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Re: [Guile-commits] GNU Guile branch, master, updated. release_1-9-1-18-

From: Andy Wingo
Subject: Re: [Guile-commits] GNU Guile branch, master, updated. release_1-9-1-18-g904a78f
Date: Tue, 04 Aug 2009 18:11:24 +0200
User-agent: Gnus/5.13 (Gnus v5.13) Emacs/23.0.92 (gnu/linux)

Hi Mike,

Another niggle:

On Sat 01 Aug 2009 19:58, Mike Gran <address@hidden> writes:

> On Fri, 2009-07-31 at 01:21 +0200, Ludovic Court├Ęs wrote:
>> "Michael Gran" <address@hidden> writes:
>> > +#define SCM_MAKE_CHAR(x) ({scm_t_int32 _x = (x);                        \
>> > +      _x < 0                                                            \
>> > +        ? SCM_MAKE_ITAG8((scm_t_bits)(unsigned char)_x, scm_tc8_char)   \
>> > +        : SCM_MAKE_ITAG8((scm_t_bits)_x, scm_tc8_char);})
>> This macro uses a GCC extension, which is not acceptable for Guile.  Can
>> you please rewrite it in standard C?  (The only risk is multiple
>> expansion of X, but that's OK.)
> OK.  There was one case of multiple expansion causing side effects, but,
> I fixed that.

Could we not just fix invokers of SCM_MAKE_CHAR() with negative values?
Are there instances of this outside Guile's source tree whose behavior
we need to preserve? That would avoid the multiple expansion problem
neatly, which the future would appreciate.

>> Does X < 0 mean ASCII?  And why is it truncated to 8 bits?  A comment
>> just above indicating the encoding trick would be handy IMO.
> OK.  Wide chars are always positive, but, the upper 128 of signed 8-bit
> C chars are negative, which is the reason for that logic.

I see. How irritating. Well, I guess that's fine, then -- barring a
requirement for SCM_LITERAL_CHAR or something.

>> Style (extraneous braces).
> Noted.  If that's the standard then so be it.   But, for this case, I
> declare, in classic flamewar fashion, that the standard is nonsense.


It is better that we follow the standard, though.



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