Java 7 -> Java8 code breakage scenarios

[Maurizio Cimadamore]

On 28/02/13 12:24, Maurizio Cimadamore wrote:
> On 28/02/13 11:45, Boaz Nahum wrote:
>>>   From your email I guessed you had to workaround new bugs. I 
>>> probably have
>>> mis-interpreted. Good to know that everything is looking almost sane on
>>> your part.
>>>
>>>
>>> Yes, I hardy can read my own English ...
>> Actually, One of dependencies problem I reported may be consider as bug,
>> because the missing dependency cause a compiler crash. You helped me to
>> find it, see thread:
>>
>> http://mail.openjdk.java.net/pipermail/compiler-dev/2013-February/005625.html 
>>
>>
>> Once the dependency was added the crash disappeared.
>>
>> I will trace back all other issues, But it will take some time.
> [moving to lambda-dev, which is more appropriate]
> I've tried to reproduce something like what you described:
>
> //A.java
> public interface A {
>     void m();
> }
>
> //B.java
> public class B implements A {
>     @Override
>     public void m() { }
>
>     public static void n() { }
> }
>
>
> //C.java
> public class C {
>     void test(B b) {
>         B.n();
>     }
> }
>
>
> I've compiled A, B, then only kept classfile for B.class.
>
> Then I tried to compile C.java against B.class - I only got an error 
> message like this:
>
> C.java:3: error: cannot access A
>         B.n();
>          ^
>   class file for A not found
> 1 error
>
> The message goes away if you compile with -source 7. That's 
> understandable, no default method lookup in JDK 7.
>
> However I could not reproduce any crash. So it seems like some 
> ingredient is missing...
>
> Maurizio
>
>>
>> Thanks
>> Boaz
>
Hehe - this did the trick:

//B.java
public class B implements A {
     @Override
     public void m() { }

     public static Object n() { return null; }
}


//C.java
public class C {
     void test(B b) {
         Tester.m(B.n());
     }
}

class Tester {
     static void m(Object o) { }
}

I got this:

An exception has occurred in the compiler (1.8.0-internal). Please file 
a bug at the Java Developer Connection 
(http://java.sun.com/webapps/bugreport)  after checking the Bug Parade 
for duplicates. Include your program and the following diagnostic in 
your report.  Thank you.
java.lang.NullPointerException
     at 
com.sun.tools.javac.comp.Flow$FlowAnalyzer.visitApply(Flow.java:1196)
     at 
com.sun.tools.javac.tree.JCTree$JCMethodInvocation.accept(JCTree.java:1440)
     at com.sun.tools.javac.tree.TreeScanner.scan(TreeScanner.java:49)
     at com.sun.tools.javac.tree.TreeScanner.visitExec(TreeScanner.java:174)
     at 
com.sun.tools.javac.tree.JCTree$JCExpressionStatement.accept(JCTree.java:1271)
     at com.sun.tools.javac.tree.TreeScanner.scan(TreeScanner.java:49)
     at com.sun.tools.javac.tree.TreeScanner.scan(TreeScanner.java:57)
     at com.sun.tools.javac.comp.Flow$FlowAnalyzer.visitBlock(Flow.java:959)
     at com.sun.tools.javac.tree.JCTree$JCBlock.accept(JCTree.java:884)
     at com.sun.tools.javac.tree.TreeScanner.scan(TreeScanner.java:49)
     at 
com.sun.tools.javac.comp.Flow$FlowAnalyzer.visitMethodDef(Flow.java:926)
     at com.sun.tools.javac.tree.JCTree$JCMethodDecl.accept(JCTree.java:771)
     at com.sun.tools.javac.tree.TreeScanner.scan(TreeScanner.java:49)
     at 
com.sun.tools.javac.comp.Flow$FlowAnalyzer.visitClassDef(Flow.java:889)
     at com.sun.tools.javac.tree.JCTree$JCClassDecl.accept(JCTree.java:686)
     at com.sun.tools.javac.tree.TreeScanner.scan(TreeScanner.java:49)
     at 
com.sun.tools.javac.comp.Flow$FlowAnalyzer.analyzeTree(Flow.java:1276)
     at 
com.sun.tools.javac.comp.Flow$FlowAnalyzer.analyzeTree(Flow.java:1266)
     at com.sun.tools.javac.comp.Flow.analyzeTree(Flow.java:212)
     at com.sun.tools.javac.main.JavaCompiler.flow(JavaCompiler.java:1330)
     at com.sun.tools.javac.main.JavaCompiler.flow(JavaCompiler.java:1304)
     at 
com.sun.tools.javac.main.JavaCompiler.compile2(JavaCompiler.java:909)
     at com.sun.tools.javac.main.JavaCompiler.compile(JavaCompiler.java:868)
     at com.sun.tools.javac.main.Main.compile(Main.java:517)
     at com.sun.tools.javac.main.Main.compile(Main.java:376)
     at com.sun.tools.javac.main.Main.compile(Main.java:365)
     at com.sun.tools.javac.main.Main.compile(Main.java:356)
     at com.sun.tools.javac.Main.compile(Main.java:77)
     at com.sun.tools.javac.Main.main(Main.java:62)

Which is the very one you got. If you'd be so kind to give me some 
details about the other stack trace you were getting (Types.rank) so 
that I can come up with some test case (i.e. what is the code that 
triggered it).

Maurizio