#194 xfig: incompatible with GCC 15 C23 standard

[Roland Rosenfeld]

Debian bug report #1098137 reports that current xfig does not compile with GCC 15, which uses to C23 standard.
According to the bug report http://gcc.gnu.org/gcc-15/porting_to.html should give some hints for porting to GCC 15 / C23.
The build log at http://qa-logs.debian.net/2025/02/16/amd64exp/xfig_3.2.9a-2_unstable_gccexp.log.gz shows the following errors:

d_arcbox.c:48:25: error: assignment to ‘void (*)(void)’ from incompatible pointer type ‘void (*)(int,  int)’ [-Wincompatible-pointer-types]
   48 |     canvas_leftbut_proc = init_arc_box_drawing;
      |                         ^
d_arcbox.c:38:17: note: ‘init_arc_box_drawing’ declared here
   38 | static void     init_arc_box_drawing(int x, int y);
      |                 ^~~~~~~~~~~~~~~~~~~~
d_arcbox.c: In function ‘init_arc_box_drawing’:
d_arcbox.c:62:25: error: assignment to ‘void (*)(void)’ from incompatible pointer type ‘void (*)(int,  int)’ [-Wincompatible-pointer-types]
   62 |     canvas_locmove_proc = resizing_box;
      |                         ^
In file included from d_arcbox.c:25:
u_elastic.h:55:17: note: ‘resizing_box’ declared here
   55 | extern void     resizing_box(int x, int y);
      |                 ^~~~~~~~~~~~
d_arcbox.c:63:25: error: assignment to ‘void (*)(void)’ from incompatible pointer type ‘void (*)(int,  int)’ [-Wincompatible-pointer-types]
   63 |     canvas_leftbut_proc = create_arc_boxobject;
      |                         ^
d_arcbox.c:36:17: note: ‘create_arc_boxobject’ declared here
   36 | static void     create_arc_boxobject(int x, int y);
      |                 ^~~~~~~~~~~~~~~~~~~~
d_spline.c: In function ‘spline_drawing_selected’:
d_spline.c:56:25: error: assignment to ‘void (*)(void)’ from incompatible pointer type ‘void (*)(int,  int)’ [-Wincompatible-pointer-types]
   56 |     canvas_leftbut_proc = init_spline_drawing;
      |                         ^
d_spline.c:43:17: note: ‘init_spline_drawing’ declared here
   43 | static void     init_spline_drawing(int x, int y);
      |                 ^~~~~~~~~~~~~~~~~~~
d_spline.c:57:27: error: assignment to ‘void (*)(void)’ from incompatible pointer type ‘void (*)(int,  int)’ [-Wincompatible-pointer-types]
   57 |     canvas_middlebut_proc = init_spline_freehand_drawing;
      |                           ^
d_spline.c:45:17: note: ‘init_spline_freehand_drawing’ declared here
   45 | static void     init_spline_freehand_drawing(int x, int y);
      |                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
d_spline.c: In function ‘init_spline_drawing2’:
d_spline.c:83:31: error: assignment to ‘void (*)(void)’ from incompatible pointer type ‘void (*)(int,  int)’ [-Wincompatible-pointer-types]
   83 |         canvas_middlebut_proc = create_splineobject;
      |                               ^
d_spline.c:44:17: note: ‘create_splineobject’ declared here
   44 | static void     create_splineobject(int x, int y);
      |                 ^~~~~~~~~~~~~~~~~~~
d_spline.c:87:31: error: assignment to ‘void (*)(void)’ from incompatible pointer type ‘void (*)(int,  int)’ [-Wincompatible-pointer-types]
   87 |         canvas_middlebut_save = create_splineobject;
      |                               ^
d_spline.c:44:17: note: ‘create_splineobject’ declared here
   44 | static void     create_splineobject(int x, int y);
      |                 ^~~~~~~~~~~~~~~~~~~
d_picobj.c: In function ‘picobj_drawing_selected’:
d_box.c: In function ‘box_drawing_selected’:
d_box.c:48:25: error: assignment to ‘void (*)(void)’ from incompatible pointer type ‘void (*)(int,  int)’ [-Wincompatible-pointer-types]
   48 |     canvas_leftbut_proc = init_box_drawing;
      |                         ^
In file included from d_box.c:18:
d_box.h:19:17: note: ‘init_box_drawing’ declared here
   19 | extern void     init_box_drawing(int x, int y);
      |                 ^~~~~~~~~~~~~~~~
d_picobj.c:53:25: error: assignment to ‘void (*)(void)’ from incompatible pointer type ‘void (*)(int,  int)’ [-Wincompatible-pointer-types]
   53 |     canvas_leftbut_proc = init_picobj_drawing;
      |                         ^
d_picobj.c:41:17: note: ‘init_picobj_drawing’ declared here
   41 | static void     init_picobj_drawing(int x, int y);
      |                 ^~~~~~~~~~~~~~~~~~~
d_box.c: In function ‘init_box_drawing’:
d_picobj.c: In function ‘init_picobj_drawing’:
d_picobj.c:64:25: error: assignment to ‘void (*)(void)’ from incompatible pointer type ‘void (*)(int,  int)’ [-Wincompatible-pointer-types]
   64 |     canvas_leftbut_proc = create_picobj;
      |                         ^
d_picobj.c:42:17: note: ‘create_picobj’ declared here
   42 | static void     create_picobj(int x, int y);
      |                 ^~~~~~~~~~~~~
d_box.c:62:25: error: assignment to ‘void (*)(void)’ from incompatible pointer type ‘void (*)(int,  int)’ [-Wincompatible-pointer-types]
   62 |     canvas_locmove_proc = resizing_box;
      |                         ^
In file included from d_box.c:27:
u_elastic.h:55:17: note: ‘resizing_box’ declared here
   55 | extern void     resizing_box(int x, int y);
      |                 ^~~~~~~~~~~~
d_box.c:63:25: error: assignment to ‘void (*)(void)’ from incompatible pointer type ‘void (*)(int,  int)’ [-Wincompatible-pointer-types]
   63 |     canvas_leftbut_proc = create_boxobject;
      |                         ^
d_box.c:37:17: note: ‘create_boxobject’ declared here
   37 | static void     create_boxobject(int x, int y);
      |                 ^~~~~~~~~~~~~~~~
make[4]: *** [Makefile:884: d_arcbox.o] Error 1
make[4]: *** Waiting for unfinished jobs....
make[4]: *** [Makefile:884: d_spline.o] Error 1
make[4]: *** [Makefile:884: d_box.o] Error 1
make[4]: *** [Makefile:884: d_picobj.o] Error 1
d_line.c: In function ‘line_drawing_selected’:
d_line.c:58:25: error: assignment to ‘void (*)(void)’ from incompatible pointer type ‘void (*)(int,  int,  int)’ [-Wincompatible-pointer-types]
   58 |     canvas_leftbut_proc = init_line_drawing;
      |                         ^
d_line.c:47:21: note: ‘init_line_drawing’ declared here
   47 | static void         init_line_drawing(int x, int y, int shift);
      |                     ^~~~~~~~~~~~~~~~~
d_line.c:59:27: error: assignment to ‘void (*)(void)’ from incompatible pointer type ‘void (*)(int,  int)’ [-Wincompatible-pointer-types]
   59 |     canvas_middlebut_proc = init_line_freehand_drawing;
      |                           ^
d_line.c:48:21: note: ‘init_line_freehand_drawing’ declared here
   48 | static void         init_line_freehand_drawing(int x, int y);
      |                     ^~~~~~~~~~~~~~~~~~~~~~~~~~
d_line.c:71:30: error: assignment to ‘void (*)(void)’ from incompatible pointer type ‘void (*)(int,  int)’ [-Wincompatible-pointer-types]
   71 |         canvas_rightbut_proc = create_lineobject;
      |                              ^
In file included from d_line.c:19:
d_line.h:25:17: note: ‘create_lineobject’ declared here
   25 | extern void     create_lineobject(int x, int y);
      |                 ^~~~~~~~~~~~~~~~~
d_line.c: In function ‘init_trace_drawing’:
d_line.c:124:25: error: assignment to ‘void (*)(void)’ from incompatible pointer type ‘void (*)(int,  int,  int)’ [-Wincompatible-pointer-types]
  124 |     canvas_leftbut_proc = get_intermediatepoint;
      |                         ^
d_line.h:26:17: note: ‘get_intermediatepoint’ declared here
   26 | extern void     get_intermediatepoint(int x, int y, int shift);
      |                 ^~~~~~~~~~~~~~~~~~~~~
d_line.c:126:29: error: assignment to ‘void (*)(void)’ from incompatible pointer type ‘void (*)(int,  int)’ [-Wincompatible-pointer-types]
  126 |         canvas_locmove_proc = freehand_get_intermediatepoint;
      |                             ^
d_line.h:27:17: note: ‘freehand_get_intermediatepoint’ declared here
   27 | extern void     freehand_get_intermediatepoint(int x, int y);
      |                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
d_line.c:130:33: error: assignment to ‘void (*)(void)’ from incompatible pointer type ‘void (*)(int,  int)’ [-Wincompatible-pointer-types]
  130 |             canvas_leftbut_proc = create_lineobject;
      |                                 ^
d_line.h:25:17: note: ‘create_lineobject’ declared here
   25 | extern void     create_lineobject(int x, int y);
      |                 ^~~~~~~~~~~~~~~~~
d_line.c:132:33: error: assignment to ‘void (*)(void)’ from incompatible pointer type ‘void (*)(int,  int)’ [-Wincompatible-pointer-types]
  132 |             canvas_locmove_proc = latex_line;
      |                                 ^
In file included from d_line.c:30:
u_elastic.h:78:17: note: ‘latex_line’ declared here
   78 | extern void     latex_line(int x, int y);
      |                 ^~~~~~~~~~
d_line.c:134:33: error: assignment to ‘void (*)(void)’ from incompatible pointer type ‘void (*)(int,  int)’ [-Wincompatible-pointer-types]
  134 |             canvas_locmove_proc = constrainedangle_line;
      |                                 ^
u_elastic.h:79:17: note: ‘constrainedangle_line’ declared here
   79 | extern void     constrainedangle_line(int x, int y);
      |                 ^~~~~~~~~~~~~~~~~~~~~
d_line.c:136:33: error: assignment to ‘void (*)(void)’ from incompatible pointer type ‘void (*)(int,  int)’ [-Wincompatible-pointer-types]
  136 |             canvas_locmove_proc = unconstrained_line;
      |                                 ^
u_elastic.h:77:17: note: ‘unconstrained_line’ declared here
   77 | extern void     unconstrained_line(int x, int y);
      |                 ^~~~~~~~~~~~~~~~~~
d_line.c:139:27: error: assignment to ‘void (*)(void)’ from incompatible pointer type ‘void (*)(int,  int)’ [-Wincompatible-pointer-types]
  139 |     canvas_middlebut_save = create_lineobject;
      |                           ^
d_line.h:25:17: note: ‘create_lineobject’ declared here
   25 | extern void     create_lineobject(int x, int y);
      |                 ^~~~~~~~~~~~~~~~~
d_line.c: In function ‘get_intermediatepoint’:
d_line.c:186:10: error: too many arguments to function ‘canvas_locmove_proc’; expected 0, have 2
  186 |         (*canvas_locmove_proc) (x, y);
      |         ~^~~~~~~~~~~~~~~~~~~~~  ~
d_arc.c: In function ‘arc_drawing_selected’:
d_arc.c:79:25: error: assignment to ‘void (*)(void)’ from incompatible pointer type ‘void (*)(int,  int)’ [-Wincompatible-pointer-types]
   79 |     canvas_leftbut_proc = init_arc_drawing;
      |                         ^
d_arc.c:60:17: note: ‘init_arc_drawing’ declared here
   60 | static void     init_arc_drawing(int x, int y);
      |                 ^~~~~~~~~~~~~~~~
d_arc.c:80:27: error: assignment to ‘void (*)(void)’ from incompatible pointer type ‘void (*)(int,  int)’ [-Wincompatible-pointer-types]
   80 |     canvas_middlebut_proc = init_arc_c_drawing;
      |                           ^
d_arc.c:62:17: note: ‘init_arc_c_drawing’ declared here
   62 | static void     init_arc_c_drawing(int x, int y);
      |                 ^~~~~~~~~~~~~~~~~~
d_arc.c: In function ‘init_arc_drawing’:
d_arc.c:108:29: error: assignment to ‘void (*)(void)’ from incompatible pointer type ‘void (*)(int,  int)’ [-Wincompatible-pointer-types]
  108 |         canvas_locmove_proc = resizing_arc;
      |                             ^
d_arc.c:63:17: note: ‘resizing_arc’ declared here
   63 | static void     resizing_arc(int x, int y);
      |                 ^~~~~~~~~~~~
d_arc.c:118:29: error: assignment to ‘void (*)(void)’ from incompatible pointer type ‘void (*)(int,  int)’ [-Wincompatible-pointer-types]
  118 |         canvas_locmove_proc = unconstrained_line;
      |                             ^
In file included from d_arc.c:36:
u_elastic.h:77:17: note: ‘unconstrained_line’ declared here
   77 | extern void     unconstrained_line(int x, int y);
      |                 ^~~~~~~~~~~~~~~~~~
d_arc.c:121:25: error: assignment to ‘void (*)(void)’ from incompatible pointer type ‘void (*)(int,  int)’ [-Wincompatible-pointer-types]
  121 |     canvas_leftbut_proc = get_arcpoint;
      |                         ^
d_arc.c:59:17: note: ‘get_arcpoint’ declared here
   59 | static void     get_arcpoint(int x, int y);
      |                 ^~~~~~~~~~~~
d_arc.c: In function ‘init_arc_c_drawing’:
d_arc.c:132:25: error: assignment to ‘void (*)(void)’ from incompatible pointer type ‘void (*)(int,  int)’ [-Wincompatible-pointer-types]
  132 |     canvas_locmove_proc = resizing_cbr;
      |                         ^
u_elastic.h:67:17: note: ‘resizing_cbr’ declared here
   67 | extern void     resizing_cbr(int x, int y), elastic_cbr(void), resizing_cbd(int x, int y), elastic_cbd(void);
      |                 ^~~~~~~~~~~~
d_arc.c: In function ‘get_arcpoint’:
d_arc.c:189:29: error: assignment to ‘void (*)(void)’ from incompatible pointer type ‘void (*)(int,  int)’ [-Wincompatible-pointer-types]
  189 |         canvas_leftbut_proc = create_arcobject;
      |                             ^
d_arc.c:58:17: note: ‘create_arcobject’ declared here
   58 | static void     create_arcobject(int lx, int ly);
      |                 ^~~~~~~~~~~~~~~~
d_ellipse.c: In function ‘circle_ellipse_byradius_drawing_selected’:
d_ellipse.c:59:25: error: assignment to ‘void (*)(void)’ from incompatible pointer type ‘void (*)(int,  int)’ [-Wincompatible-pointer-types]
   59 |     canvas_leftbut_proc = init_circlebyradius_drawing;
      |                         ^
d_ellipse.c:41:17: note: ‘init_circlebyradius_drawing’ declared here
   41 | static void     init_circlebyradius_drawing(int x, int y);
      |                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~
d_ellipse.c:60:27: error: assignment to ‘void (*)(void)’ from incompatible pointer type ‘void (*)(int,  int)’ [-Wincompatible-pointer-types]
   60 |     canvas_middlebut_proc = init_ellipsebyradius_drawing;
      |                           ^
d_ellipse.c:39:17: note: ‘init_ellipsebyradius_drawing’ declared here
   39 | static void     init_ellipsebyradius_drawing(int x, int y);
      |                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
d_regpoly.c: In function ‘regpoly_drawing_selected’:
d_regpoly.c:52:25: error: assignment to ‘void (*)(void)’ from incompatible pointer type ‘void (*)(int,  int)’ [-Wincompatible-pointer-types]
   52 |     canvas_leftbut_proc = init_regpoly_drawing;
      |                         ^
d_regpoly.c:40:17: note: ‘init_regpoly_drawing’ declared here
   40 | static void     init_regpoly_drawing(int x, int y);
      |                 ^~~~~~~~~~~~~~~~~~~~
d_ellipse.c: In function ‘init_ellipsebyradius_drawing’:
d_ellipse.c:77:25: error: assignment to ‘void (*)(void)’ from incompatible pointer type ‘void (*)(int,  int)’ [-Wincompatible-pointer-types]
   77 |     canvas_locmove_proc = resizing_ebr;
      |                         ^
In file included from d_ellipse.c:28:
u_elastic.h:68:17: note: ‘resizing_ebr’ declared here
   68 | extern void     resizing_ebr(int x, int y), elastic_ebr(void), resizing_ebd(int x, int y), elastic_ebd(void);
      |                 ^~~~~~~~~~~~
d_regpoly.c: In function ‘init_regpoly_drawing’:
d_ellipse.c:78:25: error: assignment to ‘void (*)(void)’ from incompatible pointer type ‘void (*)(int,  int)’ [-Wincompatible-pointer-types]
   78 |     canvas_leftbut_proc = create_ellipsebyrad;
      |                         ^
d_regpoly.c:67:25: error: assignment to ‘void (*)(void)’ from incompatible pointer type ‘void (*)(int,  int)’ [-Wincompatible-pointer-types]
   67 |     canvas_locmove_proc = resizing_poly;
      |                         ^
d_ellipse.c:44:17: note: ‘create_ellipsebyrad’ declared here
   44 | static void     create_ellipsebyrad(int x, int y);
      |                 ^~~~~~~~~~~~~~~~~~~
In file included from d_regpoly.c:28:
u_elastic.h:62:17: note: ‘resizing_poly’ declared here
   62 | extern void     resizing_poly(int x, int y);
      |                 ^~~~~~~~~~~~~
d_ellipse.c:79:27: error: assignment to ‘void (*)(void)’ from incompatible pointer type ‘void (*)(int,  int)’ [-Wincompatible-pointer-types]
   79 |     canvas_middlebut_proc = create_ellipsebyrad;
      |                           ^
d_regpoly.c:68:25: error: assignment to ‘void (*)(void)’ from incompatible pointer type ‘void (*)(int,  int)’ [-Wincompatible-pointer-types]
   68 |     canvas_leftbut_proc = create_regpoly;
      |                         ^
d_ellipse.c:44:17: note: ‘create_ellipsebyrad’ declared here
   44 | static void     create_ellipsebyrad(int x, int y);
      |                 ^~~~~~~~~~~~~~~~~~~
d_regpoly.c:41:17: note: ‘create_regpoly’ declared here
   41 | static void     create_regpoly(int x, int y);
      |                 ^~~~~~~~~~~~~~
d_ellipse.c: In function ‘circle_ellipse_bydiameter_drawing_selected’:
d_ellipse.c:138:25: error: assignment to ‘void (*)(void)’ from incompatible pointer type ‘void (*)(int,  int)’ [-Wincompatible-pointer-types]
  138 |     canvas_leftbut_proc = init_circlebydiameter_drawing;
      |                         ^
d_ellipse.c:42:17: note: ‘init_circlebydiameter_drawing’ declared here
   42 | static void     init_circlebydiameter_drawing(int x, int y);
      |                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
d_ellipse.c:139:27: error: assignment to ‘void (*)(void)’ from incompatible pointer type ‘void (*)(int,  int)’ [-Wincompatible-pointer-types]
  139 |     canvas_middlebut_proc = init_ellipsebydiameter_drawing;
      |                           ^
d_ellipse.c:40:17: note: ‘init_ellipsebydiameter_drawing’ declared here
   40 | static void     init_ellipsebydiameter_drawing(int x, int y);
      |                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
d_ellipse.c: In function ‘init_ellipsebydiameter_drawing’:
d_ellipse.c:155:25: error: assignment to ‘void (*)(void)’ from incompatible pointer type ‘void (*)(int,  int)’ [-Wincompatible-pointer-types]
  155 |     canvas_locmove_proc = resizing_ebd;
      |                         ^
u_elastic.h:68:64: note: ‘resizing_ebd’ declared here
   68 | extern void     resizing_ebr(int x, int y), elastic_ebr(void), resizing_ebd(int x, int y), elastic_ebd(void);
      |                                                                ^~~~~~~~~~~~
d_ellipse.c:156:25: error: assignment to ‘void (*)(void)’ from incompatible pointer type ‘void (*)(int,  int)’ [-Wincompatible-pointer-types]
  156 |     canvas_leftbut_proc = create_ellipsebydia;
      |                         ^
d_ellipse.c:43:17: note: ‘create_ellipsebydia’ declared here
   43 | static void     create_ellipsebydia(int x, int y);
      |                 ^~~~~~~~~~~~~~~~~~~
d_ellipse.c:157:27: error: assignment to ‘void (*)(void)’ from incompatible pointer type ‘void (*)(int,  int)’ [-Wincompatible-pointer-types]
  157 |     canvas_middlebut_proc = create_ellipsebydia;
      |                           ^
d_ellipse.c:43:17: note: ‘create_ellipsebydia’ declared here
   43 | static void     create_ellipsebydia(int x, int y);
      |                 ^~~~~~~~~~~~~~~~~~~
d_ellipse.c: In function ‘init_circlebyradius_drawing’:
d_ellipse.c:222:25: error: assignment to ‘void (*)(void)’ from incompatible pointer type ‘void (*)(int,  int)’ [-Wincompatible-pointer-types]
  222 |     canvas_locmove_proc = resizing_cbr;
      |                         ^
u_elastic.h:67:17: note: ‘resizing_cbr’ declared here
   67 | extern void     resizing_cbr(int x, int y), elastic_cbr(void), resizing_cbd(int x, int y), elastic_cbd(void);
      |                 ^~~~~~~~~~~~
d_ellipse.c:223:25: error: assignment to ‘void (*)(void)’ from incompatible pointer type ‘void (*)(int,  int)’ [-Wincompatible-pointer-types]
  223 |     canvas_leftbut_proc = create_circlebyrad;
      |                         ^
d_ellipse.c:45:17: note: ‘create_circlebyrad’ declared here
   45 | static void     create_circlebyrad(int x, int y);
      |                 ^~~~~~~~~~~~~~~~~~
make[4]: *** [Makefile:884: d_line.o] Error 1
d_ellipse.c: In function ‘init_circlebydiameter_drawing’:
d_ellipse.c:289:25: error: assignment to ‘void (*)(void)’ from incompatible pointer type ‘void (*)(int,  int)’ [-Wincompatible-pointer-types]
  289 |     canvas_locmove_proc = resizing_cbd;
      |                         ^
u_elastic.h:67:64: note: ‘resizing_cbd’ declared here
   67 | extern void     resizing_cbr(int x, int y), elastic_cbr(void), resizing_cbd(int x, int y), elastic_cbd(void);
      |                                                                ^~~~~~~~~~~~
d_ellipse.c:290:25: error: assignment to ‘void (*)(void)’ from incompatible pointer type ‘void (*)(int,  int)’ [-Wincompatible-pointer-types]
  290 |     canvas_leftbut_proc = create_circlebydia;
      |                         ^
d_ellipse.c:46:17: note: ‘create_circlebydia’ declared here
   46 | static void     create_circlebydia(int x, int y);
      |                 ^~~~~~~~~~~~~~~~~~

[Roland Rosenfeld]

I just noticed, that Mario Haustein already fixed the prototypes in GIT.
But when I try to build the GIT version with GCC-15, I still run into the following error:

main.c:123:17: error: expected identifier or '(' before 'true'
  123 | static Boolean  true = True;
      |                 ^~~~
main.c:124:17: error: expected identifier or '(' before 'false'
  124 | static Boolean  false = False;
      |                 ^~~~~
main.c:198:66: error: lvalue required as unary '&' operand
  198 |       XtOffset(appresPtr, allownegcoords), XtRBoolean, (caddr_t) & true},
      |                                                                  ^
main.c:200:65: error: lvalue required as unary '&' operand
  200 |       XtOffset(appresPtr, showaxislines), XtRBoolean, (caddr_t) & true},
      |                                                                 ^
main.c:202:62: error: lvalue required as unary '&' operand
  202 |       XtOffset(appresPtr, smallicons), XtRBoolean, (caddr_t) & false},
      |                                                              ^
main.c:210:66: error: lvalue required as unary '&' operand
  210 |       XtOffset(appresPtr, showallbuttons), XtRBoolean, (caddr_t) & false},
      |                                                                  ^
main.c:212:61: error: lvalue required as unary '&' operand
  212 |       XtOffset(appresPtr, RHS_PANEL), XtRBoolean, (caddr_t) & false},
      |                                                             ^
main.c:214:61: error: lvalue required as unary '&' operand
  214 |       XtOffset(appresPtr, landscape), XtRBoolean, (caddr_t) & true},
      |                                                             ^
main.c:220:60: error: lvalue required as unary '&' operand
  220 |       XtOffset(appresPtr, tracking), XtRBoolean, (caddr_t) & true},
      |                                                            ^
main.c:222:58: error: lvalue required as unary '&' operand
  222 |       XtOffset(appresPtr, INCHES), XtRBoolean, (caddr_t) & true},
      |                                                          ^
main.c:260:62: error: lvalue required as unary '&' operand
  260 |       XtOffset(appresPtr, latexfonts), XtRBoolean, (caddr_t) & false},
      |                                                              ^
main.c:262:62: error: lvalue required as unary '&' operand
  262 |       XtOffset(appresPtr, hiddentext), XtRBoolean, (caddr_t) & false},
      |                                                              ^
main.c:264:61: error: lvalue required as unary '&' operand
  264 |       XtOffset(appresPtr, rigidtext), XtRBoolean, (caddr_t) & false},
      |                                                             ^
main.c:266:63: error: lvalue required as unary '&' operand
  266 |       XtOffset(appresPtr, specialtext), XtRBoolean, (caddr_t) & false},
      |                                                               ^
main.c:268:62: error: lvalue required as unary '&' operand
  268 |       XtOffset(appresPtr, monochrome), XtRBoolean, (caddr_t) & false},
      |                                                              ^
main.c:270:62: error: lvalue required as unary '&' operand
  270 |       XtOffset(appresPtr, latexfonts), XtRBoolean, (caddr_t) & false},
      |                                                              ^
main.c:276:61: error: lvalue required as unary '&' operand
  276 |       XtOffset(appresPtr, flushleft), XtRBoolean, (caddr_t) & false},
      |                                                             ^
main.c:286:66: error: lvalue required as unary '&' operand
  286 |       XtOffset(appresPtr, installowncmap), XtRBoolean, (caddr_t) & false},
      |                                                                  ^
main.c:288:66: error: lvalue required as unary '&' operand
  288 |       XtOffset(appresPtr, dontswitchcmap), XtRBoolean, (caddr_t) & false},
      |                                                                  ^
main.c:290:58: error: lvalue required as unary '&' operand
  290 |       XtOffset(appresPtr, tablet), XtRBoolean, (caddr_t) & false},
      |                                                          ^
main.c:300:60: error: lvalue required as unary '&' operand
  300 |       XtOffset(appresPtr, multiple), XtRBoolean, (caddr_t) & false},
      |                                                            ^
main.c:302:59: error: lvalue required as unary '&' operand
  302 |       XtOffset(appresPtr, overlap), XtRBoolean, (caddr_t) & false},
      |                                                           ^
main.c:304:64: error: lvalue required as unary '&' operand
  304 |       XtOffset(appresPtr, showballoons), XtRBoolean, (caddr_t) & true},
      |                                                                ^
main.c:316:57: error: lvalue required as unary '&' operand
  316 |       XtOffset(appresPtr, DEBUG), XtRBoolean, (caddr_t) & false},
      |                                                         ^
main.c:318:63: error: lvalue required as unary '&' operand
  318 |       XtOffset(appresPtr, showlengths), XtRBoolean, (caddr_t) & false},
      |                                                               ^
main.c:320:60: error: lvalue required as unary '&' operand
  320 |       XtOffset(appresPtr, shownums), XtRBoolean, (caddr_t) & false},
      |                                                            ^
main.c:322:67: error: lvalue required as unary '&' operand
  322 |       XtOffset(appresPtr, show_pageborder), XtRBoolean, (caddr_t) & true},
      |                                                                   ^
main.c:336:68: error: lvalue required as unary '&' operand
  336 |       XtOffset(appresPtr, showdepthmanager), XtRBoolean, (caddr_t) & true},
      |                                                                    ^
main.c:338:67: error: lvalue required as unary '&' operand
  338 |       XtOffset(appresPtr, flipvisualhints), XtRBoolean, (caddr_t) & false},
      |                                                                   ^
main.c:342:61: error: lvalue required as unary '&' operand
  342 |       XtOffset(appresPtr, icon_view), XtRBoolean, (caddr_t) & true},
      |                                                             ^
main.c:346:58: error: lvalue required as unary '&' operand
  346 |       XtOffset(appresPtr, splash), XtRBoolean, (caddr_t) & true},
      |                                                          ^
main.c:354:69: error: lvalue required as unary '&' operand
  354 |       XtOffset(appresPtr, correct_font_size), XtRBoolean, (caddr_t) & true},
      |                                                                     ^
main.c:356:61: error: lvalue required as unary '&' operand
  356 |       XtOffset(appresPtr, crosshair), XtRBoolean, (caddr_t) & false},
      |                                                             ^
main.c:358:63: error: lvalue required as unary '&' operand
  358 |       XtOffset(appresPtr, autorefresh), XtRBoolean, (caddr_t) & false},
      |                                                               ^
main.c:360:61: error: lvalue required as unary '&' operand
  360 |       XtOffset(appresPtr, write_bak), XtRBoolean, (caddr_t) & true},
      |                                                             ^
main.c:362:66: error: lvalue required as unary '&' operand
  362 |        XtOffset(appresPtr, international), XtRBoolean, (caddr_t) & true},
      |                                                                  ^

[Roland Rosenfeld]

The attached patch should fix the above mentioned problem with true/false variable names.
Using this with in combination with current GIT tree allows to compile xfig with GCC 15.

[tkl]

Above patch is applied with commit [d9f210]. However, if I compile with gcc -std=c23, compilation still fails with errors, e.g., error: unknown type name 'caddr_t'. Hence, I will keep this ticket open and see, whether all issues regarding c23 can be resolved.