The compiler flags used to compile postgres modules like
postgresql-ip4r require now ports-gcc since there are a few unknown
extra -W flags passed:

cc1: error: -Werror=vla: No option -Wvla
cc1: error: unrecognized command line option "-Wimplicit-fallthrough=3"
cc1: error: unrecognized command line option "-Wcast-function-type"
cc1: error: unrecognized command line option "-Wshadow=compatible-local"
cc1: error: unrecognized command line option "-fexcess-precision=standard"
cc1: error: unrecognized command line option "-Wno-stringop-truncation"

I hit this before the update to 18. Testing that now.
-- 
:wq Claudio

Index: databases/pg_sqlite_fdw/Makefile
===================================================================
RCS file: /cvs/ports/databases/pg_sqlite_fdw/Makefile,v
diff -u -p -r1.8 Makefile
--- databases/pg_sqlite_fdw/Makefile	23 Nov 2025 03:09:57 -0000	1.8
+++ databases/pg_sqlite_fdw/Makefile	24 Nov 2025 21:36:39 -0000
@@ -16,6 +16,9 @@ PERMIT_PACKAGE =	Yes
 
 WANTLIB =		c sqlite3
 
+COMPILER =		base-clang ports-gcc
+COMPILER_LANGS =	c
+
 BUILD_DEPENDS =		databases/postgresql,-server
 RUN_DEPENDS =		databases/postgresql,-server
 LIB_DEPENDS =		databases/sqlite3
Index: databases/pgpool/Makefile
===================================================================
RCS file: /cvs/ports/databases/pgpool/Makefile,v
diff -u -p -r1.19 Makefile
--- databases/pgpool/Makefile	30 May 2025 08:28:24 -0000	1.19
+++ databases/pgpool/Makefile	24 Nov 2025 15:14:56 -0000
@@ -17,6 +17,9 @@ SITES=			https://www.pgpool.net/mediawik
 
 WANTLIB= 		c crypto m pq ssl pthread
 
+COMPILER=		base-clang ports-gcc
+COMPILER_LANG=		c
+
 CONFIGURE_STYLE= 	gnu
 CONFIGURE_ARGS= 	--with-openssl
 
Index: databases/postgresql-ip4r/Makefile
===================================================================
RCS file: /cvs/ports/databases/postgresql-ip4r/Makefile,v
diff -u -p -r1.1.1.1 Makefile
--- databases/postgresql-ip4r/Makefile	13 May 2022 12:21:45 -0000	1.1.1.1
+++ databases/postgresql-ip4r/Makefile	24 Nov 2025 15:55:08 -0000
@@ -14,6 +14,9 @@ CATEGORIES=	databases net
 # PostgreSQL license (BSD)
 PERMIT_PACKAGE=	Yes
 
+COMPILER=	base-clang ports-gcc
+COMPILER_LANGS=	c
+
 WANTLIB += c
 
 USE_GMAKE=	Yes
Index: databases/postgresql-pllua/Makefile
===================================================================
RCS file: /cvs/ports/databases/postgresql-pllua/Makefile,v
diff -u -p -r1.26 Makefile
--- databases/postgresql-pllua/Makefile	23 Nov 2025 03:07:39 -0000	1.26
+++ databases/postgresql-pllua/Makefile	24 Nov 2025 21:36:40 -0000
@@ -22,6 +22,9 @@ PERMIT_PACKAGE =	Yes
 
 WANTLIB =		c ${MODLUA_WANTLIB}
 
+COMPILER =		base-clang ports-gcc
+COMPILER_LANGS =	c
+
 MODULES =		lang/lua
 MODLUA_VERSION =	5.3
 
Index: databases/postgresql-plr/Makefile
===================================================================
RCS file: /cvs/ports/databases/postgresql-plr/Makefile,v
diff -u -p -r1.10 Makefile
--- databases/postgresql-plr/Makefile	19 Mar 2025 08:55:48 -0000	1.10
+++ databases/postgresql-plr/Makefile	24 Nov 2025 18:41:47 -0000
@@ -14,6 +14,9 @@ PERMIT_PACKAGE =	Yes
 
 WANTLIB =		c lib/R/lib/R
 
+COMPILER =		base-clang ports-gcc
+COMPILER_LANGS =	c
+
 BUILD_DEPENDS =		databases/postgresql,-server
 RUN_DEPENDS =		databases/postgresql,-server
 LIB_DEPENDS =		math/R