From 39372d46b08d34fa4a5a4278884e951ace16e91f Mon Sep 17 00:00:00 2001
From: Mike Jarvis <michael@jarvis.net>
Date: Mon, 14 Jul 2025 13:51:39 -0400
Subject: [PATCH 1/4] Allow IN_PLACE=-1 as well

---
 mockmpi/comm.py | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/mockmpi/comm.py b/mockmpi/comm.py
index 58c2713..f436900 100644
--- a/mockmpi/comm.py
+++ b/mockmpi/comm.py
@@ -3,9 +3,11 @@
 
 import numpy as np
 
-# This constant seems to have the same value in MPICH and OpenMPI
-# so we reproduce it here since it can be quite important.
-IN_PLACE = 1
+# This constant used to be 1 in both MPICH and OpenMPI,
+# but starting with mpi4py version 4, they switched it to -1.
+# Use -1 here, but when we check for it allow 1 as well.
+IN_PLACE = -1
+ALLOWED_IN_PLACE = [1, -1]
 
 
 class MockComm(object):
@@ -113,7 +115,7 @@ def allreduce(self, sendobj, op=None):
         return d
 
     def Reduce(self, sendbuf, recvbuf, op=None, root=0):
-        if isinstance(sendbuf, int) and (sendbuf == IN_PLACE):
+        if isinstance(sendbuf, int) and (sendbuf in ALLOWED_IN_PLACE):
             sendbuf = recvbuf.copy()
 
         if not isinstance(sendbuf, np.ndarray):

From 8a15c24029ec19da7c93c146c048a5eafc4f936b Mon Sep 17 00:00:00 2001
From: Mike Jarvis <michael@jarvis.net>
Date: Mon, 14 Jul 2025 13:54:36 -0400
Subject: [PATCH 2/4] update ci versions

---
 .github/workflows/ci.yml | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 843a64a..ece462e 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -21,12 +21,12 @@ jobs:
             - uses: actions/checkout@v2
 
             - name: Set up Python ${{ matrix.py }}
-              uses: actions/setup-python@v2
+              uses: actions/setup-python@v5
               with:
                 python-version: ${{ matrix.py }}
 
             - name: Cache pip
-              uses: actions/cache@v2
+              uses: actions/cache@v4
               with:
                 path: ~/.cache/pip
                 key: ${{ runner.os }}-${{ matrix.py }}-pip-${{ hashFiles('requirements.txt') }}

From 24ab6f85a53de748bfa4b359909b316729d95d03 Mon Sep 17 00:00:00 2001
From: Mike Jarvis <michael@jarvis.net>
Date: Mon, 14 Jul 2025 13:55:44 -0400
Subject: [PATCH 3/4] Check against more recent python versions in ci

---
 .github/workflows/ci.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index ece462e..b1d0329 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -15,7 +15,7 @@ jobs:
         strategy:
             matrix:
                 os: [ ubuntu-latest, macos-latest ]
-                py: [ 3.7, 3.8, 3.9 ]
+                py: [ 3.12, 3.13 ]
 
         steps:
             - uses: actions/checkout@v2

From 6afdbcd0490d7874251c4df006158859df81c5a0 Mon Sep 17 00:00:00 2001
From: Mike Jarvis <michael@jarvis.net>
Date: Mon, 14 Jul 2025 17:59:19 -0400
Subject: [PATCH 4/4] Just in case it changes again, include the real mpi4py
 IN_PLACE if available

---
 mockmpi/comm.py | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/mockmpi/comm.py b/mockmpi/comm.py
index f436900..53011d6 100644
--- a/mockmpi/comm.py
+++ b/mockmpi/comm.py
@@ -6,8 +6,12 @@
 # This constant used to be 1 in both MPICH and OpenMPI,
 # but starting with mpi4py version 4, they switched it to -1.
 # Use -1 here, but when we check for it allow 1 as well.
-IN_PLACE = -1
-ALLOWED_IN_PLACE = [1, -1]
+# And if we happen to have mpi4py installed, include whatever it actually has as well.
+try:
+    from mpi4py.MPI import IN_PLACE
+except ImportError:
+    IN_PLACE = -1
+ALLOWED_IN_PLACE = [IN_PLACE, 1, -1]
 
 
 class MockComm(object):