From d076a13c1d94d8ce56e48afc2b3e622406678560 Mon Sep 17 00:00:00 2001
From: Chris Ostrouchov <chris.ostrouchov@gmail.com>
Date: Mon, 4 Apr 2016 11:09:00 -0400
Subject: [PATCH] openmpi: patch for legitimate zero size messages

This patch is required in order to make python-mpi4py tests pass.
It is also a bug in the openmpi implementation to see full discussion
see https://www.open-mpi.org/community/lists/users/2015/11/28030.php
---
 .../development/libraries/openmpi/default.nix |  7 ++++-
 .../libraries/openmpi/nbc_copy.patch          | 30 +++++++++++++++++++
 2 files changed, 36 insertions(+), 1 deletion(-)
 create mode 100644 pkgs/development/libraries/openmpi/nbc_copy.patch

diff --git a/pkgs/development/libraries/openmpi/default.nix b/pkgs/development/libraries/openmpi/default.nix
index 18dc2251013e..c1333ff61714 100644
--- a/pkgs/development/libraries/openmpi/default.nix
+++ b/pkgs/development/libraries/openmpi/default.nix
@@ -20,6 +20,12 @@ in stdenv.mkDerivation rec {
     sha256 = "14p4px9a3qzjc22lnl6braxrcrmd9rgmy7fh4qpanawn2pgfq6br";
   };
 
+  # Bug in openmpi implementation for zero sized messages
+  # Patch required to make mpi4py pass. Will NOT
+  # be required when openmpi >= 2.0.0
+  # https://www.open-mpi.org/community/lists/users/2015/11/28030.php
+  patches = [ ./nbc_copy.patch ];
+
   buildInputs = [ gfortran libibverbs ];
 
   nativeBuildInputs = [ perl ];
@@ -42,4 +48,3 @@ in stdenv.mkDerivation rec {
     maintainers = [ stdenv.lib.maintainers.mornfall ];
   };
 }
-
diff --git a/pkgs/development/libraries/openmpi/nbc_copy.patch b/pkgs/development/libraries/openmpi/nbc_copy.patch
new file mode 100644
index 000000000000..d496c7cc2d76
--- /dev/null
+++ b/pkgs/development/libraries/openmpi/nbc_copy.patch
@@ -0,0 +1,30 @@
+commit 4ee20ba31dd64b8f899447cdad78ec2379acfce7
+Author: Gilles Gouaillardet <gilles@rist.or.jp>
+Date:   Tue Nov 10 08:59:03 2015 +0900
+
+    fix NBC_Copy for legitimate zero size messages
+    
+    (back ported from commit open-mpi/ompi@0bd765eddd33e3d4ac18ec644c60a5c160cb48dc)
+    (back ported from commit open-mpi/ompi@9a70765f27fdf17e70e1a115754fef7e5f16132a)
+
+diff --git a/ompi/mca/coll/libnbc/nbc_internal.h b/ompi/mca/coll/libnbc/nbc_internal.h
+index bf2f1cb..81be8cc 100644
+--- a/ompi/mca/coll/libnbc/nbc_internal.h
++++ b/ompi/mca/coll/libnbc/nbc_internal.h
+@@ -501,7 +501,14 @@ static inline int NBC_Copy(void *src, int srccount, MPI_Datatype srctype, void *
+   } else {
+     /* we have to pack and unpack */
+     res = MPI_Pack_size(srccount, srctype, comm, &size);
+-    if (MPI_SUCCESS != res || 0 == size) { printf("MPI Error in MPI_Pack_size() (%i:%i)\n", res, size); return (MPI_SUCCESS == res) ? MPI_ERR_SIZE : res;}
++    if (MPI_SUCCESS != res) {
++      printf ("MPI Error in MPI_Pack_size() (%i:%i)", res, size);
++      return res;
++    }
++
++    if (0 == size) {
++        return OMPI_SUCCESS;
++    }
+     packbuf = malloc(size);
+     if (NULL == packbuf) { printf("Error in malloc()\n"); return res; }
+     pos=0;
+