The following code (to be attached) contains two loops, one of which is miscompiled.
The first is an enhanced for loop, the second is the same loop, but manually desugared accorded to the JLS (JLS 3, section 14.14.2 http://java.sun.com/docs/books/jls/third_edition/html/statements.html#14.14.2). The two loops should therefore behave identically. They do not; the first loop [incorrectly] finishes normally, the second loop [correctly] throws a class cast exception. The issue is that according to the JLS, for (String s:u) ... gets desugarred to for (Type i = u.iterator(); i.hasNext(); ) { String s = i.next(); ... } where Type is the type of u.iterator(). However, after erasing generics, the initialisation of the loop variable i potentially requires a cast (after erase, in this case, u.iterator() has compile-time type Iterator, while the variable has type MyIterator). It appears that gcj does not insert the required cast. (Both Sun javac and eclipse get this wrong also, in an identical manner. It is possible that Sun will decide to change the JLS to match the compiler behaviour?) -- Summary: Incorrect code generated for enhanced for loop. Product: gcc Version: 4.4.3 Status: UNCONFIRMED Severity: normal Priority: P3 Component: java AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: suckfish at ihug dot co dot nz GCC host triplet: x86_64-redhat-linux http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42892
