(************************************************************************)
(*         *   The Coq Proof Assistant / The Coq Development Team       *)
(*  v      *   INRIA, CNRS and contributors - Copyright 1999-2018       *)
(* <O___,, *       (see CREDITS file for the list of authors)           *)
(*   \VV/  **************************************************************)
(*    //   *    This file is distributed under the terms of the         *)
(*         *     GNU Lesser General Public License Version 2.1          *)
(*         *     (see LICENSE file for the text of the license)         *)
(************************************************************************)
(* (c) Copyright 2006-2016 Microsoft Corporation and Inria.                  *)
Ltac T1 x := match goal with |- _ => set t := (x in X in _ = X) end.
Ltac T2 x := first [set t := (x in RHS)].
Ltac T3 x := first [set t := (x in Y in _ = Y)|idtac].
Ltac T4 x := set t := (x in RHS); idtac.
Ltac T5 x := match goal with |- _ => set t := (x in RHS) | |- _ => idtac end.
Open Scope nat_scope.

Lemma foo x y : x.+1 = y + x.+1.