Implementation of PEP 673 (typing.Self)

mypy/checkmember.py

@@ -7,7 +7,7 @@
     Type, Instance, AnyType, TupleType, TypedDictType, CallableType, FunctionLike,
     TypeVarLikeType, Overloaded, TypeVarType, UnionType, PartialType, TypeOfAny, LiteralType,
     DeletedType, NoneType, TypeType, has_type_vars, get_proper_type, ProperType, ParamSpecType,
-    ENUM_REMOVED_PROPS
+    SelfType, ENUM_REMOVED_PROPS,
 )
 from mypy.nodes import (
     TypeInfo, FuncBase, Var, FuncDef, SymbolNode, SymbolTable, Context,
@@ -145,6 +145,9 @@ def _analyze_member_access(name: str,
     typ = get_proper_type(typ)
     if isinstance(typ, Instance):
         return analyze_instance_member_access(name, typ, mx, override_info)
+    elif isinstance(typ, SelfType):
+        mx.self_type = typ.instance
+        return analyze_instance_member_access(name, typ.instance, mx, override_info)
     elif isinstance(typ, AnyType):
         # The base object has dynamic type.
         return AnyType(TypeOfAny.from_another_any, source_any=typ)
@@ -495,13 +498,18 @@ def analyze_descriptor_access(descriptor_type: Type,
     descriptor_type = get_proper_type(descriptor_type)
 
     if isinstance(descriptor_type, UnionType):
+        for idx, item in enumerate(descriptor_type.items):
+            if isinstance(get_proper_type(item), SelfType):
+                descriptor_type.items[idx] = instance_type
         # Map the access over union types
         return make_simplified_union([
             analyze_descriptor_access(typ, mx)
             for typ in descriptor_type.items
         ])
     elif not isinstance(descriptor_type, Instance):
         return descriptor_type
+    elif isinstance(descriptor_type, SelfType):
+        return instance_type
 
     if not descriptor_type.type.has_readable_member('__get__'):
         return descriptor_type

mypy/constraints.py

@@ -7,7 +7,7 @@
     CallableType, Type, TypeVisitor, UnboundType, AnyType, NoneType, TypeVarType, Instance,
     TupleType, TypedDictType, UnionType, Overloaded, ErasedType, PartialType, DeletedType,
     UninhabitedType, TypeType, TypeVarId, TypeQuery, is_named_instance, TypeOfAny, LiteralType,
-    ProperType, ParamSpecType, get_proper_type, TypeAliasType, is_union_with_any,
+    ProperType, ParamSpecType, get_proper_type, TypeAliasType, is_union_with_any, SelfType,
     UnpackType, callable_with_ellipsis, Parameters, TUPLE_LIKE_INSTANCE_NAMES, TypeVarTupleType,
 )
 from mypy.maptype import map_instance_to_supertype
@@ -399,6 +399,9 @@ def visit_type_var(self, template: TypeVarType) -> List[Constraint]:
         assert False, ("Unexpected TypeVarType in ConstraintBuilderVisitor"
                        " (should have been handled in infer_constraints)")
 
+    def visit_self_type(self, template: SelfType) -> List[Constraint]:
+        return self.visit_instance(template.instance)
+
     def visit_param_spec(self, template: ParamSpecType) -> List[Constraint]:
         # Can't infer ParamSpecs from component values (only via Callable[P, T]).
         return []

mypy/copytype.py

@@ -4,7 +4,7 @@
     ProperType, UnboundType, AnyType, NoneType, UninhabitedType, ErasedType, DeletedType,
     Instance, TypeVarType, ParamSpecType, PartialType, CallableType, TupleType, TypedDictType,
     LiteralType, UnionType, Overloaded, TypeType, TypeAliasType, UnpackType, Parameters,
-    TypeVarTupleType
+    TypeVarTupleType, SelfType
 )
 from mypy.type_visitor import TypeVisitor
 
@@ -75,6 +75,9 @@ def visit_unpack_type(self, t: UnpackType) -> ProperType:
         dup = UnpackType(t.type)
         return self.copy_common(t, dup)
 
+    def visit_self_type(self, t: SelfType) -> ProperType:
+        return self.copy_common(t, SelfType(t.instance, t.fullname, t.line, t.column))
+
     def visit_partial_type(self, t: PartialType) -> ProperType:
         return self.copy_common(t, PartialType(t.type, t.var, t.value_type))
 

mypy/erasetype.py

@@ -5,7 +5,7 @@
     CallableType, TupleType, TypedDictType, UnionType, Overloaded, ErasedType, PartialType,
     DeletedType, TypeTranslator, UninhabitedType, TypeType, TypeOfAny, LiteralType, ProperType,
     get_proper_type, get_proper_types, TypeAliasType, ParamSpecType, Parameters, UnpackType,
-    TypeVarTupleType
+    TypeVarTupleType, SelfType,
 )
 from mypy.nodes import ARG_STAR, ARG_STAR2
 
@@ -57,6 +57,9 @@ def visit_instance(self, t: Instance) -> ProperType:
     def visit_type_var(self, t: TypeVarType) -> ProperType:
         return AnyType(TypeOfAny.special_form)
 
+    def visit_self_type(self, t: SelfType) -> ProperType:
+        return self.visit_instance(t.instance)
+
     def visit_param_spec(self, t: ParamSpecType) -> ProperType:
         return AnyType(TypeOfAny.special_form)
 

mypy/expandtype.py

@@ -6,7 +6,7 @@
     ErasedType, PartialType, DeletedType, UninhabitedType, TypeType, TypeVarId,
     FunctionLike, TypeVarType, LiteralType, get_proper_type, ProperType,
     TypeAliasType, ParamSpecType, TypeVarLikeType, Parameters, ParamSpecFlavor,
-    UnpackType, TypeVarTupleType
+    UnpackType, TypeVarTupleType, SelfType,
 )
 
 
@@ -100,6 +100,9 @@ def visit_type_var(self, t: TypeVarType) -> Type:
         else:
             return repl
 
+    def visit_self_type(self, t: SelfType) -> Type:
+        return t
+
     def visit_param_spec(self, t: ParamSpecType) -> Type:
         repl = get_proper_type(self.variables.get(t.id, t))
         if isinstance(repl, Instance):

mypy/fixup.py

@@ -11,7 +11,7 @@
     CallableType, Instance, Overloaded, TupleType, TypedDictType,
     TypeVarType, UnboundType, UnionType, TypeVisitor, LiteralType,
     TypeType, NOT_READY, TypeAliasType, AnyType, TypeOfAny, ParamSpecType,
-    Parameters, UnpackType, TypeVarTupleType
+    Parameters, UnpackType, TypeVarTupleType, SelfType,
 )
 from mypy.visitor import NodeVisitor
 from mypy.lookup import lookup_fully_qualified
@@ -246,6 +246,9 @@ def visit_type_var(self, tvt: TypeVarType) -> None:
         if tvt.upper_bound is not None:
             tvt.upper_bound.accept(self)
 
+    def visit_self_type(self, t: SelfType) -> None:
+        return t.instance.accept(self)
+
     def visit_param_spec(self, p: ParamSpecType) -> None:
         p.upper_bound.accept(self)
 

mypy/indirection.py

@@ -64,6 +64,9 @@ def visit_deleted_type(self, t: types.DeletedType) -> Set[str]:
     def visit_type_var(self, t: types.TypeVarType) -> Set[str]:
         return self._visit(t.values) | self._visit(t.upper_bound)
 
+    def visit_self_type(self, t: types.SelfType) -> Set[str]:
+        return set()
+
     def visit_param_spec(self, t: types.ParamSpecType) -> Set[str]:
         return set()
 

mypy/join.py

@@ -8,7 +8,7 @@
     TupleType, TypedDictType, ErasedType, UnionType, FunctionLike, Overloaded, LiteralType,
     PartialType, DeletedType, UninhabitedType, TypeType, TypeOfAny, get_proper_type,
     ProperType, get_proper_types, TypeAliasType, PlaceholderType, ParamSpecType, Parameters,
-    UnpackType, TypeVarTupleType,
+    UnpackType, TypeVarTupleType, SelfType,
 )
 from mypy.maptype import map_instance_to_supertype
 from mypy.subtypes import (
@@ -256,6 +256,9 @@ def visit_type_var(self, t: TypeVarType) -> ProperType:
         else:
             return self.default(self.s)
 
+    def visit_self_type(self, t: SelfType) -> ProperType:
+        return self.join(self.s, t.instance)
+
     def visit_param_spec(self, t: ParamSpecType) -> ProperType:
         if self.s == t:
             return t

mypy/meet.py

@@ -6,7 +6,7 @@
     TupleType, TypedDictType, ErasedType, UnionType, PartialType, DeletedType,
     UninhabitedType, TypeType, TypeOfAny, Overloaded, FunctionLike, LiteralType,
     ProperType, get_proper_type, get_proper_types, TypeAliasType, TypeGuardedType,
-    ParamSpecType, Parameters, UnpackType, TypeVarTupleType, TypeVarLikeType
+    ParamSpecType, Parameters, UnpackType, TypeVarTupleType, SelfType, TypeVarLikeType
 )
 from mypy.subtypes import is_equivalent, is_subtype, is_callable_compatible, is_proper_subtype
 from mypy.erasetype import erase_type
@@ -537,6 +537,9 @@ def visit_type_var(self, t: TypeVarType) -> ProperType:
         else:
             return self.default(self.s)
 
+    def visit_self_type(self, t: SelfType) -> ProperType:
+        return self.meet(self.s, t.instance)
+
     def visit_param_spec(self, t: ParamSpecType) -> ProperType:
         if self.s == t:
             return self.s

mypy/mixedtraverser.py

@@ -5,7 +5,7 @@
     CastExpr, TypeApplication, TypeAliasExpr, TypeVarExpr, TypedDictExpr, NamedTupleExpr,
     PromoteExpr, NewTypeExpr
 )
-from mypy.types import Type
+from mypy.types import Type, SelfType
 from mypy.traverser import TraverserVisitor
 from mypy.typetraverser import TypeTraverserVisitor
 
@@ -41,6 +41,10 @@ def visit_type_var_expr(self, o: TypeVarExpr) -> None:
         for value in o.values:
             value.accept(self)
 
+    def visit_self_type(self, o: SelfType) -> None:
+        super().visit_self_type(o)
+        o.instance.accept(self)
+
     def visit_typeddict_expr(self, o: TypedDictExpr) -> None:
         super().visit_typeddict_expr(o)
         self.visit_optional_type(o.info.typeddict_type)

mypy/sametypes.py

@@ -5,7 +5,7 @@
     UnionType, CallableType, TypeVarType, Instance, TypeVisitor, ErasedType,
     Overloaded, PartialType, DeletedType, UninhabitedType, TypeType, LiteralType,
     ProperType, get_proper_type, TypeAliasType, ParamSpecType, Parameters,
-    UnpackType, TypeVarTupleType,
+    UnpackType, TypeVarTupleType, SelfType,
 )
 from mypy.typeops import tuple_fallback, make_simplified_union, is_simple_literal
 
@@ -114,6 +114,9 @@ def visit_type_var(self, left: TypeVarType) -> bool:
         return (isinstance(self.right, TypeVarType) and
                 left.id == self.right.id)
 
+    def visit_self_type(self, left: SelfType) -> bool:
+        return isinstance(self.right, SelfType) and self.right.instance == left.instance
+
     def visit_param_spec(self, left: ParamSpecType) -> bool:
         # Ignore upper bound since it's derived from flavor.
         return (isinstance(self.right, ParamSpecType) and