2 files changed, 10 insertions, 1 deletions
diff --git a/src/dotty/tools/dotc/Compiler.scala b/src/dotty/tools/dotc/Compiler.scala
index be4477ee2..db92983ef 100644
--- a/src/dotty/tools/dotc/Compiler.scala
+++ b/src/dotty/tools/dotc/Compiler.scala
@@ -103,7 +103,11 @@ class Compiler {
   def rootContext(implicit ctx: Context): Context = {
     ctx.initialize()(ctx)
     val actualPhases = if (ctx.settings.scalajs.value) {
-      phases
+      // Remove phases that Scala.js does not want
+      phases.mapConserve(_.filter {
+        case _: FunctionalInterfaces => false
+        case _ => true
+      }).filter(_.nonEmpty)
     } else {
       // Remove Scala.js-related phases
       phases.mapConserve(_.filter {
diff --git a/src/dotty/tools/dotc/config/SJSPlatform.scala b/src/dotty/tools/dotc/config/SJSPlatform.scala
index fec9c25a1..3ec8049ae 100644
--- a/src/dotty/tools/dotc/config/SJSPlatform.scala
+++ b/src/dotty/tools/dotc/config/SJSPlatform.scala
@@ -2,6 +2,7 @@ package dotty.tools.dotc.config
 
 import dotty.tools.dotc.core._
 import Contexts._
+import Symbols._
 
 import dotty.tools.backend.sjs.JSDefinitions
 
@@ -10,4 +11,8 @@ class SJSPlatform()(implicit ctx: Context) extends JavaPlatform {
   /** Scala.js-specific definitions. */
   val jsDefinitions: JSDefinitions = new JSDefinitions()
 
+  /** Is the SAMType `cls` also a SAM under the rules of the Scala.js back-end? */
+  override def isSam(cls: ClassSymbol)(implicit ctx: Context): Boolean =
+    defn.isFunctionClass(cls) || jsDefinitions.isJSFunctionClass(cls)
+
 }