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-rw-r--r--pretyping/evarutil.ml12
1 files changed, 7 insertions, 5 deletions
diff --git a/pretyping/evarutil.ml b/pretyping/evarutil.ml
index 0fe691358..100bf347f 100644
--- a/pretyping/evarutil.ml
+++ b/pretyping/evarutil.ml
@@ -1000,13 +1000,15 @@ let is_ground_env evd env =
structures *)
let is_ground_env = memo1_2 is_ground_env
+exception NoHeadEvar
+
let head_evar =
let rec hrec c = match kind_of_term c with
| Evar (evk,_) -> evk
| Case (_,_,c,_) -> hrec c
| App (c,_) -> hrec c
| Cast (c,_,_) -> hrec c
- | _ -> failwith "headconstant"
+ | _ -> raise NoHeadEvar
in
hrec
@@ -1107,10 +1109,10 @@ let solve_pattern_eqn env l1 c =
*)
let status_changed lev (pbty,_,t1,t2) =
- try
- ExistentialSet.mem (head_evar t1) lev or ExistentialSet.mem (head_evar t2) lev
- with Failure _ ->
- try ExistentialSet.mem (head_evar t2) lev with Failure _ -> false
+ try ExistentialSet.mem (head_evar t1) lev
+ with NoHeadEvar ->
+ try ExistentialSet.mem (head_evar t2) lev
+ with NoHeadEvar -> false
(* Solve pbs (?i x1..xn) = (?i y1..yn) which arises often in fixpoint
* definitions. We try to unify the xi with the yi pairwise. The pairs