Delete recursive aliases flags (#16346)

FWIW I decided to keep the old tests (where possible), just to be sure
we will not re-introduce various crashes at function scope, where
recursive aliases are not allowed.

Author: ilevkivskyi

mypy/main.py

@@ -999,15 +999,6 @@ def add_invertible_flag(
         action="store_true",
         help="Enable new experimental type inference algorithm",
     )
-    internals_group.add_argument(
-        "--disable-recursive-aliases",
-        action="store_true",
-        help="Disable experimental support for recursive type aliases",
-    )
-    # Deprecated reverse variant of the above.
-    internals_group.add_argument(
-        "--enable-recursive-aliases", action="store_true", help=argparse.SUPPRESS
-    )
     parser.add_argument(
         "--enable-incomplete-feature",
         action="append",
@@ -1392,11 +1383,6 @@ def set_strict_flags() -> None:
     if options.logical_deps:
         options.cache_fine_grained = True
 
-    if options.enable_recursive_aliases:
-        print(
-            "Warning: --enable-recursive-aliases is deprecated;"
-            " recursive types are enabled by default"
-        )
     if options.strict_concatenate and not strict_option_set:
         print("Warning: --strict-concatenate is deprecated; use --extra-checks instead")
 

mypy/options.py

@@ -362,10 +362,6 @@ def __init__(self) -> None:
         self.many_errors_threshold = defaults.MANY_ERRORS_THRESHOLD
         # Enable new experimental type inference algorithm.
         self.new_type_inference = False
-        # Disable recursive type aliases (currently experimental)
-        self.disable_recursive_aliases = False
-        # Deprecated reverse version of the above, do not use.
-        self.enable_recursive_aliases = False
         # Export line-level, limited, fine-grained dependency information in cache data
         # (undocumented feature).
         self.export_ref_info = False

mypy/semanal.py

@@ -3608,7 +3608,7 @@ def check_and_set_up_type_alias(self, s: AssignmentStmt) -> bool:
             )
             if not res:
                 return False
-            if not self.options.disable_recursive_aliases and not self.is_func_scope():
+            if not self.is_func_scope():
                 # Only marking incomplete for top-level placeholders makes recursive aliases like
                 # `A = Sequence[str | A]` valid here, similar to how we treat base classes in class
                 # definitions, allowing `class str(Sequence[str]): ...`
@@ -6296,7 +6296,7 @@ def process_placeholder(
     def cannot_resolve_name(self, name: str | None, kind: str, ctx: Context) -> None:
         name_format = f' "{name}"' if name else ""
         self.fail(f"Cannot resolve {kind}{name_format} (possible cyclic definition)", ctx)
-        if not self.options.disable_recursive_aliases and self.is_func_scope():
+        if self.is_func_scope():
             self.note("Recursive types are not allowed at function scope", ctx)
 
     def qualified_name(self, name: str) -> str:

mypy/semanal_namedtuple.py

@@ -182,8 +182,7 @@ def check_namedtuple_classdef(
                     # it would be inconsistent with type aliases.
                     analyzed = self.api.anal_type(
                         stmt.type,
-                        allow_placeholder=not self.options.disable_recursive_aliases
-                        and not self.api.is_func_scope(),
+                        allow_placeholder=not self.api.is_func_scope(),
                         prohibit_self_type="NamedTuple item type",
                     )
                     if analyzed is None:
@@ -450,8 +449,7 @@ def parse_namedtuple_fields_with_types(
                 # We never allow recursive types at function scope.
                 analyzed = self.api.anal_type(
                     type,
-                    allow_placeholder=not self.options.disable_recursive_aliases
-                    and not self.api.is_func_scope(),
+                    allow_placeholder=not self.api.is_func_scope(),
                     prohibit_self_type="NamedTuple item type",
                 )
                 # Workaround #4987 and avoid introducing a bogus UnboundType

mypy/semanal_newtype.py

@@ -207,8 +207,7 @@ def check_newtype_args(
             self.api.anal_type(
                 unanalyzed_type,
                 report_invalid_types=False,
-                allow_placeholder=not self.options.disable_recursive_aliases
-                and not self.api.is_func_scope(),
+                allow_placeholder=not self.api.is_func_scope(),
             )
         )
         should_defer = False

mypy/semanal_typeddict.py

@@ -228,10 +228,7 @@ def analyze_base_args(self, base: IndexExpr, ctx: Context) -> list[Type] | None:
                 self.fail("Invalid TypedDict type argument", ctx)
                 return None
             analyzed = self.api.anal_type(
-                type,
-                allow_required=True,
-                allow_placeholder=not self.options.disable_recursive_aliases
-                and not self.api.is_func_scope(),
+                type, allow_required=True, allow_placeholder=not self.api.is_func_scope()
             )
             if analyzed is None:
                 return None
@@ -307,8 +304,7 @@ def analyze_typeddict_classdef_fields(
                     analyzed = self.api.anal_type(
                         stmt.type,
                         allow_required=True,
-                        allow_placeholder=not self.options.disable_recursive_aliases
-                        and not self.api.is_func_scope(),
+                        allow_placeholder=not self.api.is_func_scope(),
                         prohibit_self_type="TypedDict item type",
                     )
                     if analyzed is None:
@@ -504,8 +500,7 @@ def parse_typeddict_fields_with_types(
             analyzed = self.api.anal_type(
                 type,
                 allow_required=True,
-                allow_placeholder=not self.options.disable_recursive_aliases
-                and not self.api.is_func_scope(),
+                allow_placeholder=not self.api.is_func_scope(),
                 prohibit_self_type="TypedDict item type",
             )
             if analyzed is None:

mypy/typeanal.py

@@ -490,7 +490,7 @@ def cannot_resolve_type(self, t: UnboundType) -> None:
         #       need access to MessageBuilder here. Also move the similar
         #       message generation logic in semanal.py.
         self.api.fail(f'Cannot resolve name "{t.name}" (possible cyclic definition)', t)
-        if not self.options.disable_recursive_aliases and self.api.is_func_scope():
+        if self.api.is_func_scope():
             self.note("Recursive types are not allowed at function scope", t)
 
     def apply_concatenate_operator(self, t: UnboundType) -> Type:

test-data/unit/check-classes.test

@@ -5002,12 +5002,13 @@ class A(Tuple[int, str]): pass
 -- -----------------------
 
 [case testCrashOnSelfRecursiveNamedTupleVar]
-# flags: --disable-recursive-aliases
 from typing import NamedTuple
 
-N = NamedTuple('N', [('x', N)]) # E: Cannot resolve name "N" (possible cyclic definition)
-n: N
-reveal_type(n) # N: Revealed type is "Tuple[Any, fallback=__main__.N]"
+def test() -> None:
+    N = NamedTuple('N', [('x', N)]) # E: Cannot resolve name "N" (possible cyclic definition) \
+                                    # N: Recursive types are not allowed at function scope
+    n: N
+    reveal_type(n) # N: Revealed type is "Tuple[Any, fallback=__main__.N@4]"
 [builtins fixtures/tuple.pyi]
 
 [case testCrashOnSelfRecursiveTypedDictVar]
@@ -5032,18 +5033,20 @@ lst = [n, m]
 [builtins fixtures/isinstancelist.pyi]
 
 [case testCorrectJoinOfSelfRecursiveTypedDicts]
-# flags: --disable-recursive-aliases
 from mypy_extensions import TypedDict
 
-class N(TypedDict):
-    x: N # E: Cannot resolve name "N" (possible cyclic definition)
-class M(TypedDict):
-    x: M # E: Cannot resolve name "M" (possible cyclic definition)
-
-n: N
-m: M
-lst = [n, m]
-reveal_type(lst[0]['x'])  # N: Revealed type is "Any"
+def test() -> None:
+    class N(TypedDict):
+        x: N  # E: Cannot resolve name "N" (possible cyclic definition) \
+              # N: Recursive types are not allowed at function scope
+    class M(TypedDict):
+        x: M  # E: Cannot resolve name "M" (possible cyclic definition) \
+              # N: Recursive types are not allowed at function scope
+
+    n: N
+    m: M
+    lst = [n, m]
+    reveal_type(lst[0]['x'])  # N: Revealed type is "Any"
 [builtins fixtures/isinstancelist.pyi]
 
 [case testCrashInForwardRefToNamedTupleWithIsinstance]

test-data/unit/check-incremental.test

@@ -4594,7 +4594,6 @@ def outer() -> None:
 [out2]
 
 [case testRecursiveAliasImported]
-# flags: --disable-recursive-aliases
 import a
 
 [file a.py]
@@ -4620,16 +4619,10 @@ B = List[A]
 
 [builtins fixtures/list.pyi]
 [out]
-tmp/lib.pyi:4: error: Module "other" has no attribute "B"
-tmp/other.pyi:3: error: Cannot resolve name "B" (possible cyclic definition)
 [out2]
-tmp/lib.pyi:4: error: Module "other" has no attribute "B"
-tmp/other.pyi:3: error: Cannot resolve name "B" (possible cyclic definition)
-tmp/a.py:3: note: Revealed type is "builtins.list[Any]"
-
-[case testRecursiveNamedTupleTypedDict-skip]
-# https://github.com/python/mypy/issues/7125
+tmp/a.py:3: note: Revealed type is "builtins.list[builtins.list[...]]"
 
+[case testRecursiveNamedTupleTypedDict]
 import a
 [file a.py]
 import lib
@@ -4641,15 +4634,15 @@ reveal_type(x.x['x'])
 [file lib.pyi]
 from typing import NamedTuple
 from other import B
-A = NamedTuple('A', [('x', B)])  # type: ignore
+A = NamedTuple('A', [('x', B)])
 [file other.pyi]
 from mypy_extensions import TypedDict
 from lib import A
 B = TypedDict('B', {'x': A})
 [builtins fixtures/dict.pyi]
 [out]
 [out2]
-tmp/a.py:3: note: Revealed type is "Tuple[TypedDict('other.B', {'x': Any}), fallback=lib.A]"
+tmp/a.py:3: note: Revealed type is "Tuple[TypedDict('other.B', {'x': Tuple[..., fallback=lib.A]}), fallback=lib.A]"
 
 [case testFollowImportSkipNotInvalidatedOnPresent]
 # flags: --follow-imports=skip