Assigning a pointer to _Bool should give a warning

[sirainen]

Bugzilla Link	9128
Version	trunk
OS	Linux

Extended Description

I'd expect this to give two warnings, but none is given:

_Bool foo(void) {
  _Bool x = (void *)0;
  return (void *)0;
}

Not having this warning already caused a bug in my program, so this makes _Bool type even worse to me than using "int" as the boolean type.

I guess this might be because C99 says:

"When any scalar value is converted to _Bool, the result is 0 if the value compares equal to 0; otherwise, the result is 1."

If -Wall isn't good enough place for this, maybe a new -Wstrict-bool? (Actually I'd prefer such warning to check for other things about booleans too, but that's another thing.)

[llvmbot]

If -Wall isn't good enough place for this, maybe a new -Wstrict-bool?
(Actually I'd prefer such warning to check for other things about booleans
too, but that's another thing.)

What other things would you like checks for? Anything with precedent in other compilers?

[sirainen]

Not in any other C compiler (maybe in lint? not sure). Basically I'd like C's boolean type to work the same as with Java. So comparing boolean to anything else than a boolean would give a warning (so e.g. if (!intnum) or if (!ptr) would have to be written as if (intnum == 0) or if (ptr == NULL) to avoid warnings). Also unsigned int x:1 would be treated as boolean.

[YutongZhuu]

Hi, is there still a need to implement this feature? If yes, I would like to give it a try.