dev-python/immutables: Backport hash fixes for 32-bit platforms

Closes: https://bugs.gentoo.org/801634
Signed-off-by: Michał Górny <mgorny@gentoo.org>

2 files changed, 98 insertions, 0 deletions

diff --git a/dev-python/immutables/files/immutables-0.15-32bit-hash.patch b/dev-python/immutables/files/immutables-0.15-32bit-hash.patch
new file mode 100644
index 000000000000..234dfa028c08
--- /dev/null
+++ b/dev-python/immutables/files/immutables-0.15-32bit-hash.patch
@@ -0,0 +1,76 @@
+From fa355239e70411179c70b16ed4ff7113d8008dad Mon Sep 17 00:00:00 2001
+From: Elvis Pranskevichus <elvis@edgedb.com>
+Date: Wed, 4 Aug 2021 19:25:44 -0700
+Subject: [PATCH] Fix test_none_collisions on 32-bit systems (#69)
+
+There are two issues at play here:
+
+1. Python version of `map_hash` unnecessarily performs hash truncation
+   even if the hash is already 32-bit wide, which potentially converts
+   it from signed int to unsigned long.
+
+2. The `test_none_collisions` test generates a collision node with
+   hash greater than 2^32.
+
+Both of these are problematic on 32-bit systems, where `sizeof(Py_hash_t)`
+is 4, and so anything that doesn't fit into `Py_hash_t` gets bit-mangled,
+breaking the `hash(x) != x` invariance that the test relies upon.
+
+Fixes: #53
+Fixes: #50
+---
+ .github/workflows/tests.yml | 10 +++++++++-
+ immutables/map.py           |  5 ++++-
+ tests/test_none_keys.py     | 14 +++++++++-----
+ 3 files changed, 22 insertions(+), 7 deletions(-)
+
+diff --git a/immutables/map.py b/immutables/map.py
+index 2c1ffa91..0ad28588 100644
+--- a/immutables/map.py
++++ b/immutables/map.py
+@@ -19,7 +19,10 @@
+ 
+ def map_hash(o):
+     x = hash(o)
+-    return (x & 0xffffffff) ^ ((x >> 32) & 0xffffffff)
++    if sys.hash_info.width > 32:
++        return (x & 0xffffffff) ^ ((x >> 32) & 0xffffffff)
++    else:
++        return x
+ 
+ 
+ def map_mask(hash, shift):
+diff --git a/tests/test_none_keys.py b/tests/test_none_keys.py
+index 8c0bb379..26d4220b 100644
+--- a/tests/test_none_keys.py
++++ b/tests/test_none_keys.py
+@@ -1,3 +1,4 @@
++import ctypes
+ import unittest
+ 
+ from immutables.map import map_hash, map_mask, Map as PyMap
+@@ -6,16 +7,19 @@
+ 
+ none_hash = map_hash(None)
+ assert(none_hash != 1)
+-assert((none_hash >> 32) == 0)
++assert(none_hash.bit_length() <= 32)
+ 
+-not_collision = 0xffffffff & (~none_hash)
++none_hash_u = ctypes.c_size_t(none_hash).value
++not_collision = 0xffffffff & (~none_hash_u)
+ 
+ mask = 0x7ffffffff
+-none_collisions = [none_hash & (mask >> shift)
++none_collisions = [none_hash_u & (mask >> shift)
+                    for shift in reversed(range(0, 32, 5))]
+ assert(len(none_collisions) == 7)
+-none_collisions = [h | (not_collision & (mask << shift))
+-                   for shift, h in zip(range(5, 37, 5), none_collisions)]
++none_collisions = [
++    ctypes.c_ssize_t(h | (not_collision & (mask << shift))).value
++    for shift, h in zip(range(5, 37, 5), none_collisions)
++]
+ 
+ 
+ class NoneCollision(HashKey):
diff --git a/dev-python/immutables/immutables-0.15-r1.ebuild b/dev-python/immutables/immutables-0.15-r1.ebuild
new file mode 100644
index 000000000000..f9ccd8404ee2
--- /dev/null
+++ b/dev-python/immutables/immutables-0.15-r1.ebuild
@@ -0,0 +1,22 @@
+# Copyright 2019-2021 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+EAPI=7
+
+PYTHON_COMPAT=( python3_{8..10} )
+inherit distutils-r1
+
+DESCRIPTION="A high-performance immutable mapping type for Python"
+HOMEPAGE="https://github.com/MagicStack/immutables"
+SRC_URI="https://github.com/MagicStack/${PN}/archive/v${PV}.tar.gz -> ${P}.tar.gz"
+
+LICENSE="Apache-2.0"
+SLOT="0"
+KEYWORDS="~amd64 ~arm ~arm64 ~ppc ~ppc64 ~sparc ~x86"
+
+PATCHES=(
+	# https://github.com/MagicStack/immutables/commit/fa355239e70411179c70b16ed4ff7113d8008dad
+	"${FILESDIR}"/${P}-32bit-hash.patch
+)
+
+distutils_enable_tests pytest