Cannot script transforms.Resize with int argument.

[erip]

🐛 Bug

Scripting transforms.Resize with a single int argument fails while scripting with an iterable argument succeeds.

To Reproduce

Steps to reproduce the behavior:

1. $ python -c "import torch; from torchvision import transforms; torch.jit.script(transforms.Resize((256, 256)))"
2. Observe OK.
3. $ python -c "import torch; from torchvision import transforms; torch.jit.script(transforms.Resize(256))"
4. Observe not OK with following:

Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "/Users/erip/miniconda3/envs/img/lib/python3.7/site-packages/torch/jit/_script.py", line 943, in script
    obj, torch.jit._recursive.infer_methods_to_compile
  File "/Users/erip/miniconda3/envs/img/lib/python3.7/site-packages/torch/jit/_recursive.py", line 391, in create_script_module
    return create_script_module_impl(nn_module, concrete_type, stubs_fn)
  File "/Users/erip/miniconda3/envs/img/lib/python3.7/site-packages/torch/jit/_recursive.py", line 452, in create_script_module_impl
    create_methods_and_properties_from_stubs(concrete_type, method_stubs, property_stubs)
  File "/Users/erip/miniconda3/envs/img/lib/python3.7/site-packages/torch/jit/_recursive.py", line 335, in create_methods_and_properties_from_stubs
    concrete_type._create_methods_and_properties(property_defs, property_rcbs, method_defs, method_rcbs, method_defaults)
RuntimeError:

resize(Tensor img, int[] size, Enum<__torch__.torchvision.transforms.functional.InterpolationMode> interpolation=Enum<InterpolationMode.BILINEAR>) -> (Tensor):
Expected a value of type 'List[int]' for argument 'size' but instead found type 'int'.
:
  File "/Users/erip/miniconda3/envs/img/lib/python3.7/site-packages/torchvision/transforms/transforms.py", line 273
            PIL Image or Tensor: Rescaled image.
        """
        return F.resize(img, self.size, self.interpolation)
               ~~~~~~~~ <--- HERE

Expected behavior

transforms.Resize should be scriptable in both cases.

Environment

PyTorch version: 1.8.0
Is debug build: False
CUDA used to build PyTorch: None
ROCM used to build PyTorch: N/A

OS: macOS 11.2.3 (x86_64)
GCC version: Could not collect
Clang version: 12.0.0 (clang-1200.0.32.29)
CMake version: version 3.14.0

Python version: 3.7 (64-bit runtime)
Is CUDA available: False
CUDA runtime version: No CUDA
GPU models and configuration: No CUDA
Nvidia driver version: No CUDA
cuDNN version: No CUDA
HIP runtime version: N/A
MIOpen runtime version: N/A

Versions of relevant libraries:
[pip3] numpy==1.20.2
[pip3] torch==1.8.0
[pip3] torchvision==0.9.0a0
[conda] libblas 3.9.0 8_mkl
[conda] libcblas 3.9.0 8_mkl
[conda] liblapack 3.9.0 8_mkl
[conda] mkl 2020.4 h08c4f10_301
[conda] numpy 1.20.2 py37h84c02c4_0
[conda] pytorch 1.8.0 cpu_py37hb93c03e_0
[conda] torchvision 0.9.0 py37h561b37a_0_cpu

Additional context

[erip]

Ugh. This is documented in the docstring.

[NicolasHug]

Perhaps we should make it more obvious with a .. note: or a .. warning: directive?