Merge branch 'main' into docs/whatsnew/bytecode

# Conflicts: # Doc/whatsnew/3.12.rst
hugovk · Sep 28, 2023 · Sep 25, 2023 · Sep 25, 2023 · Sep 25, 2023 · Sep 25, 2023
commit 6ddc85289e65242190a064a02dc0b8050851343f
@@ -376,6 +376,104 @@ See  :mod:`sys.monitoring` for details.
 
 (Contributed by Mark Shannon in :gh:`103082`.)
 
+.. _whatsnew312-pep688:
+
+PEP 688: Making the buffer protocol accessible in Python
+--------------------------------------------------------
+
+:pep:`688` introduces a way to use the :ref:`buffer protocol <bufferobjects>`
+from Python code. Classes that implement the :meth:`~object.__buffer__` method
+are now usable as buffer types.
+
+The new :class:`collections.abc.Buffer` ABC provides a standard
+way to represent buffer objects, for example in type annotations.
+The new :class:`inspect.BufferFlags` enum represents the flags that
+can be used to customize buffer creation.
+(Contributed by Jelle Zijlstra in :gh:`102500`.)
+
+.. _whatsnew312-pep709:
+
+PEP 709: Comprehension inlining
+-------------------------------
+
+Dictionary, list, and set comprehensions are now inlined, rather than creating a
+new single-use function object for each execution of the comprehension. This
+speeds up execution of a comprehension by up to two times.
+See :pep:`709` for further details.
+
+Comprehension iteration variables remain isolated and don't overwrite a
+variable of the same name in the outer scope, nor are they visible after the
+comprehension. Inlining does result in a few visible behavior changes:
+
+* There is no longer a separate frame for the comprehension in tracebacks,
+  and tracing/profiling no longer shows the comprehension as a function call.
+* The :mod:`symtable` module will no longer produce child symbol tables for each
+  comprehension; instead, the comprehension's locals will be included in the
+  parent function's symbol table.
+* Calling :func:`locals` inside a comprehension now includes variables
+  from outside the comprehension, and no longer includes the synthetic ``.0``
+  variable for the comprehension "argument".
+* A comprehension iterating directly over ``locals()`` (e.g. ``[k for k in
+  locals()]``) may see "RuntimeError: dictionary changed size during iteration"
+  when run under tracing (e.g. code coverage measurement). This is the same
+  behavior already seen in e.g. ``for k in locals():``. To avoid the error, first
+  create a list of keys to iterate over: ``keys = list(locals()); [k for k in
+  keys]``.
+
+(Contributed by Carl Meyer and Vladimir Matveev in :pep:`709`.)
+
+Improved Error Messages
+-----------------------
+
+* Modules from the standard library are now potentially suggested as part of
+  the error messages displayed by the interpreter when a :exc:`NameError` is
+  raised to the top level. (Contributed by Pablo Galindo in :gh:`98254`.)
+
+    >>> sys.version_info
+    Traceback (most recent call last):
+      File "<stdin>", line 1, in <module>
+    NameError: name 'sys' is not defined. Did you forget to import 'sys'?
+
+* Improve the error suggestion for :exc:`NameError` exceptions for instances.
+  Now if a :exc:`NameError` is raised in a method and the instance has an
+  attribute that's exactly equal to the name in the exception, the suggestion
+  will include ``self.<NAME>`` instead of the closest match in the method
+  scope. (Contributed by Pablo Galindo in :gh:`99139`.)
+
+    >>> class A:
+    ...    def __init__(self):
+    ...        self.blech = 1
+    ...
+    ...    def foo(self):
+    ...        somethin = blech
+    ...
+    >>> A().foo()
+    Traceback (most recent call last):
+      File "<stdin>", line 1
+        somethin = blech
+                   ^^^^^
+    NameError: name 'blech' is not defined. Did you mean: 'self.blech'?
+
+* Improve the :exc:`SyntaxError` error message when the user types ``import x
+  from y`` instead of ``from y import x``. (Contributed by Pablo Galindo in :gh:`98931`.)
+
+    >>> import a.y.z from b.y.z
+    Traceback (most recent call last):
+      File "<stdin>", line 1
+        import a.y.z from b.y.z
+        ^^^^^^^^^^^^^^^^^^^^^^^
+    SyntaxError: Did you mean to use 'from ... import ...' instead?
+
+* :exc:`ImportError` exceptions raised from failed ``from <module> import
+  <name>`` statements now include suggestions for the value of ``<name>`` based on the
+  available names in ``<module>``. (Contributed by Pablo Galindo in :gh:`91058`.)
+
+    >>> from collections import chainmap
+    Traceback (most recent call last):
+      File "<stdin>", line 1, in <module>
+    ImportError: cannot import name 'chainmap' from 'collections'. Did you mean: 'ChainMap'?
+
+
 New Features Related to Type Hints
 ==================================