Re: Japitools 1.5 support tough design issue

[Stuart Ballard]

On 9/10/05, Andrew John Hughes <address@hidden> wrote:
> Forgive me if this is stating the obvious, but for anyone who doesn't
> know, the third edition of the Java Language Spec. is now on-line
> and includes some information on binary compatibility as regards the 1.5
> additions:
> 
> http://java.sun.com/docs/books/jls/third_edition/html/binaryComp.html

As I read this, it does mostly state the obvious in an awful lot of
words ;) Basically, "as far as binary compatibility is concerned,
ignore the type parameters altogether and treat uses of them as if
they were the constraining type".

> In terms of implementing Classpath, however, I think JAPI may need to go
> beyond this, although I'm not altogether sure whether this is within its
> scope of interest.

Actually 1.5 is forcing japitools to re-evaluate its scope of
interest. In 1.4 using the binary compatibility rules (with a few
additions as noted somewhere on the japitools website) was a pretty
good way to get a meaningful compatibility test. If you were binary
compatible in both directions then in almost all cases you were source
compatible too, even though source compatibility rules have never been
written down, as far as I know, for Java.

For 1.5 this is no longer true and clearly a pure binary-compatibility
test is only of limited use (FWIW, that's effectively what we have now
in the comparisons versus 1.5 since the 1.5 binary compat rules are in
essence identical to the 1.4 rules that japi uses).

I suspect that over time the precise rules that japitools uses to test
for compatibility in the presence of 1.5 extensions will evolve as we
learn more about what situations are really problematic or not. Once
the japi results online start reflecting 1.5 features, I'll be
requesting feedback on whether there's anything being reported as an
error that shouldn't be, or vice versa.

Stuart.
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