Hi again, Below some other warnings. Regards. Jorge 'D'Elia. -- In file included from /home/bigpack/mpich-paq/mpich-5.0.0/src/mpl/include/mpl_atomic_c11.h:20,                  from /home/bigpack/mpich-paq/mpich-5.0.0/src/mpl/include/mpl_atomic.h:101,                  from /home/bigpack/mpich-paq/mpich-5.0.0/src/mpl/include/mpl.h:16,                  from ../src/include/mpiimpl.h:53,                  from ../src/mpi/attr/attrutil.c:6: In function ‘MPL_atomic_release_store_int’,     inlined from ‘MPID_Attr_alloc’ at ../src/mpi/attr/attrutil.c:48:5,     inlined from ‘MPIR_Attr_dup_list’ at ../src/mpi/attr/attrutil.c:167:17: /home/bigpack/mpich-paq/mpich-5.0.0/src/mpl/include/mpl_atomic_c11.h:59:5: warning: ‘__atomic_store_4’ writing 4 bytes into a region of size 0 overflows the destination [-Wstringop-overflow=]    59 |     atomic_store_explicit(&ptr->v, (CAST_TYPE)val, memory_order_release);      \       |     ^~~~~~~~~~~~~~~~~~~~~ /home/bigpack/mpich-paq/mpich-5.0.0/src/mpl/include/mpl_atomic_c11.h:93:9: note: in expansion of macro ‘MPLI_ATOMIC_DECL_FUNC_COMMON’    93 |         MPLI_ATOMIC_DECL_FUNC_COMMON(TYPE, NAME, ATOMIC_TYPE, CAST_TYPE) \       |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~ /home/bigpack/mpich-paq/mpich-5.0.0/src/mpl/include/mpl_atomic_c11.h:99:1: note: in expansion of macro ‘MPLI_ATOMIC_DECL_FUNC_VAL’    99 | MPLI_ATOMIC_DECL_FUNC_VAL(int, int, atomic_int, int)       | ^~~~~~~~~~~~~~~~~~~~~~~~~ In function ‘MPIR_Attr_dup_list’: cc1: note: destination object is likely at address zero. ...   CC       src/mpi/coll/barrier/lib_libmpi_la-barrier_inter_bcast.lo ../src/mpi/coll/barrier/barrier_intra_k_dissemination.c: In function ‘MPIR_Barrier_intra_k_dissemination’: ../src/mpi/coll/barrier/barrier_intra_k_dissemination.c:120:9: warning: ‘MPIC_Waitall’ accessing 8 bytes in a region of size 0 [-Wstringop-overflow=]   120 |         MPIC_Waitall(k - 1, recv_reqs + ((k - 1) * ((nphases - 1) & 1)), MPI_STATUSES_IGNORE);       |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ../src/mpi/coll/barrier/barrier_intra_k_dissemination.c:120:9: note: referencing argument 2 of type ‘MPIR_Request *[0]’ In file included from ../src/include/mpiimpl.h:208,                  from ../src/mpi/coll/barrier/barrier_intra_k_dissemination.c:6: ../src/include/mpir_coll.h:48:5: note: in a call to function ‘MPIC_Waitall’    48 | int MPIC_Waitall(int numreq, MPIR_Request * requests[], MPI_Status * statuses);       |     ^~~~~~~~~~~~   CC       src/mpi/coll/bcast/lib_libmpi_la-bcast_utils.lo   CC       src/mpid/ch4/src/lib_libmpi_la-ch4_proc.lo ../src/mpid/ch4/src/ch4_proc.c: In function ‘MPIDIU_upidhash_add’: ../src/mpid/ch4/src/ch4_proc.c:336:5: warning: ‘memcpy’ specified bound between 18446744071562067968 and 18446744073709551615 exceeds maximum object size 9223372036854775807 [-Wstringop-overflow=]   336 |     memcpy(t->upid, upid, upid_len);       |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~   CC       src/mpid/ch4/src/lib_libmpi_la-ch4_stream_enqueue.lo   end.