Fix MiMa incompatibilities

Author: denisrosca

core/src/main/scala/cats/Foldable.scala

@@ -95,13 +95,6 @@ import Foldable.sentinel
    */
   def foldRight[A, B](fa: F[A], lb: Eval[B])(f: (A, Eval[B]) => Eval[B]): Eval[B]
 
-  def foldRightDefer[G[_]: Defer, A, B](fa: F[A], gb: G[B])(fn: (A, G[B]) => G[B]): G[B] =
-    Defer[G].defer(
-      this.foldLeft(fa, (z: G[B]) => z) { (acc, elem) => z =>
-        Defer[G].defer(acc(fn(elem, z)))
-      }(gb)
-    )
-
   def reduceLeftToOption[A, B](fa: F[A])(f: A => B)(g: (B, A) => B): Option[B] =
     foldLeft(fa, Option.empty[B]) {
       case (Some(b), a) => Some(g(b, a))

core/src/main/scala/cats/syntax/foldable.scala

@@ -303,6 +303,31 @@ final class FoldableOps0[F[_], A](private val fa: F[A]) extends AnyVal {
     import cats.syntax.foldable._
     F.partitionEitherM[G, A, B, C](fa)(f)(A, M)
   }
+
+  /**
+   * Right associative lazy fold on `F` using the folding function 'f'
+   * provided that `G[_]` has a `Defer[G]` instance in scope.
+   *
+   * For more detailed information about how this method works see the
+   * documentation for `Defer[F]`.
+   *
+   * Example:
+   * {{{
+   * scala> import cats.Eval, cats.implicits._
+   * scala> val fa = Option(1)
+   *
+   * Folding by addition to zero:
+   * With syntax extensions, we can write the same thing like this:
+   * scala> val folded2 = fa.foldRightDefer(Eval.now(0))((n, a) => a.map(_ + n))
+   * scala> folded2.value
+   * res1: Int = 1
+   * }}}
+   */
+  def foldRightDefer[G[_]: Defer, B](gb: G[B])(fn: (A, G[B]) => G[B])(implicit F: Foldable[F]): G[B] = {
+    import cats.syntax.foldable._
+    F.foldRightDefer(fa, gb)(fn)
+  }
+
 }
 
 final class FoldableOps1[F[_]](private val F: Foldable[F]) extends AnyVal {
@@ -381,4 +406,30 @@ final class FoldableOps1[F[_]](private val F: Foldable[F]) extends AnyVal {
     import cats.instances.either._
     partitionBifoldM[G, Either, A, B, C](fa)(f)(A, M, Bifoldable[Either])
   }
+
+  /**
+   * Right associative lazy fold on `F` using the folding function 'f'
+   * provided that `G[_]` has a `Defer[G]` instance in scope.
+   *
+   * For more detailed information about how this method works see the
+   * documentation for `Defer[F]`.
+   *
+   * Example:
+   * {{{
+   * scala> import cats.Foldable, cats.Eval, cats.implicits._
+   * scala> val fa = Option(1)
+   *
+   * Folding by addition to zero:
+   * scala> val folded1 = Foldable[Option].foldRightDefer(fa, Eval.now(0))((n, a) => a.map(_ + n))
+   * Since `foldRightDefer` yields a lazy computation, we need to force it to inspect the result:
+   * scala> folded1.value
+   * res0: Int = 1
+   * }}}
+   */
+  def foldRightDefer[G[_]: Defer, A, B](fa: F[A], gb: G[B])(fn: (A, G[B]) => G[B]): G[B] =
+    Defer[G].defer(
+      F.foldLeft(fa, (z: G[B]) => z) { (acc, elem) => z =>
+        Defer[G].defer(acc(fn(elem, z)))
+      }(gb)
+    )
 }