From 6cf57242a375fb0186c9eefcf46fcff848d54b19 Mon Sep 17 00:00:00 2001
From: Augustin Degomme <adegomme@users.noreply.github.com>
Date: Sat, 6 Apr 2019 14:54:02 +0200
Subject: [PATCH] please herr sonar

---
 src/smpi/bindings/smpi_pmpi_coll.cpp | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/smpi/bindings/smpi_pmpi_coll.cpp b/src/smpi/bindings/smpi_pmpi_coll.cpp
index c4f8183dca..2eb62c2c09 100644
--- a/src/smpi/bindings/smpi_pmpi_coll.cpp
+++ b/src/smpi/bindings/smpi_pmpi_coll.cpp
@@ -760,7 +760,9 @@ int PMPI_Ialltoall(void* sendbuf, int sendcount, MPI_Datatype sendtype, void* re
     MPI_Datatype sendtmptype = sendtype;
     if (sendbuf == MPI_IN_PLACE) {
       sendtmpbuf = static_cast<void*>(xbt_malloc(recvcount * comm->size() * recvtype->size()));
-      memcpy(sendtmpbuf, recvbuf, recvcount * comm->size() * recvtype->size());
+      //memcpy(??,nullptr,0) is actually undefined behavor, even if harmless.
+      if(recvbuf != nullptr)
+        memcpy(sendtmpbuf, recvbuf, recvcount * comm->size() * recvtype->size());
       sendtmpcount = recvcount;
       sendtmptype  = recvtype;
     }
-- 
2.20.1