[clean strict optional] Fix more strict optional errors (#3292)

Author: ilevkivskyi

mypy/checker.py

@@ -180,6 +180,8 @@ def check_first_pass(self) -> None:
 
         all_ = self.globals.get('__all__')
         if all_ is not None and all_.type is not None:
+            all_node = all_.node
+            assert all_node is not None
             seq_str = self.named_generic_type('typing.Sequence',
                                               [self.named_type('builtins.str')])
             if self.options.python_version[0] < 3:
@@ -188,7 +190,7 @@ def check_first_pass(self) -> None:
             if not is_subtype(all_.type, seq_str):
                 str_seq_s, all_s = self.msg.format_distinctly(seq_str, all_.type)
                 self.fail(messages.ALL_MUST_BE_SEQ_STR.format(str_seq_s, all_s),
-                          all_.node)
+                          all_node)
 
     def check_second_pass(self, todo: List[DeferredNode] = None) -> bool:
         """Run second or following pass of type checking.
@@ -346,12 +348,13 @@ def check_overlapping_overloads(self, defn: OverloadedFuncDef) -> None:
                     self.msg.overloaded_signatures_arg_specific(i + 1, defn.impl)
                 impl_type_subst = impl_type
                 if impl_type.variables:
-                    impl_type_subst = unify_generic_callable(impl_type, sig1, ignore_return=False)
-                    if impl_type_subst is None:
+                    unified = unify_generic_callable(impl_type, sig1, ignore_return=False)
+                    if unified is None:
                         self.fail("Type variable mismatch between " +
                                   "overload signature {} and implementation".format(i + 1),
                                   defn.impl)
                         return
+                    impl_type_subst = unified
                 if not is_subtype(sig1.ret_type, impl_type_subst.ret_type):
                     self.msg.overloaded_signatures_ret_specific(i + 1, defn.impl)
 
@@ -593,7 +596,7 @@ def check_func_def(self, defn: FuncItem, typ: CallableType, name: str) -> None:
                             not isinstance(typ.ret_type, NoneTyp) and
                             not self.dynamic_funcs[-1]):
                         self.fail(messages.MUST_HAVE_NONE_RETURN_TYPE.format(fdef.name()),
-                                  item.type)
+                                  item)
 
                     show_untyped = not self.is_typeshed_stub or self.options.warn_incomplete_stub
                     if self.options.disallow_untyped_defs and show_untyped:
@@ -1257,7 +1260,7 @@ def check_assignment(self, lvalue: Lvalue, rvalue: Expression, infer_lvalue_type
                 self.infer_variable_type(inferred, lvalue, self.expr_checker.accept(rvalue),
                                          rvalue)
 
-    def check_compatibility_all_supers(self, lvalue: NameExpr, lvalue_type: Type,
+    def check_compatibility_all_supers(self, lvalue: NameExpr, lvalue_type: Optional[Type],
                                        rvalue: Expression) -> bool:
         lvalue_node = lvalue.node
 
@@ -1300,8 +1303,9 @@ def check_compatibility_all_supers(self, lvalue: NameExpr, lvalue_type: Type,
                     break
         return False
 
-    def check_compatibility_super(self, lvalue: NameExpr, lvalue_type: Type, rvalue: Expression,
-                                  base: TypeInfo, base_type: Type, base_node: Node) -> bool:
+    def check_compatibility_super(self, lvalue: NameExpr, lvalue_type: Optional[Type],
+                                  rvalue: Expression, base: TypeInfo, base_type: Type,
+                                  base_node: Node) -> bool:
         lvalue_node = lvalue.node
         assert isinstance(lvalue_node, Var)
 
@@ -1574,10 +1578,12 @@ def check_multi_assignment_from_iterable(self, lvalues: List[Lvalue], rvalue_typ
         else:
             self.msg.type_not_iterable(rvalue_type, context)
 
-    def check_lvalue(self, lvalue: Lvalue) -> Tuple[Type, IndexExpr, Var]:
-        lvalue_type = None  # type: Type
-        index_lvalue = None  # type: IndexExpr
-        inferred = None  # type: Var
+    def check_lvalue(self, lvalue: Lvalue) -> Tuple[Optional[Type],
+                                                    Optional[IndexExpr],
+                                                    Optional[Var]]:
+        lvalue_type = None  # type: Optional[Type]
+        index_lvalue = None  # type: Optional[IndexExpr]
+        inferred = None  # type: Optional[Var]
 
         if self.is_definition(lvalue):
             if isinstance(lvalue, NameExpr):
@@ -2750,8 +2756,8 @@ def find_isinstance_check(node: Expression,
         # Check for `x is None` and `x is not None`.
         is_not = node.operators == ['is not']
         if any(is_literal_none(n) for n in node.operands) and (is_not or node.operators == ['is']):
-            if_vars = {}  # type: Dict[Expression, Type]
-            else_vars = {}  # type: Dict[Expression, Type]
+            if_vars = {}  # type: TypeMap
+            else_vars = {}  # type: TypeMap
             for expr in node.operands:
                 if expr.literal == LITERAL_TYPE and not is_literal_none(expr) and expr in type_map:
                     # This should only be true at most once: there should be
@@ -2829,7 +2835,8 @@ def flatten_types(t: Type) -> List[Type]:
         return [t]
 
 
-def get_isinstance_type(expr: Expression, type_map: Dict[Expression, Type]) -> List[TypeRange]:
+def get_isinstance_type(expr: Expression,
+                        type_map: Dict[Expression, Type]) -> Optional[List[TypeRange]]:
     all_types = flatten_types(type_map[expr])
     types = []  # type: List[TypeRange]
     for typ in all_types:

mypy/checkexpr.py

@@ -123,7 +123,7 @@ def visit_name_expr(self, e: NameExpr) -> Type:
         return self.narrow_type_from_binder(e, result)
 
     def analyze_ref_expr(self, e: RefExpr, lvalue: bool = False) -> Type:
-        result = None  # type: Type
+        result = None  # type: Optional[Type]
         node = e.node
         if isinstance(node, Var):
             # Variable reference.
@@ -157,6 +157,7 @@ def analyze_ref_expr(self, e: RefExpr, lvalue: bool = False) -> Type:
             # Unknown reference; use any type implicitly to avoid
             # generating extra type errors.
             result = AnyType()
+        assert result is not None
         return result
 
     def analyze_var_ref(self, var: Var, context: Context) -> Type:
@@ -468,7 +469,8 @@ def analyze_type_type_callee(self, item: Type, context: Context) -> Type:
             # i.e. its constructor (a poor approximation for reality,
             # but better than AnyType...), but replace the return type
             # with typevar.
-            callee = self.analyze_type_type_callee(item.upper_bound, context)
+            callee = self.analyze_type_type_callee(item.upper_bound,
+                                                   context)  # type: Optional[Type]
             if isinstance(callee, CallableType):
                 if callee.is_generic():
                     callee = None

mypy/checkmember.py

@@ -381,7 +381,7 @@ def analyze_class_attribute_access(itype: Instance,
                                    builtin_type: Callable[[str], Instance],
                                    not_ready_callback: Callable[[str, Context], None],
                                    msg: MessageBuilder,
-                                   original_type: Type) -> Type:
+                                   original_type: Type) -> Optional[Type]:
     """original_type is the type of E in the expression E.var"""
     node = itype.type.get(name)
     if not node:
@@ -403,7 +403,9 @@ def analyze_class_attribute_access(itype: Instance,
     t = node.type
     if t:
         if isinstance(t, PartialType):
-            return handle_partial_attribute_type(t, is_lvalue, msg, node.node)
+            symnode = node.node
+            assert symnode is not None
+            return handle_partial_attribute_type(t, is_lvalue, msg, symnode)
         if not is_method and (isinstance(t, TypeVarType) or get_type_vars(t)):
             msg.fail(messages.GENERIC_INSTANCE_VAR_CLASS_ACCESS, context)
         is_classmethod = is_decorated and cast(Decorator, node.node).func.is_class
@@ -515,12 +517,10 @@ def type_object_type_from_function(init_or_new: FuncBase, info: TypeInfo,
     # We need to first map B's __init__ to the type (List[T]) -> None.
     signature = cast(FunctionLike,
                      map_type_from_supertype(signature, info, init_or_new.info))
-
+    special_sig = None  # type: Optional[str]
     if init_or_new.info.fullname() == 'builtins.dict':
         # Special signature!
         special_sig = 'dict'
-    else:
-        special_sig = None
 
     if isinstance(signature, CallableType):
         return class_callable(signature, info, fallback, special_sig)
@@ -630,6 +630,7 @@ class B(A): pass
                                        self_param_type, original_type)[0]
 
         def expand(target: Type) -> Type:
+            assert typearg is not None
             return expand_type(target, {func.variables[0].id: typearg})
 
         arg_types = [expand(x) for x in func.arg_types[1:]]

mypy/constraints.py

@@ -25,7 +25,7 @@ class Constraint:
     It can be either T <: type or T :> type (T is a type variable).
     """
 
-    type_var = None  # Type variable id
+    type_var = None  # type: TypeVarId
     op = 0           # SUBTYPE_OF or SUPERTYPE_OF
     target = None    # type: Type
 
@@ -53,10 +53,11 @@ def infer_constraints_for_callable(
 
     for i, actuals in enumerate(formal_to_actual):
         for actual in actuals:
-            if arg_types[actual] is None:
+            actual_arg_type = arg_types[actual]
+            if actual_arg_type is None:
                 continue
 
-            actual_type = get_actual_type(arg_types[actual], arg_kinds[actual],
+            actual_type = get_actual_type(actual_arg_type, arg_kinds[actual],
                                           tuple_counter)
             c = infer_constraints(callee.arg_types[i], actual_type,
                                   SUPERTYPE_OF)

mypy/exprtotype.py

@@ -50,6 +50,7 @@ def expr_to_unanalyzed_type(expr: Expression) -> Type:
         # Parse string literal type.
         try:
             result = parse_type_comment(expr.value, expr.line, None)
+            assert result is not None
         except SyntaxError:
             raise TypeTranslationError()
         return result

mypy/fastparse.py

@@ -95,7 +95,7 @@ def parse(source: Union[str, bytes], fnam: str = None, errors: Errors = None,
     return tree
 
 
-def parse_type_comment(type_comment: str, line: int, errors: Errors) -> Optional[Type]:
+def parse_type_comment(type_comment: str, line: int, errors: Optional[Errors]) -> Optional[Type]:
     try:
         typ = ast3.parse(type_comment, '<type_comment>', 'eval')
     except SyntaxError as e:

mypy/infer.py

@@ -12,7 +12,7 @@ def infer_function_type_arguments(callee_type: CallableType,
                                   arg_types: List[Optional[Type]],
                                   arg_kinds: List[int],
                                   formal_to_actual: List[List[int]],
-                                  strict: bool = True) -> List[Type]:
+                                  strict: bool = True) -> List[Optional[Type]]:
     """Infer the type arguments of a generic function.
 
     Return an array of lower bound types for the type variables -1 (at
@@ -36,7 +36,7 @@ def infer_function_type_arguments(callee_type: CallableType,
 
 
 def infer_type_arguments(type_var_ids: List[TypeVarId],
-                         template: Type, actual: Type) -> List[Type]:
+                         template: Type, actual: Type) -> List[Optional[Type]]:
     # Like infer_function_type_arguments, but only match a single type
     # against a generic type.
     constraints = infer_constraints(template, actual, SUBTYPE_OF)

mypy/join.py

@@ -1,7 +1,7 @@
 """Calculation of the least upper bound types (joins)."""
 
 from collections import OrderedDict
-from typing import cast, List
+from typing import cast, List, Optional
 
 from mypy.types import (
     Type, AnyType, NoneTyp, TypeVisitor, Instance, UnboundType,
@@ -305,7 +305,7 @@ def join_instances_via_supertype(t: Instance, s: Instance) -> Type:
     # Compute the "best" supertype of t when joined with s.
     # The definition of "best" may evolve; for now it is the one with
     # the longest MRO.  Ties are broken by using the earlier base.
-    best = None  # type: Type
+    best = None  # type: Optional[Type]
     for base in t.type.bases:
         mapped = map_instance_to_supertype(t, base.type)
         res = join_instances(mapped, s)

mypy/meet.py

@@ -1,5 +1,5 @@
 from collections import OrderedDict
-from typing import List, Optional
+from typing import List, Optional, cast, Tuple
 
 from mypy.join import is_similar_callables, combine_similar_callables, join_type_list
 from mypy.types import (
@@ -255,10 +255,15 @@ def visit_typeddict_type(self, t: TypedDictType) -> Type:
             for (_, l, r) in self.s.zip(t):
                 if not is_equivalent(l, r):
                     return self.default(self.s)
-            items = OrderedDict([
-                (item_name, s_item_type or t_item_type)
-                for (item_name, s_item_type, t_item_type) in self.s.zipall(t)
-            ])
+            item_list = []  # type: List[Tuple[str, Type]]
+            for (item_name, s_item_type, t_item_type) in self.s.zipall(t):
+                if s_item_type is not None:
+                    item_list.append((item_name, s_item_type))
+                else:
+                    # at least one of s_item_type and t_item_type is not None
+                    assert t_item_type is not None
+                    item_list.append((item_name, t_item_type))
+            items = OrderedDict(item_list)
             mapping_value_type = join_type_list(list(items.values()))
             fallback = self.s.create_anonymous_fallback(value_type=mapping_value_type)
             return TypedDictType(items, fallback)