From 7281285b6b421724ece654426006760417aaa1f4 Mon Sep 17 00:00:00 2001
From: Erik Kemperman <erikkemperman@gmail.com>
Date: Wed, 24 May 2023 16:30:37 +0200
Subject: [PATCH] Dedupe logic to see if new syntax is allowed

---
 mypy/semanal.py        | 25 ++++++++++++++-----------
 mypy/semanal_shared.py | 12 ++++++++++++
 mypy/typeanal.py       | 19 ++++---------------
 3 files changed, 30 insertions(+), 26 deletions(-)

diff --git a/mypy/semanal.py b/mypy/semanal.py
index 2eb8c0c82f781..9f0f5015cfd73 100644
--- a/mypy/semanal.py
+++ b/mypy/semanal.py
@@ -482,6 +482,19 @@ def is_typeshed_stub_file(self) -> bool:
     def final_iteration(self) -> bool:
         return self._final_iteration
 
+    @property
+    def always_allow_new_syntax(self) -> bool:
+        return self.is_stub_file or self.is_future_flag_set("annotations")
+
+    def check_pep585_name(self, fullname: str, name: str) -> bool:
+        return fullname == "typing." + name.capitalize() or (
+            fullname == "builtins." + name.lower()
+            and (
+                self.always_allow_new_syntax
+                or self.options.python_version >= (3, 9)
+            )
+        )
+
     @contextmanager
     def allow_unbound_tvars_set(self) -> Iterator[None]:
         old = self.allow_unbound_tvars
@@ -1011,17 +1024,7 @@ def is_expected_self_type(self, typ: Type, is_classmethod: bool) -> bool:
                 if (
                     sym is not None
                     and typ.args
-                    and (
-                        sym.fullname == "typing.Type"
-                        or (
-                            sym.fullname == "builtins.type"
-                            and (
-                                self.is_stub_file
-                                or self.is_future_flag_set("annotations")
-                                or self.options.python_version >= (3, 9)
-                            )
-                        )
-                    )
+                    and self.check_pep585_name(sym.fullname or "", "type")
                 ):
                     return self.is_expected_self_type(typ.args[0], is_classmethod=False)
             return False
diff --git a/mypy/semanal_shared.py b/mypy/semanal_shared.py
index c86ed828b2b9f..d5746a09f5155 100644
--- a/mypy/semanal_shared.py
+++ b/mypy/semanal_shared.py
@@ -128,6 +128,18 @@ def is_future_flag_set(self, flag: str) -> bool:
     def is_stub_file(self) -> bool:
         raise NotImplementedError
 
+    @property
+    @abstractmethod
+    def always_allow_new_syntax(self) -> bool:
+        """Should we allow new type syntax when targeting older Python versions
+        like 'list[int]' or 'X | Y' (allowed in stubs and with `__future__` import)?
+        """
+        raise NotImplementedError
+
+    @abstractmethod
+    def check_pep585_name(self, fullname: str, name: str) -> bool:
+        raise NotImplementedError
+
     @abstractmethod
     def is_func_scope(self) -> bool:
         raise NotImplementedError
diff --git a/mypy/typeanal.py b/mypy/typeanal.py
index 95acb71b45d2e..8ec75390eaa7e 100644
--- a/mypy/typeanal.py
+++ b/mypy/typeanal.py
@@ -209,11 +209,6 @@ def __init__(
         self.allow_tuple_literal = allow_tuple_literal
         # Positive if we are analyzing arguments of another (outer) type
         self.nesting_level = 0
-        # Should we allow new type syntax when targeting older Python versions
-        # like 'list[int]' or 'X | Y' (allowed in stubs and with `__future__` import)?
-        self.always_allow_new_syntax = self.api.is_stub_file or self.api.is_future_flag_set(
-            "annotations"
-        )
         # Should we accept unbound type variables? This is currently used for class bases,
         # and alias right hand sides (before they are analyzed as type aliases).
         self.allow_unbound_tvars = allow_unbound_tvars
@@ -297,7 +292,7 @@ def visit_unbound_type_nonoptional(self, t: UnboundType, defining_literal: bool)
             if (
                 fullname in get_nongen_builtins(self.options.python_version)
                 and t.args
-                and not self.always_allow_new_syntax
+                and not self.api.always_allow_new_syntax
             ):
                 self.fail(
                     no_subscript_builtin_alias(fullname, propose_alt=not self.defining_alias), t
@@ -514,10 +509,7 @@ def try_analyze_special_unbound_type(self, t: UnboundType, fullname: str) -> Typ
                 code=codes.VALID_TYPE,
             )
             return AnyType(TypeOfAny.from_error)
-        elif fullname == "typing.Tuple" or (
-            fullname == "builtins.tuple"
-            and (self.always_allow_new_syntax or self.options.python_version >= (3, 9))
-        ):
+        elif self.api.check_pep585_name(fullname, "tuple"):
             # Tuple is special because it is involved in builtin import cycle
             # and may be not ready when used.
             sym = self.api.lookup_fully_qualified_or_none("builtins.tuple")
@@ -550,10 +542,7 @@ def try_analyze_special_unbound_type(self, t: UnboundType, fullname: str) -> Typ
             return make_optional_type(item)
         elif fullname == "typing.Callable":
             return self.analyze_callable_type(t)
-        elif fullname == "typing.Type" or (
-            fullname == "builtins.type"
-            and (self.always_allow_new_syntax or self.options.python_version >= (3, 9))
-        ):
+        elif self.api.check_pep585_name(fullname, "type"):
             if len(t.args) == 0:
                 if fullname == "typing.Type":
                     any_type = self.get_omitted_any(t)
@@ -1103,7 +1092,7 @@ def visit_union_type(self, t: UnionType) -> Type:
         if (
             t.uses_pep604_syntax is True
             and t.is_evaluated is True
-            and not self.always_allow_new_syntax
+            and not self.api.always_allow_new_syntax
             and not self.options.python_version >= (3, 10)
         ):
             self.fail("X | Y syntax for unions requires Python 3.10", t, code=codes.SYNTAX)