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  1. JDK
  2. JDK-8016636

cast warning in spite of suppresswarnings when reordering

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    • Icon: Bug Bug
    • Resolution: Duplicate
    • Icon: P3 P3
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    • 7
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    • os_x

      FULL PRODUCT VERSION :
      javac -version
      javac 1.7.0_07


      ADDITIONAL OS VERSION INFORMATION :
      OS-independent

      EXTRA RELEVANT SYSTEM CONFIGURATION :
      not configuration-specific

      A DESCRIPTION OF THE PROBLEM :
      (See also discussion here: http://stackoverflow.com/questions/529085/java-how-to-generic-array-creation)

      Code alternative(1) compiles without warnings as it should, but code alternative(2) produces an " unchecked cast " warning.

      Common for both:

      class Foo<T> {
          Foo( T [] arg ) {
          }
      }

      Alternative (1):

      class Bar<T> extends Foo<T> {
          protected static final Object [] EMPTY_ARRAY = {};

          @SuppressWarnings( " unchecked " )
          Bar() {
               super( (T []) EMPTY_ARRAY );
          }
      }

      Alternative (2):

      class Bar<T> extends Foo<T> {
          @SuppressWarnings( " unchecked " )
          Bar() {
               super( (T []) EMPTY_ARRAY );
          }

          protected static final Object [] EMPTY_ARRAY = {};
      }

      Alternative (2) produces:

      javac -Xlint:unchecked Foo.java Bar.java
      Bar.java:4: warning: [unchecked] unchecked cast
                   super( (T []) EMPTY_ARRAY );
                                 ^
        required: T[]
        found: Object[]
        where T is a type-variable:
          T extends Object declared in class Bar
      1 warning

      REGRESSION. Last worked in version 6u31

      STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
      Compile above code samples.

      EXPECTED VERSUS ACTUAL BEHAVIOR :
      EXPECTED -
      I expect the @SuppressWarnings to be honored. I also expect that the compiler output does not depend on whether I declare a static variable first or last.

      REPRODUCIBILITY :
      This bug can be reproduced always.

      CUSTOMER SUBMITTED WORKAROUND :
      Reorder declarations.

            Unassigned Unassigned
            webbuggrp Webbug Group
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              Created:
              Updated:
              Resolved: