Add extension methods for input and output files

It is tedious to write (foo / allInputFiles).value so I added simple
extension method macros that expand `foo.inputFiles` to
(foo / allInputFiles).value and `foo.outputFiles` to
`(foo / allOutputFiles).value`.

main/src/main/scala/sbt/internal/FileChangesMacro.scala

@@ -34,6 +34,14 @@ object FileChangesMacro {
       "`changedOutputFiles` can only be called on a task within a task definition macro, such as :=, +=, ++=, or Def.task."
     )
     def changedOutputFiles: Option[ChangedFiles] = macro changedOutputFilesImpl[T]
+    @compileTimeOnly(
+      "`inputFiles` can only be called on a task within a task definition macro, such as :=, +=, ++=, or Def.task."
+    )
+    def inputFiles: Seq[NioPath] = macro inputFilesImpl[T]
+    @compileTimeOnly(
+      "`outputFiles` can only be called on a task within a task definition macro, such as :=, +=, ++=, or Def.task."
+    )
+    def outputFiles: Seq[NioPath] = macro outputFilesImpl[T]
   }
   def changedInputFilesImpl[T: c.WeakTypeTag](c: blackbox.Context): c.Expr[Option[ChangedFiles]] = {
     impl[T](c)(c.universe.reify(changedInputFiles), c.universe.reify(inputFileStamps))
@@ -50,16 +58,28 @@ object FileChangesMacro {
       mapKey: c.Expr[TaskKey[Seq[(NioPath, FileStamp)]]]
   ): c.Expr[Option[ChangedFiles]] = {
     import c.universe._
-    val taskTpe = c.weakTypeOf[TaskKey[T]]
+    val taskKey = getTaskKey(c)
-    lazy val err = "Couldn't expand file change macro."
-    val taskKey = c.Expr[TaskKey[T]](c.macroApplication match {
-      case Select(Apply(_, k :: Nil), _) if k.tpe <:< taskTpe => k
-      case _                                                  => c.abort(c.enclosingPosition, err)
-    })
     reify {
       val changes = (changeKey.splice in taskKey.splice).value
       import sbt.nio.FileStamp.Formats._
       Previous.runtimeInEnclosingTask(mapKey.splice in taskKey.splice).value.flatMap(changes)
     }
   }
+  def inputFilesImpl[T: c.WeakTypeTag](c: blackbox.Context): c.Expr[Seq[NioPath]] = {
+    val taskKey = getTaskKey(c)
+    c.universe.reify((allInputFiles in taskKey.splice).value)
+  }
+  def outputFilesImpl[T: c.WeakTypeTag](c: blackbox.Context): c.Expr[Seq[NioPath]] = {
+    val taskKey = getTaskKey(c)
+    c.universe.reify((allOutputFiles in taskKey.splice).value)
+  }
+  private def getTaskKey[T: c.WeakTypeTag](c: blackbox.Context): c.Expr[TaskKey[T]] = {
+    import c.universe._
+    val taskTpe = c.weakTypeOf[TaskKey[T]]
+    lazy val err = "Couldn't expand file change macro."
+    c.Expr[TaskKey[T]](c.macroApplication match {
+      case Select(Apply(_, k :: Nil), _) if k.tpe <:< taskTpe => k
+      case _                                                  => c.abort(c.enclosingPosition, err)
+    })
+  }
 }

sbt/src/sbt-test/nio/clean/build.sbt

@@ -15,7 +15,7 @@ copyFile := Def.task {
   prev match {
     case Some(v: Int) if changes.isEmpty => v
     case _ =>
-      changes.getOrElse((copyFile / allInputFiles).value).foreach { p =>
+      changes.getOrElse(copyFile.inputFiles).foreach { p =>
         val outDir = baseDirectory.value / "out"
         IO.createDirectory(outDir)
         IO.copyFile(p.toFile, outDir / p.getFileName.toString)

sbt/src/sbt-test/nio/dynamic-outputs/build.sbt

@@ -5,7 +5,7 @@ foo / fileInputs += baseDirectory.value.toGlob / "base" / "*.txt"
 foo / target := baseDirectory.value / "out"
 foo := {
   val out = baseDirectory.value / "out"
-  ((foo / allInputFiles).value: Seq[Path]).map { p =>
+  foo.inputFiles.map { p =>
     val f = p.toFile
     val target = out / f.getName
     IO.copyFile (f, target)

sbt/src/sbt-test/nio/file-hashes/build.sbt

@@ -11,7 +11,7 @@ checkModified := {
   val changes = foo.changedInputFiles
   val modified = changes.map(_.updated).getOrElse(Nil)
   println(modified)
-  val allFiles = (foo / allInputFiles).value
+  val allFiles = foo.inputFiles
   if (modified.isEmpty) assert(true)
   else {
     assert(modified != allFiles)
@@ -21,7 +21,7 @@ checkModified := {
 
 val checkRemoved = taskKey[Unit]("check that removed files are returned")
 checkRemoved := Def.taskDyn {
-  val files = (foo / allInputFiles).value
+  val files = foo.inputFiles
   val removed = foo.changedInputFiles.map(_.deleted).getOrElse(Nil)
   if (removed.isEmpty) Def.task(assert(true))
   else Def.task {
@@ -32,7 +32,7 @@ checkRemoved := Def.taskDyn {
 
 val checkAdded = taskKey[Unit]("check that modified files are returned")
 checkAdded := Def.taskDyn {
-  val files = (foo / allInputFiles).value
+  val files = foo.inputFiles
   val added = foo.changedInputFiles.map(_.created).getOrElse(Nil)
   if (added.isEmpty || (files.toSet == added.toSet)) Def.task(assert(true))
   else Def.task {

sbt/src/sbt-test/nio/glob-dsl/build.sbt

@@ -5,7 +5,7 @@ val foo = taskKey[Seq[File]]("Retrieve Foo.txt")
 
 foo / fileInputs += baseDirectory.value.toGlob / ** / "*.txt"
 
-foo := (foo / allInputFiles).value.map(_.toFile)
+foo := foo.inputFiles.map(_.toFile)
 
 val checkFoo = taskKey[Unit]("Check that the Foo.txt file is retrieved")
 
@@ -16,7 +16,7 @@ val bar = taskKey[Seq[File]]("Retrieve Bar.md")
 
 bar / fileInputs += baseDirectory.value.toGlob / "base" / "subdir" / "nested-subdir" / "*.md"
 
-bar := (bar / allInputFiles).value.map(_.toFile)
+bar := bar.inputFiles.map(_.toFile)
 
 val checkBar = taskKey[Unit]("Check that the Bar.md file is retrieved")
 
@@ -32,7 +32,7 @@ val checkAll = taskKey[Unit]("Check that the Bar.md file is retrieved")
 checkAll := {
   import sbt.dsl.LinterLevel.Ignore
   val expected = Set("Foo.txt", "Bar.md").map(baseDirectory.value / "base" / "subdir" / "nested-subdir" / _)
-  val actual = (all / allInputFiles).value.map(_.toFile).toSet
+  val actual = all.inputFiles.map(_.toFile).toSet
   assert(actual == expected)
 }
 
@@ -55,6 +55,6 @@ depth / fileInputs ++= {
 
 checkDepth := {
   val expected = Seq("Bar.md").map(baseDirectory.value / "base/subdir/nested-subdir" / _)
-  val actual = (depth / allInputFiles).value.map(_.toFile)
+  val actual = depth.inputFiles.map(_.toFile)
   assert(actual == expected)
 }

sbt/src/sbt-test/nio/make-clone/build.sbt

@@ -16,7 +16,7 @@ compileLib := {
     val name = path.getFileName.toString
     objectDir.resolve(name.substring(0, name.lastIndexOf('.')) + ".o")
   }
-  val allFiles: Seq[Path] = (compileLib / allInputFiles).value
+  val allFiles: Seq[Path] = compileLib.inputFiles
   val changedFiles: Option[Seq[Path]] = compileLib.changedInputFiles match {
     case Some(ChangedFiles(c, d, u)) =>
       d.foreach(p => Files.deleteIfExists(objectPath(p)))
@@ -52,7 +52,7 @@ linkLib / target := baseDirectory.value / "out" / "lib"
 linkLib := {
   val changedObjects = compileLib.changedOutputFiles
   val outPath = (linkLib / target).value.toPath
-  val allObjects = (compileLib / allOutputFiles).value.map(_.toString)
+  val allObjects = compileLib.outputFiles.map(_.toString)
   val logger = streams.value.log
   linkLib.previous match {
     case Some(p: Path) if changedObjects.isEmpty =>
@@ -90,7 +90,7 @@ compileMain := {
       logger.info(s"Not building $outPath: no dependencies have changed")
       p
     case _ =>
-      (compileMain / allInputFiles).value match {
+      compileMain.inputFiles match {
         case Seq(main) =>
           Files.createDirectories(outDir)
           logger.info(s"Building executable $outPath")
@@ -112,7 +112,7 @@ compileMain := {
 val executeMain = inputKey[Unit]("run the main method")
 executeMain := {
   val args = Def.spaceDelimited("<arguments>").parsed
-  val binary: Seq[Path] = (compileMain / allOutputFiles).value
+  val binary: Seq[Path] = compileMain.outputFiles
   val logger = streams.value.log
   binary match {
     case Seq(b) =>
@@ -131,7 +131,7 @@ executeMain := {
 val checkOutput = inputKey[Unit]("check the output value")
 checkOutput := {
   val args @ Seq(arg, res) = Def.spaceDelimited("").parsed
-  val binary: Path = (compileMain / allOutputFiles).value.head
+  val binary: Path = compileMain.outputFiles.head
   val output = RunBinary(binary, args, linkLib.value)
   assert(output.contains(s"f($arg) = $res"))
   ()

sbt/src/sbt-test/watch/commands/build.sbt

@@ -5,7 +5,7 @@ import scala.collection.JavaConverters._
 val foo = taskKey[Unit]("foo")
 foo := {
   val fooTxt = baseDirectory.value / "foo.txt"
-  val _ = println(s"foo inputs: ${(foo / allInputFiles).value}")
+  val _ = println(s"foo inputs: ${foo.inputFiles}")
   IO.write(fooTxt, "foo")
   println(s"foo wrote to $foo")
 }

sbt/src/sbt-test/watch/dynamic-inputs/project/Build.scala

@@ -24,7 +24,7 @@ object Build {
   lazy val root = (project in file(".")).settings(
     reloadFile := baseDirectory.value / "reload",
     foo / fileInputs += baseDirectory.value.toGlob / "foo.txt",
-    foo := (foo / allInputFiles).value,
+    foo := foo.inputFiles,
     setStringValue := Def.taskDyn {
       // This hides foo / fileInputs from the input graph
       Def.taskDyn {

sbt/src/sbt-test/watch/overlapping/build.sbt

@@ -8,7 +8,7 @@ foo / watchForceTriggerOnAnyChange := true
 foo / fileInputs := baseDirectory.value.toGlob / "files" / "foo.txt" :: Nil
 foo / watchTriggers := baseDirectory.value.toGlob / ** / "foo.txt" :: Nil
 foo := {
-  (foo / allInputFiles).value.foreach { p =>
+  foo.inputFiles.foreach { p =>
     Files.setLastModifiedTime(p, FileTime.fromMillis(Files.getLastModifiedTime(p).toMillis + 3000))
   }
   sbt.nio.Stamps.check(foo).value