inspect.signature: Use '/' to separate positional-only parameters from

the rest in Signature.__str__. #20356

2 files changed, 9 insertions, 3 deletions

diff --git a/Doc/library/inspect.rst b/Doc/library/inspect.rst
index 0a3a571..91d8831 100644
--- a/Doc/library/inspect.rst
+++ b/Doc/library/inspect.rst
@@ -510,9 +510,8 @@ function.
 
    .. attribute:: Parameter.name
 
-      The name of the parameter as a string.  Must be a valid python identifier
-      name (with the exception of ``POSITIONAL_ONLY`` parameters, which can have
-      it set to ``None``).
+      The name of the parameter as a string.  The name must be a valid
+      Python identifier.
 
    .. attribute:: Parameter.default
 
@@ -596,6 +595,10 @@ function.
          >>> str(param.replace(default=Parameter.empty, annotation='spam'))
          "foo:'spam'"
 
+    .. versionchanged:: 3.4
+        In Python 3.3 Parameter objects were allowed to have ``name`` set
+        to ``None`` if their ``kind`` was set to ``POSITIONAL_ONLY``.
+        This is no longer permitted.
 
 .. class:: BoundArguments
 
diff --git a/Doc/whatsnew/3.4.rst b/Doc/whatsnew/3.4.rst
index 1d88965..4718339 100644
--- a/Doc/whatsnew/3.4.rst
+++ b/Doc/whatsnew/3.4.rst
@@ -1488,6 +1488,9 @@ removed:
 * Support for loading the deprecated ``TYPE_INT64`` has been removed from
   :mod:`marshal`.  (Contributed by Dan Riti in :issue:`15480`.)
 
+* :class:`inspect.Signature`: positional-only parameters are now required
+  to have a valid name.
+
 
 Code Cleanups
 -------------