[3.10] bpo-43908: Add What's New entry for Py_TPFLAGS_IMMUTABLETYPE flag (GH-25816...

(cherry picked from commit a09fc9c63f1b5980c62ff2712f67500bacb92b04)

Co-authored-by: Erlend Egeberg Aasland <erlend.aasland@innova.no>
Automerge-Triggered-By: GH:gvanrossum

diff --git a/Doc/whatsnew/3.10.rst b/Doc/whatsnew/3.10.rst
index b0920294572b551f322ef46469a4d89a7b0fb76b..8fd64f86b3a2f58e560edbdb5ceae0197bb52af5 100644 (file)
--- a/Doc/whatsnew/3.10.rst
+++ b/Doc/whatsnew/3.10.rst
@@ -1838,6 +1838,10 @@ New Features
   creating type instances.
   (Contributed by Victor Stinner in :issue:`43916`.)
 
+* Add a new :c:data:`Py_TPFLAGS_IMMUTABLETYPE` type flag for creating immutable
+  type objects: type attributes cannot be set nor deleted.
+  (Contributed by Victor Stinner and Erlend E. Aasland in :issue:`43908`.)
+
 Porting to Python 3.10
 ----------------------
 
@@ -1895,6 +1899,12 @@ Porting to Python 3.10
   been included directly, consider including ``Python.h`` instead.
   (Contributed by Nicholas Sim in :issue:`35134`)
 
+* Use the :c:data:`Py_TPFLAGS_IMMUTABLETYPE` type flag to create immutable type
+  objects. Do not rely on :c:data:`Py_TPFLAGS_HEAPTYPE` to decide if a type
+  object is mutable or not; check if :c:data:`Py_TPFLAGS_IMMUTABLETYPE` is set
+  instead.
+  (Contributed by Victor Stinner and Erlend E. Aasland in :issue:`43908`.)
+
 Deprecated
 ----------