# Extra Clang Tools 4 documentation

## clang-tidy - mpi-buffer-deref

# mpi-buffer-deref

This check verifies if a buffer passed to an MPI (Message Passing Interface) function is sufficiently dereferenced. Buffers should be passed as a single pointer or array. As MPI function signatures specify `void *` for their buffer types, insufficiently dereferenced buffers can be passed, like for example as double pointers or multidimensional arrays, without a compiler warning emitted.

Examples:

    // A double pointer is passed to the MPI function.
    char *buf;
    MPI_Send(&buf, 1, MPI_CHAR, 0, 0, MPI_COMM_WORLD);

    // A multidimensional array is passed to the MPI function.
    short buf[1][1];
    MPI_Send(buf, 1, MPI_SHORT, 0, 0, MPI_COMM_WORLD);

    // A pointer to an array is passed to the MPI function.
    short *buf[1];
    MPI_Send(buf, 1, MPI_SHORT, 0, 0, MPI_COMM_WORLD);