Re: [PATCH 1/2] gettext API users: correct use of casts for Q_()

From: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Date: Mar 7, 2022, 13:54 UTC
Message-ID: <220307.86wnh5zwe0.gmgdl@evledraar.gmail.com>
In-Reply-To: <a34c37c0-b6fd-9f4f-e990-9869f375937e@github.com>

On Mon, Mar 07 2022, Derrick Stolee wrote:

Show 27 quoted lines

> On 3/7/2022 6:38 AM, Ævar Arnfjörð Bjarmason wrote:
>> Change users of the inline gettext.h Q_() function to cast its
>> argument to "unsigned long" instead of "int" or "unsigned int".
>> 
>> The ngettext() function (which Q_() resolves to) takes an "unsigned
>> long int", and so does our Q_() wrapper for it, see 0c9ea33b90f (i18n:
>> add stub Q_() wrapper for ngettext, 2011-03-09).
>> 
>> In a subsequent commit we'll be making more use of this pattern of:
>> 
>>     func(Q_(..%"PRIuMAX..., (unsigned long)x), (uintmax_t)x);
>> 
>> By making this change we ensure that this case isn't the odd one out
>> in that post-image.
>
>
>>  	if (!res)
>> -		printf(Q_("updated %d path\n",
>> -			  "updated %d paths\n", count), (int)count);
>> +		printf(Q_("updated %"PRIuMAX" path\n",
>> +			  "updated %"PRIuMAX" paths\n", (unsigned long)count),
>> +		       (uintmax_t)count);
>
> Why are we adding more uses of "unsigned long" which is not consistent
> in its size across 64-bit Linux and 64-bit Windows? Specifically, on
> Windows "unsigned long" is _not_ uintmax_t. Shouldn't we be using
> uintmax_t everywhere instead?

Whatever we do with "unsigned long" v.s. "size_t" or "uintmax_t" here we'll need to call the ngettext() function, which takes "unsigned long".

Since you're quoting the part of the commit message that's explaining that I'm not sure if you're meaning this as a suggestion that the explanation should be clearer/more explicit, or just missed that ngettext() isn't ours...

I did wonder if we should just skip the casts here and instead do:
	
	diff --git a/gettext.h b/gettext.h
	index d209911ebb8..095bf6b0e5e 100644
	--- a/gettext.h
	+++ b/gettext.h
	@@ -49,8 +49,10 @@ static inline FORMAT_PRESERVING(1) const char *_(const char *msgid)
	 }
	 
	 static inline FORMAT_PRESERVING(1) FORMAT_PRESERVING(2)
	-const char *Q_(const char *msgid, const char *plu, unsigned long n)
	+const char *Q_(const char *msgid, const char *plu, size_t n)
	 {
	+	if (n > ULONG_MAX)
	+		n = ULONG_MAX;
	 	return ngettext(msgid, plu, n);
	 }

Which I suppose would be more correct than a cast, but the edge case where we'd need that ULONG_MAX is so obscure that I don't think it's worth worrying about it.

I think for this series it probably makes more sense to drop the casts for the "n" argument entirely, what do you think?