Unnecessary "throws" declarations tend to cascade. If foo() calls
bar() and bar() falsely declares that it might throw IOException, that
often leads a programmer to declare that foo() might throw IOException
as well. Fixing the bar() throws declaration then reveals that we can
fix the foo() throws declaration too. By the time we reach a fixed
point with cleaning these up, we have removed roughly 320 unnecessary
throws declarations.
In a few cases, this cleanup even lets us remove entire "try
... catch" statements where the only thing being caught was an
exception that we now statically know cannot be thrown. Nice!
In Eclipse project configurations, upgrade any future such shenanigans
from warnings to errors. Now that we've fixed this, we don't want it
coming back again.
There is a potential drawback to this change. Conceivably some public
WALA API entry point might have declared that it could throw some
exception merely to reserve the *option* of throwing that exception in
third-party code that subclasses and overrides the API entry point in
question. I have no idea whether this is a significant concern in
practice, though.
I have *not* upgraded this problem to be treated as an error in the
future. Unfortunately Eclipse uses a single configuration setting for
both unnecessary semicolons and also for empty control-flow statements
like `while (p) ;`. I'm not convinced that it's worth rewriting all
instances of the latter into `while (p) { }`. So this is just going
to stay as a warning for now.
If a method is private, there's no risk that a subclass elsewhere
might be overriding it and depending on dynamic dispatch to choose the
right implementation. So all of these private methods can safely be
declared static without risk of regression in either WALA code or
unseen third-party code.
Removing this dependence allows our Getting Started instructions to still work.
It requires some minor code duplication, but otherwise we'd have to change a
bunch of documentation.
Ben Liblit
Julian Dolby
Julian Dolby
Manu Sridharan
Juergen Graf
Manu Sridharan