build: add -Wimplicit-fallthrough

Also:
- replace all /* fallthrough */ comments with portable fallthrough;
pseudo keyword to accomodate both gcc and clang
- add missing break; statements as required by older versions of gcc
- cleanup some code to remove unnecessary fallthrough

Signed-off-by: Igor Ryzhov <iryzhov@nfware.com>

14 files changed, 57 insertions, 52 deletions

diff --git a/lib/base64.c b/lib/base64.c
index 1507b0252..ee2e838c0 100644
--- a/lib/base64.c
+++ b/lib/base64.c
@@ -9,6 +9,7 @@
 #endif
 
 #include "base64.h"
+#include "compiler.h"
 
 static const int CHARS_PER_LINE = 72;
 static const char *ENCODING =
@@ -41,6 +42,7 @@ int base64_encode_block(const char *plaintext_in, int length_in, char *code_out,
 
 	switch (state_in->step) {
 		while (1) {
+			fallthrough;
 			case step_A:
 				if (plainchar == plaintextend) {
 					state_in->result = result;
@@ -51,7 +53,7 @@ int base64_encode_block(const char *plaintext_in, int length_in, char *code_out,
 				result = (fragment & 0x0fc) >> 2;
 				*codechar++ = base64_encode_value(result);
 				result = (fragment & 0x003) << 4;
-				/* fall through */
+				fallthrough;
 			case step_B:
 				if (plainchar == plaintextend) {
 					state_in->result = result;
@@ -62,7 +64,7 @@ int base64_encode_block(const char *plaintext_in, int length_in, char *code_out,
 				result |= (fragment & 0x0f0) >> 4;
 				*codechar++ = base64_encode_value(result);
 				result = (fragment & 0x00f) << 2;
-				/* fall through */
+				fallthrough;
 			case step_C:
 				if (plainchar == plaintextend) {
 					state_in->result = result;
@@ -146,6 +148,7 @@ int base64_decode_block(const char *code_in, int length_in, char *plaintext_out,
 
 	switch (state_in->step) {
 		while (1) {
+			fallthrough;
 			case step_a:
 				do {
 					if (codec == code_in+length_in) {
@@ -156,7 +159,7 @@ int base64_decode_block(const char *code_in, int length_in, char *plaintext_out,
 					fragmt = base64_decode_value(*codec++);
 				} while (fragmt < 0);
 				*plainc = (fragmt & 0x03f) << 2;
-				/* fall through */
+				fallthrough;
 			case step_b:
 				do {
 					if (codec == code_in+length_in) {
@@ -168,7 +171,7 @@ int base64_decode_block(const char *code_in, int length_in, char *plaintext_out,
 				} while (fragmt < 0);
 				*plainc++ |= (fragmt & 0x030) >> 4;
 				*plainc = (fragmt & 0x00f) << 4;
-				/* fall through */
+				fallthrough;
 			case step_c:
 				do {
 					if (codec == code_in+length_in) {
@@ -180,7 +183,7 @@ int base64_decode_block(const char *code_in, int length_in, char *plaintext_out,
 				} while (fragmt < 0);
 				*plainc++ |= (fragmt & 0x03c) >> 2;
 				*plainc = (fragmt & 0x003) << 6;
-				/* fall through */
+				fallthrough;
 			case step_d:
 				do {
 					if (codec == code_in+length_in) {
diff --git a/lib/command_match.c b/lib/command_match.c
index f740b7260..97e6aeb46 100644
--- a/lib/command_match.c
+++ b/lib/command_match.c
@@ -405,10 +405,10 @@ enum matcher_rv command_complete(struct graph *graph, vector vline,
 				listnode_add(next, newstack);
 				break;
 			case partly_match:
-				trace_matcher("trivial_match\n");
+				trace_matcher("partly_match\n");
 				if (exact_match_exists && !last_token)
 					break;
-			/* fallthru */
+				fallthrough;
 			case exact_match:
 				trace_matcher("exact_match\n");
 				if (last_token) {
diff --git a/lib/compiler.h b/lib/compiler.h
index ce6727685..0a54c02d2 100644
--- a/lib/compiler.h
+++ b/lib/compiler.h
@@ -33,7 +33,7 @@ extern "C" {
 #  define _RET_NONNULL    , returns_nonnull
 #endif
 #if __has_attribute(fallthrough)
-#  define _FALLTHROUGH __attribute__((fallthrough));
+#  define fallthrough __attribute__((fallthrough));
 #endif
 # define _CONSTRUCTOR(x)  constructor(x)
 # define _DEPRECATED(x) deprecated(x)
@@ -57,7 +57,7 @@ extern "C" {
 #  define __has_attribute(x) 0
 #endif
 #if __GNUC__ >= 7
-#  define _FALLTHROUGH __attribute__((fallthrough));
+#  define fallthrough __attribute__((fallthrough));
 #endif
 #endif
 
@@ -112,8 +112,8 @@ extern "C" {
 #ifndef _ALLOC_SIZE
 # define _ALLOC_SIZE(x)
 #endif
-#ifndef _FALLTHROUGH
-#define _FALLTHROUGH
+#ifndef fallthrough
+#define fallthrough
 #endif
 #ifndef _DEPRECATED
 #define _DEPRECATED(x) deprecated
diff --git a/lib/jhash.c b/lib/jhash.c
index 0d561ef3a..4e02112e0 100644
--- a/lib/jhash.c
+++ b/lib/jhash.c
@@ -86,34 +86,34 @@ uint32_t jhash(const void *key, uint32_t length, uint32_t initval)
 	switch (len) {
 	case 11:
 		c += ((uint32_t)k[10] << 24);
-	/* fallthru */
+		fallthrough;
 	case 10:
 		c += ((uint32_t)k[9] << 16);
-	/* fallthru */
+		fallthrough;
 	case 9:
 		c += ((uint32_t)k[8] << 8);
-	/* fallthru */
+		fallthrough;
 	case 8:
 		b += ((uint32_t)k[7] << 24);
-	/* fallthru */
+		fallthrough;
 	case 7:
 		b += ((uint32_t)k[6] << 16);
-	/* fallthru */
+		fallthrough;
 	case 6:
 		b += ((uint32_t)k[5] << 8);
-	/* fallthru */
+		fallthrough;
 	case 5:
 		b += k[4];
-	/* fallthru */
+		fallthrough;
 	case 4:
 		a += ((uint32_t)k[3] << 24);
-	/* fallthru */
+		fallthrough;
 	case 3:
 		a += ((uint32_t)k[2] << 16);
-	/* fallthru */
+		fallthrough;
 	case 2:
 		a += ((uint32_t)k[1] << 8);
-	/* fallthru */
+		fallthrough;
 	case 1:
 		a += k[0];
 	}
@@ -148,7 +148,7 @@ uint32_t jhash2(const uint32_t *k, uint32_t length, uint32_t initval)
 	switch (len) {
 	case 2:
 		b += k[1];
-	/* fallthru */
+		fallthrough;
 	case 1:
 		a += k[0];
 	}
diff --git a/lib/libfrr.c b/lib/libfrr.c
index 33237df5f..e80355f3b 100644
--- a/lib/libfrr.c
+++ b/lib/libfrr.c
@@ -218,7 +218,8 @@ bool frr_zclient_addr(struct sockaddr_storage *sa, socklen_t *sa_len,
 			break;
 		case '6':
 			path++;
-		/* fallthrough */
+			af = AF_INET6;
+			break;
 		default:
 			af = AF_INET6;
 			break;
diff --git a/lib/nexthop.c b/lib/nexthop.c
index 8df57e36a..4ddb53cd9 100644
--- a/lib/nexthop.c
+++ b/lib/nexthop.c
@@ -173,7 +173,7 @@ static int _nexthop_cmp_no_labels(const struct nexthop *next1,
 		ret = _nexthop_gateway_cmp(next1, next2);
 		if (ret != 0)
 			return ret;
-		/* Intentional Fall-Through */
+		fallthrough;
 	case NEXTHOP_TYPE_IFINDEX:
 		if (next1->ifindex < next2->ifindex)
 			return -1;
@@ -295,7 +295,7 @@ int nexthop_cmp_basic(const struct nexthop *nh1,
 		ret = nexthop_g_addr_cmp(nh1->type, &nh1->gate, &nh2->gate);
 		if (ret != 0)
 			return ret;
-		/* Intentional Fall-Through */
+		fallthrough;
 	case NEXTHOP_TYPE_IFINDEX:
 		if (nh1->ifindex < nh2->ifindex)
 			return -1;
diff --git a/lib/nexthop_group.c b/lib/nexthop_group.c
index 25370eba4..c75ff7b4c 100644
--- a/lib/nexthop_group.c
+++ b/lib/nexthop_group.c
@@ -180,7 +180,7 @@ static struct nexthop *nhg_nh_find(const struct nexthop_group *nhg,
 						 &nexthop->gate, &nh->gate);
 			if (ret != 0)
 				continue;
-			/* Intentional Fall-Through */
+			fallthrough;
 		case NEXTHOP_TYPE_IFINDEX:
 			if (nexthop->ifindex != nh->ifindex)
 				continue;
diff --git a/lib/printf/printf-pos.c b/lib/printf/printf-pos.c
index ac775bea4..b2ba1a714 100644
--- a/lib/printf/printf-pos.c
+++ b/lib/printf/printf-pos.c
@@ -355,7 +355,7 @@ reswitch:	switch (ch) {
 			goto rflag;
 		case 'C':
 			flags |= LONGINT;
-			/*FALLTHROUGH*/
+			fallthrough;
 		case 'c':
 			error = addtype(&types,
 					(flags & LONGINT) ? T_WINT : T_INT);
@@ -364,7 +364,7 @@ reswitch:	switch (ch) {
 			break;
 		case 'D':
 			flags |= LONGINT;
-			/*FALLTHROUGH*/
+			fallthrough;
 		case 'd':
 		case 'i':
 			if ((error = addsarg(&types, flags)))
@@ -408,7 +408,7 @@ reswitch:	switch (ch) {
 #endif
 		case 'O':
 			flags |= LONGINT;
-			/*FALLTHROUGH*/
+			fallthrough;
 		case 'o':
 			if ((error = adduarg(&types, flags)))
 				goto error;
@@ -419,7 +419,7 @@ reswitch:	switch (ch) {
 			break;
 		case 'S':
 			flags |= LONGINT;
-			/*FALLTHROUGH*/
+			fallthrough;
 		case 's':
 			error = addtype(&types,
 					(flags & LONGINT) ? TP_WCHAR : TP_CHAR);
@@ -428,7 +428,7 @@ reswitch:	switch (ch) {
 			break;
 		case 'U':
 			flags |= LONGINT;
-			/*FALLTHROUGH*/
+			fallthrough;
 		case 'u':
 		case 'X':
 		case 'x':
@@ -549,7 +549,7 @@ reswitch:	switch (ch) {
 			goto rflag;
 		case 'C':
 			flags |= LONGINT;
-			/*FALLTHROUGH*/
+			fallthrough;
 		case 'c':
 			error = addtype(&types,
 					(flags & LONGINT) ? T_WINT : T_INT);
@@ -558,7 +558,7 @@ reswitch:	switch (ch) {
 			break;
 		case 'D':
 			flags |= LONGINT;
-			/*FALLTHROUGH*/
+			fallthrough;
 		case 'd':
 		case 'i':
 			if ((error = addsarg(&types, flags)))
@@ -602,7 +602,7 @@ reswitch:	switch (ch) {
 #endif
 		case 'O':
 			flags |= LONGINT;
-			/*FALLTHROUGH*/
+			fallthrough;
 		case 'o':
 			if ((error = adduarg(&types, flags)))
 				goto error;
@@ -613,7 +613,7 @@ reswitch:	switch (ch) {
 			break;
 		case 'S':
 			flags |= LONGINT;
-			/*FALLTHROUGH*/
+			fallthrough;
 		case 's':
 			error = addtype(&types,
 			    (flags & LONGINT) ? TP_WCHAR : TP_CHAR);
@@ -622,7 +622,7 @@ reswitch:	switch (ch) {
 			break;
 		case 'U':
 			flags |= LONGINT;
-			/*FALLTHROUGH*/
+			fallthrough;
 		case 'u':
 		case 'X':
 		case 'x':
diff --git a/lib/printf/vfprintf.c b/lib/printf/vfprintf.c
index 78f8be05c..2083642d5 100644
--- a/lib/printf/vfprintf.c
+++ b/lib/printf/vfprintf.c
@@ -340,7 +340,7 @@ reswitch:	switch (ch) {
 			if (width >= 0)
 				goto rflag;
 			width = -width;
-			/* FALLTHROUGH */
+			fallthrough;
 		case '-':
 			flags |= LADJUST;
 			goto rflag;
@@ -434,7 +434,7 @@ reswitch:	switch (ch) {
 			break;
 		case 'C':
 			flags |= LONGINT;
-			/*FALLTHROUGH*/
+			fallthrough;
 		case 'c':
 #ifdef WCHAR_SUPPORT
 			if (flags & LONGINT) {
@@ -460,7 +460,7 @@ reswitch:	switch (ch) {
 			break;
 		case 'D':
 			flags |= LONGINT;
-			/*FALLTHROUGH*/
+			fallthrough;
 		case 'd':
 		case 'i':
 			if (flags & INTMAX_SIZE)
@@ -551,7 +551,7 @@ reswitch:	switch (ch) {
 			break;
 		case 'O':
 			flags |= LONGINT;
-			/*FALLTHROUGH*/
+			fallthrough;
 		case 'o':
 			if (flags & INTMAX_SIZE)
 				ujval = UJARG();
@@ -595,7 +595,7 @@ reswitch:	switch (ch) {
 			goto nosign;
 		case 'S':
 			flags |= LONGINT;
-			/*FALLTHROUGH*/
+			fallthrough;
 		case 's':
 #ifdef WCHAR_SUPPORT
 			if (flags & LONGINT) {
@@ -621,7 +621,7 @@ reswitch:	switch (ch) {
 			break;
 		case 'U':
 			flags |= LONGINT;
-			/*FALLTHROUGH*/
+			fallthrough;
 		case 'u':
 			if (flags & INTMAX_SIZE)
 				ujval = UJARG();
diff --git a/lib/routemap_northbound.c b/lib/routemap_northbound.c
index 5767e0aac..9e25d2beb 100644
--- a/lib/routemap_northbound.c
+++ b/lib/routemap_northbound.c
@@ -364,7 +364,6 @@ lib_route_map_entry_exit_policy_modify(struct nb_cb_modify_args *args)
 		case 0: /* permit-or-deny */
 			break;
 		case 1: /* next */
-			/* FALLTHROUGH */
 		case 2: /* goto */
 			rm_action =
 				yang_dnode_get_enum(args->dnode, "../action");
@@ -885,7 +884,7 @@ static int lib_route_map_entry_set_action_ipv4_address_modify(
 		yang_dnode_get_ipv4(&ia, args->dnode, NULL);
 		if (ia.s_addr == INADDR_ANY || !ipv4_unicast_valid(&ia))
 			return NB_ERR_VALIDATION;
-		/* FALLTHROUGH */
+		return NB_OK;
 	case NB_EV_PREPARE:
 	case NB_EV_ABORT:
 		return NB_OK;
@@ -944,7 +943,7 @@ static int lib_route_map_entry_set_action_ipv6_address_modify(
 		yang_dnode_get_ipv6(&i6a, args->dnode, NULL);
 		if (!IN6_IS_ADDR_LINKLOCAL(&i6a))
 			return NB_ERR_VALIDATION;
-		/* FALLTHROUGH */
+		return NB_OK;
 	case NB_EV_PREPARE:
 	case NB_EV_ABORT:
 		return NB_OK;
diff --git a/lib/vty.c b/lib/vty.c
index ed8b71ed2..ffb7274b9 100644
--- a/lib/vty.c
+++ b/lib/vty.c
@@ -1565,7 +1565,7 @@ static void vty_read(struct event *thread)
 			break;
 		case '\r':
 			vty->escape = VTY_CR;
-			/* fallthru */
+			fallthrough;
 		case '\n':
 			vty_out(vty, "\n");
 			buffer_flush_available(vty->obuf, vty->wfd);
diff --git a/lib/workqueue.c b/lib/workqueue.c
index fa5d58536..2281c4c36 100644
--- a/lib/workqueue.c
+++ b/lib/workqueue.c
@@ -271,9 +271,10 @@ void work_queue_run(struct event *thread)
 		switch (ret) {
 		case WQ_QUEUE_BLOCKED: {
 			/* decrement item->ran again, cause this isn't an item
-			 * specific error, and fall through to WQ_RETRY_LATER
+			 * specific error, and retry later
 			 */
 			item->ran--;
+			goto stats;
 		}
 		case WQ_RETRY_LATER: {
 			goto stats;
@@ -296,9 +297,10 @@ void work_queue_run(struct event *thread)
 			break;
 		}
 		case WQ_RETRY_NOW:
-		/* a RETRY_NOW that gets here has exceeded max_tries, same as
-		 * ERROR */
-		/* fallthru */
+			/* a RETRY_NOW that gets here has exceeded max_tries, same
+			 * as ERROR
+			 */
+			fallthrough;
 		case WQ_SUCCESS:
 		default: {
 			work_queue_item_remove(wq, item);
diff --git a/lib/zclient.c b/lib/zclient.c
index f8f9cf7ab..47d6c5fba 100644
--- a/lib/zclient.c
+++ b/lib/zclient.c
@@ -891,7 +891,7 @@ static int zapi_nexthop_cmp_no_labels(const struct zapi_nexthop *next1,
 					 &next2->gate);
 		if (ret != 0)
 			return ret;
-		/* Intentional Fall-Through */
+		fallthrough;
 	case NEXTHOP_TYPE_IFINDEX:
 		if (next1->ifindex < next2->ifindex)
 			return -1;
diff --git a/lib/zlog_5424.c b/lib/zlog_5424.c
index 9bc1c819a..3049e4a84 100644
--- a/lib/zlog_5424.c
+++ b/lib/zlog_5424.c
@@ -913,7 +913,7 @@ static int zlog_5424_open(struct zlog_cfg_5424 *zcf, int sock_type)
 		}
 
 		flags = O_NONBLOCK;
-		/* fallthru */
+		fallthrough;
 
 	case ZLOG_5424_DST_FILE:
 		if (!zcf->filename)