Eclipse's automated code clean-up tool did most of the heavy lifting
here: it specifically has a clean-up option for converting functional
interfaces to lambdas. I merely had to revert the automated changes
for a single enumeration class for which it produced invalid results,
and for a few test inputs that apparently aren't set up to be compiled
with Java 8.
Previously FilterIterator was very permissive regarding the type
relationships between the original iterator, the filtered iterator,
and the predicate used to prune the former down to the latter. Now we
enforce those relationships more strictly, including proper use of
covariant ("<? extends T>") and contravariant ("<? super T>")
polymorphic type parameters where appropriate.
This lets us get rid of seven suppressed warnings about generic types
and/or unchecked conversions. It also moves us toward being able to
use modern Java features like lambdas and streams more easily.
E-mail exchanged with Julian Dolby suggests that this is the right
thing to do, and that it should have been done back when we converted
other parts of the build configuration to Java 8.
These are all problems that Eclipse can detect, but that it detects no
instances of right now. Treating these as warnings instead of errors
should help prevent us from slipping backward in the future.
Each of these required careful consideration of what the original
developer *intended* as distinguished from what the developer's code
actually *does*. I believe I got each one right, and WALA's
regression tests agree. A second opinion by a core WALA developer
would be welcome, though.
We already have plenty of examples of Serializable classes with this
field, and the vast majority of those fields have generated IDs rather
than "1L". From this I infer that using proper serialVersionUID
fields is considered appropriate WALA coding style.
One such annotation was unnecessary because the thing it was
suppressing no longer happens. Any future unnecessary warning
suppressions of this kind will now be treated as errors.
The other annotations were unnecessary because the corresponding
warnings have been disabled entirely in the Eclipse projects'
configurations. There seems to be no way to tell Eclipse to treat
these as anything other than "info" diagnostics in the future, so
that's how they will remain.
Julian Dolby
Julian Dolby
Ben Liblit
Manu Sridharan
Manu Sridharan