From 4d341738164df7bab6cc41d38859205eb9e27a12 Mon Sep 17 00:00:00 2001 From: Paul Eggert Date: Sat, 4 Jul 2026 18:27:49 -0700 Subject: [PROPOSED] =?UTF-8?q?Document=20why=20zic.c=20uses=20unary=20?= =?UTF-8?q?=E2=80=98+=E2=80=99?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit * private.h (INT_PROMOTE): New macro. * zic.c (MAX_FIELDS): Use it. --- private.h | 5 +++++ zic.c | 6 +++--- 2 files changed, 8 insertions(+), 3 deletions(-) diff --git a/private.h b/private.h index b0faaeb9..7918082d 100644 --- a/private.h +++ b/private.h @@ -954,6 +954,11 @@ ATTRIBUTE_POSIX2TIME time_t time2posix_z(timezone_t, time_t); #define TYPE_SIGNED(type) (((type) -1) < 0) #define TWOS_COMPLEMENT(type) (TYPE_SIGNED (type) && (! ~ (type) -1)) +/* Yield the value of the arithmetic expression X after integer promotion. + This is safer than a cast, which in general would accept even + pointers and which might trap or yield a value not equal to X. */ +#define INT_PROMOTE(x) (+(x)) + /* Minimum and maximum of two values. Use lower case to avoid naming clashes with standard include files. */ #define max(a, b) ((a) > (b) ? (a) : (b)) diff --git a/zic.c b/zic.c index af2bb80a..a2c2dec8 100644 --- a/zic.c +++ b/zic.c @@ -412,10 +412,10 @@ enum { }; /* The maximum number of fields on any of the above lines. - (The "+"s pacify gcc -Wenum-compare.) */ + (This uses INT_PROMOTE to pacify gcc -Wenum-compare.) */ enum { - MAX_FIELDS = max(max(+RULE_FIELDS, +LINK_FIELDS), - max(+LEAP_FIELDS, +EXPIRES_FIELDS)) + MAX_FIELDS = max(max(INT_PROMOTE(RULE_FIELDS), INT_PROMOTE(LINK_FIELDS)), + max(INT_PROMOTE(LEAP_FIELDS), INT_PROMOTE(EXPIRES_FIELDS))) }; /* -- 2.53.0