Ignore false warnings for Java & Scala 2

Author: liufengyun

compiler/src/dotty/tools/dotc/transform/init/Objects.scala

@@ -664,15 +664,15 @@ object Objects:
             else
               errorReadOtherStaticObject(State.currentObject, addr.owner)
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-          else if ref.isObjectRef then
+          else if ref.isObjectRef && ref.klass.hasSource then
             report.warning("Access uninitialized field " + field.show + ". Call trace: " + Trace.show, Trace.position)
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           else
             // initialization error, reported by the initialization checker
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         else if ref.hasVal(target) then
           ref.valValue(target)
-        else if ref.isObjectRef then
+        else if ref.isObjectRef && ref.klass.hasSource then
           report.warning("Access uninitialized field " + field.show + ". Call trace: " + Trace.show, Trace.position)
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         else