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  1. JDK
  2. JDK-8133916

Regression in inference for array type with wildcard

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    • Subcomponent:
    • CPU:
      x86
    • OS:
      os_x

      Description

      FULL PRODUCT VERSION :
      java version "1.9.0-ea"
      Java(TM) SE Runtime Environment (build 1.9.0-ea-b74)
      Java HotSpot(TM) 64-Bit Server VM (build 1.9.0-ea-b74, mixed mode)

      ADDITIONAL OS VERSION INFORMATION :
      Darwin x86_64

      A DESCRIPTION OF THE PROBLEM :
      The included program has different behaviour when compiled with the jdk9 javac than with earlier versions.

      Specifically, javac9 resolves the invocation inside f() as g(Object...), and javac8 resolves g(M[]).

      This is probably related to https://bugs.openjdk.java.net/browse/JDK-8039214.

      REGRESSION. Last worked in version 8u60

      ADDITIONAL REGRESSION INFORMATION:
      java version "1.8.0_60-ea"
      Java(TM) SE Runtime Environment (build 1.8.0_60-ea-b13)
      Java HotSpot(TM) 64-Bit Server VM (build 25.60-b12, mixed mode)

      STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
      $JAVA_8_HOME/bin/javac Test.java
      $JAVA_8_HOME/bin/java Test
      one

      $JAVA_9_HOME/bin/javac Test.java
      $JAVA_9_HOME/bin/java Test
      two

      EXPECTED VERSUS ACTUAL BEHAVIOR :
      EXPECTED -
      I expected the same behaviour from both compilers.
      ACTUAL -
      The program behaved differently when compiled with javac9.

      REPRODUCIBILITY :
      This bug can be reproduced always.

      ---------- BEGIN SOURCE ----------
      public class Test {
        interface M<T> {}

        public static void main(String[] args) {
          f((M<Object>) null);
        }

        static <T> void f(M<? super T>... xs) {
          g(xs);
        }

        public static <E> void g(M<? super E>... xs) {
          System.err.println("one");
        }

        public static <E> void g(E... xs) {
          System.err.println("two");
        }
      }

      ---------- END SOURCE ----------

      CUSTOMER SUBMITTED WORKAROUND :
      Explicit type parameters:

      static <T> void f(M<? super T>... xs) {
        Test.<M<? super T>>g(xs);
      }

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              • Assignee:
                dlsmith Dan Smith
                Reporter:
                webbuggrp Webbug Group
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                Dates

                • Created:
                  Updated:
                  Resolved: