From c29c970c0653c0f74a617413471e28a4e4d08c86 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Luis=20Miguel=20Mej=C3=ADa=20Su=C3=A1rez?=
 <luismiguelmejiasuarez@gmail.com>
Date: Mon, 11 Apr 2022 20:44:22 -0500
Subject: [PATCH] Deprecate Future instances

---
 .../src/main/scala/alleycats/std/future.scala |  2 +-
 core/src/main/scala/cats/Invariant.scala      | 24 ++++++++++++++++++
 core/src/main/scala/cats/Semigroupal.scala    | 25 +++++++++++++++++++
 3 files changed, 50 insertions(+), 1 deletion(-)

diff --git a/alleycats-core/src/main/scala/alleycats/std/future.scala b/alleycats-core/src/main/scala/alleycats/std/future.scala
index bee323ce33..49bc6f2549 100644
--- a/alleycats-core/src/main/scala/alleycats/std/future.scala
+++ b/alleycats-core/src/main/scala/alleycats/std/future.scala
@@ -26,7 +26,7 @@ import scala.concurrent.Future
 
 object future extends FutureInstances
 
-trait FutureInstances {
+trait FutureInstances extends cats.instances.FutureInstances {
 
   implicit val alleycatsStdFuturePure: Pure[Future] =
     new Pure[Future] {
diff --git a/core/src/main/scala/cats/Invariant.scala b/core/src/main/scala/cats/Invariant.scala
index 626046cc9d..7af63823ed 100644
--- a/core/src/main/scala/cats/Invariant.scala
+++ b/core/src/main/scala/cats/Invariant.scala
@@ -153,6 +153,30 @@ object Invariant extends ScalaVersionSpecificInvariantInstances with InvariantIn
 
   implicit def catsInstancesForTry: MonadThrow[Try] with CoflatMap[Try] =
     cats.instances.try_.catsStdInstancesForTry
+
+  @deprecated(
+    // format: off
+    message =
+"""
+Instances for scala.concurrent.Future have been deprecated,
+and will be moved into alleycats-core in cats 3.
+
+The rationale for the change is that given the nature of Future
+cats can't guarantee the appropriate behaviour of its instance.
+
+If you want to silence this warning you can add this to your scalacOptions:
+"-Wconf:cat=deprecation&origin=cats\\..*\\..*ForFuture:s"
+
+You may also prepare for this change and use alleycats right now.
+Import the library: "org.typelevel" %% "alleycats-core" % "..."
+And import alleycats.std.future._ in this file;
+if you require the future instances in multiple files
+you can add the following scalacOptions to automatically add the import in all files:
+"-Yimports", "java.lang", "scala", "scala.Predef", "alleycats.std.future"
+""",
+    // format: on
+    since = "2.8.0"
+  )
   implicit def catsInstancesForFuture(implicit
     ec: ExecutionContext
   ): MonadThrow[Future] with CoflatMap[Future] =
diff --git a/core/src/main/scala/cats/Semigroupal.scala b/core/src/main/scala/cats/Semigroupal.scala
index 0255a5f06b..10d1f77fb3 100644
--- a/core/src/main/scala/cats/Semigroupal.scala
+++ b/core/src/main/scala/cats/Semigroupal.scala
@@ -71,8 +71,33 @@ object Semigroupal extends ScalaVersionSpecificSemigroupalInstances with Semigro
   implicit def catsSemigroupalForId: Semigroupal[Id] = catsInstancesForId
   implicit def catsSemigroupalForOption: Semigroupal[Option] = cats.instances.option.catsStdInstancesForOption
   implicit def catsSemigroupalForTry: Semigroupal[Try] = cats.instances.try_.catsStdInstancesForTry
+
+  @deprecated(
+    // format: off
+    message =
+"""
+Instances for scala.concurrent.Future have been deprecated,
+and will be moved into alleycats-core in cats 3.
+
+The rationale for the change is that given the nature of Future
+cats can't guarantee the appropriate behaviour of its instance.
+
+If you want to silence this warning you can add this to your scalacOptions:
+"-Wconf:cat=deprecation&origin=cats\\..*\\..*ForFuture:s"
+
+You may also prepare for this change and use alleycats right now.
+Import the library: "org.typelevel" %% "alleycats-core" % "..."
+And import alleycats.std.future._ in this file;
+if you require the future instances in multiple files
+you can add the following scalacOptions to automatically add the import in all files:
+"-Yimports", "java.lang", "scala", "scala.Predef", "alleycats.std.future"
+""",
+    // format: on
+    since = "2.8.0"
+  )
   implicit def catsSemigroupalForFuture(implicit ec: ExecutionContext): Semigroupal[Future] =
     cats.instances.future.catsStdInstancesForFuture(ec)
+
   implicit def catsSemigroupalForList: Semigroupal[List] = cats.instances.list.catsStdInstancesForList
   implicit def catsSemigroupalForSeq: Semigroupal[Seq] = cats.instances.seq.catsStdInstancesForSeq
   implicit def catsSemigroupalForVector: Semigroupal[Vector] = cats.instances.vector.catsStdInstancesForVector