The warning was supposedly removed by https://github.com/qemu/qemu/commit/67953a379ea5 / https://lists.gnu.org/archive/html/qemu-devel/2020-05/msg03980.html
-- You received this bug notification because you are a member of qemu- devel-ml, which is subscribed to QEMU. https://bugs.launchpad.net/bugs/1824616 Title: Build succeeds despite flex/bison missing Status in QEMU: Incomplete Bug description: I just built qemu using a fresh install, and "make" would report success despite messages of "flex: command not found" and "bison: command not found". I didn't notice any errors, but I don't know whether that's because there's a workaround in case the tools aren't there, or because I didn't exercize the code paths that would fail. To manage notifications about this bug go to: https://bugs.launchpad.net/qemu/+bug/1824616/+subscriptions
