Draft JEP: Elide deprecation warnings on import statements

[Jeremy Manson]

Agree with Stephen.  At Google, we've recently made the decision to stop
issuing warnings about these in our internal builds.

Jeremy


On Wed, Feb 5, 2014 at 2:50 PM, Stephen Colebourne <scolebourne at joda.org>wrote:

> This happens in pretty much all large codebases over time and would be
> a welcome change IMO.
> Stephen
>
> On 5 February 2014 20:20, Joe Darcy <joe.darcy at oracle.com> wrote:
> > Hello,
> >
> > Below is the text of a draft JEP we are considering submitting for JDK 9.
> >
> > Cheers,
> >
> > -Joe
> >
> >
> > Summary
> > -------
> >
> > As of Java SE 8, java compilers are required by reasonable
> > interpretations of the Java Language Specification to issue
> > deprecation warnings when a deprecated type is imported by name or
> > when a deprecated member (method, field, nested type) is imported
> > statically. These warnings are uninformative and should not be
> > required. Deprecation warnings at actual uses of deprecated members
> > should remain.
> >
> > Goals
> > -----
> >
> > The goal of this JEP is to facilitate making large code bases clean of
> > lint warnings. The deprecation warnings on imports cannot be
> > suppressed using the @SuppressWarnings annotation, unlike uses of
> > deprecated members in code. In large code bases like that of the JDK,
> > deprecated functionality must often be supported for some time and
> > merely importing a deprecated construct does not justify a warning
> > message if all the uses of the deprecated construct are intentional
> > and suppressed.
> >
> > Non-Goals
> > ---------
> >
> > It is not a goal of this JEP to actually resolve all the deprecation
> > warnings in the JDK code case. However, that might occur as part of a
> > separate maintenance effort in JDK 9.
> >
> > Description
> > -----------
> >
> > From a specification perspective, the needed change is small. In JLS 7
> > (text in JLS 8 will be similar), the section on @Deprecated states:
> >
> > "A Java compiler must produce a deprecation warning when a type,
> > method, field, or constructor whose declaration is annotated with the
> > annotation @Deprecated is used (i.e. overridden, invoked, or
> > referenced by name), unless:
> >
> >     * The use is within an entity that is itself annotated with the
> >       annotation @Deprecated; or
> >
> >     * The use is within an entity that is annotated to suppress the
> >       warning with the annotation @SuppressWarnings("deprecation"); or
> >
> >     * The use and declaration are both within the same outermost class."
> >
> > The specification change would be something like adding another bullet
> > stating the additional exclusion:
> >
> >     * The use is within an import statement.
> >
> > In the javac reference implementation, there would be a simple check
> > to skip over import statements when looking for deprecation warnings.
> >
> > Testing
> > -------
> >
> > Normal unit tests should suffice to test this feature. A handful of
> > JCK tests may need to be updated for the changed specification.
> >
> > Impact
> > ------
> >
> >   - Other JDK components: The change would ease getting and keeping
> >      the JDK code base free of deprecations warnings.
> >   - Compatibility: Since warning will be issued in fewer cases, there is
> > negligible compatibility impact.
> >   - User experience: Fewer uninformative warnings will be issued by the
> > compiler.
> >   - TCK: As noted earlier, a handful of JCK test may need updating.
> >
>
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