I have the following piece of code belonging to a larger zlib detection code. Nothing appears to execute on it, with means the variable "with_zlib" is not set to "yes", which is likely the reason the detection test fails on two "if clauses" ahead and that makes configure's execution stop. So what I need is suggestions as to how to diagnoze the reason behind the non execution of the clauses inside the piece of code. if { (ac_try="$ac_link" case "(($ac_try" in *\"* | *\`* | *\\*) ac_try_echo=\$ac_try;; *) ac_try_echo=$ac_try;; esac eval "echo \"\$as_me:$LINENO: $ac_try_echo\"") >&5 (eval "$ac_link") 2>&5 ac_status=$? echo "$as_me:$LINENO: \$? = $ac_status" >&5 (exit $ac_status); } && { ac_try='./conftest$ac_exeext' { (case "(($ac_try" in *\"* | *\`* | *\\*) ac_try_echo=\$ac_try;; *) ac_try_echo=$ac_try;; esac eval "echo \"\$as_me:$LINENO: $ac_try_echo\"") >&5 (eval "$ac_try") 2>&5 ac_status=$? echo "$as_me:$LINENO: \$? = $ac_status" >&5 (exit $ac_status); }; }; then with_zlib=yes echo "with_zlib=yes?: $with_zlib" else echo "$as_me: program exited with status $ac_status" >&5 echo "$as_me: failed program was:" >&5 sed 's/^/| /' conftest.$ac_ext >&5 ( exit $ac_status ) with_zlib=no echo "with_zlib=no?: $with_zlib" fi rm -f core *.core core.conftest.* gmon.out bb.out conftest$ac_exeext conftest.$ac_objext conftest.$ac_ext fi