Don't add :rtype: None (#538)

Author: grayjk

README.md

@@ -67,6 +67,7 @@ The following configuration options are accepted:
   or `Optional[int]`)
 - `typehints_document_rtype` (default: `True`): If `False`, never add an `:rtype:` directive. If `True`, add the
   `:rtype:` directive if no existing `:rtype:` is found.
+- `typehints_document_rtype_none` (default: `True`): If `False`, never add an `:rtype: None` directive. If `True`, add the `:rtype: None`.
 - `typehints_use_rtype` (default: `True`): Controls behavior when `typehints_document_rtype` is set to `True`. If
   `True`, document return type in the `:rtype:` directive. If `False`, document return type as part of the `:return:`
   directive, if present, otherwise fall back to using `:rtype:`. Use in conjunction with

src/sphinx_autodoc_typehints/__init__.py

@@ -912,7 +912,7 @@ def get_insert_index(app: Sphinx, lines: list[str]) -> InsertIndexInfo | None:
     return InsertIndexInfo(insert_index=len(lines))
 
 
-def _inject_rtype(  # noqa: PLR0913, PLR0917
+def _inject_rtype(  # noqa: C901, PLR0913, PLR0917
     type_hints: dict[str, Any],
     original_obj: Any,
     app: Sphinx,
@@ -926,6 +926,8 @@ def _inject_rtype(  # noqa: PLR0913, PLR0917
         return
     if not app.config.typehints_document_rtype:
         return
+    if not app.config.typehints_document_rtype_none and type_hints["return"] is types.NoneType:
+        return
 
     r = get_insert_index(app, lines)
     if r is None:
@@ -1011,6 +1013,7 @@ def setup(app: Sphinx) -> dict[str, bool]:
     app.add_config_value("always_document_param_types", False, "html")  # noqa: FBT003
     app.add_config_value("typehints_fully_qualified", False, "env")  # noqa: FBT003
     app.add_config_value("typehints_document_rtype", True, "env")  # noqa: FBT003
+    app.add_config_value("typehints_document_rtype_none", True, "env")  # noqa: FBT003
     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

tests/test_integration.py

@@ -1319,6 +1319,19 @@ def typehints_use_signature(a: AsyncGenerator) -> AsyncGenerator:
     return a
 
 
+@expected(
+    """
+    mod.typehints_no_rtype_none()
+
+       Do something.
+
+    """,
+    typehints_document_rtype_none=False,
+)
+def typehints_no_rtype_none() -> None:
+    """Do something."""
+
+
 prolog = """
 .. |test_node_start| replace:: {test_node_start}
 """.format(test_node_start="test_start")