-typedef char * (gdbarch_core_pid_to_str_ftype) (struct gdbarch *gdbarch, ptid_t ptid);
-extern char * gdbarch_core_pid_to_str (struct gdbarch *gdbarch, ptid_t ptid);
+typedef const char * (gdbarch_core_pid_to_str_ftype) (struct gdbarch *gdbarch, ptid_t ptid);
+extern const char * gdbarch_core_pid_to_str (struct gdbarch *gdbarch, ptid_t ptid);