Merge pull request #106 from JuliaParallel/eschnett/comm

Correct error in MPI_Comm_dup, and add test case

Author: eschnett

src/mpi-base.jl

@@ -132,10 +132,10 @@ function Finalized()
 end
 
 function Comm_dup(comm::Comm)
-    newcomm = MPI.Comm(0)
+    newcomm = Array(Cint, 1)
     ccall((MPI_COMM_DUP,libmpi), Void, (Ptr{Cint}, Ptr{Cint}, Ptr{Cint}),
-          &comm.val, &newcomm.val, &0)
-    newcomm
+          &comm.val, newcomm, &0)
+    MPI.Comm(newcomm[1])
 end
 
 function Comm_free(comm::Comm)

test/test_comm.jl

@@ -0,0 +1,16 @@
+using Base.Test
+using MPI
+
+MPI.Init()
+
+comm = MPI.COMM_WORLD
+MPI.Barrier(comm)
+comm2 = MPI.Comm_dup(comm)
+MPI.Barrier(comm2)
+comm3 = MPI.Comm_dup(comm2)
+MPI.Barrier(comm3)
+MPI.Comm_free(comm2)
+MPI.Barrier(comm3)
+# Don't free comm2
+
+MPI.Finalize()