Hello Eric, Paolo, m4_copy and m4_rename changed their API before being published. GCC already uses these macros from Autoconf 2.59, and expects the old semantics. I need to add some m4_undefine in order to avoid autoconf failures.
Also, GCC makes use of the undefined (and recently removed) macro _AC_CHECK_HEADER_OLD. A few other projects also have these issues, some of them because they copied the respective macro code from GCC. Just FYI. Even with these previously undocumented macros, changes might break software. It might be a good idea to note the m4_copy and m4_rename issue a bit more prominently in NEWS. Cheers, Ralf
