RFR : JDK-8197439,,Crash with -XDfind=lambda for anonymous class in anonymous class.

Jan Lahoda jan.lahoda at oracle.com
Fri Feb 9 09:31:38 UTC 2018


For certain classes -XDfind=lambda will crash javac (please see the bug 
for details):
public class AnonymousInAnonymous {
     static void s(I1 i) {}
     static {
             new I1() {
                 public I2 get() {
                     return new I2() {
     public static interface I1 {
         public static class I2 { }
         public I2 get();

The reason is that:
- -XDfind=lambda will try to replace "new I1() {...}" with a lambda and 
attribute that
-but this will make I2 unresolvable
-so Attr.visitNewClass will not (currently) attribute the inside of the 
"new I2() {}".
-so Attr.PostAttrAnalyzer will try to fill in Symbols and Types, but 
"Attr.PostAttrAnalyzer.dummyMethodType" will dereference 
MethodTree.restype, which is null for constructors (in this case an 
automatically generated constructor).

A part of the proposed fix is to enhance 
PostAttrAnalyzer.dummyMethodType to handle constructors. But attributing 
the body of an unresolvable anonymous class does not seem difficult, and 
would help API clients like JShell, so the proposed fix is doing that as 
well. One of the changes to do that also removes follow up errors that 
appear to be unnecessary (an error has already been reported to the 
anonymous class' "clazz", so unnecessary to report errors that relate to 
the anonymous class' constructor).

Bug: https://bugs.openjdk.java.net/browse/JDK-8197439
Webrev: http://cr.openjdk.java.net/~jlahoda/8197439/webrev.00/

How does this look?


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