[Bug libfortran/48950] a patch from 4.4.x not backported to 4.3.x

[burnus at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48950

Tobias Burnus <burnus at gcc dot gnu.org> changed:

           What    |Removed                     |Added
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                 CC|                            |burnus at gcc dot gnu.org,
                   |                            |jvdelisle at gcc dot
                   |                            |gnu.org

--- Comment #1 from Tobias Burnus <burnus at gcc dot gnu.org> 2011-05-10 16:28:25 UTC ---
> It is not clear to me to what extent I can mix libgfortran from
> different versions of GCC.

In principle, the libgfortran is downward compatible - as long as the library
version remains the same:
- GCC 4.1 has libgfortran.so.1
- GCC 4.2 has libgfortran.so.2
- GCC 4.3/4.4/4.5/4.6/4.7 have libgfortran.so.3

Thus, a program compiled with 4.3 should work with libgfortran
4.3/4.4/4.5/4.6/4.7, a program compiled with 4.4 should work with libgfortran
4.4/4.5/4.6/4.7 etc.


> As the 4.3.x series are still maintained (and used, e.g., in Cygwin),
> I would like to ask about backporting to 4.3.x.

The commit is: http://gcc.gnu.org/ml/gcc-cvs/2009-05/msg00864.html
That's a rather huge patch, which completely modifies the I/O system and fixes
the bugs PR 22423, PR 25561, PR 37754, PR 38654, PR 38668, PR 39664, PR 39665,
PR 39667, PR 39702, PR 39709 and PR 39782.

As the patch is rather large, I don't think it makes sense to backport it. The
chance that something breaks is rather high compared to the benefit.
Especially, as it does not seem to be a simple regression fix.

I am also not sure that how likely it is that the patch ends up in some vendor
version - I think most vendors try to be very conservative with old versions
and rather add technical previews than modifying the old version.

Regarding Cygwin: The last version I have seen was 4.5.0,
cf. http://ftp.gwdg.de/pub/linux/sources.redhat.com/cygwin/release/gcc4/
Though, admittedly, Cygwin seems to still maintain 4.3.x (file modification
date 22 March 2011); however, the file name "gcc4-4.3.4-4.tar.bz2" indicates
that it is based on 4.3.4, which was released 2009-08-04. Thus, they do not
include the fixes of 4.3.5 released 2010-05-22 - nor changes which were
committed afterwards to the branch.

(Actually, I also do not understand why they have only 4.5.0 and not the .1, .2
or .3 release - usually, the .1 release is a bit more stable/better tested than
the .0 release.)

For frequent/nightly GCC builds, see also
http://gcc.gnu.org/wiki/GFortranBinaries