Docs for Installing C++ Distributions of PyTorch needs update

[oicid]

📚 Documentation

In the C++ docs, it writes:

The first step is to download the LibTorch ZIP archive via the link above. For example:
wget https://download.pytorch.org/libtorch/nightly/cpu/libtorch-shared-with-deps-latest.zip
unzip libtorch-shared-with-deps-latest.zip

Note that the above link has CPU-only libtorch. If you would like to download a GPU-enabled libtorch, find the right link in the link selector on https://pytorch.org

However, the wget links to a GPU version libtorch. I followed this tutorial on Ubuntu 20.04.2 LTS (GNU/Linux 5.4.0-73-generic x86_64), when I run cmake -DCMAKE_PREFIX_PATH=/absolute/path/to/libtorch .., I got a CMAKE error Imported target "torch" includes non-existent path "/pytorch/torch/lib":

-- The CXX compiler identification is GNU 9.3.0
-- Check for working CXX compiler: /usr/bin/c++
-- Check for working CXX compiler: /usr/bin/c++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Looking for pthread.h
-- Looking for pthread.h - found
-- Performing Test CMAKE_HAVE_LIBC_PTHREAD
-- Performing Test CMAKE_HAVE_LIBC_PTHREAD - Failed
-- Looking for pthread_create in pthreads
-- Looking for pthread_create in pthreads - not found
-- Looking for pthread_create in pthread
-- Looking for pthread_create in pthread - found
-- Found Threads: TRUE
-- Found Torch: /root/libtorch/lib/libtorch.so
-- Configuring done
CMake Error in CMakeLists.txt:
  Imported target "torch" includes non-existent path

    "/pytorch/torch/lib"

  in its INTERFACE_INCLUDE_DIRECTORIES.  Possible reasons include:

  * The path was deleted, renamed, or moved to another location.
  * An install or uninstall procedure did not complete successfully.

  * The installation package was faulty and references files it does not
  provide.



CMake Error in CMakeLists.txt:
  Imported target "torch" includes non-existent path

    "/pytorch/torch/lib"

  in its INTERFACE_INCLUDE_DIRECTORIES.  Possible reasons include:

  * The path was deleted, renamed, or moved to another location.

  * An install or uninstall procedure did not complete successfully.

  * The installation package was faulty and references files it does not
  provide.


-- Generating done
CMake Generate step failed.  Build files cannot be regenerated correctly.

I checked some issues, and they said it's because the CUDA were not installed correctly. But I run it on the cheapest virtual server on Digital Ocean, and there's no GPU... Could it be that I downloaded the wrong one? But I was just following the docs...

Finally I deleted this version libtorch and downloaded a cpu version from https://pytorch.org/get-started/locally/ . Then everything went well as expected.

So I think shall we update the docs?

cc @brianjo @mruberry

[mruberry]

@malfet Is there a more accurate label than "docs" for this?