Fix version detection when invoked with python -m <package>

[cjolowicz]

click.version_option attempts to determine the version using pkg_resources when no version is passed. This fails when the program was invoked with python -m <package>.

Traceback

  Traceback (most recent call last):
    File ".../3.7/lib/python3.7/runpy.py", line 193, in _run_module_as_main
      "__main__", mod_spec)
    File ".../3.7/lib/python3.7/runpy.py", line 85, in _run_code
      exec(code, run_globals)
    File ".../foobar/__main__.py", line 11, in <module>
      main()
    File ".../venv/lib/python3.7/site-packages/click/core.py", line 891, in __call__
      return self.main(*args, **kwargs)
    File ".../venv/lib/python3.7/site-packages/click/core.py", line 843, in main
      with self.make_context(prog_name, args, **extra) as ctx:
    File ".../venv/lib/python3.7/site-packages/click/core.py", line 762, in make_context
      self.parse_args(ctx, args)
    File ".../venv/lib/python3.7/site-packages/click/core.py", line 1115, in parse_args
      value, args = param.handle_parse_result(ctx, opts, args)
    File ".../venv/lib/python3.7/site-packages/click/core.py", line 1705, in handle_parse_result
      value = invoke_param_callback(self.callback, ctx, self, value)
    File ".../venv/lib/python3.7/site-packages/click/core.py", line 123, in invoke_param_callback
      return callback(ctx, param, value)
    File ".../venv/lib/python3.7/site-packages/click/decorators.py", line 295, in callback
      raise RuntimeError("Could not determine version")
  RuntimeError: Could not determine version

The reason version detection fails is that __name__ in the calling module is "__main__", while entry_point.module_name is "<package>.__main__":

click/src/click/decorators.py

Lines 265 to 269 in 19fdc85

	if version is None:
	if hasattr(sys, "_getframe"):
	module = sys._getframe(1).f_globals.get("__name__")
	else:
	module = ""

click/src/click/decorators.py

Lines 288 to 293 in 19fdc85

	for dist in pkg_resources.working_set:
	scripts = dist.get_entry_map().get("console_scripts") or {}
	for _, entry_point in iteritems(scripts):
	if entry_point.module_name == module:
	ver = dist.version
	break

This PR fixes the issue by prefixing the module name with __package__ from the calling module, if it was "__main__" to begin with.

---

Minimal reproducible example:

.
├── foobar
│   ├── __init__.py
│   └── __main__.py
├── setup.cfg
└── setup.py

1 directory, 4 files

# setup.py
import setuptools
setuptools.setup()

# setup.cfg
[metadata]
name = foobar
version = 0.1.0

[options]
packages = find:
install_requires =
    click

[options.entry_points]
console_scripts =
    foobar = foobar.__main__:main

# foobar/__init__.py (empty)

# foobar/__main__.py
import click


@click.command()
@click.version_option()
def main() -> None:
    """foobar"""


if __name__ == "__main__":
    main(prog_name="foobar")

[cjolowicz]

Rebased against 7.x and added changelog.

[cjolowicz]

Rebased to resolve conflicts in CHANGES.rst due to the release of 7.1.2.

[jcrotts]

Thanks for the PR. There is a new PR for replacing pkg_resources with importlib_metadata, so this probably won't be added to master. This might still be relevant for 7.x though.

#1582

[davidism]

This PR won't apply after #1582, but the issue still happens. I've added a commit to that PR based on this fix and listed you as co-author.

[cjolowicz]

Thanks for incorporating it 🚀