Supporting OpenMP Sentinels

[hiker]

Some UM code contains declarations in OpenMP sentinels, e.g.:

!$ USE compute_chunk_size_mod, ONLY: compute_chunk_size  ! Note OpenMP sentinel

Fparser skips these lines as comment lines, and as a result, FAB misses dependencies if compilation is done with OpenMP enabled.

While I have a FAB patch that fixes it (if a comment is found, check if it starts with !$, and then try Use_Stmt.match(...), and that works fine for me), I think it could be useful if fparser could be instructed to handle !$. That should be easier than pre-processing directive (since the string following !$ must be valid Fortran - I believe we could simply pass a flag to the reader to delete the first two characters if they are !$?

If you don't think that this could be useful for fparser, let me know, and I'll get my current FAB workaround merged in.

[hiker]

As discussed in the telco, this is considered useful. It will be implemented using an optional flag to enable this. And it is expected to be handled in the reader - detect the sentinels and remove them. We just need to take care not to remove !$ for real openmp statements. According to the standard, an OpenMP directive may not have a whitespace between !$ and omp, while a sentinel must have a whitespace after !$.