[Bug c/92021] New: no warning with -Wlogical-op

[tangyixuan at mail dot dlut.edu.cn]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92021

            Bug ID: 92021
           Summary: no warning with -Wlogical-op
           Product: gcc
           Version: 7.4.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: tangyixuan at mail dot dlut.edu.cn
  Target Milestone: ---

gcc-7.4 falls to emit the warning for the following:

$ cat s.c
  int main(){
    unsigned long a = 8UL;
    if(~a || a){
    }
    return 0;
  }

$ gcc-7.4 -Wlogical-op s.c

Target: x86_64-unknown-linux-gnu
Thread model: posix

When compiled with higher version, warnings such as:

$ gcc-8.3 -Wlogical-op s.c
s.c: In function ‘main’:
s.c:3:8: warning: logical ‘or’ of collectively exhaustive tests is always true
[-Wlogical-op]
  if(~a || a){
           ^~

I do not know whether the GCC-7.4 has been maintained. If hasn't, please tell
me and treat the bug as fixed in the higher version.