`in` is no longer in

Ref https://github.com/sbt/sbt/pull/6309

This deprecates the sbt 0.13 style `key in (Compile, intask)` syntax.

main-settings/src/main/scala/sbt/Previous.scala

@@ -10,6 +10,7 @@ package sbt
 import sbt.Def.{ Initialize, ScopedKey }
 import sbt.Previous._
 import sbt.Scope.Global
+import sbt.SlashSyntax0._
 import sbt.internal.util._
 import sbt.std.TaskExtra._
 import sbt.util.StampedFormat
@@ -146,7 +147,7 @@ object Previous {
 
   /** Public as a macro implementation detail.  Do not call directly. */
   def runtime[T](skey: TaskKey[T])(implicit format: JsonFormat[T]): Initialize[Task[Option[T]]] = {
-    val inputs = (cache in Global) zip Def.validated(skey, selfRefOk = true) zip (references in Global)
+    val inputs = (Global / cache) zip Def.validated(skey, selfRefOk = true) zip (Global / references)
     inputs {
       case ((prevTask, resolved), refs) =>
         val key = Key(resolved, resolved)
@@ -159,9 +160,9 @@ object Previous {
   def runtimeInEnclosingTask[T](skey: TaskKey[T])(
       implicit format: JsonFormat[T]
   ): Initialize[Task[Option[T]]] = {
-    val inputs = (cache in Global)
+    val inputs = (Global / cache)
       .zip(Def.validated(skey, selfRefOk = true))
-      .zip(references in Global)
+      .zip(Global / references)
       .zip(Def.resolvedScoped)
     inputs {
       case (((prevTask, resolved), refs), inTask: ScopedKey[Task[_]] @unchecked) =>

main-settings/src/main/scala/sbt/Scope.scala

@@ -20,16 +20,29 @@ final case class Scope(
     task: ScopeAxis[AttributeKey[_]],
     extra: ScopeAxis[AttributeMap]
 ) {
+  @deprecated(Scope.inIsDeprecated, "1.5.0")
   def in(project: Reference, config: ConfigKey): Scope =
     copy(project = Select(project), config = Select(config))
+
+  @deprecated(Scope.inIsDeprecated, "1.5.0")
   def in(config: ConfigKey, task: AttributeKey[_]): Scope =
     copy(config = Select(config), task = Select(task))
+
+  @deprecated(Scope.inIsDeprecated, "1.5.0")
   def in(project: Reference, task: AttributeKey[_]): Scope =
     copy(project = Select(project), task = Select(task))
+
+  @deprecated(Scope.inIsDeprecated, "1.5.0")
   def in(project: Reference, config: ConfigKey, task: AttributeKey[_]): Scope =
     copy(project = Select(project), config = Select(config), task = Select(task))
+
+  @deprecated(Scope.inIsDeprecated, "1.5.0")
   def in(project: Reference): Scope = copy(project = Select(project))
+
+  @deprecated(Scope.inIsDeprecated, "1.5.0")
   def in(config: ConfigKey): Scope = copy(config = Select(config))
+
+  @deprecated(Scope.inIsDeprecated, "1.5.0")
   def in(task: AttributeKey[_]): Scope = copy(task = Select(task))
 
   override def toString: String = this match {
@@ -43,6 +56,9 @@ object Scope {
   val Global: Scope = Scope(Zero, Zero, Zero, Zero)
   val GlobalScope: Scope = Global
 
+  private[sbt] final val inIsDeprecated =
+    "`in` is deprecated; migrate to slash syntax - https://www.scala-sbt.org/1.x/docs/Migrating-from-sbt-013x.html#slash"
+
   def resolveScope(thisScope: Scope, current: URI, rootProject: URI => String): Scope => Scope =
     resolveProject(current, rootProject) compose replaceThis(thisScope) compose subThisProject
 

main-settings/src/main/scala/sbt/SlashSyntax.scala

@@ -9,6 +9,7 @@ package sbt
 
 import sbt.librarymanagement.Configuration
 import sbt.internal.util.AttributeKey
+import scala.annotation.nowarn
 
 /**
  * SlashSyntax implements the slash syntax to scope keys for build.sbt DSL.
@@ -60,19 +61,25 @@ object SlashSyntax {
 
   sealed trait HasSlashKey {
     protected def scope: Scope
+    @nowarn
     final def /[K](key: Scoped.ScopingSetting[K]): K = key in scope
   }
 
   sealed trait HasSlashKeyOrAttrKey extends HasSlashKey {
+    @nowarn
     final def /(key: AttributeKey[_]): RichScope = new RichScope(scope in key)
   }
 
   /** RichReference wraps a reference to provide the `/` operator for scoping. */
   final class RichReference(protected val scope: Scope) extends HasSlashKeyOrAttrKey {
+    @nowarn
     def /(c: ConfigKey): RichConfiguration = new RichConfiguration(scope in c)
+
+    @nowarn
     def /(c: Configuration): RichConfiguration = new RichConfiguration(scope in c)
 
     // This is for handling `Zero / Zero / name`.
+    @nowarn
     def /(configAxis: ScopeAxis[ConfigKey]): RichConfiguration =
       new RichConfiguration(scope.copy(config = configAxis))
   }

main-settings/src/main/scala/sbt/Structure.scala

@@ -68,6 +68,7 @@ sealed abstract class SettingKey[T]
 
   final def scopedKey: ScopedKey[T] = ScopedKey(scope, key)
 
+  // @deprecated(Scope.inIsDeprecated, "1.5.0")
   final def in(scope: Scope): SettingKey[T] =
     Scoped.scopedSetting(Scope.replaceThis(this.scope)(scope), this.key)
 
@@ -140,6 +141,7 @@ sealed abstract class TaskKey[T]
 
   def scopedKey: ScopedKey[Task[T]] = ScopedKey(scope, key)
 
+  // @deprecated(Scope.inIsDeprecated, "1.5.0")
   def in(scope: Scope): TaskKey[T] =
     Scoped.scopedTask(Scope.replaceThis(this.scope)(scope), this.key)
 
@@ -206,6 +208,7 @@ sealed trait InputKey[T]
 
   def scopedKey: ScopedKey[InputTask[T]] = ScopedKey(scope, key)
 
+  // @deprecated(Scope.inIsDeprecated, "1.5.0")
   def in(scope: Scope): InputKey[T] =
     Scoped.scopedInput(Scope.replaceThis(this.scope)(scope), this.key)
 
@@ -244,18 +247,32 @@ object Scoped {
    *
    */
   sealed trait ScopingSetting[ResultType] {
+    // @deprecated(Scope.inIsDeprecated, "1.5.0")
     def in(s: Scope): ResultType
 
+    @deprecated(Scope.inIsDeprecated, "1.5.0")
     def in(p: Reference): ResultType = in(Select(p), This, This)
+
+    @deprecated(Scope.inIsDeprecated, "1.5.0")
     def in(t: Scoped): ResultType = in(This, This, Select(t.key))
+
+    @deprecated(Scope.inIsDeprecated, "1.5.0")
     def in(c: ConfigKey): ResultType = in(This, Select(c), This)
+
+    @deprecated(Scope.inIsDeprecated, "1.5.0")
     def in(c: ConfigKey, t: Scoped): ResultType = in(This, Select(c), Select(t.key))
+
+    @deprecated(Scope.inIsDeprecated, "1.5.0")
     def in(p: Reference, c: ConfigKey): ResultType = in(Select(p), Select(c), This)
+
+    @deprecated(Scope.inIsDeprecated, "1.5.0")
     def in(p: Reference, t: Scoped): ResultType = in(Select(p), This, Select(t.key))
 
+    @deprecated(Scope.inIsDeprecated, "1.5.0")
     def in(p: Reference, c: ConfigKey, t: Scoped): ResultType =
       in(Select(p), Select(c), Select(t.key))
 
+    @deprecated(Scope.inIsDeprecated, "1.5.0")
     def in(
         p: ScopeAxis[Reference],
         c: ScopeAxis[ConfigKey],