SafeVarargs classfile encoding (original) (raw)

Joe Darcy joe.darcy at oracle.com
Fri Jan 21 10:56:59 PST 2011

Paul,

The additional restrictions are given in the specification of the annotation type:

http://download.java.net/jdk7/docs/api/java/lang/SafeVarargs.html

In addition to the usage restrictions imposed by its @Target meta-annotation, compilers are required to implement additional usage restrictions on this annotation type; it is a compile-time error if a method or constructor declaration is annotated with a @SafeVarargs annotation, and either: * the declaration is a fixed-arity method or constructor * the declaration is a variable-arity method that is neither static nor final.

-Joe

Paul Benedict wrote:

Joe,

Will there be any language restriction on using @SafeVarargs for non-var arg methods? After all, it's just an annotation so I wonder if normal annotation rules apply or it has restricted syntax. Paul On Fri, Jan 21, 2011 at 12:50 PM, Joe Darcy <joe.darcy at oracle.com_ _<mailto:joe.darcy at oracle.com>> wrote: Hi Rémi. A few comments, in the entirety of the "jdk" repository, there were a total of five methods where it was appropriate to add this annotation, which is not a very high density! For Coin, to keep the features small, we're avoiding JVM changes and defining a new attribute is a JVM changes of sorts. The SafeVarargs information is needed in the class file in some fashion to so that compilers can know to omit unchecked warnings that would otherwise have to be emitted. Additionally, having the information in the class file enables tools like findbugs to do additional checking on the operations of the SafeVarargs methods. Using an annotation to store this information avoids the need to add a new core reflection API to access it, Method.isSafeVarargs, etc. -Joe Rémi Forax wrote: > I wonder if encoding @SafeVarargs as a runtime annotation > in the classfile is a good idea. A runtime visible annotation is fat. > > In my opinion, @SafeVarargs should be an annotation with > retention SOURCE, translated by the compiler to an empty SafeVarargs > method attribute. > > Is there a use case where this annotation is needed at runtime ? > > Rémi > >

More information about the coin-dev mailing list