Mark adding/removing PP arguments as ABI-breaking.

Author: filip-sakel

docs/LibraryEvolution.rst

@@ -150,8 +150,8 @@ The following changes are permitted:
   the outermost wrapper is implementation-detail
   (``@ImplementationDetail @MyWrapper``).
 - Changing or removing a default argument is a `binary-compatible source-breaking change`.
-- Adding, changing, or removing arguments in the property-wrapper custom attribute
-  of an API-level wrapper (``@API(argument: 5)``) or in the custom attributes of compositions
+- Changing arguments in the property-wrapper custom attribute of an API-level wrapper 
+  (``@API(argument: 5)``) or in the custom attributes of compositions
   where the outermost wrapper is API-level  (``@API @MyWrapper(argument: 5)``) is a 
   `binary-compatible source-breaking change`.
 - Adding or removing the ``@discardableResult`` and ``@warn_unqualified_access``
@@ -163,6 +163,10 @@ No other changes are permitted; the following are particularly of note:
 - An ABI-public function may not, in any way, change API-level property 
   wrappers (``@API``) or compositions where the outermost wrapper is 
   API-level (``@API @MyWrapper``).
+- An ABI-public function may neither add nor remove arguments in the 
+  property-wrapper custom attribute of an API-level wrapper 
+  (``@API(argument: 5)``) or in the custom attributes of compositions
+  where the outermost wrapper is API-level  (``@API @MyWrapper(argument: 5)``).
 - An ABI-public function may not change its generic requirements.
 - An ABI-public function may not change its external parameter names (labels).
 - An ABI-public function may not add, remove, or reorder parameters, whether or
@@ -429,8 +433,8 @@ stored subscripts. This means that the following changes are permitted:
   (``@ImplementationDetail @MyWrapper``).
 - Changing or removing a default argument is a `binary-compatible
   source-breaking change`.
-- Adding, changing, or removing arguments in the property-wrapper custom attribute
-  of an API-level wrapper (``@API(argument: 5)``) or in the custom attributes of compositions
+- Changing arguments in the property-wrapper custom attribute of an API-level wrapper 
+  (``@API(argument: 5)``) or in the custom attributes of compositions
   where the outermost wrapper is API-level  (``@API @MyWrapper(argument: 5)``) is a 
   `binary-compatible source-breaking change`.
 
@@ -803,8 +807,8 @@ counterparts with a few small changes:
 - Adding a default argument expression to an index parameter is permitted.
 - Changing or removing a default argument is a `binary-compatible
   source-breaking change`.
-- Adding, changing, or removing arguments in the property-wrapper custom attribute
-  of an API-level wrapper (``@API(argument: 5)``) or in the custom attributes of compositions
+- Changing arguments in the property-wrapper custom attribute of an API-level wrapper 
+  (``@API(argument: 5)``) or in the custom attributes of compositions
   where the outermost wrapper is API-level  (``@API @MyWrapper(argument: 5)``) is a 
   `binary-compatible source-breaking change`.