clear up some warnings appearing with gcc 15.2.0

allmain.c: In function ‘debug_fields’:
allmain.c:1133:16: warning: assignment discards ‘const’ qualifier from pointer target type [-Wdiscarded-qualifiers]
 1133 |     while ((op = strchr(opts, ',')) != 0) {
      |                ^
cfgfiles.c: In function ‘find_optparam’:
cfgfiles.c:590:10: warning: assignment discards ‘const’ qualifier from pointer target type [-Wdiscarded-qualifiers]
  590 |     bufp = strchr(buf, '=');
      |          ^
cfgfiles.c:591:10: warning: assignment discards ‘const’ qualifier from pointer target type [-Wdiscarded-qualifiers]
  591 |     altp = strchr(buf, ':');
      |          ^
end.c: In function ‘should_query_disclose_option’:
end.c:482:14: warning: assignment discards ‘const’ qualifier from pointer target type [-Wdiscarded-qualifiers]
  482 |     if ((dop = strchr(disclosure_options, category)) != 0) {
      |              ^
invent.c: In function ‘loot_classify’:
invent.c:175:7: warning: assignment discards ‘const’ qualifier from pointer target type [-Wdiscarded-qualifiers]
  175 |     p = strchr(classorder, oclass);
      |       ^
o_init.c: In function ‘dodiscovered’:
o_init.c:774:33: warning: assignment discards ‘const’ qualifier from pointer target type [-Wdiscarded-qualifiers]
  774 |     if (!flags.discosort || !(p = strchr(disco_order_let, flags.discosort)))
      |                                 ^
o_init.c: In function ‘doclassdisco’:
o_init.c:907:33: warning: assignment discards ‘const’ qualifier from pointer target type [-Wdiscarded-qualifiers]
  907 |     if (!flags.discosort || !(p = strchr(disco_order_let, flags.discosort)))
      |                                 ^
objnam.c: In function ‘the’:
objnam.c:2200:19: warning: assignment discards ‘const’ qualifier from pointer target type [-Wdiscarded-qualifiers]
 2200 |         if (((tmp = strrchr(str, ' ')) != 0 || (tmp = strrchr(str, '-')) != 0)
      |                   ^
objnam.c:2200:53: warning: assignment discards ‘const’ qualifier from pointer target type [-Wdiscarded-qualifiers]
 2200 |         if (((tmp = strrchr(str, ' ')) != 0 || (tmp = strrchr(str, '-')) != 0)
      |                                                     ^
options.c: In function ‘optfn_disclose’:
options.c:1529:17: warning: assignment discards ‘const’ qualifier from pointer target type [-Wdiscarded-qualifiers]
 1529 |             dop = strchr(disclosure_options, c);
      |                 ^
pager.c: In function ‘add_cmap_descr’:
pager.c:1212:28: warning: assignment discards ‘const’ qualifier from pointer target type [-Wdiscarded-qualifiers]
 1212 |                     || ((p = strchr(x_str, ' ')) != 0 && !strcmpi(p, " ice"))
      |                            ^

src/allmain.c

@@ -21,7 +21,7 @@ staticfn void do_positionbar(void);
 staticfn void regen_pw(int);
 staticfn void regen_hp(int);
 staticfn void interrupt_multi(const char *);
-staticfn void debug_fields(const char *);
+staticfn void debug_fields(char *);
 #ifndef NODUMPENUMS
 staticfn void dump_enums(void);
 #endif
@@ -1041,8 +1041,11 @@ argcheck(int argc, char *argv[], enum earlyarg e_arg)
         switch(e_arg) {
         case ARG_DEBUG:
             if (extended_opt) {
-                extended_opt++;
-                debug_fields(extended_opt);
+                char *cpy_extended_opt;
+
+                cpy_extended_opt = dupstr(extended_opt);
+                debug_fields(cpy_extended_opt + 1);
+                free((genericptr_t) cpy_extended_opt);
             }
             return 1;
         case ARG_VERSION: {
@@ -1125,7 +1128,7 @@ argcheck(int argc, char *argv[], enum earlyarg e_arg)
  * fuzzer           - enable fuzzer without debugger intervention.
  */
 staticfn void
-debug_fields(const char *opts)
+debug_fields(char *opts)
 {
     char *op;
     boolean negated = FALSE;

src/cfgfiles.c

@@ -34,7 +34,7 @@ staticfn void free_config_sections(void);
 staticfn char *is_config_section(char *);
 staticfn boolean handle_config_section(char *);
 boolean parse_config_line(char *);
-staticfn char *find_optparam(const char *);
+staticfn char *find_optparam(char *);
 #ifndef SFCTOOL
 staticfn boolean cnf_line_OPTIONS(char *);
 staticfn boolean cnf_line_AUTOPICKUP_EXCEPTION(char *);
@@ -583,7 +583,7 @@ handle_config_section(char *buf)
 
 /* find the '=' or ':' */
 staticfn char *
-find_optparam(const char *buf)
+find_optparam(char *buf)
 {
     char *bufp, *altp;
 

src/end.c

@@ -476,7 +476,8 @@ staticfn boolean
 should_query_disclose_option(int category, char *defquery)
 {
     int idx;
-    char disclose, *dop;
+    char disclose;
+    const char *dop;
 
     *defquery = 'n';
     if ((dop = strchr(disclosure_options, category)) != 0) {

src/invent.c

@@ -159,7 +159,7 @@ loot_classify(Loot *sort_item, struct obj *obj)
     };
     static char armcat[8];
     const char *classorder;
-    char *p;
+    const char *p;
     int k, otyp = obj->otyp, oclass = obj->oclass;
     boolean seen, discovered = objects[otyp].oc_name_known ? TRUE : FALSE;
 

src/o_init.c

@@ -764,9 +764,10 @@ int
 dodiscovered(void) /* free after Robert Viduya */
 {
     winid tmpwin;
-    char *s, *p, oclass, prev_class,
+    char *s, oclass, prev_class,
          classes[MAXOCLASSES], buf[BUFSZ],
          *sorted_lines[NUM_OBJECTS]; /* overkill */
+    const char *p;
     int i, dis, ct, uniq_ct, arti_ct, sorted_ct, uidx;
     long sortindx;  // should be ptrdiff_t, but we don't require that exists
     boolean alphabetized, alphabyclass, lootsort;
@@ -897,9 +898,10 @@ doclassdisco(void)
     winid tmpwin = WIN_ERR;
     menu_item *pick_list = 0;
     anything any;
-    char *p, *s, c, oclass, menulet, allclasses[MAXOCLASSES],
+    char *s, c, oclass, menulet, allclasses[MAXOCLASSES],
          discosyms[3 + MAXOCLASSES + 1], buf[BUFSZ],
          *sorted_lines[NUM_OBJECTS]; /* overkill */
+    const char *p;
     int i, ct, dis, xtras, sorted_ct, uidx;
     boolean traditional, alphabetized, lootsort;
     int clr = NO_COLOR;
@@ -1105,12 +1107,14 @@ doclassdisco(void)
         } else if (sorted_ct) {
             qsort(sorted_lines, sorted_ct, sizeof (char *), discovered_cmp);
             for (i = 0; i < sorted_ct; ++i) {
-                p = sorted_lines[i];
+                char *sl;
+
+                sl = sorted_lines[i];
                 if (lootsort) {
-                    p[6] = p[0]; /* '*' or ' ' */
-                    p += 6;
+                    sl[6] = sl[0]; /* '*' or ' ' */
+                    sl += 6;
                 }
-                putstr(tmpwin, 0, p);
+                putstr(tmpwin, 0, sl);
                 free(sorted_lines[i]), sorted_lines[i] = 0;
             }
         }

src/objnam.c

@@ -2193,7 +2193,8 @@ the(const char *str)
         insert_the = TRUE;
     } else {
         /* Probably a proper name, might not need an article */
-        char *tmp, *named, *called;
+        char *named, *called;
+        const char *tmp;
         int l;
 
         /* some objects have capitalized adjectives in their names */

src/options.c

@@ -1519,7 +1519,8 @@ optfn_disclose(
                                              DISCLOSE_NO_WITHOUT_PROMPT,
                                              DISCLOSE_SPECIAL_WITHOUT_PROMPT,
                                              '\0' };
-            char c, *dop;
+            char c;
+            const char *dop;
 
             c = lowc(*op);
             if (c == 'k')

src/pager.c

@@ -1143,7 +1143,8 @@ add_cmap_descr(
     const char **firstmatch, /* output: pointer to 1st matching description */
     char *out_str)      /* input/output: current description gets appended */
 {
-    char *mbuf = NULL, *p;
+    char *mbuf = NULL;
+    const char *p;
     int absidx = abs(idx);
 
     if (glyph == NO_GLYPH) {