BUG: Fix dataclass attributes are instance vars

Fixes #378

Author: kernc

pdoc/__init__.py

@@ -19,6 +19,7 @@
 import typing
 from contextlib import contextmanager
 from copy import copy
+from dataclasses import is_dataclass
 from functools import cached_property, lru_cache, reduce, partial, wraps
 from itertools import tee, groupby
 from types import FunctionType, ModuleType
@@ -1097,7 +1098,8 @@ def definition_order_index(
                     kind="prop" if isinstance(obj, property) else "var",
                     obj=_is_descriptor(obj) and obj or None,
                     instance_var=(_is_descriptor(obj) or
-                                  name in getattr(self.obj, '__slots__', ())))
+                                  name in getattr(self.obj, '__slots__', ()) or
+                                  (is_dataclass(self.obj) and name in annotations)))
 
         for name, docstring in instance_var_docstrings.items():
             self.doc[name] = Variable(

pdoc/test/__init__.py

@@ -14,6 +14,7 @@
 import unittest
 import warnings
 from contextlib import contextmanager, redirect_stderr, redirect_stdout
+from dataclasses import dataclass
 from functools import wraps
 from glob import glob
 from io import StringIO
@@ -1788,5 +1789,16 @@ def test_head(self):
             self.assertEqual(cm.exception.code, 304)
 
 
+class RegressionsTest(unittest.TestCase):
+    def test_dataclass_has_instance_vars(self):
+        @dataclass
+        class Foo:
+            bar: int  #: baz
+
+        obj = pdoc.Class(Foo.__name__, pdoc.Module(EMPTY_MODULE), Foo)
+        self.assertTrue(obj.doc['bar'].instance_var)
+        self.assertEqual(obj.doc['bar'].docstring, 'baz')
+
+
 if __name__ == '__main__':
     unittest.main()