Fixed inconsistent data class formatting

Author: agronholm

CHANGELOG.rst

@@ -3,6 +3,7 @@ UNRELEASED
 
 * Dropped support for Sphinx < 3.0
 * Fixed ``TypeError`` when formatting a parametrized ``typing.IO`` annotation
+* Fixed data class displaying a return type in its ``__init__()`` method
 
 
 1.10.3

sphinx_autodoc_typehints.py

@@ -391,6 +391,10 @@ def process_docstring(app, what, name, obj, options, lines):
                 )
 
         if 'return' in type_hints and not inspect.isclass(original_obj):
+            # This avoids adding a return type for data class __init__ methods
+            if what == 'method' and name.endswith('.__init__'):
+                return
+
             formatted_annotation = format_annotation(
                 type_hints['return'], fully_qualified=app.config.typehints_fully_qualified)
 

tests/test_sphinx_autodoc_typehints.py

@@ -228,12 +228,6 @@ def test_sphinx_output(app, status, warning, always_document_param_types):
     else:
         format_args['undoc_params'] = ""
 
-    if sys.version_info < (3, 6):
-        format_args['dataclass_docstring'] = ('Initialize self.  See help(type(self)) for '
-                                              'accurate signature.')
-    else:
-        format_args['dataclass_docstring'] = 'Return type:\n         "None"'
-
     text_path = pathlib.Path(app.srcdir) / '_build' / 'text' / 'index.txt'
     with text_path.open('r') as f:
         text_contents = f.read().replace('–', '--')
@@ -486,7 +480,7 @@ class dummy_module.DataClass
 
            __init__()
 
-              {dataclass_docstring}
+              Initialize self.  See help(type(self)) for accurate signature.
 
         @dummy_module.Decorator(func)