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  1. JDK
  2. JDK-8056014

Type inference may be skipped for a complex receiver generic method in a parameter position

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    • Subcomponent:
    • Resolved In Build:
      b31
    • CPU:
      x86_64
    • OS:
      linux
    • Verification:
      Verified

      Backports

        Description

        FULL PRODUCT VERSION :
        java version "1.8.0_20"
        Java(TM) SE Runtime Environment (build 1.8.0_20-b26)
        Java HotSpot(TM) 64-Bit Server VM (build 25.20-b23, mixed mode)

        ADDITIONAL OS VERSION INFORMATION :
        Kubuntu 14.04 x64

        A DESCRIPTION OF THE PROBLEM :
        This works in jdk1.8.0_11 and in Eclipse but not anymore in jdk1.8.0_20:

        public class Testbed {
        public static void main(String[] args) {
        java.util.List<Dog> l = null;
        Dog d = l.get(0).copy(); // ok
        foo(l.get(0).copy()); // error
        }

        private static void foo(Dog d) { }
        }

        class Animal {
        public <T> T copy() {
        return null;
        }
        }

        class Dog extends Animal {
        }


        jdk1.8.0_20 message:

        Testbed.java:5: error: method foo in class Testbed cannot be applied to given types;
                        foo(l.get(0).copy()); // error
                        ^
          required: Dog
          found: Object
          reason: argument mismatch; Object cannot be converted to Dog
        1 error

        REGRESSION. Last worked in version 8u11

        ADDITIONAL REGRESSION INFORMATION:
        java version "1.8.0_11"
        Java(TM) SE Runtime Environment (build 1.8.0_11-b12)
        Java HotSpot(TM) 64-Bit Server VM (build 25.11-b03, mixed mode)

        STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
        Try to compile the given snippet.

        EXPECTED VERSUS ACTUAL BEHAVIOR :
        EXPECTED -
        It compiles.
        ACTUAL -
        Syntax error message.

        ERROR MESSAGES/STACK TRACES THAT OCCUR :
        Testbed.java:5: error: method foo in class Testbed cannot be applied to given types;
                        foo(l.get(0).copy()); // error
                        ^
          required: Dog
          found: Object
          reason: argument mismatch; Object cannot be converted to Dog
        1 error

        REPRODUCIBILITY :
        This bug can be reproduced always.

        ---------- BEGIN SOURCE ----------
        public class Testbed {
        public static void main(String[] args) {
        java.util.List<Dog> l = null;
        Dog d = l.get(0).copy(); // ok
        foo(l.get(0).copy()); // error
        }

        private static void foo(Dog d) { }
        }

        class Animal {
        public <T> T copy() {
        return null;
        }
        }

        class Dog extends Animal {
        }
        ---------- END SOURCE ----------

        CUSTOMER SUBMITTED WORKAROUND :
        Use jdk1.8.0_11 and be sad.

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                Assignee:
                jlahoda Jan Lahoda
                Reporter:
                webbuggrp Webbug Group
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                  Created:
                  Updated:
                  Resolved: