On 15.07.2019 16:44, Tamas K Lengyel wrote: > On Mon, Jul 15, 2019 at 8:13 AM Jan Beulich <jbeul...@suse.com> wrote: >> >> On 15.07.2019 15:41, Tamas K Lengyel wrote: >>> On Mon, Jul 15, 2019 at 4:36 AM Jan Beulich <jbeul...@suse.com> wrote: >>>> >>>> With non-empty CONFIG_DOM0_MEM clang5 produces >>>> >>>> dom0_build.c:344:24: error: use of logical '&&' with constant operand >>>> [-Werror,-Wconstant-logical-operand] >>>> if ( !dom0_mem_set && CONFIG_DOM0_MEM[0] ) >>>> ^ ~~~~~~~~~~~~~~~~~~ >>>> dom0_build.c:344:24: note: use '&' for a bitwise operation >>>> if ( !dom0_mem_set && CONFIG_DOM0_MEM[0] ) >>>> ^~ >>>> & >>>> dom0_build.c:344:24: note: remove constant to silence this warning >>>> if ( !dom0_mem_set && CONFIG_DOM0_MEM[0] ) >>>> ~^~~~~~~~~~~~~~~~~~~~~ >>>> 1 error generated. >>>> >>>> Obviously neither of the two suggestions are an option here. Oddly >>>> enough swapping the operands of the && helps, while e.g. casting or >>>> parenthesizing doesn't. Another workable variant looks to be the use of >>>> !! on the constant. >>>> >>>> Signed-off-by: Jan Beulich <jbeul...@suse.com> >>>> --- >>>> I'm open to going the !! or yet some different route. No matter which >>>> one we choose, I'm afraid it is going to remain guesswork what newer >>>> (and future) versions of clang will choke on. >>> >>> Is disabling the check itself not an option? Seems to me to be a more >>> sensible option then hacking around it. >> >> How would you envision to disable the check? It's there for a reason >> after all. > > By passing -Wno-constant-logical-operand to the compiler. It looks > like a check for a non-common situation which evidently Xen uses, so > what's the point of keeping it but hacking around with it with tricks > that are fragile?
Oh, so you meant disabling the compiler warning. That may be an option, but I wouldn't routinely suggest such as often besides unhelpful instances there are also helpful ones. Jan _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
