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  1. JDK
  2. JDK-6480391

Unbounded wildcard '?' means '? extends Object'

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    • Enhancement
    • Resolution: Fixed
    • P5
    • 8
    • 6
    • specification
    • None
    • generic
    • generic
    • Verified

    Description

      The introduction of the capture conversion simplified a lot of things. One of the things it did is make "?" equivalent to "? extends Object". Unfortunately, JLS3 doesn't say they are equivalent. It should because, for example, 4.5.1.1, which describes type argument containment, does not address the unbounded wildcard case. Similarly, the definition of Icta on page 465 seems to be missing a case for an unbounded wildcard. I expect there are others.

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          duplicates

          Bug - A problem which impairs or prevents the functions of the product. JDK-6573446 javac infers a type bound where none should exist

          • P4 - Minor loss of function, or other problem where easy workaround is present.
          • Closed
          relates to

          Bug - A problem which impairs or prevents the functions of the product. JDK-8163890 4.5.1: Clarify that ? <= ? extends Object

          • P4 - Minor loss of function, or other problem where easy workaround is present.
          • Open

          Bug - A problem which impairs or prevents the functions of the product. JDK-8268148 unchecked warnings handle ? and ? extends Object differently

          • P4 - Minor loss of function, or other problem where easy workaround is present.
          • Resolved

          Bug - A problem which impairs or prevents the functions of the product. JDK-8030148 Lambda Spec: Reduction for Foo<?> = Foo<? extends alpha>

          • P3 - Major loss of function.
          • Closed

          Bug - A problem which impairs or prevents the functions of the product. JDK-4949438 4.5: When are wildcards "the same"?

          • P4 - Minor loss of function, or other problem where easy workaround is present.
          • Open

          Bug - A problem which impairs or prevents the functions of the product. JDK-8030686 Lambda Spec: Incorporation for capture bound involving ? extends Object

          • P2 - Crashes, loss of data, severe memory leak.
          • Closed

          Enhancement - null JDK-5052943 4.10.4: Improve lub for lower-bounded wildcards and variables

          • P4 - Minor loss of function, or other problem where easy workaround is present.
          • Open

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              abuckley Alex Buckley
              ahe Peter Ahe
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