undefined behavior sanitizer dislikes (1 << 31)

[bhaller]

UndefinedBehaviorSanitizer complains:

kastore.c:654:46: runtime error: left shift of 1 by 31 places cannot be represented in type 'int'

The relevant line:

if (self->file != NULL && (self->flags & OWN_FILE)) {

The relevant define:

#define OWN_FILE (1 << 31)

The 1 here should be unsigned, I guess, or a shift of less than 31 should be used. I didn't realize that this was undefined behavior in C, but apparently it is?

[jeromekelleher]

Huh, thanks @bhaller. Ah, the compiler is right here, 1<<31 is INT32_MAX + 1. Doh. So, this is probably a bug on 32 bit platforms.

[jeromekelleher]

Simple solution is just use 1<<30, no big deal.

[bhaller]

Yeah, it shifts into the sign bit. Probably unsigned should be used for all flag values, since one never really wants to be carrying flags around in signed ints...

[jeromekelleher]

Yeah, that's true.