Fix sphinx-doc#7807: autodoc: wrong signature is shown for the functi…

…on using contextmanager

CHANGES

@@ -21,6 +21,7 @@ Bugs fixed
 
 * #7808: autodoc: Warnings raised on variable and attribute type annotations
 * #7802: autodoc: EOFError is raised on parallel build
+* #7807: autodoc: wrong signature is shown for the function using contextmanager
 * #7812: autosummary: generates broken stub files if the target code contains
   an attribute and module that are same name
 * #7811: sphinx.util.inspect causes circular import problem

sphinx/util/inspect.py

@@ -9,6 +9,7 @@
 """
 
 import builtins
+import contextlib
 import enum
 import inspect
 import re
@@ -421,6 +422,17 @@ def is_builtin_class_method(obj: Any, attr_name: str) -> bool:
     return getattr(builtins, name, None) is cls
 
 
+def _should_unwrap(subject: Callable) -> bool:
+    """Check the function should be unwrapped on getting signature."""
+    if (safe_getattr(subject, '__globals__', None) and
+            subject.__globals__.get('__name__') == 'contextlib' and  # type: ignore
+            subject.__globals__.get('__file__') == contextlib.__file__):  # type: ignore
+        # contextmanger should be unwrapped
+        return True
+
+    return False
+
+
 def signature(subject: Callable, bound_method: bool = False, follow_wrapped: bool = False
               ) -> inspect.Signature:
     """Return a Signature object for the given *subject*.
@@ -431,7 +443,10 @@ def signature(subject: Callable, bound_method: bool = False, follow_wrapped: boo
     """
     try:
         try:
-            signature = inspect.signature(subject, follow_wrapped=follow_wrapped)
+            if _should_unwrap(subject):
+                signature = inspect.signature(subject)
+            else:
+                signature = inspect.signature(subject, follow_wrapped=follow_wrapped)
         except ValueError:
             # follow built-in wrappers up (ex. functools.lru_cache)
             signature = inspect.signature(subject)

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

@@ -1,8 +1,15 @@
-# for py32 or above
+from contextlib import contextmanager
 from functools import lru_cache
+from typing import Generator
 
 
 @lru_cache(maxsize=None)
 def slow_function(message, timeout):
     """This function is slow."""
     print(message)
+
+
+@contextmanager
+def feeling_good(x: int, y: int) -> Generator[None, None, None]:
+    """You'll feel better in this context!"""
+    yield

tests/test_ext_autodoc_autofunction.py

@@ -146,3 +146,16 @@ def test_wrapped_function(app):
         '   This function is slow.',
         '',
     ]
+
+
+@pytest.mark.sphinx('html', testroot='ext-autodoc')
+def test_wrapped_function_contextmanager(app):
+    actual = do_autodoc(app, 'function', 'target.wrappedfunction.feeling_good')
+    assert list(actual) == [
+        '',
+        '.. py:function:: feeling_good(x: int, y: int) -> Generator[None, None, None]',
+        '   :module: target.wrappedfunction',
+        '',
+        "   You'll feel better in this context!",
+        '',
+    ]