Monitor meta build sources

We want to recursively monitor the project meta build, but we also want
to avoid listing directories that don't exist. To compromise, I rework
the buildSourceFileInputs to add the nested project directories if they
exist. Because the fileInputs are a setting, this means that adding a
new project directory and *.sbt or *.scala will not immediately trigger
a rebuild, but in most common cases, it will. I added a scripted test
for this.

main/src/main/scala/sbt/internal/nio/CheckBuildSources.scala

@@ -13,7 +13,10 @@ import sbt.SlashSyntax0._
 import sbt.io.syntax._
 import sbt.nio.FileChanges
 import sbt.nio.Keys._
-import sbt.nio.file.{ Glob, RecursiveGlob }
+import sbt.nio.file.{ Glob, ** }
+import sbt.nio.file.syntax._
+
+import scala.annotation.tailrec
 
 private[sbt] object CheckBuildSources {
   private[sbt] def needReloadImpl: Def.Initialize[Task[StateTransform]] = Def.task {
@@ -60,15 +63,20 @@ private[sbt] object CheckBuildSources {
   private[sbt] def buildSourceFileInputs: Def.Initialize[Seq[Glob]] = Def.setting {
     if (onChangedBuildSource.value != IgnoreSourceChanges) {
       val baseDir = (LocalRootProject / baseDirectory).value
-      val sourceFilter = "*.{sbt,scala,java}"
       val projectDir = baseDir / "project"
-      Seq(
-        Glob(baseDir, "*.sbt"),
-        Glob(projectDir, sourceFilter),
-        // We only want to recursively look in source because otherwise we have to search
-        // the project target directories which is expensive.
-        Glob(projectDir / "src", RecursiveGlob / sourceFilter),
-      )
+      @tailrec
+      def projectGlobs(projectDir: File, globs: Seq[Glob]): Seq[Glob] = {
+        val glob = projectDir.toGlob
+        val base = Seq(
+          glob / "*.{sbt,scala,java}",
+          // We only want to recursively look in source because otherwise we have to search
+          // the project target directories which is expensive.
+          glob / "src" / ** / "*.{scala,java}"
+        )
+        val nextLevel = projectDir / "project"
+        if (nextLevel.exists) projectGlobs(nextLevel, base) else base
+      }
+      projectGlobs(projectDir, baseDir.toGlob / "*.sbt" :: Nil)
     } else Nil
   }
 }

sbt/src/sbt-test/nio/reload/.scalafmt.conf

@@ -0,0 +1,21 @@
+version = 2.0.0
+maxColumn = 100
+project.git = true
+project.excludeFilters = [ "\\Wsbt-test\\W", "\\Winput_sources\\W", "\\Wcontraband-scala\\W" ]
+
+# http://docs.scala-lang.org/style/scaladoc.html recommends the JavaDoc style.
+# scala/scala is written that way too https://github.com/scala/scala/blob/v2.12.2/src/library/scala/Predef.scala
+docstrings = JavaDoc
+
+# This also seems more idiomatic to include whitespace in import x.{ yyy }
+spaces.inImportCurlyBraces = true
+
+# This is more idiomatic Scala.
+# http://docs.scala-lang.org/style/indentation.html#methods-with-numerous-arguments
+align.openParenCallSite = false
+align.openParenDefnSite = false
+
+# For better code clarity
+danglingParentheses = true
+
+trailingCommas = preserve

sbt/src/sbt-test/nio/reload/changes/ScalafmtVersion.scala

@@ -0,0 +1,3 @@
+object ScalafmtVersion {
+  val value = "2.0.4"
+}

sbt/src/sbt-test/nio/reload/project/plugins.sbt

@@ -0,0 +1,8 @@
+libraryDependencies ++= {
+  if (ScalafmtVersion.value == "2.0.4") {
+    val sbtV = (sbtBinaryVersion in pluginCrossBuild).value
+    val scalaV = (scalaBinaryVersion in update).value
+    val dep = "org.scalameta" % "sbt-scalafmt" % ScalafmtVersion.value
+    sbt.Defaults.sbtPluginExtra(dep, sbtV, scalaV) :: Nil
+  } else Nil
+}

sbt/src/sbt-test/nio/reload/project/project/ScalafmtVersion.scala

@@ -0,0 +1,3 @@
+object ScalafmtVersion {
+  val value = "2.0.3"
+}

sbt/src/sbt-test/nio/reload/test

@@ -23,3 +23,9 @@ $ copy-file changes/working.sbt build.sbt
 $ copy-file changes/sub.sbt sub/build.sbt
 
 > compile
+
+-> scalafmt
+
+$ copy-file changes/ScalafmtVersion.scala project/project/ScalafmtVersion.scala
+
+> scalafmt