gh-141004: Document PyException_HEAD

Doc/c-api/exceptions.rst

@@ -868,6 +868,22 @@ Exception Objects
 
    .. versionadded:: 3.12
 
+.. c:macro:: PyException_HEAD
+
+   This is a macro used when declaring new exception types.
+   The :c:macro:`!PyException_HEAD` macro expands to::
+
+      PyObject_HEAD
+      PyObject *dict;
+      PyObject *args;
+      PyObject *notes;
+      PyObject *traceback;
+      PyObject *context;
+      PyObject *cause;
+      char suppress_context;
+
+   See :c:macro:`PyObject_HEAD` for the base object header.
+
 .. _unicodeexceptions:
 
 Unicode Exception Objects

Doc/c-api/structures.rst

@@ -79,7 +79,7 @@ under :ref:`reference counting <countingrefs>`.
 .. c:macro:: PyObject_HEAD
 
    This is a macro used when declaring new types which represent objects
-   without a varying length.  The PyObject_HEAD macro expands to::
+   without a varying length.  The :c:macro:`!PyObject_HEAD` macro expands to::
 
       PyObject ob_base;
 
@@ -90,7 +90,7 @@ under :ref:`reference counting <countingrefs>`.
 
    This is a macro used when declaring new types which represent objects
    with a length that varies from instance to instance.
-   The PyObject_VAR_HEAD macro expands to::
+   The :c:macro:`!PyObject_VAR_HEAD` macro expands to::
 
       PyVarObject ob_base;