Revert "For class variables, lookup type in base classes (#1338, #2022, #2211)"

Author: gvanrossum

mypy/checker.py

@@ -36,17 +36,14 @@
 from mypy.sametypes import is_same_type
 from mypy.messages import MessageBuilder
 import mypy.checkexpr
-from mypy.checkmember import (
-    map_type_from_supertype, bind_self, erase_to_bound, find_type_from_bases
-)
+from mypy.checkmember import map_type_from_supertype, bind_self, erase_to_bound
 from mypy import messages
 from mypy.subtypes import (
     is_subtype, is_equivalent, is_proper_subtype, is_more_precise, restrict_subtype_away,
     is_subtype_ignoring_tvars
 )
 from mypy.maptype import map_instance_to_supertype
-from mypy.typevars import fill_typevars
-from mypy.semanal import set_callable_name, refers_to_fullname
+from mypy.semanal import fill_typevars, set_callable_name, refers_to_fullname
 from mypy.erasetype import erase_typevars
 from mypy.expandtype import expand_type
 from mypy.visitor import NodeVisitor
@@ -1116,16 +1113,6 @@ def check_assignment(self, lvalue: Lvalue, rvalue: Expression, infer_lvalue_type
         else:
             lvalue_type, index_lvalue, inferred = self.check_lvalue(lvalue)
             if lvalue_type:
-                if isinstance(lvalue, NameExpr):
-                    base_type = find_type_from_bases(lvalue)
-
-                    # If a type is known, validate the type is a subtype of the base type
-                    if base_type:
-                        self.check_subtype(lvalue_type, base_type, lvalue,
-                                           messages.INCOMPATIBLE_TYPES_IN_ASSIGNMENT,
-                                           'expression has type',
-                                           'variable has type')
-
                 if isinstance(lvalue_type, PartialType) and lvalue_type.type is None:
                     # Try to infer a proper type for a variable with a partial None type.
                     rvalue_type = self.accept(rvalue)

mypy/checkexpr.py

@@ -38,7 +38,7 @@
 from mypy.checkstrformat import StringFormatterChecker
 from mypy.expandtype import expand_type
 from mypy.util import split_module_names
-from mypy.typevars import fill_typevars
+from mypy.semanal import fill_typevars
 
 from mypy import experiments
 

mypy/checkmember.py

@@ -7,17 +7,14 @@
     Overloaded, TypeVarType, UnionType, PartialType,
     DeletedType, NoneTyp, TypeType, function_type
 )
-from mypy.nodes import (
-    TypeInfo, FuncBase, Var, FuncDef, SymbolNode, Context, MypyFile, MDEF,
-    NameExpr
-)
+from mypy.nodes import TypeInfo, FuncBase, Var, FuncDef, SymbolNode, Context, MypyFile
 from mypy.nodes import ARG_POS, ARG_STAR, ARG_STAR2
 from mypy.nodes import Decorator, OverloadedFuncDef
 from mypy.messages import MessageBuilder
 from mypy.maptype import map_instance_to_supertype
 from mypy.expandtype import expand_type_by_instance, expand_type
 from mypy.infer import infer_type_arguments
-from mypy.typevars import fill_typevars, has_no_typevars
+from mypy.semanal import fill_typevars
 from mypy import messages
 from mypy import subtypes
 MYPY = False
@@ -619,34 +616,3 @@ def erase_to_bound(t: Type):
         if isinstance(t.item, TypeVarType):
             return TypeType(t.item.upper_bound)
     return t
-
-
-def find_type_from_bases(e: NameExpr):
-    """For a NameExpr that is part of a class, walk all base classes and try
-    to find the first class that defines a Type for the same name."""
-
-    expr_node = e.node
-    if not (isinstance(expr_node, Var) and e.kind == MDEF and
-            len(expr_node.info.bases) > 0):
-        return None
-
-    expr_name = expr_node.name()
-    expr_base = expr_node.info.bases[0]
-
-    for base in expr_node.info.mro[1:]:
-        base_var = base.names.get(expr_name)
-        if base_var and base_var.type:
-            if has_no_typevars(base_var.type):
-                base_type = base_var.type
-            else:
-                itype = map_instance_to_supertype(expr_base, base)
-                base_type = expand_type_by_instance(base_var.type, itype)
-
-            if isinstance(base_type, CallableType):
-                # If we are a property, return the Type of the return value, not the Callable
-                if isinstance(base_var.node, Decorator) and base_var.node.func.is_property:
-                    base_type = base_type.ret_type
-                elif isinstance(base_var.node, FuncDef) and base_var.node.is_property:
-                    base_type = base_type.ret_type
-
-            return base_type

mypy/semanal.py

@@ -48,7 +48,6 @@
     List, Dict, Set, Tuple, cast, TypeVar, Union, Optional, Callable
 )
 
-from mypy.checkmember import find_type_from_bases
 from mypy.nodes import (
     MypyFile, TypeInfo, Node, AssignmentStmt, FuncDef, OverloadedFuncDef,
     ClassDef, Var, GDEF, MODULE_REF, FuncItem, Import, Expression, Lvalue,
@@ -68,7 +67,6 @@
     IntExpr, FloatExpr, UnicodeExpr, EllipsisExpr, TempNode,
     COVARIANT, CONTRAVARIANT, INVARIANT, UNBOUND_IMPORTED, LITERAL_YES,
 )
-from mypy.typevars import has_no_typevars, fill_typevars
 from mypy.visitor import NodeVisitor
 from mypy.traverser import TraverserVisitor
 from mypy.errors import Errors, report_internal_error
@@ -81,6 +79,7 @@
 from mypy.typeanal import TypeAnalyser, TypeAnalyserPass3, analyze_type_alias
 from mypy.exprtotype import expr_to_unanalyzed_type, TypeTranslationError
 from mypy.sametypes import is_same_type
+from mypy.erasetype import erase_typevars
 from mypy.options import Options
 from mypy import join
 
@@ -1163,15 +1162,11 @@ def visit_assignment_stmt(self, s: AssignmentStmt) -> None:
             s.type = self.anal_type(s.type, allow_tuple_literal)
         else:
             # For simple assignments, allow binding type aliases.
-            # Also use the type of the base class if available, or
-            # set the type if the rvalue is a simple literal.
+            # Also set the type if the rvalue is a simple literal.
             if (s.type is None and len(s.lvalues) == 1 and
                     isinstance(s.lvalues[0], NameExpr)):
                 if s.lvalues[0].is_def:
-                    s.type = find_type_from_bases(s.lvalues[0])
-                    if s.type is None:
-                        s.type = self.analyze_simple_literal_type(s.rvalue)
-
+                    s.type = self.analyze_simple_literal_type(s.rvalue)
                 res = analyze_type_alias(s.rvalue,
                                          self.lookup_qualified,
                                          self.lookup_fully_qualified,
@@ -3135,6 +3130,19 @@ def builtin_type(self, name: str, args: List[Type] = None) -> Instance:
         return Instance(sym.node, args or [])
 
 
+def fill_typevars(typ: TypeInfo) -> Union[Instance, TupleType]:
+    """For a non-generic type, return instance type representing the type.
+    For a generic G type with parameters T1, .., Tn, return G[T1, ..., Tn].
+    """
+    tv = []  # type: List[Type]
+    for i in range(len(typ.type_vars)):
+        tv.append(TypeVarType(typ.defn.type_vars[i]))
+    inst = Instance(typ, tv)
+    if typ.tuple_type is None:
+        return inst
+    return typ.tuple_type.copy_modified(fallback=inst)
+
+
 def replace_implicit_first_type(sig: FunctionLike, new: Type) -> FunctionLike:
     if isinstance(sig, CallableType):
         return sig.copy_modified(arg_types=[new] + sig.arg_types[1:])
@@ -3506,3 +3514,7 @@ def find_fixed_callable_return(expr: Expression) -> Optional[CallableType]:
             if isinstance(t.ret_type, CallableType):
                 return t.ret_type
     return None
+
+
+def has_no_typevars(typ: Type) -> bool:
+    return is_same_type(typ, erase_typevars(typ))

mypy/typevars.py

@@ -2123,153 +2123,3 @@ class B(object, A): # E: Cannot determine consistent method resolution order (MR
 # flags: --fast-parser
 class C(metaclass=int()):  # E: Dynamic metaclass not supported for 'C'
     pass
-
-[case testVariableSubclass]
-class A:
-    a = 1  # type: int
-class B(A):
-    a = 1
-[out]
-
-[case testVariableSubclassAssignMismatch]
-class A:
-    a = 1  # type: int
-class B(A):
-    a = "a"
-[out]
-main: note: In class "B":
-main:4: error: Incompatible types in assignment (expression has type "str", variable has type "int")
-
-[case testVariableSubclassAssignment]
-class A:
-    a = None  # type: int
-class B(A):
-    def __init__(self) -> None:
-        self.a = "a"
-[out]
-main: note: In member "__init__" of class "B":
-main:5: error: Incompatible types in assignment (expression has type "str", variable has type "int")
-
-[case testVariableSubclassTypeOverwrite]
-class A:
-    a = None  # type: int
-class B(A):
-    a = None  # type: str
-class C(B):
-    a = "a"
-[out]
-main: note: In class "B":
-main:4: error: Incompatible types in assignment (expression has type "str", variable has type "int")
-
-[case testVariableSubclassTypeOverwriteImplicit]
-class A:
-    a = 1
-class B(A):
-    a = None  # type: str
-[out]
-main: note: In class "B":
-main:4: error: Incompatible types in assignment (expression has type "str", variable has type "int")
-
-[case testVariableSuperUsage]
-class A:
-    a = []  # type: list
-class B(A):
-    a = [1, 2]
-class C(B):
-    a = B.a + [3]
-[builtins fixtures/list.pyi]
-[out]
-
-[case testVariableRvalue]
-class A:
-    a = None
-class B(A):
-    a = 1
-class C(B):
-    a = "a"
-[out]
-main: note: In class "A":
-main:2: error: Need type annotation for variable
-main: note: In class "C":
-main:6: error: Incompatible types in assignment (expression has type "str", variable has type "int")
-
-[case testVariableTypeVar]
-from typing import TypeVar, Generic
-T = TypeVar('T')
-class A(Generic[T]):
-    a = None  # type: T
-class B(A[int]):
-    a = 1
-
-[case testVariableTypeVarInvalid]
-from typing import TypeVar, Generic
-T = TypeVar('T')
-class A(Generic[T]):
-    a = None  # type: T
-class B(A[int]):
-    a = "abc"
-[out]
-main: note: In class "B":
-main:6: error: Incompatible types in assignment (expression has type "str", variable has type "int")
-
-[case testVariableTypeVarIndirectly]
-from typing import TypeVar, Generic
-T = TypeVar('T')
-class A(Generic[T]):
-    a = None  # type: T
-class B(A[int]):
-    pass
-class C(B):
-    a = "a"
-[out]
-main: note: In class "C":
-main:8: error: Incompatible types in assignment (expression has type "str", variable has type "int")
-
-[case testVariableTypeVarList]
-from typing import List, TypeVar, Generic
-T = TypeVar('T')
-class A(Generic[T]):
-    a = None  # type: List[T]
-    b = None  # type: List[T]
-class B(A[int]):
-    a = [1]
-    b = ['']
-[builtins fixtures/list.pyi]
-[out]
-main: note: In class "B":
-main:8: error: List item 0 has incompatible type "str"
-
-[case testVariableMethod]
-class A:
-    def a(self) -> None: pass
-    b = 1
-class B(A):
-    a = 1
-    def b(self) -> None: pass
-[out]
-main: note: In class "B":
-main:5: error: Incompatible types in assignment (expression has type "int", variable has type Callable[[A], None])
-main:6: error: Signature of "b" incompatible with supertype "A"
-
-[case testVariableProperty]
-class A:
-    @property
-    def a(self) -> bool: pass
-class B(A):
-    a = None  # type: bool
-class C(A):
-    a = True
-class D(A):
-    a = 1
-[builtins fixtures/property.pyi]
-[out]
-main: note: In class "D":
-main:9: error: Incompatible types in assignment (expression has type "int", variable has type "bool")
-
-[case testVariableOverwriteAny]
-from typing import Any
-class A:
-    a = 1
-class B(A):
-    a = 'x'  # type: Any
-[out]