Method visit_op_expr

mypy/checkexpr.py:3555–3662

Type check a binary operator expression.

(self, e: OpExpr)

        return self.named_type("builtins.ellipsis")

    def visit_op_expr(self, e: OpExpr) -> Type:
        """Type check a binary operator expression."""
        if e.analyzed:
            # It's actually a type expression X | Y.
            return self.accept(e.analyzed)
        if e.op == "and" or e.op == "or":
            return self.check_boolean_op(e)
        if e.op == "*" and isinstance(e.left, ListExpr):
            # Expressions of form [...] * e get special type inference.
            return self.check_list_multiply(e)
        if e.op == "%":
            if isinstance(e.left, BytesExpr):
                return self.strfrm_checker.check_str_interpolation(e.left, e.right)
            if isinstance(e.left, StrExpr):
                return self.strfrm_checker.check_str_interpolation(e.left, e.right)
        left_type = self.accept(e.left)

        proper_left_type = get_proper_type(left_type)
        if isinstance(proper_left_type, TupleType) and e.op == "+":
            left_add_method = proper_left_type.partial_fallback.type.get("__add__")
            if left_add_method and left_add_method.fullname == "builtins.tuple.__add__":
                proper_right_type = get_proper_type(self.accept(e.right))
                if isinstance(proper_right_type, TupleType):
                    right_radd_method = proper_right_type.partial_fallback.type.get("__radd__")
                    if right_radd_method is None:
                        # One cannot have two variadic items in the same tuple.
                        if (
                            find_unpack_in_list(proper_left_type.items) is None
                            or find_unpack_in_list(proper_right_type.items) is None
                        ):
                            return self.concat_tuples(proper_left_type, proper_right_type)
                elif (
                    PRECISE_TUPLE_TYPES in self.chk.options.enable_incomplete_feature
                    and isinstance(proper_right_type, Instance)
                    and self.chk.type_is_iterable(proper_right_type)
                ):
                    # Handle tuple[X, Y] + tuple[Z, ...] = tuple[X, Y, *tuple[Z, ...]].
                    right_radd_method = proper_right_type.type.get("__radd__")
                    if (
                        right_radd_method is None
                        and proper_left_type.partial_fallback.type.fullname == "builtins.tuple"
                        and find_unpack_in_list(proper_left_type.items) is None
                    ):
                        item_type = self.chk.iterable_item_type(proper_right_type, e)
                        mapped = self.chk.named_generic_type("builtins.tuple", [item_type])
                        return proper_left_type.copy_modified(
                            items=proper_left_type.items + [UnpackType(mapped)]
                        )

        use_reverse: UseReverse = USE_REVERSE_DEFAULT
        if e.op == "|":
            if is_named_instance(proper_left_type, "builtins.dict"):
                # This is a special case for `dict | TypedDict`.
                # 1. Find `dict | TypedDict` case
                # 2. Switch `dict.__or__` to `TypedDict.__ror__` (the same from both runtime and typing perspective)
                proper_right_type = get_proper_type(self.accept(e.right))
                if isinstance(proper_right_type, TypedDictType):
                    use_reverse = USE_REVERSE_ALWAYS