error: cannot combine with previous 'type-name' declaration specifier gboolean bool

[Schamschula]

While building nip2 under FreeBSD14.0-CURRENT, I get the following error

gmake[5]: Entering directory '/usr/ports/graphics/nip2/work/nip2-8.7.1/src'
cc -DHAVE_CONFIG_H -I. -I..  -I/usr/local/include   -I/usr/local/include/graphviz     -I/usr/local/include/libgsf-1 -I/usr/local/include/glib-2.0 -I/usr/local/lib/glib-2.0/include -I/usr/local/include -I/usr/local/include/libxml2    -I/usr/local/include  -I/usr/local/include -I/usr/local/include/glib-2.0 -I/usr/local/lib/glib-2.0/include -I/usr/local/include/gtk-2.0 -I/usr/local/include/pango-1.0 -I/usr/local/include/harfbuzz -I/usr/local/include/freetype2 -I/usr/local/include/fribidi -I/usr/local/include/cairo -I/usr/local/include/pixman-1 -I/usr/local/include/libpng16 -I/usr/local/include/gdk-pixbuf-2.0 -I/usr/local/include/atk-1.0 -I/usr/local/include/libxml2 -I/usr/local/include/libgsf-1 -I/usr/local/include/ImageMagick-7 -DMAGICKCORE_HDRI_ENABLE=1 -DMAGICKCORE_QUANTUM_DEPTH=16 -I/usr/local/include/orc-0.4 -I/usr/local/include/OpenEXR -I/usr/local/include/Imath -I/usr/local/include/openjpeg-2.4 -I/usr/local/include/libvmaf -DHWY_SHARED_DEFINE -I/usr/local/include/rav1e -I/usr/local/include/poppler/glib -I/usr/local/include/poppler -I/usr/local/include/librsvg-2.0 -D_THREAD_SAFE -pthread   -DG_DISABLE_ASSERT -DG_DISABLE_CHECKS     -O2 -pipe  -fstack-protector-strong -fno-strict-aliasing  -MT nip2-vipsobject.o -MD -MP -MF .deps/nip2-vipsobject.Tpo -c -o nip2-vipsobject.o `test -f 'vipsobject.c' || echo './'`vipsobject.c
In file included from vipsobject.c:30:
In file included from ./ip.h:129:
In file included from /usr/local/include/gtk-2.0/gtk/gtk.h:33:
In file included from /usr/local/include/gtk-2.0/gtk/gtkaboutdialog.h:32:
In file included from /usr/local/include/gtk-2.0/gtk/gtkdialog.h:35:
In file included from /usr/local/include/gtk-2.0/gtk/gtkwindow.h:36:
In file included from /usr/local/include/gtk-2.0/gtk/gtkbin.h:35:
In file included from /usr/local/include/gtk-2.0/gtk/gtkcontainer.h:35:
In file included from /usr/local/include/gtk-2.0/gtk/gtkwidget.h:36:
In file included from /usr/local/include/gtk-2.0/gtk/gtkobject.h:37:
/usr/local/include/gtk-2.0/gtk/gtktypeutils.h:236:34: warning: 'GTypeDebugFlags' is deprecated [-Wdeprecated-declarations]
void            gtk_type_init   (GTypeDebugFlags    debug_flags);
                                 ^
/usr/local/include/glib-2.0/gobject/gtype.h:704:19: note: 'GTypeDebugFlags' has been explicitly marked deprecated here
} GTypeDebugFlags GLIB_DEPRECATED_TYPE_IN_2_36;
                  ^
/usr/local/include/glib-2.0/glib/gversionmacros.h:548:49: note: expanded from macro 'GLIB_DEPRECATED_TYPE_IN_2_36'
# define GLIB_DEPRECATED_TYPE_IN_2_36           GLIB_DEPRECATED_TYPE
                                                ^
/usr/local/include/glib-2.0/glib/gmacros.h:1179:30: note: expanded from macro 'GLIB_DEPRECATED_TYPE'
#define GLIB_DEPRECATED_TYPE G_DEPRECATED
                             ^
/usr/local/include/glib-2.0/glib/gmacros.h:1102:37: note: expanded from macro 'G_DEPRECATED'
#define G_DEPRECATED __attribute__((__deprecated__))
                                    ^
In file included from vipsobject.c:30:
In file included from ./ip.h:129:
In file included from /usr/local/include/gtk-2.0/gtk/gtk.h:126:
In file included from /usr/local/include/gtk-2.0/gtk/gtkmenutoolbutton.h:30:
In file included from /usr/local/include/gtk-2.0/gtk/gtktoolbutton.h:30:
In file included from /usr/local/include/gtk-2.0/gtk/gtktoolitem.h:31:
/usr/local/include/gtk-2.0/gtk/gtktooltips.h:73:3: warning: 'GTimeVal' is deprecated: Use 'GDateTime' instead [-Wdeprecated-declarations]
  GTimeVal last_popdown;
  ^
/usr/local/include/glib-2.0/glib/gtypes.h:545:35: note: 'GTimeVal' has been explicitly marked deprecated here
typedef struct _GTimeVal GTimeVal GLIB_DEPRECATED_TYPE_IN_2_62_FOR(GDateTime);
                                  ^
/usr/local/include/glib-2.0/glib/gversionmacros.h:961:49: note: expanded from macro 'GLIB_DEPRECATED_TYPE_IN_2_62_FOR'
# define GLIB_DEPRECATED_TYPE_IN_2_62_FOR(f)    GLIB_DEPRECATED_TYPE_FOR(f)
                                                ^
/usr/local/include/glib-2.0/glib/gmacros.h:1180:37: note: expanded from macro 'GLIB_DEPRECATED_TYPE_FOR'
#define GLIB_DEPRECATED_TYPE_FOR(f) G_DEPRECATED_FOR(f)
                                    ^
/usr/local/include/glib-2.0/glib/gmacros.h:1112:44: note: expanded from macro 'G_DEPRECATED_FOR'
#define G_DEPRECATED_FOR(f) __attribute__((__deprecated__("Use '" #f "' instead")))
                                           ^
In file included from vipsobject.c:30:
In file included from ./ip.h:372:
./tree.h:129:12: error: cannot combine with previous 'type-name' declaration specifier
                gboolean bool;
                         ^
/usr/include/stdbool.h:39:14: note: expanded from macro 'bool'
#define bool    _Bool
                ^
In file included from vipsobject.c:30:
In file included from ./ip.h:372:
./tree.h:129:3: warning: declaration does not declare anything [-Wmissing-declarations]
                gboolean bool;
                ^~~~~~~~~~~~~
3 warnings and 1 error generated.
gmake[5]: *** [Makefile:955: nip2-vipsobject.o] Error 1