Method __post_init__

torchgen/model.py:1369–1465

(self)

        )

    def __post_init__(self) -> None:
        for arg, ret in zip(self.arguments.out, self.returns):
            assert arg.annotation == ret.annotation, (
                "Out arguments must have matching return Tensor; furthermore, "
                "the ith-argument needs to correspond to the ith return"
            )
        # We also enforce that if you have any mutable, positional args, then they are not returned.
        # This makes it easier to group these functions properly with their functional/out= counterparts.
        for a in self.arguments.post_self_positional_mutable:
            assert not any(
                a.annotation == r.annotation for r in self.returns
            ), f"If you have a schema with mutable positional args, we expect them to not be returned. schema: {str(self)}"
        # Invariant: we expect out arguments to appear as keyword arguments in the schema.
        # This means that all mutable returns should be aliased to a keyword argument
        # (except for "self", which we explicitly don't treat as an out argument because of its use in methods)
        # See Note [is_out_fn]
        out_and_self = list(self.arguments.out) + [
            arg for arg in self.arguments.flat_positional if arg.name == "self"
        ]
        mutable_returns = [
            ret
            for ret in self.returns
            if ret.annotation is not None and ret.annotation.is_write
        ]
        immutable_returns = [
            ret
            for ret in self.returns
            if ret.annotation is None or not ret.annotation.is_write
        ]
        # Some assertions: We don't want any functions with a return type of "-> (Tensor(a!), Tensor)",
        # because:
        # (1) It's more annoying to handle properly
        # (2) It's unnecessary - you can't method-chain on the first (mutated) output because it's part of a tuple.
        # Instead, we expect the (a!) argument to not be returned.
        assert (
            len(mutable_returns) == 0 or len(immutable_returns) == 0
        ), f"NativeFunctions must have either only mutable returns, or only immutable returns. Found: {str(self)}"
        for ret in mutable_returns:
            assert any(ret.annotation == arg.annotation for arg in out_and_self), (
                'All mutable returns must be aliased either to a keyword argument, or to "self". '
                "Did you forget to mark an out argument as keyword-only?"
            )
        if self.arguments.out:
            # out= ops that return their mutable inputs are only really useful for method chaining.
            # And method chaining is only really useful if the thing you're returning is a plain Tensor.
            # So ideally, we'd enforce that out= ops with a single plain mutable tensor should return the tensor,
            # and all other types of out= op schemas should return void.
            # There are a bunch of existing out= ops that return tuples of tensors though, so we're stuck with allowing that.
            if any(a.type != BaseType(BaseTy.Tensor) for a in self.arguments.out):
                assert (
                    len(self.returns) == 0
                ), "out= ops that accept tensor lists as out arguments "
                "are expected to have no return type (since you can't do method chaining on them)"
            else:
                # mutable keyword arguments whose name has _scratch_ prefix are
                # scratch tensors for memory planning and should not be returned
                assert len(
                    [