Error importing module: no signature found for builtin type `<class 'type I wrote'>`

[JesseTG]

Problem Description

When attempting to use pdoc on my package, I get a stack trace similar to the following when trying to view the doc page for any module:

Traceback (most recent call last):
  File "/home/jesse/.virtualenvs/libretro.py/lib/python3.12/site-packages/pdoc/web.py", line 82, in handle_request
    out = render.html_module(
          ^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/contextlib.py", line 81, in inner
    return func(*args, **kwds)
           ^^^^^^^^^^^^^^^^^^^
  File "/home/jesse/.virtualenvs/libretro.py/lib/python3.12/site-packages/pdoc/render.py", line 106, in html_module
    return env.get_template("module.html.jinja2").render(
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/jesse/.virtualenvs/libretro.py/lib/python3.12/site-packages/jinja2/environment.py", line 1301, in render
    self.environment.handle_exception()
  File "/home/jesse/.virtualenvs/libretro.py/lib/python3.12/site-packages/jinja2/environment.py", line 936, in handle_exception
    raise rewrite_traceback_stack(source=source)
  File "/home/jesse/.virtualenvs/libretro.py/lib/python3.12/site-packages/pdoc/templates/default/module.html.jinja2", line 311, in top-level template code
    {%- if loop.nextitem -%}
  File "/home/jesse/.virtualenvs/libretro.py/lib/python3.12/site-packages/pdoc/templates/default/frame.html.jinja2", line 36, in top-level template code
    {% block body %}
  File "/home/jesse/.virtualenvs/libretro.py/lib/python3.12/site-packages/pdoc/templates/default/frame.html.jinja2", line 42, in block 'body'
    {% block content %}{% endblock %}
    ^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/jesse/.virtualenvs/libretro.py/lib/python3.12/site-packages/pdoc/templates/default/module.html.jinja2", line 101, in block 'content'
    {% block module_contents %}
    ^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/jesse/.virtualenvs/libretro.py/lib/python3.12/site-packages/pdoc/templates/default/module.html.jinja2", line 108, in block 'module_contents'
    {{ member(m) }}
  File "/home/jesse/.virtualenvs/libretro.py/lib/python3.12/site-packages/jinja2/runtime.py", line 777, in _invoke
    rv = self._func(*arguments)
         ^^^^^^^^^^^^^^^^^^^^^^
  File "/home/jesse/.virtualenvs/libretro.py/lib/python3.12/site-packages/pdoc/templates/default/module.html.jinja2", line 198, in template
    {{ function(doc) }}
  File "/home/jesse/.virtualenvs/libretro.py/lib/python3.12/site-packages/jinja2/runtime.py", line 777, in _invoke
    rv = self._func(*arguments)
         ^^^^^^^^^^^^^^^^^^^^^^
  File "/home/jesse/.virtualenvs/libretro.py/lib/python3.12/site-packages/pdoc/templates/default/module.html.jinja2", line 176, in template
    {{- fn.signature | format_signature(colon=True) | linkify }}
    ^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/jesse/.virtualenvs/libretro.py/lib/python3.12/site-packages/pdoc/render_helpers.py", line 358, in linkify
    re.sub(
  File "/usr/lib/python3.12/re/__init__.py", line 186, in sub
    return _compile(pattern, flags).sub(repl, string, count)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/jesse/.virtualenvs/libretro.py/lib/python3.12/site-packages/pdoc/render_helpers.py", line 343, in linkify_repl
    doc is not None and context["is_public"](doc).strip()
                        ^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/jesse/.virtualenvs/libretro.py/lib/python3.12/site-packages/jinja2/runtime.py", line 777, in _invoke
    rv = self._func(*arguments)
         ^^^^^^^^^^^^^^^^^^^^^^
  File "/home/jesse/.virtualenvs/libretro.py/lib/python3.12/site-packages/pdoc/templates/default/module.html.jinja2", line 242, in template
    {% if "@private" in doc.docstring %}
    ^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/jesse/.virtualenvs/libretro.py/lib/python3.12/site-packages/jinja2/environment.py", line 485, in getattr
    return getattr(obj, attribute)
           ^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/functools.py", line 995, in __get__
    val = self.func(instance)
          ^^^^^^^^^^^^^^^^^^^
  File "/home/jesse/.virtualenvs/libretro.py/lib/python3.12/site-packages/pdoc/doc.py", line 594, in docstring
    + str(inspect.signature(self.obj)).replace(" -> None", "")
          ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/inspect.py", line 3327, in signature
    return Signature.from_callable(obj, follow_wrapped=follow_wrapped,
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/inspect.py", line 3071, in from_callable
    return _signature_from_callable(obj, sigcls=cls,
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/inspect.py", line 2633, in _signature_from_callable
    raise ValueError(
ValueError: no signature found for builtin type <class 'libretro.api.content.retro_system_info'>

Steps to reproduce the behavior:

1. On Windows or Linux, clone this repository.
2. cd to the cloned repo.
3. Run pdoc src/libretro.
4. Go to the hosted doc site.
5. Select any module.
6. You will see the above stack trace (or something similar).

System Information

pdoc: 14.4.0
Python: 3.12.2
Platform: Linux-5.15.133.1-microsoft-standard-WSL2-x86_64-with-glibc2.35

Additionally:

pdoc: 14.4.0
Python: 3.12.2
Platform: Windows-10-10.0.19045-SP0

[JesseTG]

I just noticed something; the offending types do not have explicit __init__ methods; they're auto-generated, probably by ctypes.Structure.

[JesseTG]

Okay, I think I have an idea of what's up. I have a lot of classes marked with @dataclass(init=False). I initially believed that init=False would conflict with whatever magic Structure provides; removing the init argument on them fixes the issue.

[mhils]

Thanks for tracking this down! We clearly shouldn't raise on this.