Re: [PATCH] Skip initial expansion of valid array reference tokens in unset

[Koichi Murase]

2021年4月20日(火) 9:14 konsolebox <konsolebox@gmail.com>:
> On Tue, Apr 20, 2021 at 2:08 AM Koichi Murase <myoga.murase@gmail.com> wrote:
> > AFAIK `1 << 31' causes undefined behavior when int is 32-bit signed
> > integer.  Instead, I think you may write `(int)(1u << 31)' for
> > conforming C compilers. `u << 31' is defined for unsigned integers,
> > and the conversion between signed and unsigned integers is defined to
> > be made by mod 2^{32} (when int is 32 bits).
>
> Not sure how this should be done right so I decided to just change
> 'flags' to unsigned int.
>
> -  int flags;           /* Flags associated with this word. */
> +  unsigned int flags;          /* Flags associated with this word. */

Yeah, right.  I haven't checked the type of `flags'.  We also need to
make it unsigned if we want to use bit 31.

In addition, you need to change `1 << 31' to `1u << 31'.  The literal
`1' has the type `(signed) int'.  One needs to use `1u'---the literal
of the type `unsigned int'.

--
Koichi