Bring back blockescapes test...

... by reverting a premature optimization in Erasure.

Author: odersky

src/dotty/tools/dotc/transform/Erasure.scala

@@ -318,9 +318,6 @@ object Erasure {
       }
     }
 
-    override def ensureNoLocalRefs(block: Block, pt: Type, forcedDefined: Boolean = false)(implicit ctx: Context): Tree =
-      block // optimization, no checking needed, as block symbols do not change.
-
     override def typedDefDef(ddef: untpd.DefDef, sym: Symbol)(implicit ctx: Context) = {
       val ddef1 = untpd.cpy.DefDef(ddef)(
         tparams = Nil,

test/dotc/tests.scala

@@ -26,7 +26,7 @@ class tests extends CompilerTest {
 
   @Test def pos_erasure = compileFile(posDir, "erasure", doErase)
   @Test def pos_Coder() = compileFile(posDir, "Coder", doErase)
- // @Test def pos_blockescapes() = compileFile(posDir, "blockescapes", doErase)
+  @Test def pos_blockescapes() = compileFile(posDir, "blockescapes", doErase)
   @Test def pos_collections() = compileFile(posDir, "collections", doErase)
   @Test def pos_functions1() = compileFile(posDir, "functions1", doErase)
   @Test def pos_implicits1() = compileFile(posDir, "implicits1", doErase)