[2.x] ci: Add scalafix DisableSyntax.noReturns (#8922)

.scalafix.conf

@@ -0,0 +1,5 @@
+rules = [
+  DisableSyntax
+]
+
+DisableSyntax.noReturns = true

build.sbt

@@ -45,6 +45,7 @@ ThisBuild / scmInfo := Some(
 )
 ThisBuild / resolvers += Resolver.mavenLocal
 ThisBuild / mimaFailOnNoPrevious := false
+ThisBuild / scalafixOnCompile := true
 
 Global / semanticdbEnabled := !(Global / insideCI).value
 // Change main/src/main/scala/sbt/plugins/SemanticdbPlugin.scala too, if you change this.
@@ -1022,6 +1023,10 @@ lazy val sbtwProj = (project in file("sbtw"))
     description := "Windows drop-in launcher for sbt (replaces sbt.bat)",
     scalaVersion := "3.8.2",
     crossPaths := false,
+    Compile / scalafix / unmanagedSources := {
+      // https://github.com/scalameta/scalameta/issues/4531
+      (Compile / unmanagedSources).value.filterNot(_.getName == "Main.scala")
+    },
     Compile / mainClass := Some("sbtw.Main"),
     libraryDependencies += "com.github.scopt" %% "scopt" % "4.1.0",
     libraryDependencies += scalaVerify % Test,

internal/util-complete/src/main/scala/sbt/internal/util/complete/EditDistance.scala

@@ -18,6 +18,7 @@ object EditDistance {
    * Translated from the java version at http://www.merriampark.com/ld.htm which is declared to be
    * public domain.
    */
+  @SuppressWarnings(Array("scalafix:DisableSyntax"))
   def levenshtein(
       s: String,
       t: String,

internal/util-logging/src/test/scala/Escapes.scala

@@ -67,6 +67,7 @@ object Escapes extends Properties("Escapes") {
           (original == removed)
     }
 
+  @SuppressWarnings(Array("scalafix:DisableSyntax"))
   def diffIndex(expect: String, original: String): String = {
     var i = 0;
     while (i < expect.length && i < original.length) {

lm-core/src/test/scala/sbt/internal/librarymanagement/UpdateReportPersistenceBenchmark.scala

@@ -31,6 +31,7 @@ final case class BenchmarkResult(
 
 object UpdateReportPersistenceBenchmark:
 
+  @SuppressWarnings(Array("scalafix:DisableSyntax"))
   def run(
       iterations: Int = 500,
       configs: Seq[String] = Seq("compile", "test"),

lm-coursier/src/main/scala/lmcoursier/internal/CacheUrlConversion.scala

@@ -30,6 +30,7 @@ object CacheUrlConversion {
       withForwardSlash
   }
 
+  @SuppressWarnings(Array("scalafix:DisableSyntax"))
   def cacheFileToOriginalUrl(fileUrl: String, cacheDir: File): String = {
     if (!fileUrl.startsWith(FileUrlPrefix)) return fileUrl
     val filePath = normalizedFilePath(fileUrl)

lm-ivy/src/main/scala/sbt/internal/librarymanagement/IvyUtil.scala

@@ -41,9 +41,11 @@ private[sbt] object IvyUtil {
     private val _r = """.*HTTP response code: (5\d{2}|408|429).*""".r
 
     @inline private def check(s: String): Boolean = {
-      if (s == null) return false
-
-      _r.pattern.matcher(s).matches()
+      if (s == null) {
+        false
+      } else {
+        _r.pattern.matcher(s).matches()
+      }
     }
 
     def apply(t: Throwable): Boolean = t match {

lm-ivy/src/main/scala/sbt/internal/librarymanagement/ivyint/SbtChainResolver.scala

@@ -111,14 +111,17 @@ private[sbt] case class SbtChainResolver(
 
     /* Copy pasted from `IvyStringUtils` to handle `Throwable` */
     private def getStackTrace(e: Throwable): String = {
-      if (e == null) return ""
-      val baos = new ByteArrayOutputStream()
-      val printWriter = new PrintWriter(baos)
-      e.printStackTrace(printWriter)
-      printWriter.flush()
-      val stackTrace = new String(baos.toByteArray)
-      printWriter.close()
-      stackTrace
+      if (e == null) {
+        ""
+      } else {
+        val baos = new ByteArrayOutputStream()
+        val printWriter = new PrintWriter(baos)
+        e.printStackTrace(printWriter)
+        printWriter.flush()
+        val stackTrace = new String(baos.toByteArray)
+        printWriter.close()
+        stackTrace
+      }
     }
 
     /** If None, module was not found. Otherwise, hit. */

main/src/main/scala/sbt/internal/CommandExchange.scala

@@ -516,6 +516,8 @@ private[sbt] final class CommandExchange {
   private def notifyOtherServers(): Unit = {
     val thread = new Thread("sbt-notify-other-servers") {
       setDaemon(true)
+
+      @SuppressWarnings(Array("scalafix:DisableSyntax"))
       override def run(): Unit = {
         val procDir = SysProp.globalLocalCache / "proc"
         if (!procDir.exists) return

main/src/main/scala/sbt/internal/PomGenerator.scala

@@ -240,6 +240,7 @@ private[sbt] object PomGenerator:
         (scope, optional)
 
   /** Convert Ivy-style dynamic versions to Maven range format. */
+  @SuppressWarnings(Array("scalafix:DisableSyntax"))
   private def convertVersion(version: String): String =
     if version == null then null
     else if version.endsWith("+") then

sbtw/src/main/scala/sbtw/Runner.scala

@@ -70,6 +70,7 @@ object Runner:
     if opts.jvmClient then s = s :+ "--client"
     s
 
+  @SuppressWarnings(Array("scalafix:DisableSyntax"))
   def runNativeClient(sbtBinDir: File, scriptPath: String, opts: LauncherOptions): Int =
     val sbtn = new File(sbtBinDir, "sbtn-x86_64-pc-win32.exe")
     if !sbtn.isFile then