Building byaccj with GCC 14 fails here:
https://build.opensuse.org/package/live_build_log/openSUSE:Factory:Staging:Gcc7/byaccj/standard/x86_64

Due to:

main.c: In function ‘done’:
main.c:88:43: error: implicit declaration of function ‘unlink’ [-Wimplicit-function-declaration]
   88 |   if (action_file) { fclose(action_file); unlink(action_file_name); }
      |                                           ^~~~~~





Builds with automatically generated:

Index: byaccj1.15/src/main.c
===================================================================
--- byaccj1.15.orig/src/main.c
+++ byaccj1.15/src/main.c
@@ -9,6 +9,7 @@
 #endif

 #include "defs.h"
+#include <unistd.h>

 char dflag;
 char lflag;

See the meta bug#1220571 for more info.