Ports program to C23 and allows it to compile with GCC-15.
Fix function declarations with no arguments, delete dubious extern of
library function
Fix comparators for quicksort/binary search
https://bugs.gentoo.org/944011
--- a/lib/connect.c
+++ b/lib/connect.c
@@ -45,9 +45,11 @@
  * rensetu table
  */
 static int
-cmp_pair(rensetu_pair_t * pair1, rensetu_pair_t * pair2)
+cmp_pair(const void * pair1_void, const void * pair2_void)
 {
     int ret;
+    rensetu_pair_t *pair1 = (rensetu_pair_t *)pair1_void;
+    rensetu_pair_t *pair2 = (rensetu_pair_t *)pair2_void;
 
     /*
      * 見出し語 surface form 
@@ -166,9 +168,11 @@
 }
 
 static int
-find_table(lexicon_t * mrph, rensetu_pair_t * pair)
+find_table(const void * mrph_void, const void * pair_void)
 {
     int ret;
+    lexicon_t * mrph = (lexicon_t*)mrph_void;
+    rensetu_pair_t * pair = (rensetu_pair_t*)pair_void;
 
     /*
      * 品詞分類 POS 
@@ -202,12 +206,11 @@
     rensetu_pair_t *ret;
 
     if (rensetu_tbl[0].hinsi == 0)
-	qsort(rensetu_tbl, tbl_num, sizeof(rensetu_pair_t),
-	      (int (*)()) cmp_pair);
+	qsort(rensetu_tbl, tbl_num, sizeof(rensetu_pair_t), cmp_pair);
 
     ret = (rensetu_pair_t *)
 	bsearch(mrph, rensetu_tbl, tbl_num_goi,
-		sizeof(rensetu_pair_t), (int (*)()) find_table);
+		sizeof(rensetu_pair_t), find_table);
     if (ret) {
 	mrph->con_tbl = ret->index;
 	return 1;
@@ -215,7 +218,7 @@
 
     ret = (rensetu_pair_t *)
 	bsearch(mrph, rensetu_tbl + tbl_num_goi, tbl_num - tbl_num_goi,
-		sizeof(rensetu_pair_t), (int (*)()) find_table);
+		sizeof(rensetu_pair_t), find_table);
     if (ret) {
 	mrph->con_tbl = ret->index;
 	return 1; /* if no error, return 1 */
--- a/lib/iotool.c
+++ b/lib/iotool.c
@@ -362,7 +362,7 @@
 cha_fopen_rcfile(void)
 {
     FILE *fp;
-    char *home_dir, *rc_env, *getenv();
+    char *home_dir, *rc_env;
 
     /*
      * -R option (standard alone) 
--- a/lib/print.c
+++ b/lib/print.c
@@ -47,7 +47,7 @@
 static int path_buffer[CHA_INPUT_SIZE];
 static int pos_end = 0;
 
-static void (*cha_putc) (), (*cha_puts) (), (*cha_printf) (), (*cha_write) ();
+static void (*cha_putc) (int, char*), (*cha_puts) (char*, char*), (*cha_printf) (char*, char*, ...), (*cha_write) (void*, size_t, size_t, char*);
 
 void
 cha_print_reset(void)