From philip.race at oracle.com  Fri Nov 30 01:32:09 2018
From: philip.race at oracle.com (Philip Race)
Date: Thu, 29 Nov 2018 17:32:09 -0800
Subject: <Beans Dev> [12] Review Request: 8211147 Incorrect comparator
 com.sun.beans.introspect.MethodInfo.MethodOrder
In-Reply-To: <220dfd59-2b0a-04ca-480d-47b71ed8564d@oracle.com>
References: <220dfd59-2b0a-04ca-480d-47b71ed8564d@oracle.com>
Message-ID: <5C009319.1000301@oracle.com>

+1

Can you add your notes below to the bug as an evaluation.

-phil.

On 10/5/18, 7:15 PM, Sergey Bylokhov wrote:
> Hello.
> Please review the fix for jdk12.
>
> Bug: https://bugs.openjdk.java.net/browse/JDK-8211147
> Webrev: http://cr.openjdk.java.net/~serb/8211147/webrev.00
>
> From the bug description:
> The "MethodInfo.MethodOrder" comparator violates its contract
> compare(x, y) == -(compare(y, x)) for all (x, y), so sort which use 
> this comparator can throw IllegalArgumentException.
>
>
> The reason is how this comparator compare the return types of the 
> methods. The code assumes that if two methods have the same names then 
> one of the return type should be subtype of another, because of 
> covariant return types. An example in this bug shows that it is not 
> necessary correct, which means that this method may always returns 
> "-1" if two return types are unrelated.
>
>
> Note that this class was particularly copied from 
> com.sun.jmx.mbeanserver.MethodOrder which looks like has the same bug, 
> I'll file a separate bug for it.
>