build: enable 3.0-migration compiler option for all modules for now

build.sbt

@@ -157,14 +157,6 @@ lazy val httpCore = project("akka-http-core")
       if (System.getProperty("akka.http.test-against-akka-main", "false") == "true") AkkaDependency.masterSnapshot
       else AkkaDependency.default
   )
-  .settings(
-    scalacOptions ++= {
-      if (scalaVersion.value startsWith "3")
-        Seq("-source", "3.0-migration")
-      else
-        Nil
-    },
-  )
   .settings(Dependencies.httpCore)
   .settings(VersionGenerator.versionSettings)
   .settings(scalaMacroSupport)
@@ -184,7 +176,6 @@ lazy val http = project("akka-http")
   .settings(scalaMacroSupport)
   .enablePlugins(BootstrapGenjavadoc, BoilerplatePlugin)
   .enablePlugins(ReproducibleBuildsPlugin)
-  .enablePlugins(NoScala3) // FIXME
 
 def gustavDir(kind: String) = Def.task {
   val ver =

project/Common.scala

@@ -43,7 +43,13 @@ object Common extends AutoPlugin {
     Test / compile / scalacOptions += "-Wconf:msg=match may not be exhaustive:s",
 
     mimaReportSignatureProblems := true,
-    Global / parallelExecution := sys.props.getOrElse("akka.http.parallelExecution", "true") != "false"
+    Global / parallelExecution := sys.props.getOrElse("akka.http.parallelExecution", "true") != "false",
+    scalacOptions ++= {
+      if (scalaVersion.value startsWith "3")
+        Seq("-source", "3.0-migration") // FIXME, eventually
+      else
+        Nil
+    },
   )
 
   val specificationVersion: String = sys.props("java.specification.version")