On 08/24/2011 12:12 PM, Mikael Morin wrote:
On Tuesday 23 August 2011 14:26:59 Tobias Burnus wrote:
OK for the trunk?
OK.
Thanks for the review! Committed to the 4.7 trunk (Rev. 178038); I will
backport the patch later. (For cross-readers: That's a patch for a 4.3+
ice-on-invalid-code regression.)
Isn't there some rules about backporting? The way we do it now, it
looks completely arbitrary.
I think it *is* arbitrary - and unavoidable so.
The main idea behind regression fixing is to make sure that what once
worked should continue to work. But what always had been broken can
remain broken and will be only fixed on the trunk. Reason: If you fix
more, the behaviour on the branch changes and you may introduce
regressions. If thinks are known to be broken, you can simply work
around them.
Additional ingredients are: How serious is the problem? A wrong-code
issue occurring in a potentially often used part has a different
priority than an accepts-invalid or ice-on-invalid-code issue. Also, a
patch which is huge is less suited than a small "trivial" patch.
Regressions, which existed for a long time are typically also less
important - otherwise they would have been fixed or found before.
But there are also other items such as: Which is the last maintained
version in GCC, which versions are still being used (such that it makes
sense to backport), and which patches (Linux) distributions want to see.
Additionally, as backporting takes time (bootstrap, regtesting, and
maybe even adapting the patch slightly): How much time wants the
developer spend on backporting.
My impression is that gfortran is currently doing too much
non-regression backporting, which should be left to serious ICE-on-valid
code and wrong-code issues. Especially as older versions do not see as
much testing as the trunk.
On the other hand, backporting simple fixes to regressions or really bad
wrong-code issues (which we hadn't for a while) down to 4.4 should be
also fine.
I think every modern (= F2003) developer can relatively simply update to
4.6 or the trunk. The older versions are mostly for those using the
default compiler of the system; those typically only need some Fortran
77/90 compiler, for which the older versions (4.4 or 4.5) should be fine.
But at the end it is question of style. That's similar to Linux
distributions. I think Jakub/Red Hat ports many patches (bug fixes but
also features) back to their old versions, while for instance
Richard/SUSE's package has only few patches and essentially grabs the
current branch. Both approaches makes sense and either one has
advantages and disadvantages.
I think we should try extra hard to avoid regressions on the branches
and mostly concentrate on the trunk, but we can still backport one patch
or the other to the branches.
I didn't really answer your question, did I?
Tobias
