Implement tweak

In bodies of transparent unerased method we inline only transparent erased methods.

Author: odersky

compiler/src/dotty/tools/dotc/core/TypeOps.scala

@@ -276,6 +276,10 @@ trait TypeOps { this: Context => // TODO: Make standalone object.
   /** Are we in a transparent method body? */
   def inTransparentMethod = owner.ownersIterator.exists(_.isTransparentMethod)
 
+  /** Are we in a transparent method body? */
+  def inErasedTransparentMethod = owner.ownersIterator.exists(sym =>
+    sym.isTransparentMethod && sym.is(Erased))
+
   /** Is `feature` enabled in class `owner`?
    *  This is the case if one of the following two alternatives holds:
    *

compiler/src/dotty/tools/dotc/typer/Inliner.scala

@@ -58,8 +58,12 @@ object Inliner {
   /** Should call with method `meth` be inlined in this context? */
   def isInlineable(meth: Symbol)(implicit ctx: Context): Boolean = {
 
+    /** Suppress inlining of
+     *   - non-erased methods inside a transparent method,
+     *   - all methods inside an erased transparent method
+     */
     def suppressInline =
-      ctx.inTransparentMethod ||
+      ctx.inTransparentMethod && (!meth.is(Erased) || ctx.inErasedTransparentMethod) ||
       ctx.settings.YnoInline.value ||
       ctx.isAfterTyper ||
       ctx.reporter.hasErrors

tests/run/i4735/App_2.scala

@@ -7,6 +7,7 @@ object Test {
       System.out.println(2*x)
     }
   }
+
 }
 
 class Unrolled(arr: Array[Int]) extends AnyVal {