Method visit_dict_expr

mypy/checkexpr.py:5450–5531

Type check a dict expression. Translate it into a call to dict(), with provisions for **expr.

(self, e: DictExpr)

        return typeddict_context.copy_modified()

    def visit_dict_expr(self, e: DictExpr) -> Type:
        """Type check a dict expression.

        Translate it into a call to dict(), with provisions for **expr.
        """
        # if the dict literal doesn't match TypedDict, check_typeddict_call_with_dict reports
        # an error, but returns the TypedDict type that matches the literal it found
        # that would cause a second error when that TypedDict type is returned upstream
        # to avoid the second error, we always return TypedDict type that was requested
        typeddict_contexts, exhaustive = self.find_typeddict_context(self.type_context[-1], e)
        if typeddict_contexts:
            if len(typeddict_contexts) == 1 and exhaustive:
                return self.check_typeddict_literal_in_context(e, typeddict_contexts[0])
            # Multiple items union, check if at least one of them matches cleanly.
            for typeddict_context in typeddict_contexts:
                with self.msg.filter_errors() as err, self.chk.local_type_map as tmap:
                    ret_type = self.check_typeddict_literal_in_context(e, typeddict_context)
                if err.has_new_errors():
                    continue
                self.chk.store_types(tmap)
                return ret_type
            # No item matched without an error, so we can't unambiguously choose the item.
            if exhaustive:
                self.msg.typeddict_context_ambiguous(typeddict_contexts, e)

        # fast path attempt
        dt = self.fast_dict_type(e)
        if dt:
            return dt

        # Define type variables (used in constructors below).
        kt = TypeVarType(
            "KT",
            "KT",
            id=TypeVarId(-1, namespace="<dict>"),
            values=[],
            upper_bound=self.object_type(),
            default=AnyType(TypeOfAny.from_omitted_generics),
        )
        vt = TypeVarType(
            "VT",
            "VT",
            id=TypeVarId(-2, namespace="<dict>"),
            values=[],
            upper_bound=self.object_type(),
            default=AnyType(TypeOfAny.from_omitted_generics),
        )

        # Collect function arguments, watching out for **expr.
        args: list[Expression] = []
        expected_types: list[Type] = []
        for key, value in e.items:
            if key is None:
                args.append(value)
                expected_types.append(
                    self.chk.named_generic_type("_typeshed.SupportsKeysAndGetItem", [kt, vt])
                )
            else: