Fix #7650: autodoc: undecorated signature is shown for decorated functions

CHANGES

@@ -92,6 +92,7 @@ Bugs fixed
   ``Union[foo, bar, None]``
 * #7629: autodoc: autofunction emits an unfriendly warning if an invalid object
   specified
+* #7650: autodoc: undecorated signature is shown for decorated functions
 * #7551: autosummary: a nested class is indexed as non-nested class
 * #7535: sphinx-autogen: crashes when custom template uses inheritance
 * #7536: sphinx-autogen: crashes when template uses i18n feature

sphinx/ext/autodoc/__init__.py

@@ -1051,10 +1051,12 @@ def format_args(self, **kwargs: Any) -> str:
         if self.env.config.autodoc_typehints in ('none', 'description'):
             kwargs.setdefault('show_annotation', False)
 
-        unwrapped = inspect.unwrap(self.object)
         try:
-            self.env.app.emit('autodoc-before-process-signature', unwrapped, False)
-            sig = inspect.signature(unwrapped)
+            self.env.app.emit('autodoc-before-process-signature', self.object, False)
+            if inspect.is_singledispatch_function(self.object):
+                sig = inspect.signature(self.object, follow_wrapped=True)
+            else:
+                sig = inspect.signature(self.object)
             args = stringify_signature(sig, **kwargs)
         except TypeError as exc:
             logger.warning(__("Failed to get a function signature for %s: %s"),
@@ -1451,7 +1453,6 @@ def format_args(self, **kwargs: Any) -> str:
         if self.env.config.autodoc_typehints in ('none', 'description'):
             kwargs.setdefault('show_annotation', False)
 
-        unwrapped = inspect.unwrap(self.object)
         try:
             if self.object == object.__init__ and self.parent != object:
                 # Classes not having own __init__() method are shown as no arguments.
@@ -1460,12 +1461,18 @@ def format_args(self, **kwargs: Any) -> str:
                 #       But it makes users confused.
                 args = '()'
             else:
-                if inspect.isstaticmethod(unwrapped, cls=self.parent, name=self.object_name):
-                    self.env.app.emit('autodoc-before-process-signature', unwrapped, False)
-                    sig = inspect.signature(unwrapped, bound_method=False)
+                if inspect.isstaticmethod(self.object, cls=self.parent, name=self.object_name):
+                    self.env.app.emit('autodoc-before-process-signature', self.object, False)
+                    sig = inspect.signature(self.object, bound_method=False)
                 else:
-                    self.env.app.emit('autodoc-before-process-signature', unwrapped, True)
-                    sig = inspect.signature(unwrapped, bound_method=True)
+                    self.env.app.emit('autodoc-before-process-signature', self.object, True)
+
+                    meth = self.parent.__dict__.get(self.objpath[-1], None)
+                    if meth and inspect.is_singledispatch_method(meth):
+                        sig = inspect.signature(self.object, bound_method=True,
+                                                follow_wrapped=True)
+                    else:
+                        sig = inspect.signature(self.object, bound_method=True)
                 args = stringify_signature(sig, **kwargs)
         except TypeError as exc:
             logger.warning(__("Failed to get a method signature for %s: %s"),
@@ -1522,7 +1529,9 @@ def add_singledispatch_directive_header(self, sig: str) -> None:
                 self.annotate_to_first_argument(func, typ)
 
                 documenter = MethodDocumenter(self.directive, '')
+                documenter.parent = self.parent
                 documenter.object = func
+                documenter.objpath = self.objpath
                 self.add_line('   %s%s' % (self.format_name(),
                                            documenter.format_signature()),
                               sourcename)

sphinx/util/inspect.py

@@ -408,13 +408,20 @@ def is_builtin_class_method(obj: Any, attr_name: str) -> bool:
     return getattr(builtins, name, None) is cls
 
 
-def signature(subject: Callable, bound_method: bool = False) -> inspect.Signature:
+def signature(subject: Callable, bound_method: bool = False, follow_wrapped: bool = False
+              ) -> inspect.Signature:
     """Return a Signature object for the given *subject*.
 
     :param bound_method: Specify *subject* is a bound method or not
+    :param follow_wrapped: Same as ``inspect.signature()``.
+                           Defaults to ``False`` (get a signature of *subject*).
     """
     try:
-        signature = inspect.signature(subject)
+        try:
+            signature = inspect.signature(subject, follow_wrapped=follow_wrapped)
+        except ValueError:
+            # follow built-in wrappers up (ex. functools.lru_cache)
+            signature = inspect.signature(subject)
         parameters = list(signature.parameters.values())
         return_annotation = signature.return_annotation
     except IndexError:

tests/roots/test-ext-autodoc/target/decorator.py

@@ -1,5 +1,9 @@
+from functools import wraps
+
+
 def deco1(func):
     """docstring for deco1"""
+    @wraps(func)
     def wrapper():
         return func()
 
@@ -14,3 +18,14 @@ def wrapper():
 
         return wrapper
     return decorator
+
+
+@deco1
+def foo(name=None, age=None):
+    pass
+
+
+class Bar:
+    @deco1
+    def meth(self, name=None, age=None):
+        pass

tests/test_ext_autodoc.py

@@ -142,6 +142,7 @@ def formatsig(objtype, name, obj, args, retann):
         inst = app.registry.documenters[objtype](directive, name)
         inst.fullname = name
         inst.doc_as_attr = False  # for class objtype
+        inst.parent = object  # dummy
         inst.object = obj
         inst.objpath = [name]
         inst.args = args
@@ -1243,6 +1244,17 @@ def test_autofunction_for_methoddescriptor(app):
     ]
 
 
+@pytest.mark.sphinx('html', testroot='ext-autodoc')
+def test_autofunction_for_decorated(app):
+    actual = do_autodoc(app, 'function', 'target.decorator.foo')
+    assert list(actual) == [
+        '',
+        '.. py:function:: foo()',
+        '   :module: target.decorator',
+        '',
+    ]
+
+
 @pytest.mark.sphinx('html', testroot='ext-autodoc')
 def test_automethod_for_builtin(app):
     actual = do_autodoc(app, 'method', 'builtins.int.__add__')
@@ -1256,6 +1268,17 @@ def test_automethod_for_builtin(app):
     ]
 
 
+@pytest.mark.sphinx('html', testroot='ext-autodoc')
+def test_automethod_for_decorated(app):
+    actual = do_autodoc(app, 'method', 'target.decorator.Bar.meth')
+    assert list(actual) == [
+        '',
+        '.. py:method:: Bar.meth()',
+        '   :module: target.decorator',
+        '',
+    ]
+
+
 @pytest.mark.sphinx('html', testroot='ext-autodoc')
 def test_abstractmethods(app):
     options = {"members": None,
@@ -1415,7 +1438,7 @@ def test_coroutine(app):
     actual = do_autodoc(app, 'function', 'target.coroutine.sync_func')
     assert list(actual) == [
         '',
-        '.. py:function:: sync_func()',
+        '.. py:function:: sync_func(*args, **kwargs)',
         '   :module: target.coroutine',
         '',
     ]

tests/test_util_inspect.py

@@ -97,7 +97,7 @@ def wrapped_bound_method(*args, **kwargs):
 
     # wrapped bound method
     sig = inspect.signature(wrapped_bound_method)
-    assert stringify_signature(sig) == '(arg1, **kwargs)'
+    assert stringify_signature(sig) == '(*args, **kwargs)'
 
 
 def test_signature_partialmethod():