[declare] Remove some unused `fix_exn`

In the current proof save path, the kernel can raise an exception when
checking a proof wrapped into a future.

However, in this case, the future itself will "fix" the produced
exception, with the mandatory handler set at the future's creation
time.

Thus, there is no need for the declare layer to mess with exceptions
anymore, if my logic is correct. Note that the `fix_exn` parameter to
the `Declare` API was not used anymore.

This undoes 77cf18eb844b45776b2ec67be9f71e8dd4ca002c which comes from
pre-github times, so unfortunately I didn't have access to the
discussion.

We need to be careful in `perform_buildp` as to catch the `Qed` error
and properly notify the STM about it with `State.exn_on`; this was
previously done by the declare layer using a hack [grabbing internal
state of the future, that the future itself was not using as it was
already forced], but we now do it in the caller in a more principled
way.

This has been tested in the case that tactics succeed but Qed fails
asynchronously.

1 files changed, 6 insertions, 8 deletions

diff --git a/lib/future.ml b/lib/future.ml
index 661637fcd1..23d089fb6b 100644
--- a/lib/future.ml
+++ b/lib/future.ml
@@ -67,8 +67,8 @@ and 'a computation = 'a comput ref
 
 let unnamed = "unnamed"
 
-let create ?(name=unnamed) ?(uuid=UUID.fresh ()) f x =
-  ref (Ongoing (name, CEphemeron.create (uuid, f, ref x)))
+let create ?(name=unnamed) ?(uuid=UUID.fresh ()) ~fix_exn x =
+  ref (Ongoing (name, CEphemeron.create (uuid, fix_exn, ref x)))
 let get x =
   match !x with
   | Finished v -> unnamed, UUID.invalid, id, ref (Val v)
@@ -97,9 +97,7 @@ let peek_val kx = let _, _, _, x = get kx in match !x with
 
 let uuid kx = let _, id, _, _ = get kx in id
 
-let from_val ?(fix_exn=id) v = create fix_exn (Val v)
-
-let fix_exn_of ck = let _, _, fix_exn, _ = get ck in fix_exn
+let from_val v = create ~fix_exn:id (Val v)
 
 let create_delegate ?(blocking=true) ~name fix_exn =
   let assignment signal ck = fun v ->
@@ -116,7 +114,7 @@ let create_delegate ?(blocking=true) ~name fix_exn =
     let cond = Condition.create () in
     (fun () -> Mutex.lock lock; Condition.wait cond lock; Mutex.unlock lock),
     (fun () -> Mutex.lock lock; Condition.broadcast cond; Mutex.unlock lock) in
-  let ck = create ~name fix_exn (Delegated wait) in
+  let ck = create ~name ~fix_exn (Delegated wait) in
   ck, assignment signal ck
 
 (* TODO: get rid of try/catch to be stackless *)
@@ -143,12 +141,12 @@ let force x = match compute x with
 
 let chain ck f =
   let name, uuid, fix_exn, c = get ck in
-  create ~uuid ~name fix_exn (match !c with
+  create ~uuid ~name ~fix_exn (match !c with
   | Closure _ | Delegated _ -> Closure (fun () -> f (force ck))
   | Exn _ as x -> x
   | Val v -> Val (f v))
 
-let create fix_exn f = create fix_exn (Closure f)
+let create ~fix_exn f = create ~fix_exn (Closure f)
 
 let replace kx y =
   let _, _, _, x = get kx in