches_for(info)
 
 
 class MroError(Exception):

mypy/server/astmerge.py

@@ -110,7 +110,7 @@
     UnionType,
     UnpackType,
 )
-from mypy.typestate import TypeState
+from mypy.typestate import type_state
 from mypy.util import get_prefix, replace_object_state
 
 
@@ -360,7 +360,7 @@ def fixup_and_reset_typeinfo(self, node: TypeInfo) -> TypeInfo:
             # The subclass relationships may change, so reset all caches relevant to the
             # old MRO.
             new = cast(TypeInfo, self.replacements[node])
-            TypeState.reset_all_subtype_caches_for(new)
+            type_state.reset_all_subtype_caches_for(new)
         return self.fixup(node)
 
     def fixup_type(self, typ: Type | None) -> None:

mypy/server/aststrip.py

@@ -66,7 +66,7 @@
 )
 from mypy.traverser import TraverserVisitor
 from mypy.types import CallableType
-from mypy.typestate import TypeState
+from mypy.typestate import type_state
 
 SavedAttributes: _TypeAlias = Dict[Tuple[ClassDef, str], SymbolTableNode]
 
@@ -143,7 +143,7 @@ def visit_class_def(self, node: ClassDef) -> None:
             super().visit_class_def(node)
         node.defs.body.extend(node.removed_statements)
         node.removed_statements = []
-        TypeState.reset_subtype_caches_for(node.info)
+        type_state.reset_subtype_caches_for(node.info)
         # Kill the TypeInfo, since there is none before semantic analysis.
         node.info = CLASSDEF_NO_INFO
         node.analyzed = None

mypy/server/deps.py

@@ -172,7 +172,7 @@ class 'mod.Cls'. This can also refer to an attribute inherited from a
     UnpackType,
     get_proper_type,
 )
-from mypy.typestate import TypeState
+from mypy.typestate import type_state
 from mypy.util import correct_relative_import
 
 
@@ -344,7 +344,7 @@ def process_type_info(self, info: TypeInfo) -> None:
                 self.add_dependency(
                     make_wildcard_trigger(base_info.fullname), target=make_trigger(target)
                 )
-                # More protocol dependencies are collected in TypeState._snapshot_protocol_deps
+                # More protocol dependencies are collected in type_state._snapshot_protocol_deps
                 # after a full run or update is finished.
 
         self.add_type_alias_deps(self.scope.current_target())
@@ -1123,7 +1123,7 @@ def dump_all_dependencies(
         deps = get_dependencies(node, type_map, python_version, options)
         for trigger, targets in deps.items():
             all_deps.setdefault(trigger, set()).update(targets)
-    TypeState.add_all_protocol_deps(all_deps)
+    type_state.add_all_protocol_deps(all_deps)
 
     for trigger, targets in sorted(all_deps.items(), key=lambda x: x[0]):
         print(trigger)

mypy/server/update.py

@@ -157,7 +157,7 @@
 from mypy.server.deps import get_dependencies_of_target, merge_dependencies
 from mypy.server.target import trigger_to_target
 from mypy.server.trigger import WILDCARD_TAG, make_trigger
-from mypy.typestate import TypeState
+from mypy.typestate import type_state
 from mypy.util import module_prefix, split_target
 
 MAX_ITER: Final = 1000
@@ -869,7 +869,7 @@ def propagate_changes_using_dependencies(
         # We need to do this to avoid false negatives if the protocol itself is
         # unchanged, but was marked stale because its sub- (or super-) type changed.
         for info in stale_protos:
-            TypeState.reset_subtype_caches_for(info)
+            type_state.reset_subtype_caches_for(info)
         # Then fully reprocess all targets.
         # TODO: Preserve order (set is not optimal)
         for id, nodes in sorted(todo.items(), key=lambda x: x[0]):
@@ -1081,7 +1081,7 @@ def update_deps(
         for trigger, targets in new_deps.items():
             deps.setdefault(trigger, set()).update(targets)
     # Merge also the newly added protocol deps (if any).
-    TypeState.update_protocol_deps(deps)
+    type_state.update_protocol_deps(deps)
 
 
 def lookup_target(

mypy/solve.py

@@ -18,7 +18,7 @@
     UnionType,
     get_proper_type,
 )
-from mypy.typestate import TypeState
+from mypy.typestate import type_state
 
 
 def solve_constraints(
@@ -54,7 +54,7 @@ def solve_constraints(
                 if bottom is None:
                     bottom = c.target
                 else:
-                    if TypeState.infer_unions:
+                    if type_state.infer_unions:
                         # This deviates from the general mypy semantics because
                         # recursive types are union-heavy in 95% of cases.
                         bottom = UnionType.make_union([bottom, c.target])

mypy/subtypes.py

@@ -60,7 +60,7 @@
     get_proper_type,
     is_named_instance,
 )
-from mypy.typestate import SubtypeKind, TypeState
+from mypy.typestate import SubtypeKind, type_state
 from mypy.typevars import fill_typevars_with_any
 from mypy.typevartuples import extract_unpack, fully_split_with_mapped_and_template
 
@@ -154,7 +154,7 @@ def is_subtype(
                 options,
             }
         ), "Don't pass both context and individual flags"
-    if TypeState.is_assumed_subtype(left, right):
+    if type_state.is_assumed_subtype(left, right):
         return True
     if mypy.typeops.is_recursive_pair(left, right):
         # This case requires special care because it may cause infinite recursion.
@@ -174,7 +174,7 @@ def is_subtype(
         #     B = Union[int, Tuple[B, ...]]
         # When checking if A <: B we push pair (A, B) onto 'assuming' stack, then when after few
         # steps we come back to initial call is_subtype(A, B) and immediately return True.
-        with pop_on_exit(TypeState.get_assumptions(is_proper=False), left, right):
+        with pop_on_exit(type_state.get_assumptions(is_proper=False), left, right):
             return _is_subtype(left, right, subtype_context, proper_subtype=False)
     return _is_subtype(left, right, subtype_context, proper_subtype=False)
 
@@ -215,11 +215,11 @@ def is_proper_subtype(
                 ignore_uninhabited,
             }
         ), "Don't pass both context and individual flags"
-    if TypeState.is_assumed_proper_subtype(left, right):
+    if type_state.is_assumed_proper_subtype(left, right):
         return True
     if mypy.typeops.is_recursive_pair(left, right):
         # Same as for non-proper subtype, see detailed comment there for explanation.
-        with pop_on_exit(TypeState.get_assumptions(is_proper=True), left, right):
+        with pop_on_exit(type_state.get_assumptions(is_proper=True), left, right):
             return _is_subtype(left, right, subtype_context, proper_subtype=True)
     return _is_subtype(left, right, subtype_context, proper_subtype=True)
 
@@ -445,14 +445,14 @@ def visit_instance(self, left: Instance) -> bool:
         if isinstance(right, TupleType) and mypy.typeops.tuple_fallback(right).type.is_enum:
             return self._is_subtype(left, mypy.typeops.tuple_fallback(right))
         if isinstance(right, Instance):
-            if TypeState.is_cached_subtype_check(self._subtype_kind, left, right):
+            if type_state.is_cached_subtype_check(self._subtype_kind, left, right):
                 return True
             if not self.subtype_context.ignore_promotions:
                 for base in left.type.mro:
                     if base._promote and any(
                         self._is_subtype(p, self.right) for p in base._promote
                     ):
-                        TypeState.record_subtype_cache_entry(self._subtype_kind, left, right)
+                        type_state.record_subtype_cache_entry(self._subtype_kind, left, right)
                         return True
                 # Special case: Low-level integer types are compatible with 'int'. We can't
                 # use promotions, since 'int' is already promoted to low-level integer types,
@@ -589,7 +589,7 @@ def check_mixed(
                             ):
                                 nominal = False
                 if nominal:
-                    TypeState.record_subtype_cache_entry(self._subtype_kind, left, right)
+                    type_state.record_subtype_cache_entry(self._subtype_kind, left, right)
                 return nominal
             if right.type.is_protocol and is_protocol_implementation(
                 left, right, proper_subtype=self.proper_subtype
@@ -978,7 +978,7 @@ def f(self) -> A: ...
     if skip is None:
         skip = []
     # We need to record this check to generate protocol fine-grained dependencies.
-    TypeState.record_protocol_subtype_check(left.type, right.type)
+    type_state.record_protocol_subtype_check(left.type, right.type)
     # nominal subtyping currently ignores '__init__' and '__new__' signatures
     members_not_to_check = {"__init__", "__new__"}
     members_not_to_check.update(skip)
@@ -1078,7 +1078,7 @@ def named_type(fullname: str) -> Instance:
         subtype_context=SubtypeContext(ignore_pos_arg_names=ignore_names),
         proper_subtype=proper_subtype,
     )
-    TypeState.record_subtype_cache_entry(subtype_kind, left, right)
+    type_state.record_subtype_cache_entry(subtype_kind, left, right)
     return True
 
 

mypy/test/testdeps.py

@@ -15,7 +15,7 @@
 from mypy.test.data import DataDrivenTestCase, DataSuite
 from mypy.test.helpers import assert_string_arrays_equal, find_test_files, parse_options
 from mypy.types import Type
-from mypy.typestate import TypeState
+from mypy.typestate import type_state
 
 # Only dependencies in these modules are dumped
 dumped_modules = ["__main__", "pkg", "pkg.mod"]
@@ -54,7 +54,7 @@ def run_case(self, testcase: DataDrivenTestCase) -> None:
                     for source in new_deps:
                         deps[source].update(new_deps[source])
 
-            TypeState.add_all_protocol_deps(deps)
+            type_state.add_all_protocol_deps(deps)
 
             for source, targets in sorted(deps.items()):
                 if source.startswith(("<enum", "<typing", "<mypy")):