Draft JEP for discussion: Lint and doclint clean sources

[Martijn Verburg]

Hi Joe,

Thanks for the detailed answer - helps when I/we look at these.

Cheers,
Martijn


On 28 May 2014 19:33, Joe Darcy <joe.darcy at oracle.com> wrote:

>  Hi Martijn,
>
> On 05/28/2014 10:19 AM, Martijn Verburg wrote:
>
> Looks good Joe,
>
>  One quick Q:  In your guide you talk about "Avoid introducing source
> incompatibilities<http://cr.openjdk.java.net/%7Edarcy/OpenJdkDevGuide/OpenJdkDevelopersGuide.v0.777.html#source_compatibility>".
>  Is there a possibility that adding Generics in order to fix a linting
> problem would break this guideline?
>
>
> (Basically) not if it is done right :-)
>
> At the API level, the warnings come from raw types. So if the same
> approaches that were used by libraries when they were first generified are
> followed on this remainder, we shouldn't have any more problems than were
> had when the platform was first generified.
>
> A feature of Java's erasure based generics is that libraries can be
> generified before their clients, but there are a few cases were a source
> compatibility can arise. Let's say a method was declared to return a raw
> list:
>
>     List foo() {...}
>
> and a client assigned it it a variable of type List<String>:
>
>     List<String> myStringList = foo();
>
> but in actually foo *really* returns a List<Number>. If the declaration is
> updated accordingly,
>
>     List<Number> foo() {...}
>
> then
>
>     List<String> myStringList = foo();
>
> won't compile any more. However, it is generally preferable for this kind
> of problem to be found at compile time than to suffer a ClassCastException
> at runtime. If the client anticipated the proper generification of foo,
>
>         List<Number> myNumberList = foo();
>
> then it would be fine with the change in foo.
>
> Most of the cases I think still need to be generified are raw Class types.
> These are most often changed to Class<?>, which doesn't impose any type
> constraints and this thus very source compatible.
>
> HTH,
>
> -Joe
>