add support for [[maybe_unused]] if available

include/tradstdc.h

@@ -389,6 +389,14 @@ typedef genericptr genericptr_t; /* (void *) or (char *) */
 #define FALLTHROUGH [[fallthrough]]
 /* #warning [[fallthrough]] from C23 */
 #endif  /* __has_c_attribute(fallthrough) */
+/*
+ * maybe_unused
+ */
+#if __has_c_attribute(maybe_unused)
+#ifndef ATTRUNUSED
+#define ATTRUNUSED [[maybe_unused]]
+#endif
+#endif  /* __has_c_attribute(maybe_unused) */
 #endif  /* NH_C >= 202300L */
 
 /*
@@ -416,7 +424,9 @@ typedef genericptr genericptr_t; /* (void *) or (char *) */
 #define PRINTF_F_PTR(f, v) PRINTF_F(f, v)
 #endif
 #if __GNUC__ >= 3
+#ifndef ATTRUNUSED
 #define UNUSED __attribute__((unused))
+#endif
 #ifndef ATTRNORETURN
 #ifndef NORETURN
 #define NORETURN __attribute__((noreturn))
@@ -496,6 +506,9 @@ typedef genericptr genericptr_t; /* (void *) or (char *) */
 #define NH_PRAGMA_MESSAGE 1
 #endif  /* _MSC_VER */
 
+#if !defined(UNUSED) && defined(ATTRUNUSED)
+#define UNUSED ATTRUNUSED
+#endif
 
 /* Fallback implementations */
 #ifndef PRINTF_F
@@ -507,6 +520,9 @@ typedef genericptr genericptr_t; /* (void *) or (char *) */
 #ifndef UNUSED
 #define UNUSED
 #endif
+#ifndef ATTRUNUSED
+#define ATTRUNUSED
+#endif
 #ifndef FALLTHROUGH
 #define FALLTHROUGH
 #endif

src/report.c

@@ -110,7 +110,7 @@ static char bid[40];
 
 /* ARGSUSED */
 void
-crashreport_init(int argc UNUSED, char *argv[] UNUSED)
+crashreport_init(int argc, char *argv[])
 {
     static int once = 0;
     if (once++) /* NetHackW.exe calls us twice */
@@ -169,6 +169,8 @@ crashreport_init(int argc UNUSED, char *argv[] UNUSED)
     Strcpy(bid, "unknown");
     HASH_CLEANUP(ctxp);
     HASH_PRAGMA_END
+    nhUse(argc);
+    nhUse(argv);
 }
 
 #undef HASH_CONTEXTPTR

win/share/tilemap.c

@@ -1311,7 +1311,7 @@ extern void objects_globals_init(void);
 DISABLE_WARNING_UNREACHABLE_CODE
 
 int
-main(int argc UNUSED, char *argv[] UNUSED)
+main(int argc, char *argv[])
 {
     int i, tilenum;
     char filename[30];
@@ -1395,6 +1395,8 @@ main(int argc UNUSED, char *argv[] UNUSED)
     free_tilerefs();
     exit(EXIT_SUCCESS);
     /*NOTREACHED*/
+    nhUse(argc);
+    nhUse(argv);
     return 0;
 }
 
@@ -1491,7 +1493,7 @@ add_tileref(
     const char *prefix)
 {
     struct tiles_used temp = { 0 };
-    static const char ellipsis[] UNUSED = "...";
+    static const char ellipsis[] = "...";
     char buf[BUFSZ];
 
     if (!tilelist[n]) {
@@ -1519,6 +1521,7 @@ add_tileref(
              (strlen(temp.references) >= (sizeof temp.references - 7) - 1)
                  ? buf
                  : "");
+    nhUse(ellipsis);
 }
 
 void