diff --git a/internal/util-logging/src/main/scala/sbt/internal/util/WindowsInputStream.scala b/internal/util-logging/src/main/scala/sbt/internal/util/WindowsInputStream.scala
index e6abc6924..aff4026bf 100644
--- a/internal/util-logging/src/main/scala/sbt/internal/util/WindowsInputStream.scala
+++ b/internal/util-logging/src/main/scala/sbt/internal/util/WindowsInputStream.scala
@@ -46,9 +46,6 @@ private object WindowsSupport {
  */
 private[util] class WindowsInputStream(term: org.jline.terminal.Terminal, in: InputStream)
     extends SimpleInputStream {
-  private val SHIFT_FLAG = 0x01;
-  private val ALT_FLAG = 0x02;
-  private val CTRL_FLAG = 0x04;
 
   private val RIGHT_ALT_PRESSED = 0x0001;
   private val LEFT_ALT_PRESSED = 0x0002;
diff --git a/lm-core/src/main/scala/sbt/internal/librarymanagement/cross/CrossVersionUtil.scala b/lm-core/src/main/scala/sbt/internal/librarymanagement/cross/CrossVersionUtil.scala
index 5491040ca..4d2471136 100644
--- a/lm-core/src/main/scala/sbt/internal/librarymanagement/cross/CrossVersionUtil.scala
+++ b/lm-core/src/main/scala/sbt/internal/librarymanagement/cross/CrossVersionUtil.scala
@@ -26,7 +26,6 @@ object CrossVersionUtil {
   private val ReleaseV = raw"""$basicVersion(-\d+)?""".r
   private[sbt] val BinCompatV = raw"""$basicVersion(-$tagPattern)?-bin(-.*)?""".r
   private val CandidateV = raw"""$basicVersion(-RC\d+)""".r
-  private val MilestonV = raw"""$basicVersion(-M$tagPattern)""".r
   private val NonReleaseV_n =
     raw"""$basicVersion((?:-$tagPattern)*)""".r // 0-n word suffixes, with leading dashes
   private val NonReleaseV_1 = raw"""$basicVersion(-$tagPattern)""".r // 1 word suffix, after a dash
diff --git a/lm-coursier/src/main/scala/lmcoursier/definitions/ToCoursier.scala b/lm-coursier/src/main/scala/lmcoursier/definitions/ToCoursier.scala
index 3f786d1da..baeb0baae 100644
--- a/lm-coursier/src/main/scala/lmcoursier/definitions/ToCoursier.scala
+++ b/lm-coursier/src/main/scala/lmcoursier/definitions/ToCoursier.scala
@@ -10,12 +10,6 @@ object ToCoursier {
   def configuration(configuration: Configuration): coursier.core.Configuration =
     coursier.core.Configuration(configuration.value)
 
-  private def attributes(attributes: Attributes): coursier.core.Attributes =
-    coursier.core.Attributes(
-      coursier.core.Type(attributes.`type`.value),
-      coursier.core.Classifier(attributes.classifier.value)
-    )
-
   def publication(publication: Publication): coursier.core.Publication =
     coursier.core.Publication(
       publication.name,
diff --git a/main/src/main/scala/sbt/Defaults.scala b/main/src/main/scala/sbt/Defaults.scala
index 79454b192..17269b066 100644
--- a/main/src/main/scala/sbt/Defaults.scala
+++ b/main/src/main/scala/sbt/Defaults.scala
@@ -2842,23 +2842,11 @@ object Classpaths {
       s: Setting[Task[Classpath]]
   ): Setting[Task[Classpath]] =
     s.mapInitialize(init => Def.task { exportVirtualClasspath(streams.value, init.value) })
-  private def exportClasspath(
-      s: Setting[Task[Seq[Attributed[File]]]]
-  ): Setting[Task[Seq[Attributed[File]]]] =
-    s.mapInitialize(init => Def.task { exportClasspath(streams.value, init.value) })
   private def exportVirtualClasspath(s: TaskStreams, cp: Classpath): Classpath =
     val w = s.text(ExportStream)
     try w.println(data(cp).toString)
     finally w.close() // workaround for #937
     cp
-  private def exportClasspath(
-      s: TaskStreams,
-      cp: Seq[Attributed[File]]
-  ): Seq[Attributed[File]] =
-    val w = s.text(ExportStream)
-    try w.println(Path.makeString(data(cp)))
-    finally w.close() // workaround for #937
-    cp
 
   def defaultPackageKeys = Seq(packageBin, packageSrc, packageDoc)
   lazy val defaultPackages: Seq[TaskKey[HashedVirtualFileRef]] =
diff --git a/main/src/main/scala/sbt/internal/server/BuildServerProtocol.scala b/main/src/main/scala/sbt/internal/server/BuildServerProtocol.scala
index c3097dd7c..1144d8f61 100644
--- a/main/src/main/scala/sbt/internal/server/BuildServerProtocol.scala
+++ b/main/src/main/scala/sbt/internal/server/BuildServerProtocol.scala
@@ -728,22 +728,6 @@ object BuildServerProtocol {
     )
   }
 
-  private def scalacOptionsBuildItem(
-      sbtJars: Seq[File],
-      targetId: BuildTargetIdentifier,
-      build: LoadedBuildUnit
-  ): ScalacOptionsItem = {
-    val plugins: LoadedPlugins = build.unit.plugins
-    val scalacOptions = plugins.pluginData.scalacOptions.toVector
-    val converter = plugins.pluginData.converter
-    val classpath =
-      plugins.classpath.map(f => converter.toPath(f).toFile.toURI).toVector ++
-        sbtJars.map(_.toURI).toVector
-    val classDirectory = new File(build.localBase, "project/target").toURI
-    val item = ScalacOptionsItem(targetId, scalacOptions, classpath, classDirectory)
-    item
-  }
-
   private def javacOptionsBuildItem(
       sbtJars: Array[File],
       targetId: BuildTargetIdentifier,
diff --git a/main/src/main/scala/sbt/nio/Settings.scala b/main/src/main/scala/sbt/nio/Settings.scala
index c3c74b5f8..6d1c451b0 100644
--- a/main/src/main/scala/sbt/nio/Settings.scala
+++ b/main/src/main/scala/sbt/nio/Settings.scala
@@ -174,7 +174,6 @@ private[sbt] object Settings {
     }) :: fileStamps(scopedKey) :: allFilesImpl(scope) :: changedInputFilesImpl(scope)
   }
 
-  private val seqClass = classOf[Seq[?]]
   private val pathClass = classOf[Path]
   private val fileClass = classOf[File]
   private val virtualFileRefClass = classOf[VirtualFileRef]