Merge pull request #4 from flightaware/merge-sebres-20

Merge branch 'sebresgh-20--neg-relmonth-offs'

configure.ac

@@ -17,7 +17,7 @@ dnl	to configure the system for the local environment.
 # so you can encode the package version directly into the source files.
 #-----------------------------------------------------------------------
 
-AC_INIT([tclclockmod], [8.6.706])
+AC_INIT([tclclockmod], [8.6.707])
 
 #--------------------------------------------------------------------
 # Call TEA_INIT as the first TEA_ macro to set up initial vars.

generic/tclClock.c

@@ -4144,6 +4144,11 @@ ClockCalcRelTime(
 	    yyMonth += yyRelMonth - 1;
 	    yyYear += yyMonth / 12;
 	    m = yyMonth % 12;
+	    /* compiler fix for negative offs - wrap y, m = (0, -1) -> (-1, 11) */
+	    if (m < 0) {
+		yyYear--;
+		m = 12 + m;
+	    }
 	    yyMonth = m + 1;
 
 	    /* if the day doesn't exist in the current month, repair it */

tests/clock.test

@@ -35308,6 +35308,24 @@ test clock-30.8 {clock add months, negative} {
     set x4 [clock format $f4 -format %Y-%m-%d -timezone :UTC]
     list $x1 $x2 $x3 $x4
 } {2000-02-29 2000-01-31 1999-12-31 1999-11-30}
+test clock-30.8a {clock add months, negative, over threshold of a year} {
+    set t [clock scan 2019-01-31 -format %Y-%m-%d -timezone :UTC]
+    list [clock format [clock add $t -1 month -timezone :UTC] -format %Y-%m-%d -timezone :UTC] \
+	 [clock format [clock add $t -2 month -timezone :UTC] -format %Y-%m-%d -timezone :UTC] \
+	 [clock format [clock add $t -3 month -timezone :UTC] -format %Y-%m-%d -timezone :UTC] \
+	 [clock format [clock add $t -4 month -timezone :UTC] -format %Y-%m-%d -timezone :UTC]
+} {2018-12-31 2018-11-30 2018-10-31 2018-09-30}
+test clock-30.8b {clock add months, negative, over threshold of a year} {
+    set t [clock scan 2000-01-28 -format %Y-%m-%d -timezone :UTC]
+    for {set i 1} {$i < 24} {incr i 1} {
+	set f1 [clock add $t -$i month -timezone :UTC]
+	set f2 [clock add $f1 $i month -timezone :UTC]
+	if {$f2 != $t} {
+	    error "\[clock add $t -$i month -timezone :UTC\] does not consider\
+		   \[clock add $f1 $i month -timezone :UTC\] != $t"
+	}
+    }
+} {}
 test clock-30.9 {clock add days} {
     set t [clock scan {2000-01-01 12:34:56} -format {%Y-%m-%d %H:%M:%S} \
 	       -timezone :UTC]