On Tue, Sep 27, 2016 at 10:28 AM, Bernd Edlinger <bernd.edlin...@hotmail.de> wrote: > On 09/27/16 16:10, Florian Weimer wrote: >> * Bernd Edlinger: >> >>>> “0 << 0” is used in a similar context, to create a zero constant for a >>>> multi-bit subfield of an integer. >>>> >>>> This example comes from GDB, in bfd/elf64-alpha.c: >>>> >>>> | insn = INSN_ADDQ | (16 << 21) | (0 << 16) | (0 << 0); >>>> >>> >>> Of course that is not a boolean context, and will not get a warning. >>> >>> Question is if "if (1 << 0)" is possibly a miss-spelled "if (1 < 0)". >>> >>> Maybe 1 and 0 come from macro expansion.... >> >> But what's the intent of treating 1 << 0 and 0 << 0 differently in the >> patch, then? > > I am not sure if it was a good idea. > > I saw, we had code of the form > bool flag = 1 << 2; > > another value LOOKUP_PROTECT is 1 << 0, and > bool flag = 1 << 0; > > would at least not overflow the allowed value range of a boolean.
Assigning a bit mask to a bool variable is still probably not what was intended, even if it doesn't change the value. Jason
