Fix one-argument in-place Alltoall! (#465)

Author: mtsch

src/collective.jl

@@ -453,7 +453,7 @@ end
 Alltoall!(sendbuf::InPlace, recvbuf::UBuffer, comm::Comm) =
     Alltoall!(UBuffer(IN_PLACE), recvbuf, comm)
 Alltoall!(sendrecvbuf::UBuffer, comm::Comm) =
-    Alltoall!(IN_PLACE, recvbuf, comm)
+    Alltoall!(IN_PLACE, sendrecvbuf, comm)
 
 """
     Alltoall(sendbuf::UBuffer, comm::Comm)

test/test_alltoall.jl

@@ -32,6 +32,11 @@ for T in Base.uniontypes(MPI.MPIDatatype)
     a = ArrayType{T}(fill(T(rank),size))
     MPI.Alltoall!(MPI.IN_PLACE, UBuffer(a,1), comm)
     @test a == ArrayType{T}(0:size-1)
+
+    # One-argument IN_PLACE version
+    a = ArrayType{T}(fill(T(rank),size))
+    MPI.Alltoall!(UBuffer(a,1), comm)
+    @test a == ArrayType{T}(0:size-1)
 end
 
 MPI.Finalize()