Poetry fails resolving PyTorch on MacOS

[ralbertazzi]

• Poetry version: 1.5.0 dev (post poetry-core 1.6 PR)
• Python version: 3.9
• OS version and name: MacOS Monterey 12.5.1, Apple M1
• pyproject.toml:

  
  [tool.poetry]
  authors = ["Riccardo Albertazzi <email@email.com>"]
  description = "Hello world"
  name = "torch-project"
  version = "0.1.0"

[[tool.poetry.source]] name = "torch-cpu" priority = "explicit" url = "https://download.pytorch.org/whl/cpu"

[tool.poetry.dependencies] python = "~3.9"

torch = { version = "2.0.1", source = "torch-cpu" }

[build-system] build-backend = "poetry.core.masonry.api" requires = ["poetry-core>=1.5.0"]

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- [x] I am on the [latest](https://github.com/python-poetry/poetry/releases/latest) stable Poetry version, installed using a recommended method.
- [x] I have searched the [issues](https://github.com/python-poetry/poetry/issues) of this repo and believe that this is not a duplicate. Possibly related: https://github.com/python-poetry/poetry/issues/2543
- [x] I have consulted the [FAQ](https://python-poetry.org/docs/faq/) and [blog](https://python-poetry.org/blog/) for any relevant entries or release notes.
- [x] If an exception occurs when executing a command, I executed it again in debug mode (`-vvv` option) and have included the output below.

Configuration file exists at /Users/ra/Library/Preferences/pypoetry, reusing this directory.

Consider moving TOML configuration files to /Users/ra/Library/Application Support/pypoetry, as support for the legacy directory will be removed in an upcoming release. Loading configuration file /Users/ra/Library/Preferences/pypoetry/config.toml Loading configuration file /Users/ra/Library/Preferences/pypoetry/auth.toml Adding repository torch-cpu (https://download.pytorch.org/whl/cpu) and setting it as explicit Using virtualenv: /Users/ra/projects/poetry/.venv Updating dependencies Resolving dependencies... 1: fact: torch-project is 0.1.0 1: derived: torch-project 1: fact: torch-project depends on torch (2.0.1) 1: selecting torch-project (0.1.0) 1: derived: torch (==2.0.1) [keyring.backend] Loading KWallet [keyring.backend] Loading SecretService [keyring.backend] Loading Windows [keyring.backend] Loading chainer [keyring.backend] Loading libsecret [keyring.backend] Loading macOS Creating new session for download.pytorch.org [urllib3.connectionpool] Starting new HTTPS connection (1): download.pytorch.org:443 [urllib3.connectionpool] https://download.pytorch.org:443 "GET /whl/cpu/torch/ HTTP/1.1" 200 64566 Source (torch-cpu): 2 packages found for torch 2.0.1 1: selecting torch (2.0.1+cpu) 1: Version solving took 0.784 seconds. 1: Tried 1 solutions.

Finding the necessary packages for the current system Source (poetry-repo): 1 packages found for torch 2.0.1

Package operations: 1 install, 0 updates, 0 removals

• Installing torch (2.0.1+cpu): Pending... Skipping wheel torch-2.0.1+cpu-cp310-cp310-linux_x86_64.whl as this is not supported by the current environment Skipping wheel torch-2.0.1+cpu-cp310-cp310-win_amd64.whl as this is not supported by the current environment Skipping wheel torch-2.0.1+cpu-cp311-cp311-linux_x86_64.whl as this is not supported by the current environment Skipping wheel torch-2.0.1+cpu-cp311-cp311-win_amd64.whl as this is not supported by the current environment Skipping wheel torch-2.0.1+cpu-cp38-cp38-linux_x86_64.whl as this is not supported by the current environment Skipping wheel torch-2.0.1+cpu-cp38-cp38-win_amd64.whl as this is not supported by the current environment Skipping wheel torch-2.0.1+cpu-cp39-cp39-linux_x86_64.whl as this is not supported by the current environment Skipping wheel torch-2.0.1+cpu-cp39-cp39-win_amd64.whl as this is not supported by the current environment • Installing torch (2.0.1+cpu): Failed

Stack trace:

5 ~/projects/poetry/src/poetry/installation/executor.py:286 in _execute_operation 284│ 285│ try: → 286│ result = self._do_execute_operation(operation) 287│ except EnvCommandError as e: 288│ if e.e.returncode == -2:

4 ~/projects/poetry/src/poetry/installation/executor.py:388 in _do_execute_operation 386│ return 0 387│ → 388│ result: int = getattr(self, f"execute{method}")(operation) 389│ 390│ if result != 0:

3 ~/projects/poetry/src/poetry/installation/executor.py:508 in _execute_install 506│ 507│ def _execute_install(self, operation: Install | Update) -> int: → 508│ status_code = self._install(operation) 509│ 510│ self._save_url_reference(operation)

2 ~/projects/poetry/src/poetry/installation/executor.py:546 in _install 544│ archive = self._download_link(operation, Link(package.source_url)) 545│ else: → 546│ archive = self._download(operation) 547│ 548│ operation_message = self.get_operation_message(operation)

1 ~/projects/poetry/src/poetry/installation/executor.py:736 in _download 734│ 735│ def _download(self, operation: Install | Update) -> Path: → 736│ link = self._chooser.choose_for(operation.package) 737│ 738│ if link.yanked:

RuntimeError

Unable to find installation candidates for torch (2.0.1+cpu)

at ~/projects/poetry/src/poetry/installation/chooser.py:76 in choose_for 72│ 73│ links.append(link) 74│ 75│ if not links: → 76│ raise RuntimeError(f"Unable to find installation candidates for {package}") 77│ 78│ # Get the best link 79│ chosen = max(links, key=lambda link: self._sort_key(package, link)) 80│

## Issue

Poetry fails resolving Poetry on MacOS and I think this is due to local identifiers. I don't know what's the right course of action here so I'm asking support from the core maintainers.

The PyTorch repository at https://download.pytorch.org/whl/cpu/torch contains:
- Wheels for PyTorch 2.0.1 for MacOS without local identifier. E.g. `torch-2.0.1-cp39-none-macosx_11_0_arm64.whl`, which is the one I'd like to resolve and install
- Wheels for PyTorch 2.0.1 for Linux with local identifier. E.g. `torch-2.0.1+cpu-cp39-cp39-linux_x86_64.whl`

The issue seems in how the presence/absence of local identifiers results in separate versions being treated by Poetry. The resolver in fact selects `2.0.1+cpu` as the best fitting version and the executor can't (rightfully) find a package that for MacOS that matches the selected version.

[radoering]

The issue is that "2.0.1" is equal to "==2.0.1" which allows local versions and since local versions are considered greater than non local version they will be preferred. That's all conform to PEP 440. In general, you will never get a non local version of a package from a source that also provides a local version. The only escape hatch is arbitrary equality, which is not supported by poetry. See #7256.

Even though the use of arbitrary equality is discouraged, I think in this case it's the most sensible option. I could imagine to introduce an ExactVersion in poetry.core.constraints.version with the appropriate behavior.

For now, the obvious workaround is to use an URL dependency.

[dimbleby]

6150, #7597

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