the test case attached in comment 5 builds in edgy in feisty (flex was built using gcc-4.1 in these distributions).
** Changed in: gcc-4.0 (Ubuntu) Status: Needs Info => Fix Released -- gcc-4 breaks compile of flex 2.5.31 https://launchpad.net/bugs/36993 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs