This week we merged several changes from Thomas Refis, to allow the
use of exception patterns under or-patterns, to write code such as
match foo x with
| None | exception Not_found -> ...
| Some -> ...
Unfortunately, I failed to properly assess the impact of this change,
and in particular to make sure that Luc Maranget had properly reviewed
this code -- any change to the pattern-matching machinery should be
reviewed by Luc.
The problem that I had not foreseen and that he would have immediately
realized is that, while adapting the pattern-matching *compiler* is
relatively easy (Thomas inserted a transformation at the right place
to separate exception patterns from the others and handle them
separately, using the staticraise construct used by the
pattern-matching compiler to avoid duplicating the
right-hand-side branch), adapting the pattern-matching warnings
machinery is both more subtle and easier to overlook (it may fail
silently and nobody notices, unlike wrong code production). This part
of the compiler is subtle and best understood by Luc, but he does not
have the time to do a proper review of those changes in the timeframe
for the 4.03 feature freeze (mid-December).
I believe the right move in this case, implemented in the present
commit, is to revert the change from trunk (this is not a feature that
we must *imperatively* have in 4.03), do a proper job of understanding
the changes, and integrate the change when we are confident it is
ready. I hope to do this in 2016, together with Luc Maranget and
Thomas Refis -- hopefully this would allow Thomas and I to be more
confident when changing the pattern-matching machinery in the future.
Revert "Merge pull request #343 from trefis/pr7083"
This reverts commit 22681b8d2a, reversing
changes made to a24e4edf0a.
Revert "Merge pull request #341 from trefis/or-exception"
This reverts commit f8f68bd329, reversing
changes made to 1534fe8082.
Revert "Merge pull request #305 from trefis/or-exception"
This reverts commit cfeda89396, reversing
changes made to 77cf36cf82.
Translate [%ocaml.extension_constructor <path>] to the
runtime-representation of the extension constructor denoted by
<path>. This allows one to get the extension constructor without
having to create a dummy value.
From comments in typedtree.mli:
When introduced in 2000, this [type] enabled a more efficient code
generation for optional arguments. However, today the information is
redundant as labels are passed to [transl_apply] too. Could be cleaned
up.
Damien Doligez
Gabriel Scherer
Thomas Refis
Jeremie Dimino
Nicolas Ojeda Bar
alainfrisch
Jacques Garrigue
Damien Doligez
Jérémie Dimino