Ideally, we wouldn't need to construct the classpath ourselves and instead
reuse the classpath construction code from a compiler (scalac or javac).
However, we need to ensure that we only call the compiler when needed.
Because we need to construct the classpath even when compilation might
not happen, we have to duplicate classpath construction.
Introduce a way to configure incremental compiler itself instead
of underlying Java/Scala compiler.
Specific list of changes in this commit:
* Add a method to `xsbti.compile.Setup` that returns incremental
compiler options as a `java.util.Map<String, String>`. We considered
statis interface instead of a `Map` but based on mailing
list feedback we decided that it's not the best way to go because
static interface is hard to evolve it by adding new options.
* Since passing `java.util.Map<String, String>` not very convenient
we convert it immediately to `sbt.inc.IncOptions`
* Add options argument to various methods/classes that implement
incremental compilation so in the end options reach
`sbt.inc.IncOptions` object
* Add `incOptions` task that allows users to configure incremental
compiler options in their build files. Default implementation of
that tasks returns just `IncOptions.DEFAULT`
* Both system property `xsbt.inc.debug` and `IncOptions.relationsDebug`
trigger debugging of relations now. In the near future, we should
deprecate use of `xsbt.inc.debug`.
Some methods take a lot of arguments and I'm about to add one more
which will make them too long for easy reading.
This change is changes code formatting only. That's done on purpose
to make it easier to review other changes.
Mark Harrah
Grzegorz Kossakowski
Eugene Vigdorchik
Peter Vlugter