Support ESFeatures in Scala.js

scalajslib/api/src/ScalaJSWorkerApi.scala

@@ -1,6 +1,9 @@
 package mill.scalajslib.api
+
 import java.io.File
 import mill.api.Result
+import upickle.default.{ReadWriter => RW, macroRW}
+
 trait ScalaJSWorkerApi {
   def link(
       sources: Array[File],
@@ -10,7 +13,7 @@ trait ScalaJSWorkerApi {
       testBridgeInit: Boolean,
       fullOpt: Boolean,
       moduleKind: ModuleKind,
-      useECMAScript2015: Boolean
+      esFeatures: ESFeatures
   ): Result[File]
 
   def run(config: JsEnvConfig, linkedFile: File): Unit
@@ -36,10 +39,44 @@ object ModuleKind {
   object ESModule extends ModuleKind
 }
 
+sealed trait ESVersion
+object ESVersion {
+  implicit val rw: RW[ESVersion] = macroRW[ESVersion]
+  object ES2015 extends ESVersion
+  object ES2016 extends ESVersion
+  object ES2017 extends ESVersion
+  object ES2018 extends ESVersion
+  object ES2019 extends ESVersion
+  object ES2020 extends ESVersion
+  object ES2021 extends ESVersion
+  object ES5_1 extends ESVersion
+}
+
+case class ESFeatures private (
+    allowBigIntsForLongs: Boolean,
+    avoidClasses: Boolean,
+    avoidLetsAndConsts: Boolean,
+    esVersion: ESVersion
+) {
+  def withAllowBigIntsForLongs(allowBigIntsForLongs: Boolean): ESFeatures =
+    copy(allowBigIntsForLongs = allowBigIntsForLongs)
+  def withAvoidClasses(avoidClasses: Boolean): ESFeatures = copy(avoidClasses = avoidClasses)
+  def withAvoidLetsAndConsts(avoidLetsAndConsts: Boolean): ESFeatures =
+    copy(avoidLetsAndConsts = avoidLetsAndConsts)
+  def withESVersion(esVersion: ESVersion): ESFeatures = copy(esVersion = esVersion)
+}
+object ESFeatures {
+  val Defaults: ESFeatures = ESFeatures(
+    allowBigIntsForLongs = false,
+    avoidClasses = true,
+    avoidLetsAndConsts = true,
+    esVersion = ESVersion.ES2015
+  )
+  implicit val rw: RW[ESFeatures] = macroRW[ESFeatures]
+}
+
 sealed trait JsEnvConfig
 object JsEnvConfig {
-
-  import upickle.default.{ReadWriter => RW, macroRW}
   implicit def rwNodeJs: RW[NodeJs] = macroRW
   implicit def rwJsDom: RW[JsDom] = macroRW
   implicit def rwPhantom: RW[Phantom] = macroRW

scalajslib/src/ScalaJSModule.scala

@@ -83,7 +83,7 @@ trait ScalaJSModule extends scalalib.ScalaModule { outer =>
       testBridgeInit = false,
       mode = FastOpt,
       moduleKind = moduleKind(),
-      useECMAScript2015 = useECMAScript2015()
+      esFeatures = esFeatures()
     )
   }
 
@@ -96,7 +96,7 @@ trait ScalaJSModule extends scalalib.ScalaModule { outer =>
       testBridgeInit = false,
       mode = FullOpt,
       moduleKind = moduleKind(),
-      useECMAScript2015 = useECMAScript2015()
+      esFeatures = esFeatures()
     )
   }
 
@@ -132,7 +132,7 @@ trait ScalaJSModule extends scalalib.ScalaModule { outer =>
       testBridgeInit: Boolean,
       mode: OptimizeMode,
       moduleKind: ModuleKind,
-      useECMAScript2015: Boolean
+      esFeatures: ESFeatures
   )(implicit ctx: Ctx): Result[PathRef] = {
     val outputPath = ctx.dest / "out.js"
 
@@ -154,7 +154,7 @@ trait ScalaJSModule extends scalalib.ScalaModule { outer =>
       testBridgeInit,
       mode == FullOpt,
       moduleKind,
-      useECMAScript2015
+      esFeatures
     ).map(PathRef(_))
   }
 
@@ -197,8 +197,22 @@ trait ScalaJSModule extends scalalib.ScalaModule { outer =>
 
   def moduleKind: T[ModuleKind] = T { ModuleKind.NoModule }
 
-  def useECMAScript2015: T[Boolean] = T { 
-    !scalaJSVersion().startsWith("0.")
+  @deprecated("Use esFeatures().esVersion instead", since = "mill after 0.10.0-M5")
+  def useECMAScript2015: T[Boolean] = T {
+    esFeatures().esVersion != ESVersion.ES5_1
+  }
+
+  def esFeatures: T[ESFeatures] = T {
+    if (useECMAScript2015.ctx.enclosing != s"${classOf[ScalaJSModule].getName}#useECMAScript2015") {
+      Result.Failure(
+        "Overriding `useECMAScript2015` is not supported anymore. Override `esFeatures` instead"
+      )
+    } else {
+      Result.Success {
+        if (scalaJSVersion().startsWith("0.")) ESFeatures.Defaults.withESVersion(ESVersion.ES5_1)
+        else ESFeatures.Defaults
+      }
+    }
   }
 
   @internal
@@ -239,7 +253,7 @@ trait TestScalaJSModule extends ScalaJSModule with TestModule {
       testBridgeInit = true,
       FastOpt,
       moduleKind(),
-      useECMAScript2015()
+      esFeatures()
     )
   }
 

scalajslib/src/ScalaJSWorkerApi.scala

@@ -38,7 +38,7 @@ class ScalaJSWorker {
       testBridgeInit: Boolean,
       fullOpt: Boolean,
       moduleKind: ModuleKind,
-      useECMAScript2015: Boolean
+      esFeatures: ESFeatures
   )(implicit ctx: Ctx.Home): Result[os.Path] = {
     bridge(toolsClasspath).link(
       sources.items.map(_.toIO).toArray,
@@ -48,7 +48,7 @@ class ScalaJSWorker {
       testBridgeInit,
       fullOpt,
       moduleKind,
-      useECMAScript2015
+      esFeatures
     ).map(os.Path(_))
   }