bpo-29179: Document the Py_UNUSED macro (#4341)
Py_UNUSED has a public name, and is used in the wild outside CPython,
but was not documented. Rectify that.
The macro was added in bpo-19976 and referenced in bpo-26179.
diff --git a/Doc/c-api/intro.rst b/Doc/c-api/intro.rst
index 6323180..1500610 100644
--- a/Doc/c-api/intro.rst
+++ b/Doc/c-api/intro.rst
@@ -149,6 +149,13 @@
Like ``getenv(s)``, but returns *NULL* if :option:`-E` was passed on the
command line (i.e. if ``Py_IgnoreEnvironmentFlag`` is set).
+.. c:macro:: Py_UNUSED(arg)
+
+ Use this for unused arguments in a function definition to silence compiler
+ warnings, e.g. ``PyObject* func(PyObject *Py_UNUSED(ignored))``.
+
+ .. versionadded:: 3.4
+
.. _api-objects: