Bug in JLS specification for restriction on where a return statement is allowed.

[Alex Buckley]

Ted,

Yes, that can be argued. In practice, there is almost no chance that the 
JLS text (unchanged since JLS1) has confused compiler writers or 
programmers. The C# 3.0 spec (8.9.4) has very similar wording.

On the other hand, the Scala 2.7 spec (6.20) does a better job. Absolute 
precision *is* a goal for a spec. So is making conservative changes to a 
widely-distributed document; my proposal in 6906550 minimizes rewording 
but is arguably less direct than Scala's wording. (Then again, the Scala 
spec doesn't have to worry about constructors.)

Of course, as a specification issue, this is off-topic for compiler-dev.

Alex

Ted Neward wrote:
> Can’t it be argued that the “return” doesn’t appear within the instance 
> or static initializer, but within a construct which happens to be inside 
> an initializer? (Meaning the text is, at best, ambiguous?)
> 
>  
> 
> Not trying to nit-pick, just trying to understand how deeply detailed 
> the specification needs to be, to be honest.
> 
>  
> 
> Ted Neward
> 
> Java, .NET, XML Services
> 
> Consulting, Teaching, Speaking, Writing
> 
> http://www.tedneward.com
> 
>  
> 
>  
> 
> *From:* compiler-dev-bounces at openjdk.java.net 
> [mailto:compiler-dev-bounces at openjdk.java.net] *On Behalf Of *Neal Gafter
> *Sent:* Wednesday, December 02, 2009 9:24 AM
> *To:* Alexander Buckley
> *Cc:* OpenJDK
> *Subject:* Bug in JLS specification for restriction on where a return 
> statement is allowed.
> 
>  
> 
> Alex-
> 
> JLS 14.17 says
> 
> A compile-time error occurs if a |return| statement appears within an 
> instance initializer or a static initializer (§8.7) 
> <http://java.sun.com/docs/books/jls/third_edition/html/classes.html#39245>.
> 
> 
> However, javac allows a return statement within an instance or static 
> initializer if there is an intervening nested inner class with a method.
> 
> *static { // static initializer*
> *    class X {*
> *        void foo() {*
> *            return; // yet return allowed within it*
> *        }*
> *    }*
> *}*
> 
> 
> I believe this is a bug in the specification.
> 
> Cheers,
> Neal
>