module-info platform dependencies

[Jonathan Gibbons]

On May 14, 2009, at 9:20 PM, Mark Reinhold wrote:

>> Date: Thu, 14 May 2009 13:50:44 -0700
>> From: jonathan.gibbons at sun.com
>
>> Could you (briefly) outline your current ideas regarding platform
>> specification in the module-info file. You alluded to some ideas  
>> when I
>> saw you in your office earlier this week.  If you have a tangible
>> proposal, I'll see what I can do to accomodate it in javac.
>
> Sure.
>
> The basic idea is that the compiler can ask Jigsaw whether a  
> particular
> dependence is upon a known, available platform or profile module,  
> and it
> can also ask what the default is.  If a module-info file declares at
> least one dependence upon a platform module then the compiler does
> nothing.  If it does not declare such a dependence then the compiler
> inserts a dependence upon the default.
>
> The org.openjdk.jigsaw.Platform class already contains a method to  
> tell
> whether a module name is that of a platform module; it would be  
> trivial
> to add another to return a module-id query for the default.  (The  
> present
> addPlatformDependenceDefault method isn't really suitable; it assumes
> that ModuleInfo objects are mutable, which they shouldn't be but are
> temporarily so that the current configuration-time defaulting  
> mechanism
> can work.)
>
> So from the compiler's point of view the API would be something like:
>
>    public class org.openjdk.jigsaw.Platform {
>        boolean isPlatformModuleName(String mn);
>        ModuleIdQuery defaultPlatformModule();
>    }
>
> There is a latent security issue here -- we need to ensure that  
> platform
> modules really are, well, platform modules.  That's a problem for the
> runtime code, however, not the compiler.
>
> - Mark


Thanks.  There is something of a problem for the compiler as well as the
runtime, in that the compiler has expectations of the platform that  
must be
satisfied. It must have a java.lang package (otherwise an immediate  
fatal error
occurs) and within java.lang, there must be Striing, Object, and other  
obvious
basis classes, all with the right signatures.

-- Jon