Throw a better error message when a malformed requirement is being parsed

[jayceslesar]

Is your feature request related to a problem? Please describe.

I had a malformed requirement of

git+ssh://git@github.com/me/my-project@my-branch

which is a malformed requirement (and should be)

my-project @ git+ssh://git@github.com/me/my-project@my-branch

and an error message of

Traceback (most recent call last):
  File "/tmp/pdm-build-env-_3xcxqno-shared/lib/python3.8/site-packages/pdm/pep517/_vendor/packaging/requirements.py", line 102, in __init__
    req = REQUIREMENT.parseString(requirement_string)
  File "/tmp/pdm-build-env-_3xcxqno-shared/lib/python3.8/site-packages/pdm/pep517/_vendor/pyparsing/core.py", line 1134, in parse_string
    raise exc.with_traceback(None)
pdm.pep517._vendor.pyparsing.exceptions.ParseException: Expected string_end, found '+'  (at char 3), (line:1, col:4)

Describe the solution you'd like

A better error message that says something like "invalid requirement at location (location) or something "

[frostming]

Can you show the full traceback? I would like to the see caller stack

[jayceslesar]

Traceback (most recent call last):
  File "/tmp/pdm-build-env-_3xcxqno-shared/lib/python3.8/site-packages/pdm/pep517/_vendor/packaging/requirements.py", line 102, in __init__
    req = REQUIREMENT.parseString(requirement_string)
  File "/tmp/pdm-build-env-_3xcxqno-shared/lib/python3.8/site-packages/pdm/pep517/_vendor/pyparsing/core.py", line 1134, in parse_string
    raise exc.with_traceback(None)
pdm.pep517._vendor.pyparsing.exceptions.ParseException: Expected string_end, found '+'  (at char 3), (line:1, col:4)
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
  File "/tmp/builds/H7BWEQYC/2/my-code/my-project/venv/lib/python3.8/site-packages/pep517/in_process/_in_process.py", line 363, in <module>
    main()
  File "/tmp/builds/H7BWEQYC/2/my-code/my-project/venv/lib/python3.8/site-packages/pep517/in_process/_in_process.py", line 345, in main
    json_out['return_val'] = hook(**hook_input['kwargs'])
  File "/tmp/builds/H7BWEQYC/2/my-code/my-project/venv/lib/python3.8/site-packages/pep517/in_process/_in_process.py", line 261, in build_wheel
    return _build_backend().build_wheel(wheel_directory, config_settings,
  File "/tmp/pdm-build-env-_3xcxqno-shared/lib/python3.8/site-packages/pdm/pep517/api.py", line 72, in build_wheel
    return Path(builder.build(wheel_directory)).name
  File "/tmp/pdm-build-env-_3xcxqno-shared/lib/python3.8/site-packages/pdm/pep517/wheel.py", line 78, in build
    self._write_metadata(zip_file)
  File "/tmp/pdm-build-env-_3xcxqno-shared/lib/python3.8/site-packages/pdm/pep517/wheel.py", line 151, in _write_metadata
    self._write_metadata_file(f)
  File "/tmp/pdm-build-env-_3xcxqno-shared/lib/python3.8/site-packages/pdm/pep517/wheel.py", line 300, in _write_metadata_file
    fp.write(self.format_pkginfo())
  File "/tmp/pdm-build-env-_3xcxqno-shared/lib/python3.8/site-packages/pdm/pep517/base.py", line 415, in format_pkginfo
    for extra, reqs in sorted(meta.requires_extra.items()):
  File "/tmp/pdm-build-env-_3xcxqno-shared/lib/python3.8/site-packages/pdm/pep517/metadata.py", line 273, in requires_extra
    parsed = Requirement(r)
  File "/tmp/pdm-build-env-_3xcxqno-shared/lib/python3.8/site-packages/pdm/pep517/_vendor/packaging/requirements.py", line 104, in __init__
    raise InvalidRequirement(
pdm.pep517._vendor.packaging.requirements.InvalidRequirement: Parse error at "'+ssh://g'": Expected string_end
Install my-project 2.0.1.dev33+g0154204 failed
Traceback (most recent call last):
  File "/tmp/builds/H7BWEQYC/2/my-code/my-project/venv/bin/pdm", line 8, in <module>
    sys.exit(main())
  File "/tmp/builds/H7BWEQYC/2/my-code/my-project/venv/lib/python3.8/site-packages/pdm/core.py", line 232, in main
    return Core().main(args)
  File "/tmp/builds/H7BWEQYC/2/my-code/my-project/venv/lib/python3.8/site-packages/pdm/core.py", line 167, in main
    raise cast(Exception, err).with_traceback(traceback)
  File "/tmp/builds/H7BWEQYC/2/my-code/my-project/venv/lib/python3.8/site-packages/pdm/core.py", line 162, in main
    f(options.project, options)
  File "/tmp/builds/H7BWEQYC/2/my-code/my-project/venv/lib/python3.8/site-packages/pdm/cli/commands/sync.py", line 33, in handle
    actions.do_sync(
  File "/tmp/builds/H7BWEQYC/2/my-code/my-project/venv/lib/python3.8/site-packages/pdm/cli/actions.py", line 209, in do_sync
    handler.synchronize()
  File "/tmp/builds/H7BWEQYC/2/my-code/my-project/venv/lib/python3.8/site-packages/pdm/installers/synchronizers.py", line 389, in synchronize
    self.install_candidate(self_key)
  File "/tmp/builds/H7BWEQYC/2/my-code/my-project/venv/lib/python3.8/site-packages/pdm/installers/synchronizers.py", line 207, in install_candidate
    self.manager.install(can)
  File "/tmp/builds/H7BWEQYC/2/my-code/my-project/venv/lib/python3.8/site-packages/pdm/installers/manager.py", line 39, in install
    installer(prepared.build(), self.environment, prepared.direct_url())
  File "/tmp/builds/H7BWEQYC/2/my-code/my-project/venv/lib/python3.8/site-packages/pdm/models/candidates.py", line 331, in build
    self.wheel = builder.build(build_dir, metadata_directory=self._metadata_dir)
  File "/tmp/builds/H7BWEQYC/2/my-code/my-project/venv/lib/python3.8/site-packages/pdm/builders/wheel.py", line 28, in build
    filename = self._hook.build_wheel(out_dir, config_settings, metadata_directory)
  File "/tmp/builds/H7BWEQYC/2/my-code/my-project/venv/lib/python3.8/site-packages/pep517/wrappers.py", line 208, in build_wheel
    return self._call_hook('build_wheel', {
  File "/tmp/builds/H7BWEQYC/2/my-code/my-project/venv/lib/python3.8/site-packages/pep517/wrappers.py", line 322, in _call_hook
    self._subprocess_runner(
  File "/tmp/builds/H7BWEQYC/2/my-code/my-project/venv/lib/python3.8/site-packages/pdm/builders/base.py", line 246, in subprocess_runner
    return log_subprocessor(cmd, cwd, extra_environ=env)
  File "/tmp/builds/H7BWEQYC/2/my-code/my-project/venv/lib/python3.8/site-packages/pdm/builders/base.py", line 87, in log_subprocessor
    raise BuildError(
pdm.exceptions.BuildError: Call command ['/tmp/builds/H7BWEQYC/2/my-code/my-project/venv/bin/python', '/tmp/builds/H7BWEQYC/2/my-code/my-project/venv/lib/python3.8/site-packages/pep517/in_process/_in_process.py', 'build_wheel', '/tmp/tmpp2ja5nb3'] return non-zero status(1).