mpich: fix MPI_Barrier segfault (#5235)

* mpich: fix MPI_Barrier segfault

* one more link

var/spack/repos/builtin/packages/mpich/mpich32_clang.patch

@@ -0,0 +1,13 @@
+diff --git a/src/include/mpiimpl.h b/src/include/mpiimpl.h
+index e705e5d..3bfcbee 100644
+--- a/src/include/mpiimpl.h
++++ b/src/include/mpiimpl.h
+@@ -1528,7 +1528,7 @@ typedef struct MPID_Request {
+ #ifdef MPID_DEV_REQUEST_DECL
+     MPID_DEV_REQUEST_DECL
+ #endif
+-} MPID_Request ATTRIBUTE((__aligned__(32)));
++} ATTRIBUTE((__aligned__(32))) MPID_Request;
+ 
+ extern MPIU_Object_alloc_t MPID_Request_mem;
+ /* Preallocated request objects */

var/spack/repos/builtin/packages/mpich/package.py

@@ -51,6 +51,11 @@ class Mpich(AutotoolsPackage):
     provides('mpi@:3.0', when='@3:')
     provides('mpi@:1.3', when='@1:')
 
+    # fix MPI_Barrier segmentation fault
+    # see https://lists.mpich.org/pipermail/discuss/2016-May/004764.html
+    # and https://lists.mpich.org/pipermail/discuss/2016-June/004768.html
+    patch('mpich32_clang.patch', when='@3.2%clang')
+
     def setup_dependent_environment(self, spack_env, run_env, dependent_spec):
         # On Cray, the regular compiler wrappers *are* the MPI wrappers.
         if 'platform=cray' in self.spec: