Unification constraint handling (#4763, #5149)

Refine fix for bug #4763, fixing #5149

Tactic [Refine.solve_constraints] and global option

Adds a new multi-goal tactic [Refine.solve_constraints] that forces solving of
unification constraints and evar candidates to be solved. run_tactic now calls
[solve_constraints] at every [.], preserving (mostly) the 8.4/8.5 behavior of tactics.
The option allows to unset the forced solving unification constraints at
each ".", letting the user control the places where the use of
heuristics is done.

Fix test-suite files too.

3 files changed, 32 insertions, 0 deletions

diff --git a/proofs/pfedit.ml b/proofs/pfedit.ml
index a3ece1913..9c71e107c 100644
--- a/proofs/pfedit.ml
+++ b/proofs/pfedit.ml
@@ -13,6 +13,17 @@ open Entries
 open Environ
 open Evd
 
+let use_unification_heuristics_ref = ref true
+let _ = Goptions.declare_bool_option {
+  Goptions.optsync = true; Goptions.optdepr = false;
+  Goptions.optname = "Unification heuristics are applied at every .";
+  Goptions.optkey = ["Use";"Unification";"Heuristics"];
+  Goptions.optread = (fun () -> !use_unification_heuristics_ref);
+  Goptions.optwrite = (fun a -> use_unification_heuristics_ref:=a);
+}
+
+let use_unification_heuristics () = !use_unification_heuristics_ref
+
 let refining = Proof_global.there_are_pending_proofs
 let check_no_pending_proofs = Proof_global.check_no_pending_proof
 
@@ -119,6 +130,11 @@ let solve ?with_end_tac gi info_lvl tac pr =
       | Vernacexpr.SelectId id -> Proofview.tclFOCUSID id tac
       | Vernacexpr.SelectAll -> tac
     in
+    let tac =
+      if use_unification_heuristics () then
+        Proofview.tclTHEN tac Refine.solve_constraints
+      else tac
+    in
     let (p,(status,info)) = Proof.run_tactic (Global.env ()) tac pr in
     let () =
       match info_lvl with
diff --git a/proofs/refine.ml b/proofs/refine.ml
index e5114a2ec..2f2142890 100644
--- a/proofs/refine.ml
+++ b/proofs/refine.ml
@@ -149,3 +149,14 @@ let refine_casted ?unsafe f = Proofview.Goal.enter { enter = begin fun gl ->
   } in
   refine ?unsafe f
 end }
+
+(** {7 solve_constraints}
+
+  Ensure no remaining unification problems are left. Run at every "." by default. *)
+
+let solve_constraints =
+  let open Proofview in
+  tclENV >>= fun env -> tclEVARMAP >>= fun sigma ->
+   try let sigma = Evarconv.consider_remaining_unif_problems env sigma in
+       Unsafe.tclEVARSADVANCE sigma
+   with e -> tclZERO e
diff --git a/proofs/refine.mli b/proofs/refine.mli
index 3d140f036..a44632eff 100644
--- a/proofs/refine.mli
+++ b/proofs/refine.mli
@@ -43,3 +43,8 @@ val with_type : Environ.env -> Evd.evar_map ->
 val refine_casted : ?unsafe:bool -> Constr.t Sigma.run -> unit tactic
 (** Like {!refine} except the refined term is coerced to the conclusion of the
     current goal. *)
+
+(** {7 Unification constraint handling} *)
+
+val solve_constraints : unit tactic
+(** Solve any remaining unification problems, applying heuristics. *)