Fix C23-related conformance bug

Problem reported by Houge Langley for ‘gcc -std=gnu99’ in:
https://bugs.gentoo.org/show_bug.cgi?id=883719
* NEWS: Mention this.
* date.c, localtime.c, private.h, zdump.c, zic.c:
Use ATTRIBUTE_* at the start of function declarations,
not later (such as after the keyword ‘static’).
This is required for strict conformance to C23.

NEWS

@@ -4,6 +4,7 @@ Unreleased, experimental changes
 
   Briefly:
     tzcode no longer supports C89 unless built with -DSUPPORT_C89
+    Fix use of C23 attributes.
 
   Changes to code
 
@@ -12,6 +13,11 @@ Unreleased, experimental changes
     that is planned to be removed in a near-future version, when C99
     or later will be required.
 
+    On C23-compatible platforms tzcode no longer uses syntax like
+    'static [[noreturn]] void usage(void);'.  Instead, it uses
+    '[[noreturn]] static void usage(void);' as strict C23 requires.
+    (Problem reported by Houge Langley.)
+
 
 Release 2022g - 2022-11-29 08:58:31 -0800
 

date.c

@@ -42,7 +42,7 @@ static void		display(const char *, time_t);
 static void		dogmt(void);
 static void		errensure(void);
 static void		timeout(FILE *, const char *, const struct tm *);
-static ATTRIBUTE_NORETURN void usage(void);
+ATTRIBUTE_NORETURN static void usage(void);
 
 int
 main(const int argc, char *argv[])

localtime.c

@@ -843,7 +843,7 @@ is_digit(char c)
 ** Return a pointer to that character.
 */
 
-static ATTRIBUTE_REPRODUCIBLE const char *
+ATTRIBUTE_REPRODUCIBLE static const char *
 getzname(register const char *strp)
 {
 	register char	c;
@@ -864,7 +864,7 @@ getzname(register const char *strp)
 ** We don't do any checking here; checking is done later in common-case code.
 */
 
-static ATTRIBUTE_REPRODUCIBLE const char *
+ATTRIBUTE_REPRODUCIBLE static const char *
 getqzname(register const char *strp, const int delim)
 {
 	register int	c;

private.h

@@ -646,7 +646,7 @@ DEPRECATED_IN_C23 char *asctime(struct tm const *);
 char *asctime_r(struct tm const *restrict, char *restrict);
 DEPRECATED_IN_C23 char *ctime(time_t const *);
 char *ctime_r(time_t const *, char *);
-double difftime(time_t, time_t) ATTRIBUTE_UNSEQUENCED;
+ATTRIBUTE_UNSEQUENCED double difftime(time_t, time_t);
 size_t strftime(char *restrict, size_t, char const *restrict,
 		struct tm const *restrict);
 # if HAVE_STRFTIME_L
@@ -765,10 +765,10 @@ timezone_t tzalloc(char const *);
 void tzfree(timezone_t);
 # if STD_INSPIRED
 #  if TZ_TIME_T || !defined posix2time_z
-time_t posix2time_z(timezone_t, time_t) ATTRIBUTE_REPRODUCIBLE;
+ATTRIBUTE_REPRODUCIBLE time_t posix2time_z(timezone_t, time_t);
 #  endif
 #  if TZ_TIME_T || !defined time2posix_z
-time_t time2posix_z(timezone_t, time_t) ATTRIBUTE_REPRODUCIBLE;
+ATTRIBUTE_REPRODUCIBLE time_t time2posix_z(timezone_t, time_t);
 #  endif
 # endif
 #endif

zdump.c

@@ -89,7 +89,7 @@ static bool	warned;
 static bool	errout;
 
 static char const *abbr(struct tm const *);
-static intmax_t	delta(struct tm *, struct tm *) ATTRIBUTE_REPRODUCIBLE;
+ATTRIBUTE_REPRODUCIBLE static intmax_t delta(struct tm *, struct tm *);
 static void dumptime(struct tm const *);
 static time_t hunt(timezone_t, time_t, time_t, bool);
 static void show(timezone_t, char *, time_t, bool);
@@ -97,7 +97,7 @@ static void showextrema(timezone_t, char *, time_t, struct tm *, time_t);
 static void showtrans(char const *, struct tm const *, time_t, char const *,
 		      char const *);
 static const char *tformat(void);
-static time_t yeartot(intmax_t) ATTRIBUTE_REPRODUCIBLE;
+ATTRIBUTE_REPRODUCIBLE static time_t yeartot(intmax_t);
 
 /* Is C an ASCII digit?  */
 static bool
@@ -125,7 +125,7 @@ is_alpha(char a)
 	}
 }
 
-static ATTRIBUTE_NORETURN void
+ATTRIBUTE_NORETURN static void
 size_overflow(void)
 {
   fprintf(stderr, _("%s: size overflow\n"), progname);
@@ -134,7 +134,7 @@ size_overflow(void)
 
 /* Return A + B, exiting if the result would overflow either ptrdiff_t
    or size_t.  */
-static ATTRIBUTE_REPRODUCIBLE ptrdiff_t
+ATTRIBUTE_REPRODUCIBLE static ptrdiff_t
 sumsize(size_t a, size_t b)
 {
 #ifdef ckd_add
@@ -151,7 +151,7 @@ sumsize(size_t a, size_t b)
 
 /* Return a pointer to a newly allocated buffer of size SIZE, exiting
    on failure.  SIZE should be nonzero.  */
-static void * ATTRIBUTE_MALLOC
+ATTRIBUTE_MALLOC static void *
 xmalloc(size_t size)
 {
   void *p = malloc(size);
@@ -916,7 +916,7 @@ showextrema(timezone_t tz, char *zone, time_t lo, struct tm *lotmp, time_t hi)
 # include <stdarg.h>
 
 /* A substitute for snprintf that is good enough for zdump.  */
-static int ATTRIBUTE_FORMAT((printf, 3, 4))
+ATTRIBUTE_FORMAT((printf, 3, 4)) static int
 my_snprintf(char *s, size_t size, char const *format, ...)
 {
   int n;

zic.c

@@ -459,20 +459,20 @@ static char		roll[TZ_MAX_LEAPS];
 ** Memory allocation.
 */
 
-static ATTRIBUTE_NORETURN void
+ATTRIBUTE_NORETURN static void
 memory_exhausted(const char *msg)
 {
 	fprintf(stderr, _("%s: Memory exhausted: %s\n"), progname, msg);
 	exit(EXIT_FAILURE);
 }
 
-static ATTRIBUTE_NORETURN void
+ATTRIBUTE_NORETURN static void
 size_overflow(void)
 {
   memory_exhausted(_("size overflow"));
 }
 
-static ATTRIBUTE_REPRODUCIBLE ptrdiff_t
+ATTRIBUTE_REPRODUCIBLE static ptrdiff_t
 size_sum(size_t a, size_t b)
 {
 #ifdef ckd_add
@@ -487,7 +487,7 @@ size_sum(size_t a, size_t b)
   size_overflow();
 }
 
-static ATTRIBUTE_REPRODUCIBLE ptrdiff_t
+ATTRIBUTE_REPRODUCIBLE static ptrdiff_t
 size_product(ptrdiff_t nitems, ptrdiff_t itemsize)
 {
 #ifdef ckd_mul
@@ -502,7 +502,7 @@ size_product(ptrdiff_t nitems, ptrdiff_t itemsize)
   size_overflow();
 }
 
-static ATTRIBUTE_REPRODUCIBLE ptrdiff_t
+ATTRIBUTE_REPRODUCIBLE static ptrdiff_t
 align_to(ptrdiff_t size, ptrdiff_t alignment)
 {
   ptrdiff_t lo_bits = alignment - 1, sum = size_sum(size, lo_bits);
@@ -526,7 +526,7 @@ memcheck(void *ptr)
 	return ptr;
 }
 
-static void * ATTRIBUTE_MALLOC
+ATTRIBUTE_MALLOC static void *
 emalloc(size_t size)
 {
   return memcheck(malloc(size));
@@ -538,7 +538,7 @@ erealloc(void *ptr, size_t size)
   return memcheck(realloc(ptr, size));
 }
 
-static char * ATTRIBUTE_MALLOC
+ATTRIBUTE_MALLOC static char *
 estrdup(char const *str)
 {
   return memcheck(strdup(str));
@@ -608,7 +608,7 @@ eat(int fnum, lineno num)
 	eats(fnum, num, 0, -1);
 }
 
-static void ATTRIBUTE_FORMAT((printf, 1, 0))
+ATTRIBUTE_FORMAT((printf, 1, 0)) static void
 verror(const char *const string, va_list args)
 {
 	/*
@@ -626,7 +626,7 @@ verror(const char *const string, va_list args)
 	fprintf(stderr, "\n");
 }
 
-static void ATTRIBUTE_FORMAT((printf, 1, 2))
+ATTRIBUTE_FORMAT((printf, 1, 2)) static void
 error(const char *const string, ...)
 {
 	va_list args;
@@ -636,7 +636,7 @@ error(const char *const string, ...)
 	errors = true;
 }
 
-static void ATTRIBUTE_FORMAT((printf, 1, 2))
+ATTRIBUTE_FORMAT((printf, 1, 2)) static void
 warning(const char *const string, ...)
 {
 	va_list args;
@@ -666,7 +666,7 @@ close_file(FILE *stream, char const *dir, char const *name,
   }
 }
 
-static ATTRIBUTE_NORETURN void
+ATTRIBUTE_NORETURN static void
 usage(FILE *stream, int status)
 {
   fprintf(stream,
@@ -3597,7 +3597,7 @@ lowerit(char a)
 }
 
 /* case-insensitive equality */
-static ATTRIBUTE_REPRODUCIBLE bool
+ATTRIBUTE_REPRODUCIBLE static bool
 ciequal(register const char *ap, register const char *bp)
 {
 	while (lowerit(*ap) == lowerit(*bp++))
@@ -3606,7 +3606,7 @@ ciequal(register const char *ap, register const char *bp)
 	return false;
 }
 
-static ATTRIBUTE_REPRODUCIBLE bool
+ATTRIBUTE_REPRODUCIBLE static bool
 itsabbr(register const char *abbr, register const char *word)
 {
 	if (lowerit(*abbr) != lowerit(*word))
@@ -3622,7 +3622,7 @@ itsabbr(register const char *abbr, register const char *word)
 
 /* Return true if ABBR is an initial prefix of WORD, ignoring ASCII case.  */
 
-static ATTRIBUTE_REPRODUCIBLE bool
+ATTRIBUTE_REPRODUCIBLE static bool
 ciprefix(char const *abbr, char const *word)
 {
   do
@@ -3725,14 +3725,14 @@ getfields(char *cp, char **array, int arrayelts)
 	return nsubs;
 }
 
-static ATTRIBUTE_NORETURN void
+ATTRIBUTE_NORETURN static void
 time_overflow(void)
 {
   error(_("time overflow"));
   exit(EXIT_FAILURE);
 }
 
-static ATTRIBUTE_REPRODUCIBLE zic_t
+ATTRIBUTE_REPRODUCIBLE static zic_t
 oadd(zic_t t1, zic_t t2)
 {
 #ifdef ckd_add
@@ -3746,7 +3746,7 @@ oadd(zic_t t1, zic_t t2)
   time_overflow();
 }
 
-static ATTRIBUTE_REPRODUCIBLE zic_t
+ATTRIBUTE_REPRODUCIBLE static zic_t
 tadd(zic_t t1, zic_t t2)
 {
 #ifdef ckd_add