proposal: require GnuTLS 3.1.x (previous stable) (was: Build failure (master; MS-Windows))

[Ted Zlatanov <tzz@lifelogs.com>]

On Mon, 24 Nov 2014 00:09:40 +0100 Dani Moncayo <dmoncayo@gmail.com> wrote: 

>>> Now I the bootstrap ends without errors, but I still see these warnings:
>>> 
>>> c:/cygwin64/home/Dani/devel/emacs/repo/src/gnutls.c:130:1: warning:
>>> 'gnutls_connection_end_t' is deprecated [-Wdeprecated-declarations]
>> 
>> That line has been unchanged there for quite a while, I think.  The
>> definition here is the same as it is in gnutls 2.12.

DM> Ok, I've now realized that I updated my GnuTLS library on 2014-11-10,
DM> from version 3.0.9 to 3.3.9:

DM>   ftp://ftp.gnutls.org/gcrypt/gnutls/w32/gnutls-3.3.9-w32.zip

DM> I guess that explains the warning.

Maintainers: we're now targeting Emacs 25 in the master branch and 3.3.x
is the "next stable" version of GnuTLS. I think we should require GnuTLS
3.1.x ("previous stable") instead of 2.6.6 as we do now. In the C
source, that would make HAVE_GNUTLS3 always true, and we'll also may add
HAVE_GNUTLS3_2 and HAVE_GNUTLS3_3 (or special macros for each feature we
need).

Conditionally supporting GnuTLS 2.6.6 is a pain because many functions
were added since then. It complicates the code significantly today and
for the future, possibly hiding bugs in the compatibility layers. We're
already starting to see these compilation issues in the bug tracker and
on emacs-devel and it would be nice to cut the cord now.

Ted