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  1. JDK
  2. JDK-6738538

javac crashes when using a type parameter as a covariant method return type

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    Details

    • Subcomponent:
    • Resolved In Build:
      b39
    • CPU:
      generic, x86
    • OS:
      generic, windows_xp
    • Verification:
      Not verified

      Description

      FULL PRODUCT VERSION :
      java version "1.6.0_10-rc"
      Java(TM) SE Runtime Environment (build 1.6.0_10-rc-b28)
      Java HotSpot(TM) Client VM (build 11.0-b15, mixed mode, sharing)

      ADDITIONAL OS VERSION INFORMATION :
      Microsoft Windows XP [Version 5.1.2600]
      Linux 2.6.22-14-generic i686 GNU/Linux

      A DESCRIPTION OF THE PROBLEM :
      When trying to compile the two sample files attached to this case, javac crashes. The crash is probably caused while parsing the line "public T getObject()" in the class GraphNode<T> .

      Please note that this problem only happens when the classes and interfaces are distributed over two source files (as seen in the Workarounds section)

      This was tested with 1.6.0_03 (Windows + Linux) as well as with javac 1.6.0_10-rc (Windows)

      STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
      1. Create the two files from the sample source code attached to this case
      2. javac *.java

      EXPECTED VERSUS ACTUAL BEHAVIOR :
      EXPECTED -
      The two files are compiled properly although I'm not too sure about this. It might also be a case that should lead to a compiler error.
      ACTUAL -
      javac crashes

      ERROR MESSAGES/STACK TRACES THAT OCCUR :
      An exception has occurred in the compiler (1.6.0_10-rc). Please file a bug at th
      e Java Developer Connection (http://java.sun.com/webapps/bugreport) after check
      ing the Bug Parade for duplicates. Include your program and the following diagno
      stic in your report. Thank you.
      java.lang.AssertionError: isSubtype 15
              at com.sun.tools.javac.code.Types$5.visitType(Types.java:347)
              at com.sun.tools.javac.code.Types$5.visitType(Types.java:328)
              at com.sun.tools.javac.code.Types$DefaultTypeVisitor.visitWildcardType(T
      ypes.java:3163)
              at com.sun.tools.javac.code.Type$WildcardType.accept(Type.java:416)
              at com.sun.tools.javac.code.Types$DefaultTypeVisitor.visit(Types.java:31
      61)
              at com.sun.tools.javac.code.Types.isSubtype(Types.java:324)
              at com.sun.tools.javac.code.Types.isSubtype(Types.java:308)
              at com.sun.tools.javac.code.Types.isSubtypeUnchecked(Types.java:288)
              at com.sun.tools.javac.code.Types.isConvertible(Types.java:257)
              at com.sun.tools.javac.code.Types.isAssignable(Types.java:1476)
              at com.sun.tools.javac.code.Types.covariantReturnType(Types.java:2677)
              at com.sun.tools.javac.code.Types.returnTypeSubstitutable(Types.java:266
      1)
              at com.sun.tools.javac.comp.Check.checkOverride(Check.java:1120)
              at com.sun.tools.javac.comp.Check.checkImplementations(Check.java:1540)
              at com.sun.tools.javac.comp.Check.checkImplementations(Check.java:1515)
              at com.sun.tools.javac.comp.Attr.attribClassBody(Attr.java:2693)
              at com.sun.tools.javac.comp.Attr.attribClass(Attr.java:2628)
              at com.sun.tools.javac.comp.Attr.attribClass(Attr.java:2564)
              at com.sun.tools.javac.comp.Attr.attribBounds(Attr.java:442)
              at com.sun.tools.javac.comp.MemberEnter.finishClass(MemberEnter.java:409
      )
              at com.sun.tools.javac.comp.MemberEnter.finish(MemberEnter.java:1000)
              at com.sun.tools.javac.comp.MemberEnter.complete(MemberEnter.java:967)
              at com.sun.tools.javac.code.Symbol.complete(Symbol.java:386)
              at com.sun.tools.javac.code.Symbol$ClassSymbol.complete(Symbol.java:758)

              at com.sun.tools.javac.comp.Enter.complete(Enter.java:451)
              at com.sun.tools.javac.comp.Enter.main(Enter.java:429)
              at com.sun.tools.javac.main.JavaCompiler.enterTrees(JavaCompiler.java:81
      9)
              at com.sun.tools.javac.main.JavaCompiler.compile(JavaCompiler.java:727)
              at com.sun.tools.javac.main.Main.compile(Main.java:353)
              at com.sun.tools.javac.main.Main.compile(Main.java:279)
              at com.sun.tools.javac.main.Main.compile(Main.java:270)
              at com.sun.tools.javac.Main.compile(Main.java:69)
              at com.sun.tools.javac.Main.main(Main.java:54)

      REPRODUCIBILITY :
      This bug can be reproduced always.

      ---------- BEGIN SOURCE ----------
      // File GraphNode.java

      interface IObjectNode
      {
      Object getObject();
      }

      public class GraphNode<T> implements IObjectNode
      {
      // The important line is the following one
      public T getObject()
      {
      return null;
      }
      }

      // File UnusedObject.java

      interface ISelectableNode
      {
      boolean isSelected();
      }

      public class UnusedObject<NodeType extends GraphNode<?> & ISelectableNode>
      {
      }

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

      CUSTOMER SUBMITTED WORKAROUND :
      1. Use type "Object" instead of type "T" as the return method of getObject in class GraphNode<T>

      OR

      2. Change "class UnusedObject<NodeType extends GraphNode<?> & ISelectableNode>" to "class UnusedObject<NodeType extends GraphNode & ISelectableNode>"

      OR

      3. Move all interfaces and classes into the same file.

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              Assignee:
              mcimadamore Maurizio Cimadamore
              Reporter:
              ndcosta Nelson Dcosta (Inactive)
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