Re: AC_PACKAGE_VERSION visibility slightly changed in autoconf-2.69c. Bug or feature?

[Paul Eggert]

On 10/22/20 6:26 AM, Zack Weinberg wrote:
> The concrete problem is that, without the hack I described, we cannot
> support both
>
> AC_INIT([foo], [1.0], [foo-bug@foo.org], [foo-AC_PACKAGE_VERSION])
>
> and
>
> AC_INIT([bar], [1.0], [foo-bug@[192.0.2.1]])

I doubt whether the latter sort of thing is used much if at all. If someone 
needs it, we can suggest that they use AC_INIT([bar], [1.0], 
[foo-bug@@<:@192.0.2.1@:>@]), which should work with both old and new Autoconf.

I expect the main problem is more with examples that you mentioned downthread, 
like this one from GMP:

AC_INIT(GNU MP, GMP_VERSION, [gmp-bugs@gmplib.org, see 
https://gmplib.org/manual/Reporting-Bugs.html], gmp)

For this particular case, a simple workaround is to use " -" rather than "," in 
the 3rd argument; this should work with both old and new Autoconf. It may be 
that requiring this sort of workaround would be better than a hacky 
implementation of AC_INIT that attempts to guess what was intended. After all, 
GMP's use of AC_INIT doesn't conform to the 2.69 manual, which says that the 3rd 
arg should be an email address.

After writing the above it strikes me that there should be a quadrigraph for 
",", though of course this won't help in code intended to be portable to 2.69.