Project Leyden: Beginnings

[Anton Kozlov]

On 5/31/22 12:32, Andrew Dinn wrote:
> One has to bear in mind that a closed world as defined by full program analysis (possibly supplemented with user directives to embrace things like reflective targets) can exclude everything that is not marked as reachable during the analysis from its generated image, maybe whole classes in some cases, or maybe just static/instance fields and methods of some classes.

I didn't use this exact definition but meant closed world image as the result
of a whole program analysis under a set of assumptions that are more strict
that the Java language.

For example, user directives is a meta-language describing white areas of the
program that cannot be analyzed by the compiler during the build.  A
meta-language in theory may be able to express a rich set of assumptions about
unknown areas.  E.g. Class.forName, a meta-language probably may express not
exact possible target classes, but assumed properties of those classes, like
the class does not use reflection itself, so cannot access private fields, and
the subsequent checkcast should succeed, so the unknown class won't be able to
access protected fields beyond own class hierarchy.

So a point of the program that is impossible/hard to reason about (e.g. the
reflection) may specify no assumptions except it has minimal interference with
the part that can be analyzed.  E.g. a servlet should not access the internal
details of the servlet container.  Then analyzeable part may probably be
optimized almost as efficiently as a completely analyzeable program.  Java
modules may indeed be useful to separate parts of the program to make the
analysis easier.

Thanks,
Anton