Append ref qualifier to signed-as type on 'this'

[slburson]

This PR goes with libresect #13 and cl-resect #1.

The problem was that I was getting duplicate-definition errors from SBCL (well, it calls them warnings, but then it aborts compilation) on operator= methods. The cause turned out to be that some pairs of these in libtorch were distinguished only by ref qualifiers, which Claw was not capturing. So then iffi:defifun would emit defuns for both of them, causing the error.

I have arranged for the qualifier to appear in the :signed-as type for the this parameter.

[borodust]

Can you drop a link to the header with the offending C++ functions? I would like to have a look what libtorch does.

[slburson]

Here are some examples. There are others.

• https://github.com/pytorch/pytorch/blob/3846afb154f4f3681e11e606cba6022b359dbe11/aten/src/ATen/templates/TensorBody.h#L213 (compare line 225)
• https://github.com/pytorch/pytorch/blob/3846afb154f4f3681e11e606cba6022b359dbe11/aten/src/ATen/core/TensorBase.h#L230

[borodust]

Hm-m. I was pretty sure I've added support for these kinds, because I've had similar issues in the libraries I'd wrapped. I'll have another look.

[borodust]

Like these

[borodust]

C++ methods with different signatures should have had different mangled names and that should have guaranteed unique defun expansions. It's strange you've got the warning from SBCL. Did the methods have the same mangled name in your case?

[slburson]

The mangled names were different, but the Lisp names were the same. The signed-param-types computed in iffi:defifun were also the same. defifun suppresses the defun in all but one case, where those cases are distinguished by signed-param-types. So if two defifun forms for the same name have the same signed-param-types, it will emit defun forms for both of them.

[slburson]

Oh, when SBCL says "duplicate definition" it doesn't mean the two defun forms were identical; it just means they defined the same symbol.

[slburson]

Output from the first link above, before my change (ignore the slight discrepancy in line numbers):

(iffi:defifun ("__claw__ZNR2at6TensoraSEOS0_" %torch::at+operator=)
    (:pointer %torch::at+tensor)
  "Tensor &at::Tensor::operator=(Tensor &&x) & noexcept;
/home/gyro/Repos/Claw-Torch/src/lib/torch-bin/include/ATen/core/TensorBody.h:214:11"
  (%torch::%%claw-this- (:pointer %torch::at+tensor))
  (%torch::x (:pointer %torch::at+tensor) :signed-as (:reference %torch::at+tensor :rvalue)))

(iffi:defifun ("__claw__ZNO2at6TensoraSEOS0_" %torch::at+operator=)
    (:pointer %torch::at+tensor)
  "Tensor &at::Tensor::operator=(Tensor &&rhs) &&;
/home/gyro/Repos/Claw-Torch/src/lib/torch-bin/include/ATen/core/TensorBody.h:226:11"
  (%torch::%%claw-this- (:pointer %torch::at+tensor))
  (%torch::rhs (:pointer %torch::at+tensor) :signed-as (:reference %torch::at+tensor :rvalue)))

After the change:

(iffi:defifun ("__claw__ZNR2at6TensoraSEOS0_" %torch::at+operator=)
    (:pointer %torch::at+tensor)
  "Tensor &at::Tensor::operator=(Tensor &&x) & noexcept;
/home/gyro/Repos/Claw-Torch/libtorch/include/ATen/core/TensorBody.h:214:11"
  (%torch::%%claw-this- (:pointer %torch::at+tensor) :signed-as (:pointer %torch::at+tensor :lvalue))
  (%torch::x (:pointer %torch::at+tensor) :signed-as (:reference %torch::at+tensor :rvalue)))

(iffi:defifun ("__claw__ZNO2at6TensoraSEOS0_" %torch::at+operator=)
    (:pointer %torch::at+tensor)
  "Tensor &at::Tensor::operator=(Tensor &&rhs) &&;
/home/gyro/Repos/Claw-Torch/libtorch/include/ATen/core/TensorBody.h:226:11"
  (%torch::%%claw-this- (:pointer %torch::at+tensor) :signed-as (:pointer %torch::at+tensor :rvalue))
  (%torch::rhs (:pointer %torch::at+tensor) :signed-as (:reference %torch::at+tensor :rvalue)))

[slburson]

The scope of this PR has expanded slightly, with a few other fixes:

• I modified claw.resect:parse-methods to skip deleted methods. (I also noticed that claw.spec:foreign-method-deleted-p was never used nor set, so I removed it.)
• Two other small tweaks were necessary for certain rare cases of overload resolution: on const methods, declaring __claw_this_ as a pointer to const, and on rvalue methods, calling std::move in the right spot to generate an rvalue.