From 0daae2bd1ab518d8fcb6d59a5616786ade94d1e5 Mon Sep 17 00:00:00 2001
From: Pierre-Marie Pédrot <pierre-marie.pedrot@inria.fr>
Date: Fri, 22 Dec 2017 16:26:24 +0100
Subject: Deprecate implicit tactic solving.

---
 plugins/ltac/extratactics.ml4       |  6 +++++
 test-suite/bugs/closed/4882.v       | 50 -------------------------------------
 test-suite/success/ImplicitTactic.v | 16 ------------
 theories/Logic/Diaconescu.v         |  2 --
 4 files changed, 6 insertions(+), 68 deletions(-)
 delete mode 100644 test-suite/bugs/closed/4882.v
 delete mode 100644 test-suite/success/ImplicitTactic.v

diff --git a/plugins/ltac/extratactics.ml4 b/plugins/ltac/extratactics.ml4
index c5254b37c..2a6e8c060 100644
--- a/plugins/ltac/extratactics.ml4
+++ b/plugins/ltac/extratactics.ml4
@@ -594,10 +594,16 @@ let inImplicitTactic : glob_tactic_expr option -> obj =
        subst_function = subst_implicit_tactic;
        classify_function = (fun o -> Dispose)}
 
+let warn_deprecated_implicit_tactic =
+  CWarnings.create ~name:"deprecated-implicit-tactic" ~category:"deprecated"
+    (fun () -> strbrk "Implicit tactics are deprecated")
+
 let declare_implicit_tactic tac =
+  let () = warn_deprecated_implicit_tactic () in
   Lib.add_anonymous_leaf (inImplicitTactic (Some (Tacintern.glob_tactic tac)))
 
 let clear_implicit_tactic () =
+  let () = warn_deprecated_implicit_tactic () in
   Lib.add_anonymous_leaf (inImplicitTactic None)
 
 VERNAC COMMAND EXTEND ImplicitTactic CLASSIFIED AS SIDEFF
diff --git a/test-suite/bugs/closed/4882.v b/test-suite/bugs/closed/4882.v
deleted file mode 100644
index 8c26af708..000000000
--- a/test-suite/bugs/closed/4882.v
+++ /dev/null
@@ -1,50 +0,0 @@
-
-Definition Foo {T}{a : T} : T := a.
-
-Module A.
-
-  Declare Implicit Tactic eauto.
-
-  Goal forall A (x : A), A.
-  intros.
-  apply Foo. (* Check defined evars are normalized *)
-  (*  Qed. *)
-  Abort.
-
-End A.
-
-Module B.
-
-  Definition Foo {T}{a : T} : T := a.
-
-  Declare Implicit Tactic eassumption.
-
-  Goal forall A (x : A), A.
-  intros.
-  apply Foo.
-  (*  Qed. *)
-  Abort.
-
-End B.
-
-Module C.
-
-  Declare Implicit Tactic first [exact True|assumption].
-
-  Goal forall (x : True), True.
-  intros.
-  apply (@Foo _ _).
-  Qed.
-
-End C.
-
-Module D.
-
-  Declare Implicit Tactic assumption.
-
-  Goal forall A (x : A), A.
-  intros.
-  exact _.
-  Qed.
-
-End D.
diff --git a/test-suite/success/ImplicitTactic.v b/test-suite/success/ImplicitTactic.v
deleted file mode 100644
index d8fa3043d..000000000
--- a/test-suite/success/ImplicitTactic.v
+++ /dev/null
@@ -1,16 +0,0 @@
-(* A Wiedijk-Cruz-Filipe style tactic for solving implicit arguments *)
-
-(* Declare a term expression with a hole *)
-Parameter quo : nat -> forall n:nat, n<>0 -> nat.
-Notation "x / y" := (quo x y _) : nat_scope.
-
-(* Declare the tactic for resolving implicit arguments still
-   unresolved after type-checking; it must complete the subgoal to
-   succeed *)
-Declare Implicit Tactic assumption.
-
-Goal forall n d, d<>0 -> { q:nat & { r:nat | d * q + r = n }}.
-intros.
-(* Here, assumption is used to solve the implicit argument of quo *)
-exists (n / d).
-
diff --git a/theories/Logic/Diaconescu.v b/theories/Logic/Diaconescu.v
index 3317766c9..66e82ddbf 100644
--- a/theories/Logic/Diaconescu.v
+++ b/theories/Logic/Diaconescu.v
@@ -234,8 +234,6 @@ Qed.
 (** An alternative more concise proof can be done by directly using
     the guarded relational choice *)
 
-Declare Implicit Tactic auto.
-
 Lemma proof_irrel_rel_choice_imp_eq_dec' : a1=a2 \/ ~a1=a2.
 Proof.
   assert (decide: forall x:A, x=a1 \/ x=a2 ->
-- 
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