[cleanup] Unify all calls to the error function.

This is the continuation of #244, we now deprecate `CErrors.error`,
the single entry point in Coq is `user_err`.

The rationale is to allow for easier grepping, and to ease a future
cleanup of error messages. In particular, we would like to
systematically classify all error messages raised by Coq and be sure
they are properly documented.

We restore the two functions removed in #244 to improve compatibility,
but mark them deprecated.

1 files changed, 4 insertions, 4 deletions

diff --git a/tactics/tacticals.ml b/tactics/tacticals.ml
index fe9cb123c..c495b5ece 100644
--- a/tactics/tacticals.ml
+++ b/tactics/tacticals.ml
@@ -69,7 +69,7 @@ let tclTHENSEQ       = tclTHENLIST
 
 let nthDecl m gl =
   try List.nth (pf_hyps gl) (m-1)
-  with Failure _ -> error "No such assumption."
+  with Failure _ -> user_err Pp.(str "No such assumption.")
 
 let nthHypId m gl = nthDecl m gl |> NamedDecl.get_id
 let nthHyp m gl   = mkVar (nthHypId m gl)
@@ -80,7 +80,7 @@ let lastHyp gl    = nthHyp 1 gl
 
 let nLastDecls n gl =
   try List.firstn n (pf_hyps gl)
-  with Failure _ -> error "Not enough hypotheses in the goal."
+  with Failure _ -> user_err Pp.(str "Not enough hypotheses in the goal.")
 
 let nLastHypsId n gl = List.map (NamedDecl.get_id) (nLastDecls n gl)
 let nLastHyps n gl   = List.map mkVar (nLastHypsId n gl)
@@ -533,11 +533,11 @@ module New = struct
     let hyps = Proofview.Goal.hyps gl in
     try
       List.nth hyps (m-1)
-    with Failure _ -> CErrors.error "No such assumption."
+    with Failure _ -> CErrors.user_err Pp.(str "No such assumption.")
 
   let nLastDecls gl n =
     try List.firstn n (Proofview.Goal.hyps gl)
-    with Failure _ -> error "Not enough hypotheses in the goal."
+    with Failure _ -> CErrors.user_err Pp.(str "Not enough hypotheses in the goal.")
 
   let nthHypId m gl =
     (** We only use [id] *)