Allow to specify fixed source version for project to allow for compil…

…ation of legacy/unmaintained projects

coordinator/configs/projects-config.conf

@@ -91,6 +91,7 @@ armanbilge_feral.projects.exclude = [
   "com.armanbilge%feral-lambda-api-gateway-proxy-http4s"
 ]
 armanbilge_gcp4s.tests = compile-only
+armanbilge_van-cats.source-version=3.4 // override -source:future
 assist-iot-sripas_scala-mqtt-wrapper {
   sbt.commands = [
     "excludeLibraryDependency org.wartremover:wartremover_{scalaVersion}",

coordinator/src/main/resources/buildPlan.reference.conf

@@ -13,6 +13,9 @@ projects {
   overrides = {}
 }
 
+// A fixed Scala `-source` setting to be applied to the project. 
+source-version = null
+
 // Mode of tests execution one of disabled|compile-only|full
 tests = full
 

coordinator/src/main/scala/core.scala

@@ -105,6 +105,7 @@ case class ProjectBuildConfig(
     sbt: SbtConfig = SbtConfig(),
     mill: MillConfig = MillConfig(),
     tests: TestingMode = TestingMode.Full,
+    sourceVersion: Option[String] = None,
     // We should use Option[Int] here, but json4s fails to resolve signature https://github.com/json4s/json4s/issues/1035
     sourcePatches: List[SourcePatch] = Nil
 ) derives ConfigReader

project-builder/build-revision.sh

@@ -29,7 +29,18 @@ scalaBinaryVersionMajor=`echo $scalaVersion | cut -d . -f 1`
 scalaBinaryVersionMinor=`echo $scalaVersion | cut -d . -f 2`
 echo "Scala binary version found: $scalaBinaryVersion"
 
-commonAppendScalacOptions="-source:$scalaBinaryVersion-migration,-Wconf:msg=can be rewritten automatically under:s"
+sourceVersion=`echo $projectConfig | jq -r '.sourceVersion // ""'`
+sourceVersionSetting=""
+if [[ -z "$sourceVersion" ]]; then
+  sourceVersion="$scalaBinaryVersion-migration"
+  sourceVersionSetting="-source:$sourceVersion"
+  echo "Implicitly using source version $sourceVersion"
+else 
+  echo "Using configured source version: $sourceVersion"
+  sourceVersionSetting="REQUIRE:-source:$sourceVersion"
+fi
+
+commonAppendScalacOptions="$sourceVersionSetting,-Wconf:msg=can be rewritten automatically under:s"
 commonRemoveScalacOptions="-deprecation,-feature,-Xfatal-warnings,-Werror,MATCH:.*-Wconf.*any:e,-migration,"
 echo "Would try to apply common scalacOption (best-effort, sbt/mill only):"
 echo "Append: $commonAppendScalacOptions"

project-builder/shared/CommunityBuildCore.scala

@@ -349,32 +349,40 @@ object Scala3CommunityBuild {
     ): Seq[String] = {
       val (removeMatchSettings, removeSettings) = remove.partition { _.startsWith("MATCH:") }
       val matchPatterns = removeMatchSettings.map(_.stripPrefix("MATCH:"))
+
+      val (required, standardAppendSettings) = append.partition(_.startsWith("REQUIRE:"))
+      val requiredAppendSettings = required.map(_.stripPrefix("REQUIRE:"))
 
       def isSourceVersion(v: String) = v.matches(raw"^-?-source(:(future|(\d\.\d+))(-migration)?)?")
+      def resolveSourceVersion(v: String): Option[String] = v.split(":").drop(1).headOption
       val SourceVersionPattern = raw"^((3\.\d+|future)(-migration)?)$$".r
       val definedSourceSetting = current.find(isSourceVersion)
       lazy val definedSourceVersion: Option[String] = 
-        definedSourceSetting.flatMap(_.split(":").drop(1).headOption) // -source:version
+        definedSourceSetting.flatMap(resolveSourceVersion) // -source:version
         .orElse(current.find(SourceVersionPattern.findFirstIn(_).isDefined)) // -source version
         .flatMap(SourceVersionPattern.findFirstMatchIn(_))
         .flatMap(m => Option(m.group(1)))
-      val forceFutureMigrationVersion = definedSourceVersion.contains("future")
+      lazy val requiredSourceVersion = requiredAppendSettings.find(isSourceVersion).flatMap(resolveSourceVersion)
+      val forceSourceVersion = definedSourceVersion.contains("future") || requiredSourceVersion.isDefined
 
       val appendSettings = {
         def excludeIf(setting: String, expr: Boolean, reason: => String) = {
           if(expr) logOnce(s"Would not apply setting `$setting`: $reason")
           expr
         }
+
         val forcedAppendSettings: Seq[String] = Seq( 
-          if(forceFutureMigrationVersion) Some("-source:future-migration") else None
+          if(forceSourceVersion) Some(s"-source:${requiredSourceVersion.getOrElse("future-migration")}") else None
         ).flatten
-        append.filterNot{  setting => 
+
+        standardAppendSettings.filterNot{  setting => 
           excludeIf(setting, 
-            isSourceVersion(setting) && (definedSourceSetting.nonEmpty || forceFutureMigrationVersion),
+            isSourceVersion(setting) && (definedSourceSetting.nonEmpty || forceSourceVersion),
             s"Project has predefined source version: ${definedSourceSetting.get}"
           )
         } ++ forcedAppendSettings
       }
+
       val normalizedExcludePatterns = (appendSettings ++ removeSettings).distinct.map { setting =>
         Seq[String => String](
           setting => if (setting.startsWith("--")) setting.tail else setting,