From: Ondřej Surý <ondrej@sury.org>
Date: Wed, 7 Nov 2018 08:00:07 +0000 (+0700)
Subject: Hint the compiler with ISC_UNREACHABLE(); that code after INSIST(0); cannot be reached
X-Git-Tag: v9.13.4~46^2~1
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=23fff6c569e656274cf1543ac36b014e25c906ed;p=thirdparty%2Fbind9.git

Hint the compiler with ISC_UNREACHABLE(); that code after INSIST(0); cannot be reached
---

diff --git a/bin/check/named-checkconf.c b/bin/check/named-checkconf.c
index 1f1acb0de09..753f5ba69c3 100644
--- a/bin/check/named-checkconf.c
+++ b/bin/check/named-checkconf.c
@@ -282,8 +282,10 @@ configure_zone(const char *vclass, const char *view,
 		} else if (strcasecmp(cfg_obj_asstring(obj), "ignore") == 0) {
 			zone_options &= ~DNS_ZONEOPT_CHECKDUPRR;
 			zone_options &= ~DNS_ZONEOPT_CHECKDUPRRFAIL;
-		} else
+		} else {
 			INSIST(0);
+			ISC_UNREACHABLE();
+		}
 	} else {
 		zone_options |= DNS_ZONEOPT_CHECKDUPRR;
 		zone_options &= ~DNS_ZONEOPT_CHECKDUPRRFAIL;
@@ -300,8 +302,10 @@ configure_zone(const char *vclass, const char *view,
 		} else if (strcasecmp(cfg_obj_asstring(obj), "ignore") == 0) {
 			zone_options &= ~DNS_ZONEOPT_CHECKMX;
 			zone_options &= ~DNS_ZONEOPT_CHECKMXFAIL;
-		} else
+		} else {
 			INSIST(0);
+			ISC_UNREACHABLE();
+		}
 	} else {
 		zone_options |= DNS_ZONEOPT_CHECKMX;
 		zone_options &= ~DNS_ZONEOPT_CHECKMXFAIL;
@@ -327,8 +331,10 @@ configure_zone(const char *vclass, const char *view,
 		} else if (strcasecmp(cfg_obj_asstring(obj), "ignore") == 0) {
 			zone_options |= DNS_ZONEOPT_WARNMXCNAME;
 			zone_options |= DNS_ZONEOPT_IGNOREMXCNAME;
-		} else
+		} else {
 			INSIST(0);
+			ISC_UNREACHABLE();
+		}
 	} else {
 		zone_options |= DNS_ZONEOPT_WARNMXCNAME;
 		zone_options &= ~DNS_ZONEOPT_IGNOREMXCNAME;
@@ -345,8 +351,10 @@ configure_zone(const char *vclass, const char *view,
 		} else if (strcasecmp(cfg_obj_asstring(obj), "ignore") == 0) {
 			zone_options |= DNS_ZONEOPT_WARNSRVCNAME;
 			zone_options |= DNS_ZONEOPT_IGNORESRVCNAME;
-		} else
+		} else {
 			INSIST(0);
+			ISC_UNREACHABLE();
+		}
 	} else {
 		zone_options |= DNS_ZONEOPT_WARNSRVCNAME;
 		zone_options &= ~DNS_ZONEOPT_IGNORESRVCNAME;
@@ -366,8 +374,10 @@ configure_zone(const char *vclass, const char *view,
 			zone_options |= DNS_ZONEOPT_CHECKSPF;
 		} else if (strcasecmp(cfg_obj_asstring(obj), "ignore") == 0) {
 			zone_options &= ~DNS_ZONEOPT_CHECKSPF;
-		} else
+		} else {
 			INSIST(0);
+			ISC_UNREACHABLE();
+		}
 	} else {
 		zone_options |= DNS_ZONEOPT_CHECKSPF;
 	}
@@ -383,8 +393,10 @@ configure_zone(const char *vclass, const char *view,
 		} else if (strcasecmp(cfg_obj_asstring(obj), "ignore") == 0) {
 			zone_options &= ~DNS_ZONEOPT_CHECKNAMES;
 			zone_options &= ~DNS_ZONEOPT_CHECKNAMESFAIL;
-		} else
+		} else {
 			INSIST(0);
+			ISC_UNREACHABLE();
+		}
 	} else {
 	       zone_options |= DNS_ZONEOPT_CHECKNAMES;
 	       zone_options |= DNS_ZONEOPT_CHECKNAMESFAIL;
@@ -394,14 +406,16 @@ configure_zone(const char *vclass, const char *view,
 	fmtobj = NULL;
 	if (get_maps(maps, "masterfile-format", &fmtobj)) {
 		const char *masterformatstr = cfg_obj_asstring(fmtobj);
-		if (strcasecmp(masterformatstr, "text") == 0)
+		if (strcasecmp(masterformatstr, "text") == 0) {
 			masterformat = dns_masterformat_text;
-		else if (strcasecmp(masterformatstr, "raw") == 0)
+		} else if (strcasecmp(masterformatstr, "raw") == 0) {
 			masterformat = dns_masterformat_raw;
-		else if (strcasecmp(masterformatstr, "map") == 0)
+		} else if (strcasecmp(masterformatstr, "map") == 0) {
 			masterformat = dns_masterformat_map;
-		else
+		} else {
 			INSIST(0);
+			ISC_UNREACHABLE();
+		}
 	}
 
 	obj = NULL;
diff --git a/bin/check/named-checkzone.c b/bin/check/named-checkzone.c
index a51e57dd5fe..061e39c5cc8 100644
--- a/bin/check/named-checkzone.c
+++ b/bin/check/named-checkzone.c
@@ -139,12 +139,14 @@ main(int argc, char **argv) {
 #define PROGCMP(X) \
 	(strcasecmp(prog_name, X) == 0 || strcasecmp(prog_name, X ".exe") == 0)
 
-	if (PROGCMP("named-checkzone"))
+	if (PROGCMP("named-checkzone")) {
 		progmode = progmode_check;
-	else if (PROGCMP("named-compilezone"))
+	} else if (PROGCMP("named-compilezone")) {
 		progmode = progmode_compile;
-	else
+	} else {
 		INSIST(0);
+		ISC_UNREACHABLE();
+	}
 
 	/* Compilation specific defaults */
 	if (progmode == progmode_compile) {
diff --git a/bin/confgen/ddns-confgen.c b/bin/confgen/ddns-confgen.c
index 18322465b09..56e56da34aa 100644
--- a/bin/confgen/ddns-confgen.c
+++ b/bin/confgen/ddns-confgen.c
@@ -125,10 +125,12 @@ main(int argc, char **argv) {
 	if (PROGCMP("tsig-keygen")) {
 		progmode = progmode_keygen;
 		quiet = true;
-	} else if (PROGCMP("ddns-confgen"))
+	} else if (PROGCMP("ddns-confgen")) {
 		progmode = progmode_confgen;
-	else
+	} else {
 		INSIST(0);
+		ISC_UNREACHABLE();
+	}
 
 	isc_commandline_errprint = false;
 
diff --git a/bin/delv/delv.c b/bin/delv/delv.c
index 53cd971e300..e83a35de57b 100644
--- a/bin/delv/delv.c
+++ b/bin/delv/delv.c
@@ -1224,6 +1224,7 @@ dash_option(char *option, char *next, bool *open_type_class) {
 			/* NOTREACHED */
 		default:
 			INSIST(0);
+			ISC_UNREACHABLE();
 		}
 		if (strlen(option) > 1U)
 			option = &option[1];
diff --git a/bin/dig/dighost.c b/bin/dig/dighost.c
index daf7a923dd4..f4e5e55ae6e 100644
--- a/bin/dig/dighost.c
+++ b/bin/dig/dighost.c
@@ -2348,6 +2348,7 @@ setup_lookup(dig_lookup_t *lookup) {
 				break;
 			default:
 				INSIST(0);
+				ISC_UNREACHABLE();
 			}
 
 			isc_buffer_init(&b, ecsbuf, sizeof(ecsbuf));
diff --git a/bin/named/config.c b/bin/named/config.c
index 9ce79bfd574..3b15ad2974a 100644
--- a/bin/named/config.c
+++ b/bin/named/config.c
@@ -457,6 +457,7 @@ named_config_getzonetype(const cfg_obj_t *zonetypeobj) {
 		ztype = dns_zone_redirect;
 	} else {
 		INSIST(0);
+		ISC_UNREACHABLE();
 	}
 	return (ztype);
 }
@@ -1029,6 +1030,7 @@ named_config_getkeyalgorithm2(const char *str, const dns_name_t **name,
 		case hmacsha512: *name = dns_tsig_hmacsha512_name; break;
 		default:
 			INSIST(0);
+			ISC_UNREACHABLE();
 		}
 	}
 	if (typep != NULL)
diff --git a/bin/named/logconf.c b/bin/named/logconf.c
index d60e7fc8f06..f3dea3a6fcf 100644
--- a/bin/named/logconf.c
+++ b/bin/named/logconf.c
@@ -157,6 +157,7 @@ channel_fromconf(const cfg_obj_t *channel, isc_logconfig_t *logconfig) {
 			break;
 		default:
 			INSIST(0);
+			ISC_UNREACHABLE();
 		}
 
 		type = ISC_LOG_TOFILE;
diff --git a/bin/named/server.c b/bin/named/server.c
index 2aecc630923..ee75c1b3b7e 100644
--- a/bin/named/server.c
+++ b/bin/named/server.c
@@ -1145,6 +1145,7 @@ get_view_querysource_dispatch(const cfg_obj_t **maps, int af,
 		break;
 	default:
 		INSIST(0);
+		ISC_UNREACHABLE();
 	}
 
 	sa = *(cfg_obj_assockaddr(obj));
@@ -1166,6 +1167,7 @@ get_view_querysource_dispatch(const cfg_obj_t **maps, int af,
 		break;
 	default:
 		INSIST(0);
+		ISC_UNREACHABLE();
 	}
 	if (result != ISC_R_SUCCESS)
 		return (ISC_R_SUCCESS);
@@ -1273,20 +1275,22 @@ configure_order(dns_order_t *order, const cfg_obj_t *ent) {
 	obj = cfg_tuple_get(ent, "ordering");
 	INSIST(cfg_obj_isstring(obj));
 	str = cfg_obj_asstring(obj);
-	if (!strcasecmp(str, "fixed"))
+	if (!strcasecmp(str, "fixed")) {
 #if DNS_RDATASET_FIXED
 		mode = DNS_RDATASETATTR_FIXEDORDER;
 #else
 		mode = DNS_RDATASETATTR_CYCLIC;
 #endif /* DNS_RDATASET_FIXED */
-	else if (!strcasecmp(str, "random"))
+	} else if (!strcasecmp(str, "random")) {
 		mode = DNS_RDATASETATTR_RANDOMIZE;
-	else if (!strcasecmp(str, "cyclic"))
+	} else if (!strcasecmp(str, "cyclic")) {
 		mode = DNS_RDATASETATTR_CYCLIC;
-	else if (!strcasecmp(str, "none"))
+	} else if (!strcasecmp(str, "none")) {
 		mode = DNS_RDATASETATTR_NONE;
-	else
+	} else {
 		INSIST(0);
+		ISC_UNREACHABLE();
+	}
 
 	/*
 	 * "*" should match everything including the root (BIND 8 compat).
@@ -1418,14 +1422,16 @@ configure_peer(const cfg_obj_t *cpeer, isc_mem_t *mctx, dns_peer_t **peerp) {
 	(void)cfg_map_get(cpeer, "transfer-format", &obj);
 	if (obj != NULL) {
 		str = cfg_obj_asstring(obj);
-		if (strcasecmp(str, "many-answers") == 0)
+		if (strcasecmp(str, "many-answers") == 0) {
 			CHECK(dns_peer_settransferformat(peer,
 							 dns_many_answers));
-		else if (strcasecmp(str, "one-answer") == 0)
+		} else if (strcasecmp(str, "one-answer") == 0) {
 			CHECK(dns_peer_settransferformat(peer,
 							 dns_one_answer));
-		else
+		} else {
 			INSIST(0);
+			ISC_UNREACHABLE();
+		}
 	}
 
 	obj = NULL;
@@ -3943,8 +3949,10 @@ configure_view(dns_view_t *view, dns_viewlist_t *viewlist,
 		view->checknames = false;
 	} else if (strcasecmp(str, "ignore") == 0) {
 		view->checknames = false;
-	} else
+	} else {
 		INSIST(0);
+		ISC_UNREACHABLE();
+	}
 
 	obj = NULL;
 	result = named_config_get(maps, "zero-no-soa-ttl-cache", &obj);
@@ -4358,12 +4366,14 @@ configure_view(dns_view_t *view, dns_viewlist_t *viewlist,
 			const char *resp = cfg_obj_asstring(obj2);
 			isc_result_t r = DNS_R_SERVFAIL;
 
-			if (strcasecmp(resp, "drop") == 0)
+			if (strcasecmp(resp, "drop") == 0) {
 				r = DNS_R_DROP;
-			else if (strcasecmp(resp, "fail") == 0)
+			} else if (strcasecmp(resp, "fail") == 0) {
 				r = DNS_R_SERVFAIL;
-			else
+			} else {
 				INSIST(0);
+				ISC_UNREACHABLE();
+			}
 
 			dns_resolver_setquotaresponse(view->resolver,
 						      dns_quotatype_server, r);
@@ -4709,20 +4719,24 @@ configure_view(dns_view_t *view, dns_viewlist_t *viewlist,
 			view->minimalresponses = dns_minimal_noauth;
 		} else if (strcasecmp(str, "no-auth-recursive") == 0) {
 			view->minimalresponses = dns_minimal_noauthrec;
-		} else
+		} else {
 			INSIST(0);
+			ISC_UNREACHABLE();
+		}
 	}
 
 	obj = NULL;
 	result = named_config_get(maps, "transfer-format", &obj);
 	INSIST(result == ISC_R_SUCCESS);
 	str = cfg_obj_asstring(obj);
-	if (strcasecmp(str, "many-answers") == 0)
+	if (strcasecmp(str, "many-answers") == 0) {
 		view->transfer_format = dns_many_answers;
-	else if (strcasecmp(str, "one-answer") == 0)
+	} else if (strcasecmp(str, "one-answer") == 0) {
 		view->transfer_format = dns_one_answer;
-	else
+	} else {
 		INSIST(0);
+		ISC_UNREACHABLE();
+	}
 
 	obj = NULL;
 	result = named_config_get(maps, "trust-anchor-telemetry", &obj);
@@ -5038,12 +5052,14 @@ configure_view(dns_view_t *view, dns_viewlist_t *viewlist,
 		const char *resp = cfg_obj_asstring(obj2);
 		isc_result_t r = DNS_R_SERVFAIL;
 
-		if (strcasecmp(resp, "drop") == 0)
+		if (strcasecmp(resp, "drop") == 0) {
 			r = DNS_R_DROP;
-		else if (strcasecmp(resp, "fail") == 0)
+		} else if (strcasecmp(resp, "fail") == 0) {
 			r = DNS_R_SERVFAIL;
-		else
+		} else {
 			INSIST(0);
+			ISC_UNREACHABLE();
+		}
 
 		dns_resolver_setquotaresponse(view->resolver,
 					      dns_quotatype_zone, r);
@@ -5059,10 +5075,12 @@ configure_view(dns_view_t *view, dns_viewlist_t *viewlist,
 			view->v4_aaaa = dns_aaaa_ok;
 	} else {
 		const char *v4_aaaastr = cfg_obj_asstring(obj);
-		if (strcasecmp(v4_aaaastr, "break-dnssec") == 0)
+		if (strcasecmp(v4_aaaastr, "break-dnssec") == 0) {
 			view->v4_aaaa = dns_aaaa_break_dnssec;
-		else
+		} else {
 			INSIST(0);
+			ISC_UNREACHABLE();
+		}
 	}
 
 	obj = NULL;
@@ -5075,10 +5093,12 @@ configure_view(dns_view_t *view, dns_viewlist_t *viewlist,
 			view->v6_aaaa = dns_aaaa_ok;
 	} else {
 		const char *v6_aaaastr = cfg_obj_asstring(obj);
-		if (strcasecmp(v6_aaaastr, "break-dnssec") == 0)
+		if (strcasecmp(v6_aaaastr, "break-dnssec") == 0) {
 			view->v6_aaaa = dns_aaaa_break_dnssec;
-		else
+		} else {
 			INSIST(0);
+			ISC_UNREACHABLE();
+		}
 	}
 
 	CHECK(configure_view_acl(vconfig, config, named_g_config,
@@ -5319,14 +5339,16 @@ configure_view(dns_view_t *view, dns_viewlist_t *viewlist,
 				statlevel = dns_zonestat_none;
 		} else {
 			const char *levelstr = cfg_obj_asstring(obj);
-			if (strcasecmp(levelstr, "full") == 0)
+			if (strcasecmp(levelstr, "full") == 0) {
 				statlevel = dns_zonestat_full;
-			else if (strcasecmp(levelstr, "terse") == 0)
+			} else if (strcasecmp(levelstr, "terse") == 0) {
 				statlevel = dns_zonestat_terse;
-			else if (strcasecmp(levelstr, "none") == 0)
+			} else if (strcasecmp(levelstr, "none") == 0) {
 				statlevel = dns_zonestat_none;
-			else
+			} else {
 				INSIST(0);
+				ISC_UNREACHABLE();
+			}
 		}
 
 		for (empty = empty_zones[empty_zone];
@@ -5686,16 +5708,18 @@ configure_forward(const cfg_obj_t *config, dns_view_t *view,
 				    "forwarding");
 		fwdpolicy = dns_fwdpolicy_none;
 	} else {
-		if (forwardtype == NULL)
+		if (forwardtype == NULL) {
 			fwdpolicy = dns_fwdpolicy_first;
-		else {
+		} else {
 			const char *forwardstr = cfg_obj_asstring(forwardtype);
-			if (strcasecmp(forwardstr, "first") == 0)
+			if (strcasecmp(forwardstr, "first") == 0) {
 				fwdpolicy = dns_fwdpolicy_first;
-			else if (strcasecmp(forwardstr, "only") == 0)
+			} else if (strcasecmp(forwardstr, "only") == 0) {
 				fwdpolicy = dns_fwdpolicy_only;
-			else
+			} else {
 				INSIST(0);
+				ISC_UNREACHABLE();
+			}
 		}
 	}
 
@@ -9001,6 +9025,7 @@ load_configuration(const char *filename, named_server_t *server,
 		server->sctx->cookiealg = ns_cookiealg_sha256;
 	} else {
 		INSIST(0);
+		ISC_UNREACHABLE();
 	}
 
 	obj = NULL;
@@ -12597,12 +12622,14 @@ newzone_parse(named_server_t *server, char *command, dns_view_t **viewp,
 	isc_buffer_init(&argbuf, command, (unsigned int) strlen(command));
 	isc_buffer_add(&argbuf, strlen(command));
 
-	if (strncasecmp(command, "add", 3) == 0)
+	if (strncasecmp(command, "add", 3) == 0) {
 		bn = "addzone";
-	else if (strncasecmp(command, "mod", 3) == 0)
+	} else if (strncasecmp(command, "mod", 3) == 0) {
 		bn = "modzone";
-	else
+	} else {
 		INSIST(0);
+		ISC_UNREACHABLE();
+	}
 
 	/*
 	 * Convert the "addzone" or "modzone" to just "zone", for
@@ -14988,6 +15015,7 @@ named_server_mkeys(named_server_t *server, isc_lex_t *lex,
 			break;
 		default:
 			INSIST(0);
+			ISC_UNREACHABLE();
 		}
 
 		if (viewtxt != NULL) {
diff --git a/bin/named/zoneconf.c b/bin/named/zoneconf.c
index f01004a8ba0..e365089abcc 100644
--- a/bin/named/zoneconf.c
+++ b/bin/named/zoneconf.c
@@ -125,7 +125,7 @@ configure_zone_acl(const cfg_obj_t *zconfig, const cfg_obj_t *vconfig,
 		break;
 	    default:
 		INSIST(0);
-		return (ISC_R_FAILURE);
+		ISC_UNREACHABLE();
 	}
 
 	/* First check to see if ACL is defined within the zone */
@@ -231,12 +231,14 @@ configure_zone_ssutable(const cfg_obj_t *zconfig, dns_zone_t *zone,
 		unsigned int i, n;
 
 		str = cfg_obj_asstring(mode);
-		if (strcasecmp(str, "grant") == 0)
+		if (strcasecmp(str, "grant") == 0) {
 			grant = true;
-		else if (strcasecmp(str, "deny") == 0)
+		} else if (strcasecmp(str, "deny") == 0) {
 			grant = false;
-		else
+		} else {
 			INSIST(0);
+			ISC_UNREACHABLE();
+		}
 
 		str = cfg_obj_asstring(matchtype);
 		CHECK(dns_ssu_mtypefromstring(str, &mtype));
@@ -764,6 +766,7 @@ checknames(dns_zonetype_t ztype, const cfg_obj_t **maps,
 		break;
 	default:
 		INSIST(0);
+		ISC_UNREACHABLE();
 	}
 	result = named_checknames_get(maps, zone, objp);
 	INSIST(result == ISC_R_SUCCESS && objp != NULL && *objp != NULL);
@@ -1027,14 +1030,16 @@ named_zone_configure(const cfg_obj_t *config, const cfg_obj_t *vconfig,
 	if (result == ISC_R_SUCCESS) {
 		const char *masterformatstr = cfg_obj_asstring(obj);
 
-		if (strcasecmp(masterformatstr, "text") == 0)
+		if (strcasecmp(masterformatstr, "text") == 0) {
 			masterformat = dns_masterformat_text;
-		else if (strcasecmp(masterformatstr, "raw") == 0)
+		} else if (strcasecmp(masterformatstr, "raw") == 0) {
 			masterformat = dns_masterformat_raw;
-		else if (strcasecmp(masterformatstr, "map") == 0)
+		} else if (strcasecmp(masterformatstr, "map") == 0) {
 			masterformat = dns_masterformat_map;
-		else
+		} else {
 			INSIST(0);
+			ISC_UNREACHABLE();
+		}
 	}
 
 	obj = NULL;
@@ -1050,12 +1055,14 @@ named_zone_configure(const cfg_obj_t *config, const cfg_obj_t *vconfig,
 			return (ISC_R_FAILURE);
 		}
 
-		if (strcasecmp(masterstylestr, "full") == 0)
+		if (strcasecmp(masterstylestr, "full") == 0) {
 			masterstyle = &dns_master_style_full;
-		else if (strcasecmp(masterstylestr, "relative") == 0)
+		} else if (strcasecmp(masterstylestr, "relative") == 0) {
 			masterstyle = &dns_master_style_default;
-		else
+		} else {
 			INSIST(0);
+			ISC_UNREACHABLE();
+		}
 	}
 
 	obj = NULL;
@@ -1141,16 +1148,18 @@ named_zone_configure(const cfg_obj_t *config, const cfg_obj_t *vconfig,
 			dialup = dns_dialuptype_no;
 	} else {
 		const char *dialupstr = cfg_obj_asstring(obj);
-		if (strcasecmp(dialupstr, "notify") == 0)
+		if (strcasecmp(dialupstr, "notify") == 0) {
 			dialup = dns_dialuptype_notify;
-		else if (strcasecmp(dialupstr, "notify-passive") == 0)
+		} else if (strcasecmp(dialupstr, "notify-passive") == 0) {
 			dialup = dns_dialuptype_notifypassive;
-		else if (strcasecmp(dialupstr, "refresh") == 0)
+		} else if (strcasecmp(dialupstr, "refresh") == 0) {
 			dialup = dns_dialuptype_refresh;
-		else if (strcasecmp(dialupstr, "passive") == 0)
+		} else if (strcasecmp(dialupstr, "passive") == 0) {
 			dialup = dns_dialuptype_passive;
-		else
+		} else {
 			INSIST(0);
+			ISC_UNREACHABLE();
+		}
 	}
 	if (raw != NULL)
 		dns_zone_setdialup(raw, dialup);
@@ -1166,14 +1175,16 @@ named_zone_configure(const cfg_obj_t *config, const cfg_obj_t *vconfig,
 			statlevel = dns_zonestat_none;
 	} else {
 		const char *levelstr = cfg_obj_asstring(obj);
-		if (strcasecmp(levelstr, "full") == 0)
+		if (strcasecmp(levelstr, "full") == 0) {
 			statlevel = dns_zonestat_full;
-		else if (strcasecmp(levelstr, "terse") == 0)
+		} else if (strcasecmp(levelstr, "terse") == 0) {
 			statlevel = dns_zonestat_terse;
-		else if (strcasecmp(levelstr, "none") == 0)
+		} else if (strcasecmp(levelstr, "none") == 0) {
 			statlevel = dns_zonestat_none;
-		else
+		} else {
 			INSIST(0);
+			ISC_UNREACHABLE();
+		}
 	}
 	dns_zone_setstatlevel(zone, statlevel);
 
@@ -1211,12 +1222,14 @@ named_zone_configure(const cfg_obj_t *config, const cfg_obj_t *vconfig,
 				notifytype = dns_notifytype_no;
 		} else {
 			const char *notifystr = cfg_obj_asstring(obj);
-			if (strcasecmp(notifystr, "explicit") == 0)
+			if (strcasecmp(notifystr, "explicit") == 0) {
 				notifytype = dns_notifytype_explicit;
-			else if (strcasecmp(notifystr, "master-only") == 0)
+			} else if (strcasecmp(notifystr, "master-only") == 0) {
 				notifytype = dns_notifytype_masteronly;
-			else
+			} else {
 				INSIST(0);
+				ISC_UNREACHABLE();
+			}
 		}
 		notifytype = process_notifytype(notifytype, ztype, zname,
 						nodefault);
@@ -1374,8 +1387,10 @@ named_zone_configure(const cfg_obj_t *config, const cfg_obj_t *vconfig,
 			fail = check = true;
 		} else if (strcasecmp(cfg_obj_asstring(obj), "ignore") == 0) {
 			fail = check = false;
-		} else
+		} else {
 			INSIST(0);
+			ISC_UNREACHABLE();
+		}
 		if (raw != NULL) {
 			dns_zone_setoption(raw, DNS_ZONEOPT_CHECKNAMES,
 					   check);
@@ -1410,8 +1425,10 @@ named_zone_configure(const cfg_obj_t *config, const cfg_obj_t *vconfig,
 			check = true;
 		} else if (strcasecmp(cfg_obj_asstring(obj), "ignore") == 0) {
 			check = false;
-		} else
+		} else {
 			INSIST(0);
+			ISC_UNREACHABLE();
+		}
 		dns_zone_setoption(zone, DNS_ZONEOPT_CHECKSPF, check);
 
 		obj = NULL;
@@ -1562,14 +1579,16 @@ named_zone_configure(const cfg_obj_t *config, const cfg_obj_t *vconfig,
 		result = cfg_map_get(zoptions, "auto-dnssec", &obj);
 		if (result == ISC_R_SUCCESS) {
 			const char *arg = cfg_obj_asstring(obj);
-			if (strcasecmp(arg, "allow") == 0)
+			if (strcasecmp(arg, "allow") == 0) {
 				allow = true;
-			else if (strcasecmp(arg, "maintain") == 0)
+			} else if (strcasecmp(arg, "maintain") == 0) {
 				allow = maint = true;
-			else if (strcasecmp(arg, "off") == 0)
+			} else if (strcasecmp(arg, "off") == 0) {
 				;
-			else
+			} else {
 				INSIST(0);
+				ISC_UNREACHABLE();
+			}
 			dns_zone_setkeyopt(zone, DNS_ZONEKEY_ALLOW, allow);
 			dns_zone_setkeyopt(zone, DNS_ZONEKEY_MAINTAIN, maint);
 		}
@@ -1622,8 +1641,10 @@ named_zone_configure(const cfg_obj_t *config, const cfg_obj_t *vconfig,
 			fail = check = true;
 		} else if (strcasecmp(dupcheck, "ignore") == 0) {
 			fail = check = false;
-		} else
+		} else {
 			INSIST(0);
+			ISC_UNREACHABLE();
+		}
 		dns_zone_setoption(mayberaw, DNS_ZONEOPT_CHECKDUPRR, check);
 		dns_zone_setoption(mayberaw, DNS_ZONEOPT_CHECKDUPRRFAIL, fail);
 
@@ -1637,8 +1658,10 @@ named_zone_configure(const cfg_obj_t *config, const cfg_obj_t *vconfig,
 			fail = check = true;
 		} else if (strcasecmp(cfg_obj_asstring(obj), "ignore") == 0) {
 			fail = check = false;
-		} else
+		} else {
 			INSIST(0);
+			ISC_UNREACHABLE();
+		}
 		dns_zone_setoption(mayberaw, DNS_ZONEOPT_CHECKMX, check);
 		dns_zone_setoption(mayberaw, DNS_ZONEOPT_CHECKMXFAIL, fail);
 
@@ -1674,8 +1697,10 @@ named_zone_configure(const cfg_obj_t *config, const cfg_obj_t *vconfig,
 			warn = ignore = false;
 		} else if (strcasecmp(cfg_obj_asstring(obj), "ignore") == 0) {
 			warn = ignore = true;
-		} else
+		} else {
 			INSIST(0);
+			ISC_UNREACHABLE();
+		}
 		dns_zone_setoption(mayberaw, DNS_ZONEOPT_WARNMXCNAME, warn);
 		dns_zone_setoption(mayberaw, DNS_ZONEOPT_IGNOREMXCNAME, ignore);
 
@@ -1689,8 +1714,10 @@ named_zone_configure(const cfg_obj_t *config, const cfg_obj_t *vconfig,
 			warn = ignore = false;
 		} else if (strcasecmp(cfg_obj_asstring(obj), "ignore") == 0) {
 			warn = ignore = true;
-		} else
+		} else {
 			INSIST(0);
+			ISC_UNREACHABLE();
+		}
 		dns_zone_setoption(mayberaw, DNS_ZONEOPT_WARNSRVCNAME, warn);
 		dns_zone_setoption(mayberaw, DNS_ZONEOPT_IGNORESRVCNAME,
 				   ignore);
@@ -1706,13 +1733,15 @@ named_zone_configure(const cfg_obj_t *config, const cfg_obj_t *vconfig,
 		result = cfg_map_get(zoptions, "dnssec-update-mode", &obj);
 		if (result == ISC_R_SUCCESS) {
 			const char *arg = cfg_obj_asstring(obj);
-			if (strcasecmp(arg, "no-resign") == 0)
+			if (strcasecmp(arg, "no-resign") == 0) {
 				dns_zone_setkeyopt(zone, DNS_ZONEKEY_NORESIGN,
 						   true);
-			else if (strcasecmp(arg, "maintain") == 0)
+			} else if (strcasecmp(arg, "maintain") == 0) {
 				;
-			else
+			} else {
 				INSIST(0);
+				ISC_UNREACHABLE();
+			}
 		}
 
 		obj = NULL;
diff --git a/lib/bind9/check.c b/lib/bind9/check.c
index 8928e10a5eb..cdbc7270e4e 100644
--- a/lib/bind9/check.c
+++ b/lib/bind9/check.c
@@ -1863,6 +1863,7 @@ check_update_policy(const cfg_obj_t *policy, isc_log_t *logctx) {
 			break;
 		default:
 			INSIST(0);
+			ISC_UNREACHABLE();
 		}
 
 		for (element2 = cfg_list_first(typelist);
@@ -2233,6 +2234,7 @@ check_zoneconf(const cfg_obj_t *zconfig, const cfg_obj_t *voptions,
 
 		default:
 			INSIST(0);
+			ISC_UNREACHABLE();
 		}
 	}
 
@@ -2658,14 +2660,16 @@ check_zoneconf(const cfg_obj_t *zconfig, const cfg_obj_t *voptions,
 	(void)cfg_map_get(zoptions, "masterfile-format", &obj);
 	if (obj != NULL) {
 		const char *masterformatstr = cfg_obj_asstring(obj);
-		if (strcasecmp(masterformatstr, "text") == 0)
+		if (strcasecmp(masterformatstr, "text") == 0) {
 			masterformat = dns_masterformat_text;
-		else if (strcasecmp(masterformatstr, "raw") == 0)
+		} else if (strcasecmp(masterformatstr, "raw") == 0) {
 			masterformat = dns_masterformat_raw;
-		else if (strcasecmp(masterformatstr, "map") == 0)
+		} else if (strcasecmp(masterformatstr, "map") == 0) {
 			masterformat = dns_masterformat_map;
-		else
+		} else {
 			INSIST(0);
+			ISC_UNREACHABLE();
+		}
 	}
 
 	if (masterformat == dns_masterformat_map) {
diff --git a/lib/dns/acl.c b/lib/dns/acl.c
index 69d3b524bdc..f941512a463 100644
--- a/lib/dns/acl.c
+++ b/lib/dns/acl.c
@@ -416,8 +416,8 @@ dns_aclelement_match(const isc_netaddr_t *reqaddr,
 		return (dns_geoip_match(reqaddr, env->geoip, &e->geoip_elem));
 #endif
 	default:
-		/* Should be impossible. */
 		INSIST(0);
+		ISC_UNREACHABLE();
 	}
 
 	result = dns_acl_match(reqaddr, reqsigner, inner, env,
@@ -593,7 +593,7 @@ dns_acl_isinsecure(const dns_acl_t *a) {
 
 		default:
 			INSIST(0);
-			return (true);
+			ISC_UNREACHABLE();
 		}
 	}
 
diff --git a/lib/dns/client.c b/lib/dns/client.c
index 4a196156a36..6c96a40b300 100644
--- a/lib/dns/client.c
+++ b/lib/dns/client.c
@@ -273,6 +273,7 @@ getudpdispatch(int family, dns_dispatchmgr_t *dispatchmgr,
 		break;
 	default:
 		INSIST(0);
+		ISC_UNREACHABLE();
 	}
 	attrmask = 0;
 	attrmask |= DNS_DISPATCHATTR_UDP;
@@ -3177,6 +3178,7 @@ dns_client_updaterec(dns_client_updateop_t op, const dns_name_t *owner,
 		break;
 	default:
 		INSIST(0);
+		ISC_UNREACHABLE();
 	}
 
 	rdatalist->type = rdata->type;
diff --git a/lib/dns/diff.c b/lib/dns/diff.c
index 910326f38bc..3fac1e74789 100644
--- a/lib/dns/diff.c
+++ b/lib/dns/diff.c
@@ -378,6 +378,7 @@ diff_apply(dns_diff_t *diff, dns_db_t *db, dns_dbversion_t *ver,
 				break;
 			default:
 				INSIST(0);
+				ISC_UNREACHABLE();
 			}
 
 			if (result == ISC_R_SUCCESS) {
diff --git a/lib/dns/dispatch.c b/lib/dns/dispatch.c
index 007b35e0c17..e46cd055cdf 100644
--- a/lib/dns/dispatch.c
+++ b/lib/dns/dispatch.c
@@ -908,7 +908,7 @@ free_buffer(dns_dispatch_t *disp, void *buf, unsigned int len) {
 		break;
 	default:
 		INSIST(0);
-		break;
+		ISC_UNREACHABLE();
 	}
 }
 
@@ -1577,7 +1577,7 @@ startrecv(dns_dispatch_t *disp, dispsocket_t *dispsock) {
 		break;
 	default:
 		INSIST(0);
-		break;
+		ISC_UNREACHABLE();
 	}
 
 	return (ISC_R_SUCCESS);
diff --git a/lib/dns/dnsrps.c b/lib/dns/dnsrps.c
index a85e48ca693..b217b795d8e 100644
--- a/lib/dns/dnsrps.c
+++ b/lib/dns/dnsrps.c
@@ -311,6 +311,7 @@ dns_dnsrps_2policy(librpz_policy_t rps_policy) {
 	case LIBRPZ_POLICY_DISABLED:
 	default:
 		INSIST(0);
+		ISC_UNREACHABLE();
 	}
 }
 
diff --git a/lib/dns/dnstap.c b/lib/dns/dnstap.c
index 3368d901052..d93e22d103d 100644
--- a/lib/dns/dnstap.c
+++ b/lib/dns/dnstap.c
@@ -1043,6 +1043,7 @@ dns_dt_open(const char *filename, dns_dtmode_t mode, isc_mem_t *mctx,
 		return (ISC_R_NOTIMPLEMENTED);
 	default:
 		INSIST(0);
+		ISC_UNREACHABLE();
 	}
 
 	isc_mem_attach(mctx, &handle->mctx);
diff --git a/lib/dns/geoip.c b/lib/dns/geoip.c
index 4ebc1a143e8..49bdd7faac5 100644
--- a/lib/dns/geoip.c
+++ b/lib/dns/geoip.c
@@ -285,6 +285,7 @@ country_lookup(GeoIP *db, dns_geoip_subtype_t subtype,
 			break;
 		default:
 			INSIST(0);
+			ISC_UNREACHABLE();
 		}
 
 		if (text == NULL)
@@ -349,6 +350,7 @@ city_string(GeoIPRecord *record, dns_geoip_subtype_t subtype, int *maxlen) {
 		return (deconst);
 	default:
 		INSIST(0);
+		ISC_UNREACHABLE();
 	}
 }
 
@@ -437,6 +439,7 @@ static char * region_string(GeoIPRegion *region, dns_geoip_subtype_t subtype, in
 		return (deconst);
 	default:
 		INSIST(0);
+		ISC_UNREACHABLE();
 	}
 }
 
@@ -807,6 +810,7 @@ dns_geoip_match(const isc_netaddr_t *reqaddr,
 
 	default:
 		INSIST(0);
+		ISC_UNREACHABLE()
 	}
 
 	return (false);
diff --git a/lib/dns/hmac_link.c b/lib/dns/hmac_link.c
index 71d1b6a2b5a..39e39179316 100644
--- a/lib/dns/hmac_link.c
+++ b/lib/dns/hmac_link.c
@@ -392,6 +392,7 @@ hmac__get_tag_key(isc_md_type_t type) {
 		return (TAG_HMACSHA512_KEY);
 	} else {
 		INSIST(0);
+		ISC_UNREACHABLE();
 	}
 }
 
@@ -411,6 +412,7 @@ hmac__get_tag_bits(isc_md_type_t type) {
 		return (TAG_HMACSHA512_BITS);
 	} else {
 		INSIST(0);
+		ISC_UNREACHABLE();
 	}
 }
 
@@ -462,6 +464,7 @@ hmac__to_dst_alg(isc_md_type_t type) {
 		return (DST_ALG_HMACSHA512);
 	} else {
 		INSIST(0);
+		ISC_UNREACHABLE();
 	}
 }
 
diff --git a/lib/dns/journal.c b/lib/dns/journal.c
index b8bbe78c812..4a820382860 100644
--- a/lib/dns/journal.c
+++ b/lib/dns/journal.c
@@ -745,6 +745,7 @@ ixfr_order(const void *av, const void *bv) {
 		break;
 	default:
 		INSIST(0);
+		ISC_UNREACHABLE();
 	}
 
 	switch (b->op) {
@@ -758,6 +759,7 @@ ixfr_order(const void *av, const void *bv) {
 		break;
 	default:
 		INSIST(0);
+		ISC_UNREACHABLE();
 	}
 
 	r = bop - aop;
diff --git a/lib/dns/masterdump.c b/lib/dns/masterdump.c
index 796a5955a8e..df779c6a432 100644
--- a/lib/dns/masterdump.c
+++ b/lib/dns/masterdump.c
@@ -1494,7 +1494,7 @@ dumpctx_create(isc_mem_t *mctx, dns_db_t *db, dns_dbversion_t *version,
 		break;
 	default:
 		INSIST(0);
-		break;
+		ISC_UNREACHABLE();
 	}
 
 	result = totext_ctx_init(style, &dctx->tctx);
@@ -1634,6 +1634,7 @@ writeheader(dns_dumpctx_t *dctx) {
 		break;
 	default:
 		INSIST(0);
+		ISC_UNREACHABLE();
 	}
 
 	isc_mem_put(dctx->mctx, buffer.base, buffer.length);
diff --git a/lib/dns/message.c b/lib/dns/message.c
index ec6dde5155f..4a811d28dbc 100644
--- a/lib/dns/message.c
+++ b/lib/dns/message.c
@@ -920,8 +920,8 @@ getname(dns_name_t *name, isc_buffer_t *source, dns_message_t *msg,
 		}
 	}
 
-	INSIST(0);  /* Cannot get here... */
-	return (ISC_R_UNEXPECTED);
+	INSIST(0);
+	ISC_UNREACHABLE();
 }
 
 static isc_result_t
diff --git a/lib/dns/openssleddsa_link.c b/lib/dns/openssleddsa_link.c
index 86b771f2f35..ffe5c239d82 100644
--- a/lib/dns/openssleddsa_link.c
+++ b/lib/dns/openssleddsa_link.c
@@ -569,8 +569,8 @@ openssleddsa_todns(const dst_key_t *key, isc_buffer_t *data) {
 		return (result);
 	default:
 		INSIST(0);
+		ISC_UNREACHABLE();
 	}
-	return (DST_R_OPENSSLFAILURE);
 }
 
 static isc_result_t
diff --git a/lib/dns/opensslrsa_link.c b/lib/dns/opensslrsa_link.c
index fabdd2f59e9..4ae80c37d40 100644
--- a/lib/dns/opensslrsa_link.c
+++ b/lib/dns/opensslrsa_link.c
@@ -222,6 +222,7 @@ opensslrsa_createctx(dst_key_t *key, dst_context_t *dctx) {
 		break;
 	default:
 		INSIST(0);
+		ISC_UNREACHABLE();
 	}
 
 	evp_md_ctx = EVP_MD_CTX_create();
@@ -244,6 +245,7 @@ opensslrsa_createctx(dst_key_t *key, dst_context_t *dctx) {
 		break;
 	default:
 		INSIST(0);
+		ISC_UNREACHABLE();
 	}
 
 	if (!EVP_DigestInit_ex(evp_md_ctx, type, NULL)) {
@@ -481,6 +483,7 @@ opensslrsa_generate(dst_key_t *key, int exp, void (*callback)(int)) {
 		break;
 	default:
 		INSIST(0);
+		ISC_UNREACHABLE();
 	}
 
 	if (rsa == NULL || e == NULL || cb == NULL)
diff --git a/lib/dns/peer.c b/lib/dns/peer.c
index 89447cc545e..85f895a2cba 100644
--- a/lib/dns/peer.c
+++ b/lib/dns/peer.c
@@ -206,10 +206,11 @@ dns_peer_new(isc_mem_t *mem, const isc_netaddr_t *addr, dns_peer_t **peerptr) {
 		prefixlen = 32;
 		break;
 	case AF_INET6:
-		 prefixlen = 128;
+		prefixlen = 128;
 		break;
 	default:
 		INSIST(0);
+		ISC_UNREACHABLE();
 	}
 
 	return (dns_peer_newprefix(mem, addr, prefixlen, peerptr));
diff --git a/lib/dns/pkcs11rsa_link.c b/lib/dns/pkcs11rsa_link.c
index ef452d58fd6..133c4a05945 100644
--- a/lib/dns/pkcs11rsa_link.c
+++ b/lib/dns/pkcs11rsa_link.c
@@ -112,6 +112,7 @@ pkcs11rsa_createctx_sign(dst_key_t *key, dst_context_t *dctx) {
 		break;
 	default:
 		INSIST(0);
+		ISC_UNREACHABLE();
 	}
 
 	rsa = key->keydata.pkey;
@@ -247,6 +248,7 @@ pkcs11rsa_createctx_sign(dst_key_t *key, dst_context_t *dctx) {
 		break;
 	default:
 		INSIST(0);
+		ISC_UNREACHABLE();
 	}
 
 	PK11_RET(pkcs_C_SignInit,
@@ -339,6 +341,7 @@ pkcs11rsa_createctx_verify(dst_key_t *key, unsigned int maxbits,
 		break;
 	default:
 		INSIST(0);
+		ISC_UNREACHABLE();
 	}
 
 	rsa = key->keydata.pkey;
@@ -406,6 +409,7 @@ pkcs11rsa_createctx_verify(dst_key_t *key, unsigned int maxbits,
 		break;
 	default:
 		INSIST(0);
+		ISC_UNREACHABLE();
 	}
 
 	PK11_RET(pkcs_C_VerifyInit,
@@ -605,6 +609,7 @@ pkcs11rsa_createctx(dst_key_t *key, dst_context_t *dctx) {
 		break;
 	default:
 		INSIST(0);
+		ISC_UNREACHABLE();
 	}
 
 	switch (key->key_alg) {
@@ -623,6 +628,7 @@ pkcs11rsa_createctx(dst_key_t *key, dst_context_t *dctx) {
 		break;
 	default:
 		INSIST(0);
+		ISC_UNREACHABLE();
 	}
 
 	pk11_ctx = (pk11_context_t *) isc_mem_get(dctx->mctx,
@@ -752,6 +758,7 @@ pkcs11rsa_sign(dst_context_t *dctx, isc_buffer_t *sig) {
 		break;
 	default:
 		INSIST(0);
+		ISC_UNREACHABLE();
 	}
 
 	switch (key->key_alg) {
@@ -778,6 +785,7 @@ pkcs11rsa_sign(dst_context_t *dctx, isc_buffer_t *sig) {
 		break;
 	default:
 		INSIST(0);
+		ISC_UNREACHABLE();
 	}
 	dgstlen = derlen + hashlen;
 	INSIST(dgstlen <= sizeof(digest));
@@ -993,6 +1001,7 @@ pkcs11rsa_verify(dst_context_t *dctx, const isc_region_t *sig) {
 		break;
 	default:
 		INSIST(0);
+		ISC_UNREACHABLE();
 	}
 	dgstlen = derlen + hashlen;
 	INSIST(dgstlen <= sizeof(digest));
@@ -1184,6 +1193,7 @@ pkcs11rsa_generate(dst_key_t *key, int exp, void (*callback)(int)) {
 		break;
 	default:
 		INSIST(0);
+		ISC_UNREACHABLE();
 	}
 
 	pk11_ctx = (pk11_context_t *) isc_mem_get(key->mctx,
diff --git a/lib/dns/resolver.c b/lib/dns/resolver.c
index 9fdbe583e3a..7ecd6ffbe90 100644
--- a/lib/dns/resolver.c
+++ b/lib/dns/resolver.c
@@ -6808,6 +6808,7 @@ is_answertarget_allowed(fetchctx_t *fctx, dns_name_t *qname, dns_name_t *rname,
 		break;
 	default:
 		INSIST(0);
+		ISC_UNREACHABLE();
 	}
 
 	if (chainingp != NULL)
diff --git a/lib/dns/rpz.c b/lib/dns/rpz.c
index 798ce84c99f..c8d55208b7b 100644
--- a/lib/dns/rpz.c
+++ b/lib/dns/rpz.c
@@ -268,9 +268,8 @@ dns_rpz_policy2str(dns_rpz_policy_t policy) {
 		str = "MISS";
 		break;
 	default:
-		str = "";
-		POST(str);
 		INSIST(0);
+		ISC_UNREACHABLE();
 	}
 	return (str);
 }
diff --git a/lib/dns/rrl.c b/lib/dns/rrl.c
index 70e308cd577..4b3ad7d67a5 100644
--- a/lib/dns/rrl.c
+++ b/lib/dns/rrl.c
@@ -465,8 +465,8 @@ get_rate(dns_rrl_t *rrl, dns_rrl_rtype_t rtype) {
 		return (&rrl->all_per_second);
 	default:
 		INSIST(0);
+		ISC_UNREACHABLE();
 	}
-	return (NULL);
 }
 
 static int
@@ -823,7 +823,7 @@ make_log_buf(dns_rrl_t *rrl, dns_rrl_entry_t *e,
 		break;
 	default:
 		INSIST(0);
-		break;
+		ISC_UNREACHABLE();
 	}
 
 	switch (e->key.s.rtype) {
@@ -852,6 +852,7 @@ make_log_buf(dns_rrl_t *rrl, dns_rrl_entry_t *e,
 		break;
 	default:
 		INSIST(0);
+		ISC_UNREACHABLE();
 	}
 
 	if (plural)
diff --git a/lib/dns/sdb.c b/lib/dns/sdb.c
index f00fdb00bdb..e8331bf2eb3 100644
--- a/lib/dns/sdb.c
+++ b/lib/dns/sdb.c
@@ -1052,7 +1052,7 @@ expirenode(dns_db_t *db, dns_dbnode_t *node, isc_stdtime_t now) {
 	UNUSED(node);
 	UNUSED(now);
 	INSIST(0);
-	return (ISC_R_UNEXPECTED);
+	ISC_UNREACHABLE();
 }
 
 static void
diff --git a/lib/dns/sdlz.c b/lib/dns/sdlz.c
index c7538c686cc..015a358c37a 100644
--- a/lib/dns/sdlz.c
+++ b/lib/dns/sdlz.c
@@ -781,7 +781,7 @@ expirenode(dns_db_t *db, dns_dbnode_t *node, isc_stdtime_t now) {
 	UNUSED(node);
 	UNUSED(now);
 	INSIST(0);
-	return (ISC_R_UNEXPECTED);
+	ISC_UNREACHABLE();
 }
 
 static void
diff --git a/lib/dns/ssu.c b/lib/dns/ssu.c
index 8767e0ab1a4..908569dba9a 100644
--- a/lib/dns/ssu.c
+++ b/lib/dns/ssu.c
@@ -291,6 +291,7 @@ reverse_from_address(dns_name_t *tcpself, const isc_netaddr_t *tcpaddr) {
 		break;
 	default:
 		INSIST(0);
+		ISC_UNREACHABLE();
 	}
 	isc_buffer_init(&b, buf, strlen(buf));
 	isc_buffer_add(&b, strlen(buf));
@@ -333,6 +334,7 @@ stf_from_address(dns_name_t *stfself, const isc_netaddr_t *tcpaddr) {
 		break;
 	default:
 		INSIST(0);
+		ISC_UNREACHABLE();
 	}
 	isc_buffer_init(&b, buf, strlen(buf));
 	isc_buffer_add(&b, strlen(buf));
diff --git a/lib/dns/tsec.c b/lib/dns/tsec.c
index 084e354f239..4fb2bcc75f1 100644
--- a/lib/dns/tsec.c
+++ b/lib/dns/tsec.c
@@ -98,6 +98,7 @@ dns_tsec_create(isc_mem_t *mctx, dns_tsectype_t type, dst_key_t *key,
 		break;
 	default:
 		INSIST(0);
+		ISC_UNREACHABLE();
 	}
 
 	tsec->magic = DNS_TSEC_MAGIC;
@@ -123,6 +124,7 @@ dns_tsec_destroy(dns_tsec_t **tsecp) {
 		break;
 	default:
 		INSIST(0);
+		ISC_UNREACHABLE();
 	}
 
 	tsec->magic = 0;
@@ -152,5 +154,6 @@ dns_tsec_getkey(dns_tsec_t *tsec, void *keyp) {
 		break;
 	default:
 		INSIST(0);
+		ISC_UNREACHABLE();
 	}
 }
diff --git a/lib/dns/update.c b/lib/dns/update.c
index 2cd439ee12f..120ab5939cc 100644
--- a/lib/dns/update.c
+++ b/lib/dns/update.c
@@ -1827,6 +1827,7 @@ dns_update_signaturesinc(dns_update_log_t *log, dns_zone_t *zone, dns_db_t *db,
 				sigs++;
 			} else {
 				INSIST(0);
+				ISC_UNREACHABLE();
 			}
 			ISC_LIST_UNLINK(state->nsec_mindiff.tuples, t, link);
 			ISC_LIST_APPEND(state->work.tuples, t, link);
@@ -2000,6 +2001,7 @@ dns_update_signaturesinc(dns_update_log_t *log, dns_zone_t *zone, dns_db_t *db,
 				sigs++;
 			} else {
 				INSIST(0);
+				ISC_UNREACHABLE();
 			}
 			ISC_LIST_UNLINK(state->nsec_mindiff.tuples, t, link);
 			ISC_LIST_APPEND(state->work.tuples, t, link);
@@ -2026,6 +2028,7 @@ dns_update_signaturesinc(dns_update_log_t *log, dns_zone_t *zone, dns_db_t *db,
 		break;
 	default:
 		INSIST(0);
+		ISC_UNREACHABLE();
 	}
 
  failure:
diff --git a/lib/dns/validator.c b/lib/dns/validator.c
index d8983947048..60bc81bbc09 100644
--- a/lib/dns/validator.c
+++ b/lib/dns/validator.c
@@ -3704,10 +3704,8 @@ validator_start(isc_task_t *task, isc_event_t *event) {
 			val->attributes |= VALATTR_NEEDNODATA;
 		result = nsecvalidate(val, false);
 	} else {
-		/*
-		 * This shouldn't happen.
-		 */
 		INSIST(0);
+		ISC_UNREACHABLE();
 	}
 
 	if (result != DNS_R_WAIT) {
diff --git a/lib/dns/xfrin.c b/lib/dns/xfrin.c
index 024d6d9d056..f7e5cb3ab51 100644
--- a/lib/dns/xfrin.c
+++ b/lib/dns/xfrin.c
@@ -625,7 +625,7 @@ xfr_rr(dns_xfrin_ctx_t *xfr, dns_name_t *name, uint32_t ttl,
 		/* FALLTHROUGH */
 	default:
 		INSIST(0);
-		break;
+		ISC_UNREACHABLE();
 	}
 	result = ISC_R_SUCCESS;
  failure:
diff --git a/lib/dns/zone.c b/lib/dns/zone.c
index 6b52d102bc9..3f27bfd97a4 100644
--- a/lib/dns/zone.c
+++ b/lib/dns/zone.c
@@ -8982,6 +8982,7 @@ normalize_key(dns_rdata_t *rr, dns_rdata_t *target,
 		break;
 	    default:
 		INSIST(0);
+		ISC_UNREACHABLE();
 	}
 	return (ISC_R_SUCCESS);
 }
@@ -15806,7 +15807,8 @@ got_transfer_quota(isc_task_t *task, isc_event_t *event) {
 		break;
 	default:
 		INSIST(0);
-	};
+		ISC_UNREACHABLE();
+	}
 	UNLOCK_ZONE(zone);
 	INSIST(isc_sockaddr_pf(&masteraddr) == isc_sockaddr_pf(&sourceaddr));
 	result = dns_xfrin_create(zone, xfrtype, &masteraddr, &sourceaddr,
@@ -17259,6 +17261,7 @@ dns_zone_setdialup(dns_zone_t *zone, dns_dialuptype_t dialup) {
 		break;
 	default:
 		INSIST(0);
+		ISC_UNREACHABLE();
 	}
 	UNLOCK_ZONE(zone);
 }
@@ -17334,6 +17337,7 @@ dns_zonemgr_getcount(dns_zonemgr_t *zmgr, int state) {
 		break;
 	default:
 		INSIST(0);
+		ISC_UNREACHABLE();
 	}
 
 	RWUNLOCK(&zmgr->rwlock, isc_rwlocktype_read);
diff --git a/lib/irs/getnameinfo.c b/lib/irs/getnameinfo.c
index 0da6ba1eb9d..676575894a8 100644
--- a/lib/irs/getnameinfo.c
+++ b/lib/irs/getnameinfo.c
@@ -196,6 +196,7 @@ getnameinfo(const struct sockaddr *sa, socklen_t salen,
 
 	default:
 		INSIST(0);
+		ISC_UNREACHABLE();
 	}
 	proto = ((flags & NI_DGRAM) != 0) ? "udp" : "tcp";
 
diff --git a/lib/isc/mem.c b/lib/isc/mem.c
index f08dfc800f3..0b72e41e8d6 100644
--- a/lib/isc/mem.c
+++ b/lib/isc/mem.c
@@ -322,6 +322,7 @@ delete_trace_entry(isc__mem_t *mctx, const void *ptr, size_t size,
 	 * screwed.
 	 */
 	INSIST(0);
+	ISC_UNREACHABLE();
 }
 #endif /* ISC_MEM_TRACKLINES */
 
@@ -2101,6 +2102,7 @@ isc_mem_checkdestroyed(FILE *file) {
 		}
 #endif
 		INSIST(0);
+		ISC_UNREACHABLE();
 	}
 	UNLOCK(&contextslock);
 }
diff --git a/lib/isc/netaddr.c b/lib/isc/netaddr.c
index 56f6f4e08bb..be4e708e6af 100644
--- a/lib/isc/netaddr.c
+++ b/lib/isc/netaddr.c
@@ -346,6 +346,7 @@ isc_netaddr_fromsockaddr(isc_netaddr_t *t, const isc_sockaddr_t *s) {
 #endif
 	default:
 		INSIST(0);
+		ISC_UNREACHABLE();
 	}
 }
 
diff --git a/lib/isc/sockaddr.c b/lib/isc/sockaddr.c
index 2fe1a5ba64f..aa64071213f 100644
--- a/lib/isc/sockaddr.c
+++ b/lib/isc/sockaddr.c
@@ -282,6 +282,7 @@ isc_sockaddr_anyofpf(isc_sockaddr_t *sockaddr, int pf) {
 	     break;
      default:
 	     INSIST(0);
+	     ISC_UNREACHABLE();
      }
 }
 
@@ -359,6 +360,7 @@ isc_sockaddr_fromnetaddr(isc_sockaddr_t *sockaddr, const isc_netaddr_t *na,
 		break;
 	default:
 		INSIST(0);
+		ISC_UNREACHABLE();
 	}
 	ISC_LINK_INIT(sockaddr, link);
 }
diff --git a/lib/isc/unix/interfaceiter.c b/lib/isc/unix/interfaceiter.c
index 3f0f1053c20..acfd65f0a09 100644
--- a/lib/isc/unix/interfaceiter.c
+++ b/lib/isc/unix/interfaceiter.c
@@ -128,7 +128,7 @@ get_addr(unsigned int family, isc_netaddr_t *dst, struct sockaddr *src,
 		break;
 	default:
 		INSIST(0);
-		break;
+		ISC_UNREACHABLE();
 	}
 }
 
diff --git a/lib/isc/unix/net.c b/lib/isc/unix/net.c
index 7d663c2df43..907579413de 100644
--- a/lib/isc/unix/net.c
+++ b/lib/isc/unix/net.c
@@ -513,6 +513,7 @@ cmsgsend(int s, int level, int type, struct addrinfo *res) {
 #endif
 	default:
 		INSIST(0);
+		ISC_UNREACHABLE();
 	}
 
 	if (sendmsg(s, &msg, 0) < 0) {
diff --git a/lib/isc/unix/socket.c b/lib/isc/unix/socket.c
index 0a79e2eeb11..364531e125b 100644
--- a/lib/isc/unix/socket.c
+++ b/lib/isc/unix/socket.c
@@ -1587,6 +1587,7 @@ doio_recv(isc__socket_t *sock, isc_socketevent_t *dev) {
 	case isc_sockettype_fdwatch:
 	default:
 		INSIST(0);
+		ISC_UNREACHABLE();
 	}
 
 	if (sock->type == isc_sockettype_udp) {
@@ -2250,7 +2251,7 @@ opensocket(isc__socketmgr_t *manager, isc__socket_t *sock,
 			 * sockets.
 			 */
 			INSIST(0);
-			break;
+			ISC_UNREACHABLE();
 		}
 	} else {
 		sock->fd = dup(dup_socket->fd);
@@ -2609,6 +2610,7 @@ socket_create(isc_socketmgr_t *manager0, int pf, isc_sockettype_t type,
 		break;
 	default:
 		INSIST(0);
+		ISC_UNREACHABLE();
 	}
 
 	sock->pf = pf;
diff --git a/lib/isc/win32/include/isc/stdatomic.h b/lib/isc/win32/include/isc/stdatomic.h
index e429d0454c1..7a6aec9b5d0 100644
--- a/lib/isc/win32/include/isc/stdatomic.h
+++ b/lib/isc/win32/include/isc/stdatomic.h
@@ -80,7 +80,7 @@ static inline
 void
 atomic_store_abort() {
 	INSIST(0);
-	return;
+	ISC_UNREACHABLE();
 }
 
 #define atomic_store_explicit(obj, desired, order) 		\
@@ -120,7 +120,7 @@ static inline
 int8_t
 atomic_load_abort() {
 	INSIST(0);
-	return (0);
+	ISC_UNREACHABLE();
 }
 
 #define atomic_load_explicit(obj, order)			\
@@ -160,7 +160,7 @@ static inline
 int8_t
 atomic_add_abort() {
 	INSIST(0);
-	return (0);
+	ISC_UNREACHABLE();
 }
 
 #define atomic_fetch_add_explicit(obj, arg, order)		\
@@ -247,7 +247,7 @@ static inline
 bool
 atomic_compare_exchange_abort() {
 	INSIST(0);
-	return (false);
+	ISC_UNREACHABLE();
 }
 
 #define atomic_compare_exchange_strong_explicit(obj, expected, desired, \
diff --git a/lib/isc/win32/interfaceiter.c b/lib/isc/win32/interfaceiter.c
index da6d282b049..6884221b30a 100644
--- a/lib/isc/win32/interfaceiter.c
+++ b/lib/isc/win32/interfaceiter.c
@@ -97,7 +97,7 @@ get_addr(unsigned int family, isc_netaddr_t *dst, struct sockaddr *src) {
 		break;
 	default:
 		INSIST(0);
-		break;
+		ISC_UNREACHABLE();
 	}
 }
 
diff --git a/lib/isccc/sexpr.c b/lib/isccc/sexpr.c
index 68dbe446c7b..bb9565b2fd6 100644
--- a/lib/isccc/sexpr.c
+++ b/lib/isccc/sexpr.c
@@ -202,6 +202,7 @@ isccc_sexpr_print(isccc_sexpr_t *sexpr, FILE *stream) {
 		break;
 	default:
 		INSIST(0);
+		ISC_UNREACHABLE();
 	}
 }
 
diff --git a/lib/isccfg/aclconf.c b/lib/isccfg/aclconf.c
index 02c18209849..47b15060bc0 100644
--- a/lib/isccfg/aclconf.c
+++ b/lib/isccfg/aclconf.c
@@ -389,6 +389,7 @@ get_subtype(const cfg_obj_t *obj, isc_log_t *lctx,
 		return (subtype);
 	default:
 		INSIST(0);
+		ISC_UNREACHABLE();
 	}
 }
 
@@ -583,8 +584,10 @@ parse_geoip_element(const cfg_obj_t *obj, isc_log_t *lctx,
 	} else if (strcasecmp(stype, "netspeed") == 0) {
 		subtype = dns_geoip_netspeed_id;
 		de.geoip_elem.as_int = atoi(search);
-	} else
+	} else {
 		INSIST(0);
+		ISC_UNREACHABLE();
+	}
 
 	de.geoip_elem.subtype = get_subtype(obj, lctx, subtype, dbname);
 
diff --git a/lib/isccfg/namedconf.c b/lib/isccfg/namedconf.c
index 8abd76c6afd..7467b6af391 100644
--- a/lib/isccfg/namedconf.c
+++ b/lib/isccfg/namedconf.c
@@ -3262,12 +3262,14 @@ parse_querysource(cfg_parser_t *pctx, const cfg_type_t *type,
 	unsigned int have_dscp = 0;
 	const unsigned int *flagp = type->of;
 
-	if ((*flagp & CFG_ADDR_V4OK) != 0)
+	if ((*flagp & CFG_ADDR_V4OK) != 0) {
 		isc_netaddr_any(&netaddr);
-	else if ((*flagp & CFG_ADDR_V6OK) != 0)
+	} else if ((*flagp & CFG_ADDR_V6OK) != 0) {
 		isc_netaddr_any6(&netaddr);
-	else
+	} else {
 		INSIST(0);
+		ISC_UNREACHABLE();
+	}
 
 	for (;;) {
 		CHECK(cfg_peektoken(pctx, 0));
@@ -3355,6 +3357,7 @@ doc_querysource(cfg_printer_t *pctx, const cfg_type_t *type) {
 		cfg_print_cstr(pctx, "<ipv6_address>");
 	} else {
 		INSIST(0);
+		ISC_UNREACHABLE();
 	}
 	cfg_print_cstr(pctx, " | * ) [ port ( <integer> | * ) ] ) | "
 		       "( [ [ address ] ( ");
@@ -3364,6 +3367,7 @@ doc_querysource(cfg_printer_t *pctx, const cfg_type_t *type) {
 		cfg_print_cstr(pctx, "<ipv6_address>");
 	} else {
 		INSIST(0);
+		ISC_UNREACHABLE();
 	}
 	cfg_print_cstr(pctx, " | * ) ] port ( <integer> | * ) ) )"
 		       " [ dscp <integer> ]");
@@ -4155,6 +4159,7 @@ cfg_print_zonegrammar(const unsigned int zonetype,
 		break;
 	default:
 		INSIST(0);
+		ISC_UNREACHABLE();
 	}
 
 	for (clause = clauses; clause->name != NULL; clause++) {
diff --git a/lib/isccfg/parser.c b/lib/isccfg/parser.c
index 39c15ab3638..7211d9ef766 100644
--- a/lib/isccfg/parser.c
+++ b/lib/isccfg/parser.c
@@ -368,7 +368,7 @@ cfg_tuple_get(const cfg_obj_t *tupleobj, const char* name) {
 			return (tupleobj->value.tuple[i]);
 	}
 	INSIST(0);
-	return (NULL);
+	ISC_UNREACHABLE();
 }
 
 isc_result_t
@@ -1982,6 +1982,7 @@ cfg_print_mapbody(cfg_printer_t *pctx, const cfg_obj_t *obj) {
 				; /* do nothing */
 			} else {
 				INSIST(0);
+				ISC_UNREACHABLE();
 			}
 		}
 	}
@@ -2297,6 +2298,7 @@ token_addr(cfg_parser_t *pctx, unsigned int flags, isc_netaddr_t *na) {
 			return (ISC_R_SUCCESS);
 		} else {
 			INSIST(0);
+			ISC_UNREACHABLE();
 		}
 	} else {
 		if ((flags & (CFG_ADDR_V4OK | CFG_ADDR_V4PREFIXOK)) != 0) {
@@ -2571,7 +2573,7 @@ cfg_parse_netprefix(cfg_parser_t *pctx, const cfg_type_t *type,
 		break;
 	default:
 		INSIST(0);
-		break;
+		ISC_UNREACHABLE();
 	}
 	CHECK(cfg_peektoken(pctx, 0));
 	if (pctx->token.type == isc_tokentype_special &&
diff --git a/lib/ns/client.c b/lib/ns/client.c
index 6a8d2084989..60929a8dba4 100644
--- a/lib/ns/client.c
+++ b/lib/ns/client.c
@@ -645,6 +645,7 @@ exit_check(ns_client_t *client) {
 		{
 			isc_mem_stats(client->mctx, stderr);
 			INSIST(0);
+			ISC_UNREACHABLE();
 		}
 
 		/*
@@ -1269,7 +1270,7 @@ client_send(ns_client_t *client) {
 			break;
 		default:
 			INSIST(0);
-			break;
+			ISC_UNREACHABLE();
 		}
 	} else {
 #ifdef HAVE_DNSTAP
@@ -1300,7 +1301,7 @@ client_send(ns_client_t *client) {
 			break;
 		default:
 			INSIST(0);
-			break;
+			ISC_UNREACHABLE();
 		}
 	}
 
@@ -1712,6 +1713,7 @@ ns_client_addopt(ns_client_t *client, dns_message_t *message,
 			break;
 		default:
 			INSIST(0);
+			ISC_UNREACHABLE();
 		}
 
 		isc_buffer_init(&buf, ecs, sizeof(ecs));
@@ -1857,6 +1859,7 @@ compute_cookie(ns_client_t *client, uint32_t when, uint32_t nonce,
 			break;
 		default:
 			INSIST(0);
+			ISC_UNREACHABLE();
 		}
 
 		/*
@@ -1872,6 +1875,7 @@ compute_cookie(ns_client_t *client, uint32_t when, uint32_t nonce,
 
 	default:
 		INSIST(0);
+		ISC_UNREACHABLE();
 	}
 }
 
@@ -2431,7 +2435,7 @@ ns__client_request(isc_task_t *task, isc_event_t *event) {
 			break;
 		default:
 			INSIST(0);
-			break;
+			ISC_UNREACHABLE();
 		}
 	} else {
 		switch (isc_sockaddr_pf(&client->peeraddr)) {
@@ -2445,7 +2449,7 @@ ns__client_request(isc_task_t *task, isc_event_t *event) {
 			break;
 		default:
 			INSIST(0);
-			break;
+			ISC_UNREACHABLE();
 		}
 	}
 
diff --git a/lib/ns/query.c b/lib/ns/query.c
index 39e87bca7d7..b1c6255d112 100644
--- a/lib/ns/query.c
+++ b/lib/ns/query.c
@@ -2637,7 +2637,7 @@ rpz_get_zbits(ns_client_t *client,
 		break;
 	default:
 		INSIST(0);
-		break;
+		ISC_UNREACHABLE();
 	}
 
 	/*
@@ -2861,6 +2861,7 @@ rpz_get_p_name(ns_client_t *client, dns_name_t *p_name,
 		break;
 	default:
 		INSIST(0);
+		ISC_UNREACHABLE();
 	}
 
 	/*
@@ -3278,6 +3279,7 @@ dnsrps_rewrite_ip(ns_client_t *client, const isc_netaddr_t *netaddr,
 		break;
 	default:
 		INSIST(0);
+		ISC_UNREACHABLE();
 	}
 
 	do {
@@ -3330,6 +3332,7 @@ dnsrps_rewrite_name(ns_client_t *client, dns_name_t *trig_name,
 		break;
 	default:
 		INSIST(0);
+		ISC_UNREACHABLE();
 	}
 
 	dns_name_toregion(trig_name, &r);
@@ -6459,6 +6462,7 @@ query_checkrpz(query_ctx_t *qctx, isc_result_t result) {
 			return (ISC_R_COMPLETE);
 		default:
 			INSIST(0);
+			ISC_UNREACHABLE();
 		}
 
 		/*
@@ -8281,6 +8285,7 @@ query_nodata(query_ctx_t *qctx, isc_result_t result) {
 			break;
 		default:
 			INSIST(0);
+			ISC_UNREACHABLE();
 		}
 
 		SAVE(qctx->client->query.dns64_aaaa, qctx->rdataset);
@@ -10606,7 +10611,7 @@ query_setup_sortlist(query_ctx_t *qctx) {
 		break;
 	default:
 		INSIST(0);
-		break;
+		ISC_UNREACHABLE();
 	}
 }
 
diff --git a/lib/ns/tests/query_test.c b/lib/ns/tests/query_test.c
index 81818c2d9ba..554893f6427 100644
--- a/lib/ns/tests/query_test.c
+++ b/lib/ns/tests/query_test.c
@@ -379,7 +379,7 @@ ns__query_start_test(const ns__query_start_test_params_t *test) {
 		break;
 	default:
 		INSIST(0);
-		break;
+		ISC_UNREACHABLE();
 	}
 
 	/*
diff --git a/lib/ns/xfrout.c b/lib/ns/xfrout.c
index 04102762094..e6810048076 100644
--- a/lib/ns/xfrout.c
+++ b/lib/ns/xfrout.c
@@ -764,7 +764,7 @@ ns_xfr_start(ns_client_t *client, dns_rdatatype_t reqtype) {
 		break;
 	default:
 		INSIST(0);
-		break;
+		ISC_UNREACHABLE();
 	}
 
 	ns_client_log(client,