is ClassLoader.loadClass() supposed to work on module-info classes?

[Remi Forax]

----- Mail original -----
> De: "David M. Lloyd" <david.lloyd at redhat.com>
> À: jigsaw-dev at openjdk.java.net
> Envoyé: Mercredi 2 Décembre 2015 15:52:56
> Objet: Re: is ClassLoader.loadClass() supposed to work on module-info	classes?
> 
> On 12/02/2015 08:46 AM, Remi Forax wrote:
> > ----- Mail original -----
> >> De: "Alan Bateman" <Alan.Bateman at oracle.com>
> >> À: "Stephane Epardaud" <stef at epardaud.fr>, jigsaw-dev at openjdk.java.net
> >> Envoyé: Mercredi 2 Décembre 2015 14:56:00
> >> Objet: Re: is ClassLoader.loadClass() supposed to work on module-info
> >> 	classes?
> >>
> >> On 02/12/2015 11:01, Stephane Epardaud wrote:
> >>> Just tried it and got:
> >>>
> >>> Exception in thread "main" java.lang.ClassFormatError: Illegal class
> >>> name "com.ceylon.java9.Test" in class file module-info
> >>>       at java.lang.ClassLoader.defineClass1(java.base at 9.0/Native Method)
> >>>       at
> >>>       java.lang.ClassLoader.defineClass(java.base at 9.0/ClassLoader.java:854)
> >>>       at
> >>> java.security.SecureClassLoader.defineClass(java.base at 9.0/SecureClassLoader.java:152)
> >>>       at
> >>> java.net.URLClassLoader.defineClass(java.base at 9.0/URLClassLoader.java:462)
> >>>       at
> >>> java.net.URLClassLoader.access$100(java.base at 9.0/URLClassLoader.java:75)
> >>>       at
> >>>       java.net.URLClassLoader$1.run(java.base at 9.0/URLClassLoader.java:370)
> >>>       at
> >>>       java.net.URLClassLoader$1.run(java.base at 9.0/URLClassLoader.java:364)
> >>>       at java.security.AccessController.doPrivileged(java.base at 9.0/Native
> >>> Method)
> >>>       at
> >>> java.net.URLClassLoader.findClass(java.base at 9.0/URLClassLoader.java:363)
> >>>       at
> >>>       java.lang.ClassLoader.loadClass(java.base at 9.0/ClassLoader.java:440)
> >>>       at
> >>>       java.lang.ClassLoader.loadClass(java.base at 9.0/ClassLoader.java:373)
> >>>
> >>> I know it works for package-info.class files, but is it supposed to work
> >>> with module-info.class files too? Or is it just not implemented yet?
> >>>
> >> The this_class should be <internal-name>/module-info but in any case,
> >> this isn't the way to "define" a module to the run-time. Instead modules
> >> are defined in layers, with Layer.create the method to create a Layer.
> >
> > Alan,
> > there are two issues, the first one is should a module-info be accessible
> > at runtime as a Class and the second is that the current binary format for
> > a module-info.class break the invariant that the name of the .class is the
> > same as the name inside of the .class because the name used for a
> > module-info.class is the name of the module.
> >
> > 1) I think module-info should not be reified to a class, defineClass should
> > reject any .class that has a module bit set in the class file format.
> >     If we allow to create a Class from a module-info, a class loader may be
> >     able to load several module-info.class and it will be a real mess
> >     because module-info.class is not qualified in the jar file so the
> >     classloader will return the first seen.
> > 2) In term of backward compatibility, I think i prefer that the
> > module-info.class uses "module-info" as class name and store the name of
> > the module inside an attribute.
> >     An already existing tool that parses the bytecode format may forget to
> >     check the class version and use the module name to do something, if
> >     the name inside the module-info is "module-info", it will be easier to
> >     diagnose because the error will report a failure on "module-info" and
> >     not on a name that can also be a package name.
> 
> If it's not a class, it's pretty bizarre to call it "module-info.class".
>   At this point can we admit we're bending over backwards for principles
> that don't really add up?

We already had this discussion, no ?

It's a ".class" but not a java.lang.reflect.Class, i.e it's a compiled artifact of the Java platform,
and the real question is why the file format of Java the platform is .class and not .btcd (for bytecode). 

> 
> --
> - DML
> 

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