Re: Update timezone to C99

Peter Eisentraut <peter(at)eisentraut(dot)org> writes:
> On 12.11.25 19:02, Tom Lane wrote:
>> Hm, I've had "re-sync TZ code with upstream" on my TODO list for
>> several years now. I believe there's been quite a bit of churn
>> upstream since tzcode2020d, some of it oriented towards this same
>> issue of code modernization. Maybe we should try to sync with
>> a newer release while we're at it.

> My idea was to do this C99 adjustment first so that the differences to
> upstream are reduced, which would hopefully simplify updating to that
> newer code.

Fair enough. I looked through the patch briefly and had a couple of
minor quibbles:

@@ -905,7 +906,7 @@ transtime(const int year, const struct rule *const rulep,
for (i = 1; i < rulep->r_week; ++i)
{
if (d + DAYSPERWEEK >=
- mon_lengths[(int) leapyear][rulep->r_mon - 1])
+ mon_lengths[leapyear][rulep->r_mon - 1])
break;
d += DAYSPERWEEK;
}
@@ -915,7 +916,7 @@ transtime(const int year, const struct rule *const rulep,
*/
value = d * SECSPERDAY;
for (i = 0; i < rulep->r_mon - 1; ++i)
- value += mon_lengths[(int) leapyear][i] * SECSPERDAY;
+ value += mon_lengths[leapyear][i] * SECSPERDAY;
break;
}

"leapyear" is bool, and I believe these casts-to-int were put in to
suppress compiler bleats about up-casting that to int. This probably
dates from when we equated bool to char, and maybe it's moot now,
but I'm not sure.

@@ -47,12 +49,15 @@ typedef int64 zic_t;
static ptrdiff_t const PTRDIFF_MAX = MAXVAL(ptrdiff_t, TYPE_BIT(ptrdiff_t));
#endif

-/*
- * The type for line numbers. In Postgres, use %d to format them; upstream
- * uses PRIdMAX but we prefer not to rely on that, not least because it
- * results in platform-dependent strings to be translated.
- */
-typedef int lineno_t;
+/* The minimum alignment of a type, for pre-C11 platforms. */
+#if __STDC_VERSION__ < 201112
+#define _Alignof(type) offsetof(struct { char a; type b; }, b)
+#endif

Since we've dropped pre-C11 support, I wonder why we'd include this
upstream workaround for that.

regards, tom lane