As John Altstadt wrote:
I raised bug #13416 about the autoconf problem against
avr-libc-1.2.3.
I'm afraid I have to close that bug some day unresolved.
First, we could not fix a released version of the source code anyway.
Second, avr-libc's configuration currently only has a `supported'
status for the exact versions as they are listed in the files, newer
versions are explicitly unsupported.
It looks like different versions of autoconf were used to create
various files, ...
Nope. I've symlinked the exact versions that are required to their
generic names in my $PATH, and then ran ./reconf. There's not much
chance the tools would have picked different versions.
Once shipped, the library should have no reason to use the auto*
tools of the target system again. But I know, occasionally these
tools get the stupid idea they need to be called again... In that
case, for sure, you will likely run into versioning conflicts, as
the versions I've been using to configure the release tarballs is
almost certainly different from your tools.
Upgrading the build system to newer auto* tools is on the list of
tasks to do, but we mainly lack a resident auto* hacker for this
to happen soon.