From 9f52d7dd3f5d29fe6fa9ce17cabe3728cc517c36 Mon Sep 17 00:00:00 2001
From: Takeshi KOMIYA <i.tkomiya@gmail.com>
Date: Sat, 2 Apr 2022 14:45:52 +0900
Subject: [PATCH] Fix #10280: autodoc_docstring_signature generates needless
 return typehint

Basically, autodoc suppresses return value typehint for class
constructors.  But it was unexpectedly shown if
`autodoc_docstring_signature` is enabled and docstring has multiple
signatures.
---
 CHANGES                                       |  2 ++
 sphinx/ext/autodoc/__init__.py                | 13 ++++++++++++
 .../target/docstring_signature.py             |  6 ++++--
 tests/test_ext_autodoc_configs.py             | 20 +++++++++++--------
 4 files changed, 31 insertions(+), 10 deletions(-)

diff --git a/CHANGES b/CHANGES
index 7037723fe50..64cf4333d68 100644
--- a/CHANGES
+++ b/CHANGES
@@ -67,6 +67,8 @@ Bugs fixed
 
 * #10279: autodoc: Default values for keyword only arguments in overloaded
   functions are rendered as a string literal
+* #10280: autodoc: :confval:`autodoc_docstring_signature` unexpectedly generates
+  return value typehint for constructors if docstring has multiple signatures
 * #10236: html search: objects are duplicated in search result
 * #9962: texinfo: Deprecation message for ``@definfoenclose`` command on
   bulding texinfo document
diff --git a/sphinx/ext/autodoc/__init__.py b/sphinx/ext/autodoc/__init__.py
index 295e0bf7d67..8c2ab38dc0c 100644
--- a/sphinx/ext/autodoc/__init__.py
+++ b/sphinx/ext/autodoc/__init__.py
@@ -1580,6 +1580,19 @@ def format_args(self, **kwargs: Any) -> str:
 
         return stringify_signature(sig, show_return_annotation=False, **kwargs)
 
+    def _find_signature(self) -> Tuple[str, str]:
+        result = super()._find_signature()
+        if result is not None:
+            # Strip a return value from signature of constructor in docstring (first entry)
+            result = (result[0], None)
+
+        for i, sig in enumerate(self._signatures):
+            if sig.endswith(' -> None'):
+                # Strip a return value from signatures of constructor in docstring (subsequent entries)
+                self._signatures[i] = sig[:-8]
+
+        return result
+
     def format_signature(self, **kwargs: Any) -> str:
         if self.doc_as_attr:
             return ''
diff --git a/tests/roots/test-ext-autodoc/target/docstring_signature.py b/tests/roots/test-ext-autodoc/target/docstring_signature.py
index d9deb6244ac..27252c521e5 100644
--- a/tests/roots/test-ext-autodoc/target/docstring_signature.py
+++ b/tests/roots/test-ext-autodoc/target/docstring_signature.py
@@ -22,10 +22,12 @@ def __init__(self):
 class E:
     def __init__(self):
         """E(foo: int, bar: int, baz: int) -> None \\
-        E(foo: str, bar: str, baz: str) -> None"""
+        E(foo: str, bar: str, baz: str) -> None \\
+        E(foo: float, bar: float, baz: float)"""
 
 
 class F:
     def __init__(self):
         """F(foo: int, bar: int, baz: int) -> None
-        F(foo: str, bar: str, baz: str) -> None"""
+        F(foo: str, bar: str, baz: str) -> None
+        F(foo: float, bar: float, baz: float) -> None"""
diff --git a/tests/test_ext_autodoc_configs.py b/tests/test_ext_autodoc_configs.py
index 70515bca12d..273e08210da 100644
--- a/tests/test_ext_autodoc_configs.py
+++ b/tests/test_ext_autodoc_configs.py
@@ -467,13 +467,15 @@ def test_autoclass_content_and_docstring_signature_init(app):
         '   :module: target.docstring_signature',
         '',
         '',
-        '.. py:class:: E(foo: int, bar: int, baz: int) -> None',
-        '              E(foo: str, bar: str, baz: str) -> None',
+        '.. py:class:: E(foo: int, bar: int, baz: int)',
+        '              E(foo: str, bar: str, baz: str)',
+        '              E(foo: float, bar: float, baz: float)',
         '   :module: target.docstring_signature',
         '',
         '',
-        '.. py:class:: F(foo: int, bar: int, baz: int) -> None',
-        '              F(foo: str, bar: str, baz: str) -> None',
+        '.. py:class:: F(foo: int, bar: int, baz: int)',
+        '              F(foo: str, bar: str, baz: str)',
+        '              F(foo: float, bar: float, baz: float)',
         '   :module: target.docstring_signature',
         '',
     ]
@@ -510,13 +512,15 @@ def test_autoclass_content_and_docstring_signature_both(app):
         '   :module: target.docstring_signature',
         '',
         '',
-        '.. py:class:: E(foo: int, bar: int, baz: int) -> None',
-        '              E(foo: str, bar: str, baz: str) -> None',
+        '.. py:class:: E(foo: int, bar: int, baz: int)',
+        '              E(foo: str, bar: str, baz: str)',
+        '              E(foo: float, bar: float, baz: float)',
         '   :module: target.docstring_signature',
         '',
         '',
-        '.. py:class:: F(foo: int, bar: int, baz: int) -> None',
-        '              F(foo: str, bar: str, baz: str) -> None',
+        '.. py:class:: F(foo: int, bar: int, baz: int)',
+        '              F(foo: str, bar: str, baz: str)',
+        '              F(foo: float, bar: float, baz: float)',
         '   :module: target.docstring_signature',
         '',
     ]