Re: master 37889523278: Add new `swap` macro and use it

[Andreas Schwab]

On Jan 06 2024, Stefan Kangas wrote:

> diff --git a/src/lisp.h b/src/lisp.h
> index f96932ab0c1..a9782868157 100644
> --- a/src/lisp.h
> +++ b/src/lisp.h
> @@ -68,8 +68,13 @@ #define max(a, b) ((a) > (b) ? (a) : (b))
>  #define min(a, b) ((a) < (b) ? (a) : (b))
>  
>  /* Swap values of a and b.  */
> -#define swap(a, b) \
> -  do { typeof (a) __tmp; __tmp = (a); (a) = (b); (b) = __tmp; } while (0);
> +#if _GL_HAVE___TYPEOF__
> +#define swap(type, a, b)                                                     
> \
> +  do { __typeof__ (a) __tmp; __tmp = (a); (a) = (b); (b) = __tmp; } while 
> (0);
> +#else
> +#define swap(type, a, b)                                                     
> \
> +  do { type __tmp; __tmp = (a); (a) = (b); (b) = __tmp; } while (0);
> +#endif

Neither of these definitions are future proof: __tmp as a reserved
identifier might clash with future implementations.  Moreover, the first
argument can easily become out of date without notice.

-- 
Andreas Schwab, schwab@linux-m68k.org
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