Improve error message when running pyodide build on an unsupported Python version

[agriyakhetarpal]

I came across this one today.

Running pyodide build displays

───────────────────────────────────────────────────────── Traceback (most recent call last) ──────────────────────────────────────────────────────────╮
│ /Users/agriyakhetarpal/envs/skimage-dev/lib/python3.13/site-packages/pyodide_build/cli/build.py:180 in main                                          │
│                                                                                                                                                      │
│   177 │   ctx: typer.Context = typer.Context,  # type: ignore[assignment]                                                                            │
│   178 ) -> None:                                                                                                                                     │
│   179 │   """Use pypa/build to build a Python package from source, pypi or url."""                                                                   │
│ ❱ 180 │   init_environment()                                                                                                                         │
│   181 │   try:                                                                                                                                       │
│   182 │   │   check_emscripten_version()                                                                                                             │
│   183 │   except RuntimeError as e:                                                                                                                  │
│                                                                                                                                                      │
│ /Users/agriyakhetarpal/envs/skimage-dev/lib/python3.13/site-packages/pyodide_build/build_env.py:59 in init_environment                               │
│                                                                                                                                                      │
│    56 │                                                                                                                                              │
│    57 │   root = search_pyodide_root(Path.cwd())                                                                                                     │
│    58 │   if not root:  # Not in Pyodide tree                                                                                                        │
│ ❱  59 │   │   root = _init_xbuild_env(quiet=quiet)                                                                                                   │
│    60 │                                                                                                                                              │
│    61 │   os.environ["PYODIDE_ROOT"] = str(root)                                                                                                     │
│    62                                                                                                                                                │
│                                                                                                                                                      │
│ /Users/agriyakhetarpal/envs/skimage-dev/lib/python3.13/site-packages/pyodide_build/build_env.py:84 in _init_xbuild_env                               │
│                                                                                                                                                      │
│    81 │   with context:                                                                                                                              │
│    82 │   │   manager = CrossBuildEnvManager(xbuildenv_path)                                                                                         │
│    83 │   │   if manager.current_version is None:                                                                                                    │
│ ❱  84 │   │   │   manager.install()                                                                                                                  │
│    85 │   │                                                                                                                                          │
│    86 │   │   manager.check_version_marker()                                                                                                         │
│    87                                                                                                                                                │
│                                                                                                                                                      │
│ /Users/agriyakhetarpal/envs/skimage-dev/lib/python3.13/site-packages/pyodide_build/xbuildenv.py:175 in install                                       │
│                                                                                                                                                      │
│   172 │   │   │   version = _url_to_version(url)                                                                                                     │
│   173 │   │   │   download_url = url                                                                                                                 │
│   174 │   │   else:                                                                                                                                  │
│ ❱ 175 │   │   │   version = version or self._find_latest_version()                                                                                   │
│   176 │   │   │                                                                                                                                      │
│   177 │   │   │   local_versions = build_env.local_versions()                                                                                        │
│   178 │   │   │   release = self._find_remote_release(version)                                                                                       │
│                                                                                                                                                      │
│ /Users/agriyakhetarpal/envs/skimage-dev/lib/python3.13/site-packages/pyodide_build/xbuildenv.py:239 in _find_latest_version                          │
│                                                                                                                                                      │
│   236 │   │   )                                                                                                                                      │
│   237 │   │                                                                                                                                          │
│   238 │   │   if not latest:                                                                                                                         │
│ ❱ 239 │   │   │   raise ValueError("No compatible cross-build environment found")                                                                    │
│   240 │   │                                                                                                                                          │
│   241 │   │   return latest.version                                                                                                                  │
│   242                                                                                                                                                │
╰──────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────╯
ValueError: No compatible cross-build environment found

and running pyodide xbuildenv install 0.27.2 gives

╭───────────────────────────────────────────────────────── Traceback (most recent call last) ──────────────────────────────────────────────────────────╮
│ /Users/agriyakhetarpal/envs/skimage-dev/lib/python3.13/site-packages/pyodide_build/cli/xbuildenv.py:61 in _install                                   │
│                                                                                                                                                      │
│    58 │   if url:                                                                                                                                    │
│    59 │   │   manager.install(url=url, force_install=force_install)                                                                                  │
│    60 │   else:                                                                                                                                      │
│ ❱  61 │   │   manager.install(version=version, force_install=force_install)                                                                          │
│    62 │                                                                                                                                              │
│    63 │   typer.echo(f"Pyodide cross-build environment installed at {path.resolve()}")                                                               │
│    64                                                                                                                                                │
│                                                                                                                                                      │
│ /Users/agriyakhetarpal/envs/skimage-dev/lib/python3.13/site-packages/pyodide_build/xbuildenv.py:183 in install                                       │
│                                                                                                                                                      │
│   180 │   │   │   │   python_version=local_versions["python"],                                                                                       │
│   181 │   │   │   │   pyodide_build_version=local_versions["pyodide-build"],                                                                         │
│   182 │   │   │   ):                                                                                                                                 │
│ ❱ 183 │   │   │   │   raise ValueError(                                                                                                              │
│   184 │   │   │   │   │   f"Version {version} is not compatible with the current environment."                                                       │
│   185 │   │   │   │   )                                                                                                                              │
│   186                                                                                                                                                │
╰──────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────╯
ValueError: Version 0.27.2 is not compatible with the current environment.

So, I checked the Python version and I got Python 3.13.1 (main, Dec 3 2024, 17:59:52) [Clang 16.0.0 (clang-1600.0.26.4)].

I feel that this could be reported better, somehow, perhaps through a simple check when running pyodide build, which sees if sys.version_info >= (3,12) and sys.version_info < (3, 13) returns True (or whichever the value of requires-python is in the metadata) and asks users to switch a supported Python version.

[ryanking13]

+1. Thanks for opening the issue.

Also, I would like to remove the stack trace when it is an expected error. The long stack trace is very confusing.