blurb, docs, cleanup

Author: tiran

Doc/whatsnew/3.11.rst

@@ -245,6 +245,12 @@ fractions
   that an ``isinstance(some_fraction, typing.SupportsInt)`` check passes.
   (Contributed by Mark Dickinson in :issue:`44547`.)
 
+hashlib
+-------
+
+* :func:`hashlib.blake2b` and :func:`hashlib.blake2s` now prefer `libb2
+  <https://www.blake2.net/>`_ over Python's vendored copy.
+  (Contributed by Christian Heimes in :issue:`47095`.)
 
 IDLE and idlelib
 ----------------
@@ -1060,6 +1066,9 @@ Porting to Python 3.11
   <https://github.com/python/pythoncapi_compat>`__ to get these functions
   on old Python functions.
 
+* Distributors are encouraged to build Python with optimized Blake2 library
+  `libb2 <https://www.blake2.net>`_.
+
 
 Deprecated
 ----------

Misc/NEWS.d/next/Library/2022-03-23-12-07-26.bpo-47095.P3YTrh.rst

@@ -0,0 +1,2 @@
+:mod:`hashlib`'s internal ``_blake2`` module now prefers ``libb2`` from
+https://www.blake2.net/ over Python's vendored copy of blake2.

configure

@@ -6391,13 +6391,12 @@ for builtin_hash in $with_builtin_hashlib_hashes; do
 done
 IFS=$as_save_IFS
 
-dnl libb2 for blake2
-dnl _blake2 module falls back to vendored copy
+dnl libb2 for blake2. _blake2 module falls back to vendored copy.
 AS_VAR_IF([with_builtin_blake2], [yes], [
   PKG_CHECK_MODULES([LIBB2], [libb2], [
-    have_libb2=yes
-    AC_DEFINE([HAVE_LIBB2], [1], [Define to 1 if you want to build _blake2 with libb2])
-  ], [have_libb2=no])
+    AC_DEFINE([HAVE_LIBB2], [1],
+              [Define to 1 if you want to build _blake2 module with libb2])
+  ])
 ])
 
 # --with-experimental-isolated-subinterpreters

configure.ac

@@ -622,7 +622,7 @@
 /* Define to 1 if you have the `lchown' function. */
 #undef HAVE_LCHOWN
 
-/* Define to 1 if you want to build _blake2 with libb2 */
+/* Define to 1 if you want to build _blake2 module with libb2 */
 #undef HAVE_LIBB2
 
 /* Define to 1 if you have the `db' library (-ldb). */