PEP 702 (@deprecated): consider all possible type positions (#17926)

This pull request generalises #17899.  

Initially, it started with extending #17899 to function signatures only,
as can be seen from the following initial comments and the subsequent
discussions.

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

Author: tyralla

mypy/checker.py

@@ -287,18 +287,6 @@ class PartialTypeScope(NamedTuple):
     is_local: bool
 
 
-class InstanceDeprecatedVisitor(TypeTraverserVisitor):
-    """Visitor that recursively checks for deprecations in nested instances."""
-
-    def __init__(self, typechecker: TypeChecker, context: Context) -> None:
-        self.typechecker = typechecker
-        self.context = context
-
-    def visit_instance(self, t: Instance) -> None:
-        super().visit_instance(t)
-        self.typechecker.check_deprecated(t.type, self.context)
-
-
 class TypeChecker(NodeVisitor[None], CheckerPluginInterface):
     """Mypy type checker.
 
@@ -2958,15 +2946,6 @@ def visit_assignment_stmt(self, s: AssignmentStmt) -> None:
         Handle all kinds of assignment statements (simple, indexed, multiple).
         """
 
-        if s.unanalyzed_type is not None:
-            for lvalue in s.lvalues:
-                if (
-                    isinstance(lvalue, NameExpr)
-                    and isinstance(var := lvalue.node, Var)
-                    and (var.type is not None)
-                ):
-                    var.type.accept(InstanceDeprecatedVisitor(typechecker=self, context=s))
-
         # Avoid type checking type aliases in stubs to avoid false
         # positives about modern type syntax available in stubs such
         # as X | Y.
@@ -7655,8 +7634,10 @@ def warn_deprecated(self, node: SymbolNode | None, context: Context) -> None:
         """Warn if deprecated."""
         if isinstance(node, Decorator):
             node = node.func
-        if isinstance(node, (FuncDef, OverloadedFuncDef, TypeInfo)) and (
-            (deprecated := node.deprecated) is not None
+        if (
+            isinstance(node, (FuncDef, OverloadedFuncDef, TypeInfo))
+            and ((deprecated := node.deprecated) is not None)
+            and not self.is_typeshed_stub
         ):
             warn = self.msg.fail if self.options.report_deprecated_as_error else self.msg.note
             warn(deprecated, context, code=codes.DEPRECATED)

mypy/semanal.py

@@ -3870,6 +3870,7 @@ def analyze_alias(
                 self.tvar_scope,
                 self.plugin,
                 self.options,
+                self.cur_mod_node,
                 self.is_typeshed_stub_file,
                 allow_placeholder=allow_placeholder,
                 in_dynamic_func=dynamic,
@@ -7308,6 +7309,7 @@ def type_analyzer(
             tvar_scope,
             self.plugin,
             self.options,
+            self.cur_mod_node,
             self.is_typeshed_stub_file,
             allow_unbound_tvars=allow_unbound_tvars,
             allow_tuple_literal=allow_tuple_literal,

mypy/server/astdiff.py

@@ -303,6 +303,7 @@ def snapshot_definition(node: SymbolNode | None, common: SymbolSnapshot) -> Symb
             [snapshot_type(base) for base in node.bases],
             [snapshot_type(p) for p in node._promote],
             dataclass_transform_spec.serialize() if dataclass_transform_spec is not None else None,
+            node.deprecated,
         )
         prefix = node.fullname
         symbol_table = snapshot_symbol_table(prefix, node.names)

mypy/typeanal.py

@@ -34,6 +34,7 @@
     ArgKind,
     Context,
     Decorator,
+    ImportFrom,
     MypyFile,
     ParamSpecExpr,
     PlaceholderNode,
@@ -148,6 +149,7 @@ def analyze_type_alias(
     tvar_scope: TypeVarLikeScope,
     plugin: Plugin,
     options: Options,
+    cur_mod_node: MypyFile,
     is_typeshed_stub: bool,
     allow_placeholder: bool = False,
     in_dynamic_func: bool = False,
@@ -167,6 +169,7 @@ def analyze_type_alias(
         tvar_scope,
         plugin,
         options,
+        cur_mod_node,
         is_typeshed_stub,
         defining_alias=True,
         allow_placeholder=allow_placeholder,
@@ -213,6 +216,7 @@ def __init__(
         tvar_scope: TypeVarLikeScope,
         plugin: Plugin,
         options: Options,
+        cur_mod_node: MypyFile,
         is_typeshed_stub: bool,
         *,
         defining_alias: bool = False,
@@ -266,6 +270,7 @@ def __init__(
         self.report_invalid_types = report_invalid_types
         self.plugin = plugin
         self.options = options
+        self.cur_mod_node = cur_mod_node
         self.is_typeshed_stub = is_typeshed_stub
         # Names of type aliases encountered while analysing a type will be collected here.
         self.aliases_used: set[str] = set()
@@ -771,6 +776,21 @@ def get_omitted_any(self, typ: Type, fullname: str | None = None) -> AnyType:
         disallow_any = not self.is_typeshed_stub and self.options.disallow_any_generics
         return get_omitted_any(disallow_any, self.fail, self.note, typ, self.options, fullname)
 
+    def check_and_warn_deprecated(self, info: TypeInfo, ctx: Context) -> None:
+        """Similar logic to `TypeChecker.check_deprecated` and `TypeChecker.warn_deprecated."""
+
+        if (
+            (deprecated := info.deprecated)
+            and not self.is_typeshed_stub
+            and not (self.api.type and (self.api.type.fullname == info.fullname))
+        ):
+            for imp in self.cur_mod_node.imports:
+                if isinstance(imp, ImportFrom) and any(info.name == n[0] for n in imp.names):
+                    break
+            else:
+                warn = self.fail if self.options.report_deprecated_as_error else self.note
+                warn(deprecated, ctx, code=codes.DEPRECATED)
+
     def analyze_type_with_type_info(
         self, info: TypeInfo, args: Sequence[Type], ctx: Context, empty_tuple_index: bool
     ) -> Type:
@@ -779,6 +799,8 @@ def analyze_type_with_type_info(
         This handles simple cases like 'int', 'modname.UserClass[str]', etc.
         """
 
+        self.check_and_warn_deprecated(info, ctx)
+
         if len(args) > 0 and info.fullname == "builtins.tuple":
             fallback = Instance(info, [AnyType(TypeOfAny.special_form)], ctx.line)
             return TupleType(self.anal_array(args, allow_unpack=True), fallback, ctx.line)

test-data/unit/check-deprecated.test

@@ -142,23 +142,129 @@ x9: Callable[[int], C]  # N: class __main__.C is deprecated: use C2 instead
 x10: Callable[[int, C, int], int]  # N: class __main__.C is deprecated: use C2 instead
 
 T = TypeVar("T")
-A1: TypeAlias = Optional[C]  # ToDo
+A1: TypeAlias = Optional[C]  # N: class __main__.C is deprecated: use C2 instead
 x11: A1
-A2: TypeAlias = List[Union[A2, C]]  # ToDo
+A2: TypeAlias = List[Union[A2, C]]  # N: class __main__.C is deprecated: use C2 instead
 x12: A2
 A3: TypeAlias = List[Optional[T]]
 x13: A3[C]  # N: class __main__.C is deprecated: use C2 instead
 
 [builtins fixtures/tuple.pyi]
 
 
+[case testDeprecatedBaseClass]
+
+from typing_extensions import deprecated
+
+@deprecated("use C2 instead")
+class C: ...
+
+class D(C): ...  # N: class __main__.C is deprecated: use C2 instead
+class E(D): ...
+class F(D, C): ...  # N: class __main__.C is deprecated: use C2 instead
+
+[builtins fixtures/tuple.pyi]
+
+
+[case testDeprecatedClassInTypeVar]
+
+from typing import Generic, TypeVar
+from typing_extensions import deprecated
+
+class B: ...
+@deprecated("use C2 instead")
+class C: ...
+
+T = TypeVar("T", bound=C)  # N: class __main__.C is deprecated: use C2 instead
+def f(x: T) -> T: ...
+class D(Generic[T]): ...
+
+V = TypeVar("V", B, C)  # N: class __main__.C is deprecated: use C2 instead
+def g(x: V) -> V: ...
+class E(Generic[V]): ...
+
+[builtins fixtures/tuple.pyi]
+
+
+[case testDeprecatedClassInCast]
+
+from typing import cast, Generic
+from typing_extensions import deprecated
+
+class B: ...
+@deprecated("use C2 instead")
+class C: ...
+
+c = C()  # N: class __main__.C is deprecated: use C2 instead
+b = cast(B, c)
+
+[builtins fixtures/tuple.pyi]
+
+
+[case testDeprecatedInstanceInFunctionDefinition]
+
+from typing import Generic, List, Optional, TypeVar
+from typing_extensions import deprecated
+
+@deprecated("use C2 instead")
+class C: ...
+
+def f1(c: C) -> None:  # N: class __main__.C is deprecated: use C2 instead
+    def g1() -> None: ...
+
+def f2(c: List[Optional[C]]) -> None:  # N: class __main__.C is deprecated: use C2 instead
+    def g2() -> None: ...
+
+def f3() -> C:  # N: class __main__.C is deprecated: use C2 instead
+    def g3() -> None: ...
+    return C()  # N: class __main__.C is deprecated: use C2 instead
+
+def f4() -> List[Optional[C]]:  # N: class __main__.C is deprecated: use C2 instead
+    def g4() -> None: ...
+    return []
+
+def f5() -> None:
+    def g5(c: C) -> None: ...  # N: class __main__.C is deprecated: use C2 instead
+
+def f6() -> None:
+    def g6() -> C: ...  # N: class __main__.C is deprecated: use C2 instead
+
+
+@deprecated("use D2 instead")
+class D:
+
+    def f1(self, c: C) -> None:  # N: class __main__.C is deprecated: use C2 instead
+        def g1() -> None: ...
+
+    def f2(self, c: List[Optional[C]]) -> None:  # N: class __main__.C is deprecated: use C2 instead
+        def g2() -> None: ...
+
+    def f3(self) -> None:
+        def g3(c: C) -> None: ...  # N: class __main__.C is deprecated: use C2 instead
+
+    def f4(self) -> None:
+        def g4() -> C: ...  # N: class __main__.C is deprecated: use C2 instead
+
+T = TypeVar("T")
+
+@deprecated("use E2 instead")
+class E(Generic[T]):
+
+    def f1(self: E[C]) -> None: ...  # N: class __main__.C is deprecated: use C2 instead
+    def f2(self, e: E[C]) -> None: ...  # N: class __main__.C is deprecated: use C2 instead
+    def f3(self) -> E[C]: ...  # N: class __main__.C is deprecated: use C2 instead
+
+[builtins fixtures/tuple.pyi]
+
+
 [case testDeprecatedClassDifferentModule]
 
 import m
 import p.s
 import m as n
 import p.s as ps
-from m import C  # N: class m.C is deprecated: use C2 instead
+from m import B, C  # N: class m.B is deprecated: use B2 instead \
+                    # N: class m.C is deprecated: use C2 instead
 from p.s import D  # N: class p.s.D is deprecated: use D2 instead
 from k import *
 
@@ -170,9 +276,20 @@ C()
 D()
 E()  # N: class k.E is deprecated: use E2 instead
 
+x1: m.A  # N: class m.A is deprecated: use A2 instead
+x2: m.A = m.A()  # N: class m.A is deprecated: use A2 instead
+y1: B
+y2: B = B()
+
 [file m.py]
 from typing_extensions import deprecated
 
+@deprecated("use A2 instead")
+class A: ...
+
+@deprecated("use B2 instead")
+class B: ...
+
 @deprecated("use C2 instead")
 class C: ...