PackagingDrafts/AutoConf

--Dmalcolm 00:27, 12 March 2010 (UTC): I believe this draft, as written, is controversial. For what it's worth, I strongly disagree with the proposed policy, see also http://lists.fedoraproject.org/pipermail/devel/2009-February/023647.html

Using autoconf/automake in spec files

This document seeks to document the usage of autoconf, automake, and libtoolize during a package build in Fedora; i.e. the usage of older packages like autoconf213 and automake1{4,5,6,7}.

Problem

• Autoconf, Automake, and Libtool (collectively, the “autotools”) can by used for many Fedora packages to create configure scripts and Makefiles. The resulting configure scripts and Makefiles might be different on systems with a different set of installed packages and thus might lead to unpredictable results. In particular, when any of Fedora's autotools packages is upgraded, the new version may not be compatible with the autotools input files in Fedora's numerous autotools-derived upstream source packages.

• Some packages use old autotools versions in order to build their configure scripts and Makefiles. Some of these older helper tools aren't multilib capable and patches need to be applied to be able to build the package on multilib systems. Upstream doesn't maintain these tools anymore and so the tools won't get any bugfixes.

Solution

• Autotools-generated source packages are intended to be buildable without requiring the autotools on the host system. autoconf, automake, libtoolize and the accompanying autoreconf shouldn't be used in the %prep or %build sections of a package's spec file. Applying a patch to update the configure scripts and Makefile.ins is preferred as the results are predictable and packages are more reproducible.

• When manual modification of configure or Makefile.in for the purpose of generating a patch is impractical, packagers can create a patch by regenerating configure and/or Makefile.in to use as input to diff. In general, autoreconf should not be used for this purpose because it will regenerate files that probably don't need to be regenerated.
  • If only Makefile.am has been touched, run automake to regenerate Makefile.in.
  • If configure.ac (or in older packages, configure.in) has been modified, but no additional Autoconf macros were invoked, run autoconf to regenerate configure.
  • If new macro invocations have been added to configure.ac, first run aclocal (to regenerate aclocal.m4), then run autoconf. Many projects distribute their own Autoconf macros in an “m4” or “macros” subdirectory; you will need to provide aclocal with a -I flag with the path to these macros. Note that you do not need to include modifications to aclocal.m4 in your patch.

• Package maintainers should work with upstream to port the scripts to recent autotools. Sometimes this won't work due to time constraints or due to compatibility concerns for multi-platform packages such as p.e. Firefox; but at least an attempt should be made.

Further reading

Updating from autoconf213 to a recent version is covered at Upgrading From Version 2.13.

Tips to update from older Automake versions are available at Upgrading a Package to a Newer Automake Version (dead link). The NEWS file in the latest automake package also lists differences between the versions and gives some hint what one has to look out for.