Debian has some interesting patch for autoconf-2.59: http://ftp.debian.org/debian/pool/main/a/autoconf/autoconf_2.59a-3.diff.gz especially two hunks (starting at line 267 in patch-file) for lib/autoconf/general.m4 definitely fix shell-syntax errors: AS_IF([_AC_EVAL_STDERR($ac_compile) && - AC_TRY_COMMAND([test -z "$ac_[]_AC_LANG_ABBREV[]_werror_flag" + AC_TRY_COMMAND([test -z "$ac_[]_AC_LANG_ABBREV[]_werror_flag"[]dnl || test ! -s conftest.err]) && The problem is the newline before "|| test ! -s ..."
i dont know why they use that patch but it appears to be pointless the code is used like this: ac_try='test -z "$ac_c_werror_flag" || test ! -s conftest.err' eval $ac_try the whitespace isnt expanded such that it will cause an error
