#1240 False positive BC_UNCONFIRMED_CAST with multiple generics

[David Shepherdson]

Steps to reproduce:

1. Expand the attached .tgz file.
2. Edit build.xml and point `findbugs-home` at a FindBugs installation.
3. `ant findbugs`.
4. Produces `findbugs.xml` with one bug reported.

The 'bug' is supposedly an unconfirmed cast on line 5 of Renderer.java. FindBugs claims that value is an Enum, and therefore we can't call a method from Displayable without an implied cast.

However, the generics in the definition of the type param T at the beginning of the class state that T extends Enum<T> & Displayable, and therefore the value passed into the method in question must be both an Enum and a Displayable -- therefore calling the method from Displayable is safe.

By comparison, doing exactly the same thing with FindBugs 1.3.9 does not produce any bug warnings.

Java Versions: reproduced with both 1.7.0_45 and 1.6.0_65
OS: Mac OS X 10.8.5

[William Pugh]

Reproduced as a low priority warning, correct?

[David Shepherdson]

Yes, that's right -- as with [#1242], not a very common scenario, but I felt worth logging given the change in behaviour from 1.3.9.

Thanks William,

David