Enable warning-free compilation even with -Wextra.

configure

@@ -3976,7 +3976,7 @@ fi
 
 
 if test "$GCC" = yes; then
-	CFLAGS="$CFLAGS -Wall -Wstrict-prototypes"
+	CFLAGS="$CFLAGS -Wall -Wextra -Wstrict-prototypes"
 fi
 
 for ac_func in setenv unsetenv glob mbstowcs setlocale

configure.in

@@ -71,7 +71,7 @@ AC_FUNC_UTIME_NULL
 AC_HEADER_TIME
 
 if test "$GCC" = yes; then
-	CFLAGS="$CFLAGS -Wall -Wstrict-prototypes"
+	CFLAGS="$CFLAGS -Wall -Wextra -Wstrict-prototypes"
 fi
 
 AC_CHECK_FUNCS(setenv unsetenv glob mbstowcs setlocale)

src/calendar.c

@@ -955,7 +955,7 @@ static int DoCalRem(ParsePtr p, int col)
 	return E_EOLN;
     }
     if (trig.typ == SAT_TYPE) {
-	r=DoSatRemind(&trig, &tim, p);
+	r=DoSatRemind(&trig, p);
 	if (r) {
 	    FreeTrig(&trig);
 	    if (r == E_EXPIRED) return OK;

src/dorem.c

@@ -68,7 +68,7 @@ int DoRem(ParsePtr p)
     if (trig.typ == SAT_TYPE) {
 	PurgeEchoLine("%s\n", "#!P: Cannot purge SATISFY-type reminders");
 	PurgeEchoLine("%s\n", CurLine);
-	r=DoSatRemind(&trig, &tim, p);
+	r=DoSatRemind(&trig, p);
 	if (r) {
 	    FreeTrig(&trig);
 	    if (r == E_EXPIRED) return OK;
@@ -1019,7 +1019,7 @@ int ShouldTriggerReminder(Trigger *t, TimeTrig *tim, int jul, int *err)
 /*  Do the "satisfying..." remind calculation.                 */
 /*                                                             */
 /***************************************************************/
-int DoSatRemind(Trigger *trig, TimeTrig *tim, ParsePtr p)
+int DoSatRemind(Trigger *trig, ParsePtr p)
 {
     int iter, jul, r;
     Value v;

src/expr.c

@@ -798,7 +798,7 @@ static int Add(void)
 	v3.type = STR_TYPE;
 	l1 = strlen(v1.v.str);
 	l2 = strlen(v2.v.str);
-	if (MaxStringLen && (l1 + l2 > MaxStringLen)) {
+	if (MaxStringLen && (l1 + l2 > (size_t) MaxStringLen)) {
 	    DestroyValue(v1); DestroyValue(v2);
 	    return E_STRING_TOO_LONG;
 	}

src/main.c

@@ -713,7 +713,7 @@ int DoIf(ParsePtr p)
     int r;
     unsigned syndrome;
 
-    if (NumIfs >= IF_NEST) return E_NESTED_IF;
+    if ((size_t) NumIfs >= IF_NEST) return E_NESTED_IF;
 
     if (ShouldIgnoreLine()) syndrome = IF_TRUE | BEFORE_ELSE;
     else {
@@ -794,7 +794,7 @@ int DoIfTrig(ParsePtr p)
     int jul;
 
 
-    if (NumIfs >= IF_NEST) return E_NESTED_IF;
+    if ((size_t) NumIfs >= IF_NEST) return E_NESTED_IF;
     if (ShouldIgnoreLine()) syndrome = IF_TRUE | BEFORE_ELSE;
     else {
 	if ( (r=ParseRem(p, &trig, &tim, 1)) ) return r;
@@ -1302,6 +1302,7 @@ void UTCToLocal(int utcdate, int utctime, int *locdate, int *loctime)
 
 void SigIntHandler(int d)
 {
+    UNUSED(d);
     signal(SIGINT, SigIntHandler);
     GotSigInt();
     exit(0);

src/protos.h

@@ -9,6 +9,9 @@
 /*                                                             */
 /***************************************************************/
 
+/* Suppress unused variable warnings */
+#define UNUSED(x) (void) x
+
 /* Define a string assignment macro - be careful!!! */
 #define STRSET(x, str) { if (x) free(x); (x) = StrDup(str); }
 
@@ -102,7 +105,7 @@ void DumpVarTable (void);
 void DestroyVars (int all);
 int PreserveVar (char const *name);
 int DoPreserve  (Parser *p);
-int DoSatRemind (Trigger *trig, TimeTrig *tim, ParsePtr p);
+int DoSatRemind (Trigger *trig, ParsePtr p);
 int DoMsgCommand (char const *cmd, char const *msg);
 int ParseNonSpaceChar (ParsePtr p, int *err, int peek);
 unsigned int HashVal (char const *str);

src/queue.c

@@ -179,7 +179,7 @@ void HandleQueuedReminders(void)
 	while (TimeToSleep > 0L) {
 	    SleepTime = TimeToSleep;
 
-	    if (Daemon > 0 && SleepTime > 60*Daemon) SleepTime = 60*Daemon;
+	    if (Daemon > 0 && SleepTime > (unsigned int) 60*Daemon) SleepTime = 60*Daemon;
 
 	    /* Wake up once a minute to recalibrate sleep time in
 	       case of laptop hibernation */

src/rem2ps.c

@@ -62,7 +62,7 @@ char const *SmallCalLoc[] = {
     "sbt",
 };
 
-#define NUMSMALL (sizeof(SmallCalLoc)/sizeof(SmallCalLoc[0]))
+#define NUMSMALL ((int) (sizeof(SmallCalLoc)/sizeof(SmallCalLoc[0])))
 char const *SmallLocation;
 int SmallCol1, SmallCol2;
 
@@ -669,7 +669,8 @@ void Init(int argc, char *argv[])
     char const *s;
     char const *t;
     int i=1;
-    int j;
+    size_t j;
+    int k;
     int offset;
 
     PortraitMode = 1;
@@ -798,13 +799,13 @@ void Init(int argc, char *argv[])
 
 	case 'i': UseISO = 1; break;
 
-	case 'c': j=(*s);
-	    if (!j) {
+	case 'c': k=(*s);
+	    if (!k) {
 		SmallLocation = SmallCalLoc[0];
 	    } else {
-		j -= '0';
-		if (j>=0 && j<NUMSMALL) {
-		    SmallLocation = SmallCalLoc[j];
+		k -= '0';
+		if (k>=0 && k<NUMSMALL) {
+		    SmallLocation = SmallCalLoc[k];
 		} else {
 		    SmallLocation = SmallCalLoc[0];
 		}

src/var.c

@@ -37,6 +37,7 @@ typedef int (*SysVarFunc)(int, Value *);
 
 static int trig_date_func(int do_set, Value *val)
 {
+    UNUSED(do_set);
     val->type = DATE_TYPE;
     if (!LastTrigValid) {
 	val->v.val = 0;
@@ -48,6 +49,7 @@ static int trig_date_func(int do_set, Value *val)
 static int trig_day_func(int do_set, Value *val)
 {
     int y, m, d;
+    UNUSED(do_set);
     val->type = INT_TYPE;
     if (!LastTrigValid) {
 	val->v.val = -1;
@@ -62,6 +64,7 @@ static int trig_day_func(int do_set, Value *val)
 static int trig_mon_func(int do_set, Value *val)
 {
     int y, m, d;
+    UNUSED(do_set);
     val->type = INT_TYPE;
     if (!LastTrigValid) {
 	val->v.val = -1;
@@ -76,6 +79,7 @@ static int trig_mon_func(int do_set, Value *val)
 static int trig_year_func(int do_set, Value *val)
 {
     int y, m, d;
+    UNUSED(do_set);
     val->type = INT_TYPE;
     if (!LastTrigValid) {
 	val->v.val = -1;
@@ -90,6 +94,7 @@ static int trig_year_func(int do_set, Value *val)
 static int trig_wday_func(int do_set, Value *val)
 {
     val->type = INT_TYPE;
+    UNUSED(do_set);
     if (!LastTrigValid) {
 	val->v.val = -1;
 	return OK;
@@ -101,6 +106,7 @@ static int trig_wday_func(int do_set, Value *val)
 
 static int today_date_func(int do_set, Value *val)
 {
+    UNUSED(do_set);
     val->type = DATE_TYPE;
     val->v.val = JulianToday;
     return OK;
@@ -108,6 +114,7 @@ static int today_date_func(int do_set, Value *val)
 static int today_day_func(int do_set, Value *val)
 {
     int y, m, d;
+    UNUSED(do_set);
     val->type = INT_TYPE;
     FromJulian(JulianToday, &y, &m, &d);
     val->v.val = d;
@@ -117,6 +124,7 @@ static int today_day_func(int do_set, Value *val)
 static int today_mon_func(int do_set, Value *val)
 {
     int y, m, d;
+    UNUSED(do_set);
     val->type = INT_TYPE;
     FromJulian(JulianToday, &y, &m, &d);
     val->v.val = m+1;
@@ -126,6 +134,7 @@ static int today_mon_func(int do_set, Value *val)
 static int today_year_func(int do_set, Value *val)
 {
     int y, m, d;
+    UNUSED(do_set);
     val->type = INT_TYPE;
     FromJulian(JulianToday, &y, &m, &d);
     val->v.val = y;
@@ -134,6 +143,7 @@ static int today_year_func(int do_set, Value *val)
 
 static int today_wday_func(int do_set, Value *val)
 {
+    UNUSED(do_set);
     val->type = INT_TYPE;
     val->v.val = (JulianToday + 1) % 7;
     return OK;
@@ -748,7 +758,7 @@ static SysVar *FindSysVar(char const *name)
 /***************************************************************/
 void DumpSysVarByName(char const *name)
 {
-    int i;
+    size_t i;
     SysVar *v;
 
     if (!name || !*name) {