Make LazyVals.getOffset work on j.l.Class instead of taking the instance.

Author: DarkDimius

src/dotty/runtime/LazyVals.scala

@@ -65,7 +65,7 @@ object LazyVals {
     monitors(id)
   }
 
-  @inline def getOffset(obj: Object, name: String) = unsafe.objectFieldOffset(obj.getClass.getDeclaredField(name))
+  @inline def getOffset(clz: Class[_], name: String) = unsafe.objectFieldOffset(clz.getDeclaredField(name))
 
   object Names {
     final val state = "STATE"

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

@@ -289,7 +289,7 @@ class LazyVals extends MiniPhaseTransform with IdentityDenotTransformer {
 
         val tpe = x.tpe.widen.resultType.widen
         val claz = x.symbol.owner.asClass
-        val thiz = This(claz)(ctx.fresh.setOwner(claz))
+        val thizClass = Literal(Constant(claz.info))
         val companion = claz.companionModule
         val helperModule = ctx.requiredModule("dotty.runtime.LazyVals")
         val getOffset = Select(ref(helperModule), RLazyValsNames_getOffset)
@@ -313,7 +313,7 @@ class LazyVals extends MiniPhaseTransform with IdentityDenotTransformer {
               val flagName = (StdNames.nme.BITMAP_PREFIX + id.toString).toTermName
               val flagSymbol = ctx.newSymbol(claz, flagName, containerFlags, defn.LongType).enteredAfter(this)
               flag = ValDef(flagSymbol, Literal(Constants.Constant(0L)))
-              val offsetTree = ValDef(offsetSymbol, getOffset.appliedTo(thiz, Literal(Constant(flagName.toString))))
+              val offsetTree = ValDef(offsetSymbol, getOffset.appliedTo(thizClass, Literal(Constant(flagName.toString))))
               info.defs = offsetTree :: info.defs
             }
 
@@ -322,7 +322,7 @@ class LazyVals extends MiniPhaseTransform with IdentityDenotTransformer {
             val flagName = (StdNames.nme.BITMAP_PREFIX + "0").toTermName
             val flagSymbol = ctx.newSymbol(claz, flagName, containerFlags, defn.LongType).enteredAfter(this)
             flag = ValDef(flagSymbol, Literal(Constants.Constant(0L)))
-            val offsetTree = ValDef(offsetSymbol, getOffset.appliedTo(thiz, Literal(Constant(flagName.toString))))
+            val offsetTree = ValDef(offsetSymbol, getOffset.appliedTo(thizClass, Literal(Constant(flagName.toString))))
             appendOffsetDefs += (companion.name.moduleClassName -> new OffsetInfo(List(offsetTree), ord))
         }