RFR: JDK-8193561: Cyclic hierarchy causes a NullPointerException when setting DEFAULT flag

[Maurizio Cimadamore]

Looks good - owner and enclClass() should have identical effects in this 
case (e.g. go one level up to the method owner).

Maurizio


On 14/09/18 12:33, Jan Lahoda wrote:
> Hi,
>
> Consider code like:
> ---
> package p;
>
> interface T8193561 extends p.T8193561.I {
>
>     interface I  extends T8193561 {
>         default boolean m() {
>             return false;
>         }
>     }
>
>     default boolean m() {
>         return false;
>     }
>
> }
> ---
>
> There is apparently a cycle between the interfaces, and an error will 
> be reported correctly for it, but then it will crash in MemberEnter:
> ---
> $ javac -XDdev T8193561.java
> T8193561.java:9: error: cyclic inheritance involving T8193561
> interface T8193561 extends p.T8193561.I {
> ^
> 1 error
> An exception has occurred in the compiler (12-internal). Please file a 
> bug against the Java compiler via the Java bug reporting page 
> (http://bugreport.java.com) after checking the Bug Database 
> (http://bugs.java.com) for duplicates. Include your program and the 
> following diagnostic in your report. Thank you.
> java.lang.NullPointerException
>         at 
> jdk.compiler/com.sun.tools.javac.comp.MemberEnter.visitMethodDef(MemberEnter.java:186)
> [snip]
> ---
>
> (Note the -XDdev - as there is an error already reported, the 
> exception would normally be hidden, but the crash is still observable 
> in certain cases, e.g. in tests.)
>
> The offending line is:
>             m.enclClass().flags_field |= DEFAULT;
>
> The issue here, IMO, is that when the cycle is detected, the 
> class/interface is marked as erroneous, and m.enclClass() won't return 
> erroneous owner (will return null instead). Seems that using "m.owner" 
> instead of "m.enclClass()" should be sufficient at this place?
>
> Proposed patch: http://cr.openjdk.java.net/~jlahoda/8193561/webrev.00/
> Bug: https://bugs.openjdk.java.net/browse/JDK-8193561
>
> How does this look?
>
> Thanks,
>     Jan