Autotools New World Order

[Ade Lovett]

As some of you may have noticed, a tree-wide commit went in a short  
while back, radically changing the mechanisms for invoking the GNU  
autotools (automake, autoconf, libtool, et al) within the context of  
building a FreeBSD port.

Without getting into the more religious issues, simply stated there  
is a requirement for a number of different versions of each autotool  
to co-exist on a machine in order to build various different ports.

Previously, this required a myriad of different variables to be set,  
depending on the tool (or tools) that were required to build a port.

These variables have now been collapsed into a single Makefile
construct of the form:

USE_AUTOTOOLS= <tool>:<version>[:<operation>] ...

where:

<tool> can be one of 'libtool', 'libltdl', 'autoconf', 'autoheader',  
'automake' and 'aclocal',
<version> specifies the particular tool revision to be used, and
<operation> is an optional extension to modify how the tool is used.

It cannot be stressed highly enough that these constructs, and the  
versioned autotools ports they use, are for use ONLY in building  
other ports.  For cross-development work, the devel/gnu- 
{automake,autoconf,libtool} ports should be used, such as within an  
IDE.  devel/anjuta and devel/kdevelop (GNOME and KDE respectively)  
are good examples of how to achieve this.

Here's a simple conversion table from old to new:

USE_LIBTOOL_VER=13		libtool:13
USE_INC_LIBTOOL_VER=15		libtool:15:inc
WANT_LIBTOOL_VER=15		libtool:15:env
USE_LIBLTDL=YES			libltdl:15
USE_AUTOCONF_VER=213		autoconf:213
WANT_AUTOCONF_VER=259		autoconf:259:env
USE_AUTOHEADER_VER=253		autoheader:253 (implies autoconf:253)
USE_AUTOMAKE_VER=14		automake:14
WANT_AUTOMAKE_VER=15		automake:15:env
USE_ACLOCAL_VER=19		aclocal:19 (implies automake:19)

Note that the other variables associated with autotools -  
AUTOMAKE_ARGS, ACLOCAL_ARGS, AUTOCONF_ARGS, AUTOHEADER_ARGS,  
LIBTOOLFLAGS and LIBTOOLFILES are unchanged.  Most ports do not need  
to concern themselves with these.

Every effort has been made to create a new autotools usage method  
which is both extensible not only in terms of easily adding new  
versions if a drop-in upgrade is not possible, but also, through the  
<operation> keyword, of adding further tweaks with the minimum of fuss.

By means of an example, compare the following sets of constructs,  
which says that a port wants the automake 1.9.x environment, needs to  
run both autoconf 2.53 and the associated autoheader as well as  
needing libtool 1.3.5 (with the second type of configure file  
patching), and the libltdl library.

Previously, this would have been done with:

WANT_AUTOMAKE_VER=	19
USE_AUTOCONF_VER=	253
USE_AUTOHEADER_VER=	253
USE_INC_LIBTOOL_VER=	13
USE_LIBLTDL=		YES

Now, we can reduce this to:

USE_AUTOTOOLS=	automake:19:env autoheader:253 libtool:13:inc libltdl:15

which vastly improves Makefile readability, whilst leaving the heavy  
lifting where it should be, in the infrastructural background,  
allowing for considerably easier implementation of ports that require  
the use of one or more autotools.

The Porters Handbook is in the process of being updated with new text  
to reflect the changes (hi pav!).

-aDe