Handle Base.OffsetCConvert

Author: eschnett

src/buffers.jl

@@ -7,6 +7,10 @@ function Base.unsafe_convert(::Type{MPIPtr}, x::MPIBuffertype{T}) where T
     ptr = Base.unsafe_convert(Ptr{T}, x)
     reinterpret(MPIPtr, ptr)
 end
+function Base.unsafe_convert(::Type{MPIPtr}, x::Base.OffsetCConvert{T}) where {T}
+    ptr = Base.unsafe_convert(Ptr{T}, x)   # Base handles offset arithmetic
+    reinterpret(MPIPtr, ptr)
+end
 
 
 Base.cconvert(::Type{MPIPtr}, x::String) = x