Proposed change to zic.c and northamerica

[Olson, Arthur David (NIH/NCI)]

Getting a jump on DST season, here are proposed minor changes to zic.c and
northamerica.
The zic.c changes allow rules containing specifications such as...
	Sun>=25
...to go past the end of a month; this allows simpler descriptions of the
sort of situation that existed in Toronto between 1927 and 1937.
Commentary is added to the northamerica file indicating how things could be
made simpler, but the data is kept as is to allow folks to continue to use
it with pre-2004 versions of zic.
(The motive in making the change to zic is to ensure that zic can handle it
if some jurisdiction adopts a similar scheme in the future.)

				--ado

------- zic.c -------
*** /tmp/geta957	Tue Mar  2 10:54:54 2004
--- /tmp/getb957	Tue Mar  2 10:54:55 2004
***************
*** 1,4 ****
! static char	elsieid[] = "@(#)zic.c	7.115";
  
  #include "private.h"
  #include "locale.h"
--- 1,4 ----
! static char	elsieid[] = "@(#)zic.c	7.116";
  
  #include "private.h"
  #include "locale.h"
***************
*** 2139,2146 ****
  				--i;
  			}
  		if (i < 0 || i >= len_months[isleap(y)][m]) {
! 			error(_("no day in month matches rule"));
! 			(void) exit(EXIT_FAILURE);
  		}
  	}
  	if (dayoff < 0 && !TYPE_SIGNED(time_t))
--- 2139,2146 ----
  				--i;
  			}
  		if (i < 0 || i >= len_months[isleap(y)][m]) {
! 			if (noise)
! 				warning(_("rule goes past start/end of
month--will not work with pre-2004 versions of zic"));
  		}
  	}
  	if (dayoff < 0 && !TYPE_SIGNED(time_t))

------- northamerica -------
*** /tmp/geta975	Tue Mar  2 10:54:55 2004
--- /tmp/getb975	Tue Mar  2 10:54:55 2004
***************
*** 1,4 ****
! # @(#)northamerica	7.67
  # also includes Central America and the Caribbean
  
  # This data is by no means authoritative; if you think you know better,
--- 1,4 ----
! # @(#)northamerica	7.68
  # also includes Central America and the Caribbean
  
  # This data is by no means authoritative; if you think you know better,
***************
*** 989,994 ****
--- 989,1001 ----
  # Shanks says 1923-09-19; assume it's a typo and that "-16" was meant.
  Rule	Toronto	1922	1926	-	Sep	Sun>=15	2:00	0	S
  Rule	Toronto	1924	1927	-	May	Sun>=1	2:00	1:00	D
+ # The 1927-to-1939 rules can be expressed more simply as
+ # Rule	Toronto	1927	1937	-	Sep	Sun>=25	2:00	0
S
+ # Rule	Toronto	1928	1937	-	Apr	Sun>=25	2:00	1:00
D
+ # Rule	Toronto	1938	1940	-	Apr	lastSun	2:00	1:00
D
+ # Rule	Toronto	1938	1939	-	Sep	lastSun	2:00	0
S
+ # The rules below avoid use of Sun>=25
+ # (which pre-2004 versions of zic cannot handle).
  Rule	Toronto	1927	1932	-	Sep	lastSun	2:00	0	S
  Rule	Toronto	1928	1931	-	Apr	lastSun	2:00	1:00	D
  Rule	Toronto	1932	only	-	May	1	2:00	1:00	D