Test struct existance against sizeof() operator Instead of declaring an "unused-variable" or "unused-but-set-variable" structure. This avoid unexpected broken configurations when using something like: $ ./configure CFLAGS="-Wall -Wextra -Werror" It causes AC_COMPILE_IFELSE to fail and thus leading to a mismatch configuration (because the CFLAGS are passed to the macro).

#!/bin/bash
if cvs log $1 >/dev/null 2>/dev/null; then exit 0; else echo "$1 shouldn't be here" ; exit 1; fi