Not sure what the heck is wrong with control-center and the fact it fails
to include gdesktop-enums.h. But the other two just need a modern
compiler.

All three build for me like this with gcc15 (but gcc8 should also be able
to do that).
-- 
:wq Claudio

Index: x11/gnome/control-center/Makefile
===================================================================
RCS file: /cvs/ports/x11/gnome/control-center/Makefile,v
diff -u -p -r1.139 Makefile
--- x11/gnome/control-center/Makefile	29 Nov 2025 10:01:30 -0000	1.139
+++ x11/gnome/control-center/Makefile	4 Dec 2025 12:39:08 -0000
@@ -21,6 +21,10 @@ WANTLIB += gtop-2.0 ibus-1.0 intl json-g
 WANTLIB += pulse pulse-mainloop-glib pwquality secret-1 smbclient
 WANTLIB += soup-3.0 upower-glib wayland-client xml2
 
+# base-gcc fails to include gdesktop-enums.h in panels/background
+COMPILER=		base-clang ports-gcc
+COMPILER_LANGS=		c
+
 MODULES=		devel/meson \
 			devel/dconf \
 			security/heimdal \
Index: x11/gnome/ghex/Makefile
===================================================================
RCS file: /cvs/ports/x11/gnome/ghex/Makefile,v
diff -u -p -r1.107 Makefile
--- x11/gnome/ghex/Makefile	5 Nov 2025 08:52:52 -0000	1.107
+++ x11/gnome/ghex/Makefile	4 Dec 2025 12:39:08 -0000
@@ -13,6 +13,10 @@ PERMIT_PACKAGE=		Yes
 WANTLIB += adwaita-1 c cairo gio-2.0 glib-2.0 gmodule-2.0 gobject-2.0
 WANTLIB += gtk-4 intl pango-1.0 pangocairo-1.0
 
+# needs C11 unicode support
+COMPILER=		base-clang ports-gcc
+COMPILER_LANGS=		c
+
 MODULES=		devel/dconf \
 			devel/meson \
 			x11/gnome
Index: x11/gnome/msgraph/Makefile
===================================================================
RCS file: /cvs/ports/x11/gnome/msgraph/Makefile,v
diff -u -p -r1.5 Makefile
--- x11/gnome/msgraph/Makefile	28 Jan 2025 08:54:11 -0000	1.5
+++ x11/gnome/msgraph/Makefile	4 Dec 2025 12:39:08 -0000
@@ -11,6 +11,10 @@ PERMIT_PACKAGE=		Yes
 WANTLIB += gio-2.0 glib-2.0 goa-1.0 gobject-2.0 intl json-glib-1.0
 WANTLIB += soup-3.0
 
+# needs -std=gnu11
+COMPILER=		base-clang ports-gcc
+COMPILER_LANGS=		c
+
 MODULES=		devel/meson \
 			x11/gnome