minor: in constrintern.ml:sort_fields, clarify build_patt

The code was a big "try..with" defining all useful quantities at
once. I tried to lift definitions out of this try..with to define them
as early as possible: the record's information and the first field
name are fetched before processing the other fields.

There were two calls in the try..with body that could raise the
Not_found exception (or at least I don't know the code well enough to
be sure that either of them cannot): `shortest_qualid_of_global` and
`build_patt`. They are now split in two separate try..with blocks,
both raising the same exception (with a shared error message named
`env_error_msg`). Someone familiar with the invariants at play could
probably remove one of the two blocks, streamlining the code even
further.

I'm a bit surprised by the main logic part (the big (if .. else if
.. else if ..) block in the new code), and there is a question in
a comment. I hope to get it answered during code review and remove it
(and maybe simplify the code).

Finally, there was an apparently-stale comment in the code:
  (* insertion of Constextern.reference_global *)
of course Constextern.reference_global corresponds to now function
that I could find. After trying to understand the meaning of this
comment, I decided to just remove it.

0 files changed, 0 insertions, 0 deletions