Uses abort() instead of raising a SIGABRT signal [-Werror] error: ‘noreturn’ function does return [-Werror] abort() is a noreturn function while raise() is not. And because crypt_argchk() is flagged as __attribute__(noreturn), abort() appears to be a better condidate. This compilation warning has probably been introduced by commit 1809f741cba865b03d4db5c4ba8c41364a55d6bc.

open(IN,"<crypt.ind");
open(OUT,">crypt.ind.tmp");
$a = <IN>;
print OUT  "$a\n\\addcontentsline{toc}{chapter}{Index}\n";
while (<IN>) {
   print OUT $_;
}
close OUT;
close IN;
system("mv -f crypt.ind.tmp crypt.ind");