coqpp: add new ![] specifiers for structured proof interaction

![proof_stack] is equivalent to the old meaning of ![proof]: the body
has type `pstate:Proof_global.t option -> Proof_global.t option`

The other specifiers are for the following body types:

~~~
![open_proof] `is_ontop:bool -> pstate`

![maybe_open_proof] `is_ontop:bool -> pstate option`

![proof] `pstate:pstate -> pstate`

![proof_opt_query] `pstate:pstate option -> unit`

![proof_query] `pstate:pstate -> unit`
~~~

The `is_ontop` is only used for the warning message when declaring a
section variable inside a proof, we could also just stop warning.

The specifiers look closely related to stm classifiers, but currently
they're unconnected. Notably this means that a ![proof_query] doesn't
have to be classified QUERY.

![proof_stack] is only used by g_rewrite/rewrite whose behaviour I
 don't fully understand, maybe we can drop it in the future.

For compat we may want to consider keeping ![proof] with its old
meaning and using some new name for the new meaning. OTOH fixing
plugins to be stricter is easier if we change it as the errors tell us
where it's used.

1 files changed, 8 insertions, 7 deletions

diff --git a/vernac/classes.ml b/vernac/classes.ml
index c783531f91..b9f57c0727 100644
--- a/vernac/classes.ml
+++ b/vernac/classes.ml
@@ -404,7 +404,7 @@ let declare_instance_open sigma ?hook ~tac ~global ~poly id pri imps decl ids te
   | None ->
     pstate
 
-let do_instance ~pstate env env' sigma ?hook ~tac ~global ~poly ~program_mode cty k u ctx ctx' pri decl imps subst id props =
+let do_instance env env' sigma ?hook ~tac ~global ~poly ~program_mode cty k u ctx ctx' pri decl imps subst id props =
   let props =
     match props with
     | Some (true, { CAst.v = CRecord fs }) ->
@@ -487,17 +487,18 @@ let do_instance ~pstate env env' sigma ?hook ~tac ~global ~poly ~program_mode ct
     if not (Evd.has_undefined sigma) && not (Option.is_empty props) then
       let term = to_constr sigma (Option.get term) in
       (declare_instance_constant pri global imps ?hook id decl poly sigma term termtype;
-       pstate)
+       None)
     else if program_mode then
-      (declare_instance_program  env sigma ~global ~poly id pri imps decl term termtype ; pstate)
+      (declare_instance_program  env sigma ~global ~poly id pri imps decl term termtype;
+       None)
     else if Option.is_empty props then
-      let pstate' =
+      let pstate =
         Flags.silently (fun () ->
             declare_instance_open sigma ?hook ~tac ~global ~poly
               id pri imps decl (List.map RelDecl.get_name ctx) term termtype)
           ()
       in
-      Some (Proof_global.push ~ontop:pstate pstate')
+      Some pstate
     else CErrors.user_err Pp.(str "Unsolved obligations remaining.") in
   id, pstate
 
@@ -529,7 +530,7 @@ let interp_instance_context ~program_mode env ctx ?(generalize=false) pl tclass
   let sigma = resolve_typeclasses ~filter:Typeclasses.all_evars ~fail:true env sigma in
   sigma, cl, u, c', ctx', ctx, imps, args, decl
 
-let new_instance ~pstate ?(global=false) ~program_mode
+let new_instance ?(global=false) ~program_mode
     poly instid ctx cl props
     ?(generalize=true) ?(tac:unit Proofview.tactic option) ?hook pri =
   let env = Global.env() in
@@ -545,7 +546,7 @@ let new_instance ~pstate ?(global=false) ~program_mode
       Namegen.next_global_ident_away i (Termops.vars_of_env env)
   in
   let env' = push_rel_context ctx env in
-  do_instance ~pstate env env' sigma ?hook ~tac ~global ~poly ~program_mode
+  do_instance env env' sigma ?hook ~tac ~global ~poly ~program_mode
     cty k u ctx ctx' pri decl imps subst id props
 
 let declare_new_instance ?(global=false) ~program_mode poly instid ctx cl pri =