gh-118761: Improve import time of the pickle module. (#128732)

Importing `pickle` is now roughly 25% faster.

Importing the `re` module is no longer needed and
thus `re` is no more implicitly exposed as `pickle.re`.

---------

Co-authored-by: Adam Turner <[email protected]>

Author: picnixz

Diff for: Lib/pickle.py

@@ -31,7 +31,6 @@
 import sys
 from sys import maxsize
 from struct import pack, unpack
-import re
 import io
 import codecs
 import _compat_pickle
@@ -188,7 +187,7 @@ def __init__(self, value):
 NEXT_BUFFER      = b'\x97'  # push next out-of-band buffer
 READONLY_BUFFER  = b'\x98'  # make top of stack readonly
 
-__all__.extend([x for x in dir() if re.match("[A-Z][A-Z0-9_]+$", x)])
+__all__.extend(x for x in dir() if x.isupper() and not x.startswith('_'))
 
 
 class _Framer:

Diff for: Misc/NEWS.d/next/Library/2025-01-10-13-34-33.gh-issue-118761.qRB8nS.rst

@@ -0,0 +1,3 @@
+Improve import time of :mod:`pickle` by 25% by removing an unnecessary
+regular expression. As such, :mod:`re` is no more implicitly available
+as ``pickle.re``. Patch by Bénédikt Tran.