Add option to force unions (and options) to be rendered with bars

src/sphinx_autodoc_typehints/__init__.py

@@ -215,6 +215,13 @@ def format_annotation(annotation: Any, config: Config) -> str:  # noqa: C901, PL
     args_format = "\\[{}]"
     formatted_args: str | None = ""
 
+    always_use_bars_union: bool = getattr(config, "always_use_bars_union", True)
+    is_bars_union = full_name == "types.UnionType" or (
+        always_use_bars_union and type(annotation).__qualname__ == "_UnionGenericAlias"
+    )
+    if is_bars_union:
+        full_name = ""
+
     # Some types require special handling
     if full_name == "typing.NewType":
         args_format = f"\\(``{annotation.__name__}``, {{}})"
@@ -248,7 +255,7 @@ def format_annotation(annotation: Any, config: Config) -> str:  # noqa: C901, PL
         formatted_args = f"\\[\\[{', '.join(fmt[:-1])}], {fmt[-1]}]"
     elif full_name == "typing.Literal":
         formatted_args = f"\\[{', '.join(f'``{arg!r}``' for arg in args)}]"
-    elif full_name == "types.UnionType":
+    elif is_bars_union:
         return " | ".join([format_annotation(arg, config) for arg in args])
 
     if args and not formatted_args:
@@ -929,6 +936,7 @@ def setup(app: Sphinx) -> dict[str, bool]:
     app.add_config_value("typehints_use_rtype", True, "env")  # noqa: FBT003
     app.add_config_value("typehints_defaults", None, "env")
     app.add_config_value("simplify_optional_unions", True, "env")  # noqa: FBT003
+    app.add_config_value("always_use_bars_union", False, "env")  # noqa: FBT003
     app.add_config_value("typehints_formatter", None, "env")
     app.add_config_value("typehints_use_signature", False, "env")  # noqa: FBT003
     app.add_config_value("typehints_use_signature_return", False, "env")  # noqa: FBT003

tests/test_sphinx_autodoc_typehints.py

@@ -413,6 +413,26 @@ def test_format_annotation(inv: Inventory, annotation: Any, expected_result: str
             assert m.group("role") == expected_role
 
 
+@pytest.mark.parametrize(
+    ("annotation", "expected_result"),
+    [
+        ("int | float", ":py:class:`int` | :py:class:`float`"),
+        ("int | float | None", ":py:class:`int` | :py:class:`float` | :py:obj:`None`"),
+        ("Union[int, float]", ":py:class:`int` | :py:class:`float`"),
+        ("Union[int, float, None]", ":py:class:`int` | :py:class:`float` | :py:obj:`None`"),
+        ("Optional[int | float]", ":py:class:`int` | :py:class:`float` | :py:obj:`None`"),
+        ("Optional[Union[int, float]]", ":py:class:`int` | :py:class:`float` | :py:obj:`None`"),
+        ("Union[int | float, str]", ":py:class:`int` | :py:class:`float` | :py:class:`str`"),
+        ("Union[int, float] | str", ":py:class:`int` | :py:class:`float` | :py:class:`str`"),
+    ],
+)
+@pytest.mark.skipif(not PY310_PLUS, reason="| union doesn't work before py310")
+def test_always_use_bars_union(annotation: str, expected_result: str) -> None:
+    conf = create_autospec(Config, always_use_bars_union=True)
+    result = format_annotation(eval(annotation), conf)  # noqa: S307
+    assert result == expected_result
+
+
 @pytest.mark.parametrize("library", [typing, typing_extensions], ids=["typing", "typing_extensions"])
 @pytest.mark.parametrize(
     ("annotation", "params", "expected_result"),
@@ -519,12 +539,13 @@ class dummy_module.DataClass(x)
 
 
 def maybe_fix_py310(expected_contents: str) -> str:
+    if sys.version_info >= (3, 11):
+        return expected_contents
     if not PY310_PLUS:
         return expected_contents.replace('"', "")
 
     for old, new in [
-        ("bool | None", '"Optional"["bool"]'),
-        ("str | None", '"Optional"["str"]'),
+        ('"str" | "None"', '"Optional"["str"]'),
     ]:
         expected_contents = expected_contents.replace(old, new)
     return expected_contents
@@ -550,15 +571,16 @@ def test_sphinx_output_future_annotations(app: SphinxTestApp, status: StringIO)
        Method docstring.
 
        Parameters:
-          * **x** (bool | None) -- foo
+          * **x** ("bool" | "None") -- foo
 
           * **y** ("int" | "str" | "float") -- bar
 
-          * **z** (str | None) -- baz
+          * **z** ("str" | "None") -- baz
 
        Return type:
           "str"
     """
+    expected_contents = dedent(expected_contents)
     expected_contents = maybe_fix_py310(dedent(expected_contents))
     assert contents == expected_contents