automake-history - phpMan

File: automake-history.info, Node: Top, Next: Timeline, Up: (dir)

Brief History of Automake
*************************

This manual describes (part of) the history of GNU Automake, a program
that creates GNU standards-compliant Makefiles from template files.

Permission is granted to copy, distribute and/or modify this
document under the terms of the GNU Free Documentation License,
Version 1.3 or any later version published by the Free Software
Foundation; with no Invariant Sections, with no Front-Cover texts,
and with no Back-Cover Texts. A copy of the license is included in
the section entitled "GNU Free Documentation License."

* Menu:

* Timeline:: The Automake story.
* Dependency Tracking Evolution:: Evolution of Automatic Dependency Tracking
* Releases:: Release statistics
* Copying This Manual:: How to make copies of this manual

-- The Detailed Node Listing --

Evolution of Automatic Dependency Tracking

* First Take on Dependencies:: Precomputed dependency tracking
* Dependencies As Side Effects:: Update at developer compile time
* Dependencies for the User:: Update at user compile time
* Techniques for Dependencies:: Alternative approaches

Techniques for Computing Dependencies

* Recommendations for Tool Writers::
* Future Directions for Dependencies::

Copying This Manual

* GNU Free Documentation License:: License for copying this manual

File: automake-history.info, Node: Timeline, Next: Dependency Tracking Evolution, Prev: Top, Up: Top

1 Timeline
**********

1994-09-19 First CVS commit.

If we can trust the CVS repository, David J. MacKenzie (djm)
started working on Automake (or AutoMake, as it was spelt then)
this Monday.

The first version of the 'automake' script looks as follows.

#!/bin/sh

status=0

for makefile
do
if test ! -f ${makefile}.am; then
echo "automake: ${makefile}.am: No such honkin' file"
status=1
continue
fi

exec 4> ${makefile}.in

done

From this you can already see that Automake will be about reading
'*.am' file and producing '*.in' files. You cannot see anything
else, but if you also know that David is the one who created
Autoconf two years before you can guess the rest.

Several commits follow, and by the end of the day Automake is
reported to work for GNU fileutils and GNU m4.

The modus operandi is the one that is still used today: variable
assignments in 'Makefile.am' files trigger injections of precanned
'Makefile' fragments into the generated 'Makefile.in'. The use of
'Makefile' fragments was inspired by the 4.4BSD 'make' and include
files, however Automake aims to be portable and to conform to the
GNU standards for 'Makefile' variables and targets.

At this point, the most recent release of Autoconf is version 1.11,
and David is preparing to release Autoconf 2.0 in late October. As
a matter of fact, he will barely touch Automake after September.

1994-11-05 David MacKenzie's last commit.

At this point Automake is a 200 line portable shell script, plus
332 lines of 'Makefile' fragments. In the 'README', David states
his ambivalence between "portable shell" and "more appropriate
language":

I wrote it keeping in mind the possibility of it becoming an
Autoconf macro, so it would run at configure-time. That would
slow configuration down a bit, but allow users to modify the
Makefile.am without needing to fetch the AutoMake package.
And, the Makefile.in files wouldn't need to be distributed.
But all of AutoMake would. So I might reimplement AutoMake in
Perl, m4, or some other more appropriate language.

Automake is described as "an experimental Makefile generator".
There is no documentation. Adventurous users are referred to the
examples and patches needed to use Automake with GNU m4 1.3,
fileutils 3.9, time 1.6, and development versions of find and
indent.

These examples seem to have been lost. However at the time of
writing (10 years later in September, 2004) the FSF still
distributes a package that uses this version of Automake: check out
GNU termutils 2.0.

1995-11-12 Tom Tromey's first commit.

After one year of inactivity, Tom Tromey takes over the package.
Tom was working on GNU cpio back then, and doing this just for fun,
having trouble finding a project to contribute to. So while
hacking he wanted to bring the 'Makefile.in' up to GNU standards.
This was hard, and one day he saw Automake on
<ftp://alpha.gnu.org/>, grabbed it and tried it out.

Tom didn't talk to djm about it until later, just to make sure he
didn't mind if he made a release. He did a bunch of early releases
to the Gnits folks.

Gnits was (and still is) totally informal, just a few GNU friends
who Franc,ois Pinard knew, who were all interested in making a
common infrastructure for GNU projects, and shared a similar
outlook on how to do it. So they were able to make some progress.
It came along with Autoconf and extensions thereof, and then
Automake from David and Tom (who were both gnitsians). One of
their ideas was to write a document paralleling the GNU standards,
that was more strict in some ways and more detailed. They never
finished the GNITS standards, but the ideas mostly made their way
into Automake.

1995-11-23 Automake 0.20

Besides introducing automatic dependency tracking (*note Dependency
Tracking Evolution::), this version also supplies a 9-page manual.

At this time 'aclocal' and 'AM_INIT_AUTOMAKE' did not exist, so
many things had to be done by hand. For instance, here is what a
configure.in (this is the former name of the 'configure.ac' we use
today) must contain in order to use Automake 0.20:

PACKAGE=cpio
VERSION=2.3.911
AC_DEFINE_UNQUOTED(PACKAGE, "$PACKAGE")
AC_DEFINE_UNQUOTED(VERSION, "$VERSION")
AC_SUBST(PACKAGE)
AC_SUBST(VERSION)
AC_ARG_PROGRAM
AC_PROG_INSTALL

(Today all of the above is achieved by 'AC_INIT' and
'AM_INIT_AUTOMAKE'.)

Here is how programs are specified in 'Makefile.am':

PROGRAMS = hello
hello_SOURCES = hello.c

This looks pretty much like what we do today, except the 'PROGRAMS'
variable has no directory prefix specifying where 'hello' should be
installed: all programs are installed in '$(bindir)'.
'LIBPROGRAMS' can be used to specify programs that must be built
but not installed (it is called 'noinst_PROGRAMS' nowadays).

Programs can be built conditionally using 'AC_SUBST'itutions:

PROGRAMS = @progs@
AM_PROGRAMS = foo bar baz

('AM_PROGRAMS' has since then been renamed to 'EXTRA_PROGRAMS'.)

Similarly scripts, static libraries, and data can be built and
installed using the 'LIBRARIES', 'SCRIPTS', and 'DATA' variables.
However 'LIBRARIES' were treated a bit specially in that Automake
did automatically supply the 'lib' and '.a' prefixes. Therefore to
build 'libcpio.a', one had to write

LIBRARIES = cpio
cpio_SOURCES = ...

Extra files to distribute must be listed in 'DIST_OTHER' (the
ancestor of 'EXTRA_DIST'). Also extra directories that are to be
distributed should appear in 'DIST_SUBDIRS', but the manual
describes this as a temporary ugly hack (today extra directories
should also be listed in 'EXTRA_DIST', and 'DIST_SUBDIRS' is used
for another purpose, *note Conditional Subdirectories:
(automake)Conditional Subdirectories.).

1995-11-26 Automake 0.21

In less time than it takes to cook a frozen pizza, Tom rewrites
Automake using Perl. At this time Perl 5 is only one year old, and
Perl 4.036 is in use at many sites. Supporting several Perl
versions has been a source of problems through the whole history of
Automake.

If you never used Perl 4, imagine Perl 5 without objects, without
'my' variables (only dynamically scoped 'local' variables), without
function prototypes, with function calls that needs to be prefixed
with '&', etc. Traces of this old style can still be found in
today's 'automake'.

1995-11-28 Automake 0.22
1995-11-29 Automake 0.23

Bug fixes.

1995-12-08 Automake 0.24
1995-12-10 Automake 0.25

Releases are raining. 0.24 introduces the uniform naming scheme we
use today, i.e., 'bin_PROGRAMS' instead of 'PROGRAMS',
'noinst_LIBRARIES' instead of 'LIBLIBRARIES', etc. (However
'EXTRA_PROGRAMS' does not exist yet, 'AM_PROGRAMS' is still in use;
and 'TEXINFOS' and 'MANS' still have no directory prefixes.)
Adding support for prefixes like that was one of the major ideas in
'automake'; it has lasted pretty well.

AutoMake is renamed to Automake (Tom seems to recall it was
Franc,ois Pinard's doing).

0.25 fixes a Perl 4 portability bug.

1995-12-18 Jim Meyering starts using Automake in GNU Textutils.
1995-12-31 Franc,ois Pinard starts using Automake in GNU tar.

1996-01-03 Automake 0.26
1996-01-03 Automake 0.27

Of the many changes and suggestions sent by Franc,ois Pinard and
included in 0.26, perhaps the most important is the advice that to
ease customization a user rule or variable definition should always
override an Automake rule or definition.

Gordon Matzigkeit and Jim Meyering are two other early contributors
that have been sending fixes.

0.27 fixes yet another Perl 4 portability bug.

1996-01-13 Automake 0.28

Automake starts scanning 'configure.in' for 'LIBOBJS' support.
This is an important step because until this version Automake only
knew about the 'Makefile.am's it processed. 'configure.in' was
Autoconf's world and the link between Autoconf and Automake had to
be done by the 'Makefile.am' author. For instance, if 'config.h'
was generated by 'configure', it was the package maintainer's
responsibility to define the 'CONFIG_HEADER' variable in each
'Makefile.am'.

Succeeding releases will rely more and more on scanning
'configure.in' to better automate the Autoconf integration.

0.28 also introduces the 'AUTOMAKE_OPTIONS' variable and the
'--gnu' and '--gnits' options, the latter being stricter.

1996-02-07 Automake 0.29

Thanks to 'configure.in' scanning, 'CONFIG_HEADER' is gone, and
rebuild rules for 'configure'-generated file are automatically
output.

'TEXINFOS' and 'MANS' converted to the uniform naming scheme.

1996-02-24 Automake 0.30

The test suite is born. It contains 9 tests. From now on test
cases will be added pretty regularly (*note Releases::), and this
proved to be really helpful later on.

'EXTRA_PROGRAMS' finally replaces 'AM_PROGRAMS'.

All the third-party Autoconf macros, written mostly by Franc,ois
Pinard (and later Jim Meyering), are distributed in Automake's
hand-written 'aclocal.m4' file. Package maintainers are expected
to extract the necessary macros from this file. (In previous
versions you had to copy and paste them from the manual...)

1996-03-11 Automake 0.31

The test suite in 0.30 was run via a long 'check-local' rule. Upon
Ulrich Drepper's suggestion, 0.31 makes it an Automake rule output
whenever the 'TESTS' variable is defined.

'DIST_OTHER' is renamed to 'EXTRA_DIST', and the 'check_' prefix is
introduced. The syntax is now the same as today.

1996-03-15 Gordon Matzigkeit starts writing libtool.

1996-04-27 Automake 0.32

'-hook' targets are introduced; an idea from Dieter Baron.

'*.info' files, which were output in the build directory are now
built in the source directory, because they are distributed. It
seems these files like to move back and forth as that will happen
again in future versions.

1996-05-18 Automake 0.33

Gord Matzigkeit's main two contributions:

* very preliminary libtool support
* the distcheck rule

Although they were very basic at this point, these are probably
among the top features for Automake today.

Jim Meyering also provides the infamous 'jm_MAINTAINER_MODE', since
then renamed to 'AM_MAINTAINER_MODE' and abandoned by its author
(*note maintainer-mode: (automake)maintainer-mode.).

1996-05-28 Automake 1.0

After only six months of heavy development, the 'automake' script
is 3134 lines long, plus 973 lines of 'Makefile' fragments. The
package has 30 pages of documentation, and 38 test cases.
'aclocal.m4' contains 4 macros.

From now on and until version 1.4, new releases will occur at a
rate of about one a year. 1.1 did not exist, actually 1.1b to 1.1p
have been the name of beta releases for 1.2. This is the first
time Automake uses suffix letters to designate beta releases, a
habit that lasts.

1996-10-10 Kevin Dalley packages Automake 1.0 for Debian GNU/Linux.

1996-11-26 David J. MacKenzie releases Autoconf 2.12.

Between June and October, the Autoconf development is almost
stalled. Roland McGrath has been working at the beginning of the
year. David comes back in November to release 2.12, but he won't
touch Autoconf anymore after this year, and Autoconf then really
stagnates. The desolate Autoconf 'ChangeLog' for 1997 lists only 7
commits.

1997-02-28 <automake AT gnu.edu> list alive

The mailing list is announced as follows:
I've created the "automake" mailing list. It is
"automake AT gnu.edu". Administrivia, as always, to
automake-request AT gnu.edu.

The charter of this list is discussion of automake, autoconf, and
other configuration/portability tools (e.g., libtool). It is expected
that discussion will range from pleas for help all the way up to
patches.

This list is archived on the FSF machines. Offhand I don't know if
you can get the archive without an account there.

This list is open to anybody who wants to join. Tell all your
friends!
-- Tom Tromey

Before that people were discussing Automake privately, on the Gnits
mailing list (which is not public either), and less frequently on
'gnu.misc.discuss'.

'gnu.ai.mit.edu' is now 'gnu.org', in case you never noticed. The
archives of the early years of the 'automake AT gnu.org' list have
been lost, so today it is almost impossible to find traces of
discussions that occurred before 1999. This has been annoying more
than once, as such discussions can be useful to understand the
rationale behind a piece of uncommented code that was introduced
back then.

1997-06-22 Automake 1.2

Automake developments continues, and more and more new Autoconf
macros are required. Distributing them in 'aclocal.m4' and
requiring people to browse this file to extract the relevant macros
becomes uncomfortable. Ideally, some of them should be contributed
to Autoconf so that they can be used directly, however Autoconf is
currently inactive. Automake 1.2 consequently introduces 'aclocal'
('aclocal' was actually started on 1996-07-28), a tool that
automatically constructs an 'aclocal.m4' file from a repository of
third-party macros. Because Autoconf has stalled, Automake also
becomes a kind of repository for such third-party macros, even
macros completely unrelated to Automake (for instance macros that
fix broken Autoconf macros).

The 1.2 release contains 20 macros, including the
'AM_INIT_AUTOMAKE' macro that simplifies the creation of
'configure.in'.

Libtool is fully supported using '*_LTLIBRARIES'.

The missing script is introduced by Franc,ois Pinard; it is meant to
be a better solution than 'AM_MAINTAINER_MODE' (*note
maintainer-mode: (automake)maintainer-mode.).

Conditionals support was implemented by Ian Lance Taylor. At the
time, Tom and Ian were working on an internal project at Cygnus.
They were using ILU, which is pretty similar to CORBA. They wanted
to integrate ILU into their build, which was all 'configure'-based,
and Ian thought that adding conditionals to 'automake' was simpler
than doing all the work in 'configure' (which was the standard at
the time). So this was actually funded by Cygnus.

This very useful but tricky feature will take a lot of time to
stabilize. (At the time this text is written, there are still
primaries that have not been updated to support conditional
definitions in Automake 1.9.)

The 'automake' script has almost doubled: 6089 lines of Perl, plus
1294 lines of 'Makefile' fragments.

1997-07-08 Gordon Matzigkeit releases Libtool 1.0.

1998-04-05 Automake 1.3

This is a small advance compared to 1.2. It adds support for
assembly, and preliminary support for Java.

Perl 5.004_04 is out, but fixes to support Perl 4 are still
regularly submitted whenever Automake breaks it.

1998-09-06 'sourceware.cygnus.com' is on-line.

Sourceware was setup by Jason Molenda to host open source projects.

1998-09-19 Automake CVS repository moved to 'sourceware.cygnus.com'
1998-10-26 'sourceware.cygnus.com' announces it hosts Automake:
Automake is now hosted on 'sourceware.cygnus.com'. It has a
publicly accessible CVS repository. This CVS repository is a copy
of the one Tom was using on his machine, which in turn is based on
a copy of the CVS repository of David MacKenzie. This is why we
still have to full source history. (Automake was on Sourceware
until 2007-10-29, when it moved to a git repository on
'savannah.gnu.org', but the Sourceware host had been renamed to
'sources.redhat.com'.)

The oldest file in the administrative directory of the CVS
repository that was created on Sourceware is dated 1998-09-19,
while the announcement that 'automake' and 'autoconf' had joined
'sourceware' was made on 1998-10-26. They were among the first
projects to be hosted there.

The heedful reader will have noticed Automake was exactly 4 years
old on 1998-09-19.

1999-01-05 Ben Elliston releases Autoconf 2.13.

1999-01-14 Automake 1.4

This release adds support for Fortran 77 and for the 'include'
statement. Also, '+=' assignments are introduced, but it is still
quite easy to fool Automake when mixing this with conditionals.

These two releases, Automake 1.4 and Autoconf 2.13 make a duo that
will be used together for years.

'automake' is 7228 lines, plus 1591 lines of Makefile fragment, 20
macros (some 1.3 macros were finally contributed back to Autoconf),
197 test cases, and 51 pages of documentation.

1999-03-27 The 'user-dep-branch' is created on the CVS repository.

This implements a new dependency tracking schemed that should be
able to handle automatic dependency tracking using any compiler
(not just gcc) and any make (not just GNU 'make'). In addition,
the new scheme should be more reliable than the old one, as
dependencies are generated on the end user's machine. Alexandre
Oliva creates depcomp for this purpose.

*Note Dependency Tracking Evolution::, for more details about the
evolution of automatic dependency tracking in Automake.

1999-11-21 The 'user-dep-branch' is merged into the main trunk.

This was a huge problem since we also had patches going in on the
trunk. The merge took a long time and was very painful.

2000-05-10

Since September 1999 and until 2003, Akim Demaille will be
zealously revamping Autoconf.

I think the next release should be called "3.0".
Let's face it: you've basically rewritten autoconf.
Every weekend there are 30 new patches.
I don't see how we could call this "2.15" with a straight
face.
- Tom Tromey on <autoconf AT gnu.org>

Actually Akim works like a submarine: he will pile up patches while
he works off-line during the weekend, and flush them in batch when
he resurfaces on Monday.

2001-01-24

On this Wednesday, Autoconf 2.49c, the last beta before Autoconf
2.50 is out, and Akim has to find something to do during his
week-end :)

2001-01-28

Akim sends a batch of 14 patches to <automake AT gnu.org>.

Aiieeee! I was dreading the day that the Demaillator turned
his sights on automake... and now it has arrived! - Tom
Tromey

It's only the beginning: in two months he will send 192 patches.
Then he would slow down so Tom can catch up and review all this.
Initially Tom actually read all of these patches, then he probably
trustingly answered OK to most of them, and finally gave up and let
Akim apply whatever he wanted. There was no way to keep up with
that patch rate.

Anyway the patch below won't apply since it predates Akim's
sourcequake; I have yet to figure where the relevant passage
has been moved :) - Alexandre Duret-Lutz

All of these patches were sent to and discussed on
<automake AT gnu.org>, so subscribed users were literally drowning in
technical mails. Eventually, the <automake-patches AT gnu.org>
mailing list was created in May.

Year after year, Automake had drifted away from its initial design:
construct 'Makefile.in' by assembling various 'Makefile' fragments.
In 1.4, lots of 'Makefile' rules are being emitted at various
places in the 'automake' script itself; this does not help ensuring
a consistent treatment of these rules (for instance making sure
that user-defined rules override Automake's own rules). One of
Akim's goal was moving all of these hard-coded rules to separate
'Makefile' fragments, so the logic could be centralized in a
'Makefile' fragment processor.

Another significant contribution of Akim is the interface with the
"trace" feature of Autoconf. The way to scan 'configure.in' at
this time was to read the file and grep the various macro of
interest to Automake. Doing so could break in many unexpected
ways; 'automake' could miss some definition (for instance
'AC_SUBST([$1], [$2])' where the arguments are known only when M4
is run), or conversely it could detect some macro that was not
expanded (because it is called conditionally). In the CVS version
of Autoconf, Akim had implemented the '--trace' option, which
provides accurate information about where macros are actually
called and with what arguments. Akim will equip Automake with a
second 'configure.in' scanner that uses this '--trace' interface.
Since it was not sensible to drop the Autoconf 2.13 compatibility
yet, this experimental scanner was only used when an environment
variable was set, the traditional grep-scanner being still the
default.

2001-04-25 Gary V. Vaughan releases Libtool 1.4

It has been more than two years since Automake 1.4, CVS Automake
has suffered lot's of heavy changes and still is not ready for
release. Libtool 1.4 had to be distributed with a patch against
Automake 1.4.

2001-05-08 Automake 1.4-p1
2001-05-24 Automake 1.4-p2

Gary V. Vaughan, the principal Libtool maintainer, makes a "patch
release" of Automake:

The main purpose of this release is to have a stable automake
which is compatible with the latest stable libtool.

The release also contains obvious fixes for bugs in Automake 1.4,
some of which were reported almost monthly.

2001-05-21 Akim Demaille releases Autoconf 2.50

2001-06-07 Automake 1.4-p3
2001-06-10 Automake 1.4-p4
2001-07-15 Automake 1.4-p5

Gary continues his patch-release series. These also add support
for some new Autoconf 2.50 idioms. Essentially, Autoconf now
advocates 'configure.ac' over 'configure.in', and it introduces a
new syntax for 'AC_OUTPUT'ing files.

2001-08-23 Automake 1.5

A major and long-awaited release, that comes more than two years
after 1.4. It brings many changes, among which:
* The new dependency tracking scheme that uses 'depcomp'. Aside
from the improvement on the dependency tracking itself (*note
Dependency Tracking Evolution::), this also streamlines the
use of 'automake'-generated 'Makefile.in's as the
'Makefile.in's used during development are now the same as
those used in distributions. Before that the 'Makefile.in's
generated for maintainers required GNU 'make' and GCC, they
were different from the portable 'Makefile' generated for
distribution; this was causing some confusion.

* Support for per-target compilation flags.

* Support for reference to files in subdirectories in most
'Makefile.am' variables.

* Introduction of the 'dist_', 'nodist_', and 'nobase_'
prefixes.
* Perl 4 support is finally dropped.

1.5 did break several packages that worked with 1.4. Enough so
that Linux distributions could not easily install the new Automake
version without breaking many of the packages for which they had to
run 'automake'.

Some of these breakages were effectively bugs that would eventually
be fixed in the next release. However, a lot of damage was caused
by some changes made deliberately to render Automake stricter on
some setup we did consider bogus. For instance, 'make distcheck'
was improved to check that 'make uninstall' did remove all the
files 'make install' installed, that 'make distclean' did not omit
some file, and that a VPATH build would work even if the source
directory was read-only. Similarly, Automake now rejects multiple
definitions of the same variable (because that would mix very badly
with conditionals), and '+=' assignments with no previous
definition. Because these changes all occurred suddenly after 1.4
had been established for more than two years, it hurt users.

To make matter worse, meanwhile Autoconf (now at version 2.52) was
facing similar troubles, for similar reasons.

2002-03-05 Automake 1.6

This release introduced versioned installation (*note API
Versioning: (automake)API Versioning.). This was mainly pushed by
Havoc Pennington, taking the GNOME source tree as motive: due to
incompatibilities between the autotools it's impossible for the
GNOME packages to switch to Autoconf 2.53 and Automake 1.5 all at
once, so they are currently stuck with Autoconf 2.13 and Automake
1.4.

The idea was to call this version 'automake-1.6', call all its
bug-fix versions identically, and switch to 'automake-1.7' for the
next release that adds new features or changes some rules. This
scheme implies maintaining a bug-fix branch in addition to the
development trunk, which means more work from the maintainer, but
providing regular bug-fix releases proved to be really worthwhile.

Like 1.5, 1.6 also introduced a bunch of incompatibilities,
intentional or not. Perhaps the more annoying was the dependence
on the newly released Autoconf 2.53. Autoconf seemed to have
stabilized enough since its explosive 2.50 release and included
changes required to fix some bugs in Automake. In order to upgrade
to Automake 1.6, people now had to upgrade Autoconf too; for some
packages it was no picnic.

While versioned installation helped people to upgrade, it also
unfortunately allowed people not to upgrade. At the time of
writing, some Linux distributions are shipping packages for
Automake 1.4, 1.5, 1.6, 1.7, 1.8, and 1.9. Most of these still
install 1.4 by default. Some distribution also call 1.4 the
"stable" version, and present "1.9" as the development version;
this does not really makes sense since 1.9 is way more solid than
1.4. All this does not help the newcomer.

2002-04-11 Automake 1.6.1

1.6, and the upcoming 1.4-p6 release were the last release by Tom.
This one and those following will be handled by Alexandre
Duret-Lutz. Tom is still around, and will be there until about
1.7, but his interest into Automake is drifting away towards
projects like 'gcj'.

Alexandre has been using Automake since 2000, and started to
contribute mostly on Akim's incitement (Akim and Alexandre have
been working in the same room from 1999 to 2002). In 2001 and 2002
he had a lot of free time to enjoy hacking Automake.

2002-06-14 Automake 1.6.2

2002-07-28 Automake 1.6.3
2002-07-28 Automake 1.4-p6

Two releases on the same day. 1.6.3 is a bug-fix release.

Tom Tromey backported the versioned installation mechanism on the
1.4 branch, so that Automake 1.6.x and Automake 1.4-p6 could be
installed side by side. Another request from the GNOME folks.

2002-09-25 Automake 1.7

This release switches to the new 'configure.ac' scanner Akim was
experimenting in 1.5.

2002-10-16 Automake 1.7.1
2002-12-06 Automake 1.7.2
2003-02-20 Automake 1.7.3
2003-04-23 Automake 1.7.4
2003-05-18 Automake 1.7.5
2003-07-10 Automake 1.7.6
2003-09-07 Automake 1.7.7
2003-10-07 Automake 1.7.8

Many bug-fix releases. 1.7 lasted because the development version
(upcoming 1.8) was suffering some major internal revamping.

2003-10-26 Automake on screen

Episode 49, 'Repercussions', in the third season of the 'Alias' TV
show is first aired.

Marshall, one of the characters, is working on a computer virus
that he has to modify before it gets into the wrong hands or
something like that. The screenshots you see do not show any
program code, they show a 'Makefile.in' generated by automake...

2003-11-09 Automake 1.7.9

2003-12-10 Automake 1.8

The most striking update is probably that of 'aclocal'.

'aclocal' now uses 'm4_include' in the produced 'aclocal.m4' when
the included macros are already distributed with the package (an
idiom used in many packages), which reduces code duplication. Many
people liked that, but in fact this change was really introduced to
fix a bug in rebuild rules: 'Makefile.in' must be rebuilt whenever
a dependency of 'configure' changes, but all the 'm4' files
included in 'aclocal.m4' where unknown from 'automake'. Now
'automake' can just trace the 'm4_include's to discover the
dependencies.

'aclocal' also starts using the '--trace' Autoconf option in order
to discover used macros more accurately. This will turn out to be
very tricky (later releases will improve this) as people had
devised many ways to cope with the limitation of previous 'aclocal'
versions, notably using handwritten 'm4_include's: 'aclocal' must
make sure not to redefine a rule that is already included by such
statement.

Automake also has seen its guts rewritten. Although this rewriting
took a lot of efforts, it is only apparent to the users in that
some constructions previously disallowed by the implementation now
work nicely. Conditionals, Locations, Variable and Rule
definitions, Options: these items on which Automake works have been
rewritten as separate Perl modules, and documented.

2004-01-11 Automake 1.8.1
2004-01-12 Automake 1.8.2
2004-03-07 Automake 1.8.3
2004-04-25 Automake 1.8.4
2004-05-16 Automake 1.8.5

2004-07-28 Automake 1.9

This release tries to simplify the compilation rules it outputs to
reduce the size of the Makefile. The complaint initially come from
the libgcj developers. Their 'Makefile.in' generated with Automake
1.4 and custom build rules (1.4 did not support compiled Java) is
250KB. The one generated by 1.8 was over 9MB! 1.9 gets it down to
1.2MB.

Aside from this it contains mainly minor changes and bug-fixes.

2004-08-11 Automake 1.9.1
2004-09-19 Automake 1.9.2

Automake has ten years. This chapter of the manual was initially
written for this occasion.

2007-10-29 Automake repository moves to 'savannah.gnu.org'
and uses git as primary repository.

File: automake-history.info, Node: Dependency Tracking Evolution, Next: Releases, Prev: Timeline, Up: Top

2 Evolution of Automatic Dependency Tracking
********************************************

Over the years Automake has deployed three different dependency tracking
methods. Each method, including the current one, has had flaws of
various sorts. Here we lay out the different dependency tracking
methods, their flaws, and their fixes. We conclude with recommendations
for tool writers, and by indicating future directions for dependency
tracking work in Automake.

* Menu:

File: automake-history.info, Node: First Take on Dependencies, Next: Dependencies As Side Effects, Up: Dependency Tracking Evolution

2.1 First Take on Dependency Tracking
=====================================

Description
-----------

Our first attempt at automatic dependency tracking was based on the
method recommended by GNU 'make'. (*note Generating Prerequisites
Automatically: (make)Automatic Prerequisites.)

This version worked by precomputing dependencies ahead of time. For
each source file, it had a special '.P' file that held the dependencies.
There was a rule to generate a '.P' file by invoking the compiler
appropriately. All such '.P' files were included by the 'Makefile',
thus implicitly becoming dependencies of 'Makefile'.

Bugs
----

This approach had several critical bugs.

* The code to generate the '.P' file relied on 'gcc'. (A limitation,
not technically a bug.)
* The dependency tracking mechanism itself relied on GNU 'make'. (A
limitation, not technically a bug.)
* Because each '.P' file was a dependency of 'Makefile', this meant
that dependency tracking was done eagerly by 'make'. For instance,
'make clean' would cause all the dependency files to be updated,
and then immediately removed. This eagerness also caused problems
with some configurations; if a certain source file could not be
compiled on a given architecture for some reason, dependency
tracking would fail, aborting the entire build.
* As dependency tracking was done as a pre-pass, compile times were
doubled-the compiler had to be run twice per source file.
* 'make dist' re-ran 'automake' to generate a 'Makefile' that did not
have automatic dependency tracking (and that was thus portable to
any version of 'make'). In order to do this portably, Automake had
to scan the dependency files and remove any reference that was to a
source file not in the distribution. This process was error-prone.
Also, if 'make dist' was run in an environment where some object
file had a dependency on a source file that was only conditionally
created, Automake would generate a 'Makefile' that referred to a
file that might not appear in the end user's build. A special,
hacky mechanism was required to work around this.

Historical Note
---------------

The code generated by Automake is often inspired by the 'Makefile' style
of a particular author. In the case of the first implementation of
dependency tracking, I believe the impetus and inspiration was Jim
Meyering. (I could be mistaken. If you know otherwise feel free to
correct me.)

File: automake-history.info, Node: Dependencies As Side Effects, Next: Dependencies for the User, Prev: First Take on Dependencies, Up: Dependency Tracking Evolution

2.2 Dependencies As Side Effects
================================

Description
-----------

The next refinement of Automake's automatic dependency tracking scheme
was to implement dependencies as side effects of the compilation. This
was aimed at solving the most commonly reported problems with the first
approach. In particular we were most concerned with eliminating the
weird rebuilding effect associated with make clean.

In this approach, the '.P' files were included using the '-include'
command, which let us create these files lazily. This avoided the 'make
clean' problem.

We only computed dependencies when a file was actually compiled.
This avoided the performance penalty associated with scanning each file
twice. It also let us avoid the other problems associated with the
first, eager, implementation. For instance, dependencies would never be
generated for a source file that was not compilable on a given
architecture (because it in fact would never be compiled).

Bugs
----

* This approach also relied on the existence of 'gcc' and GNU 'make'.
(A limitation, not technically a bug.)
* Dependency tracking was still done by the developer, so the
problems from the first implementation relating to massaging of
dependencies by 'make dist' were still in effect.
* This implementation suffered from the "deleted header file"
problem. Suppose a lazily-created '.P' file includes a dependency
on a given header file, like this:

maude.o: maude.c something.h

Now suppose that you remove 'something.h' and update 'maude.c' so
that this include is no longer needed. If you run 'make', you will
get an error because there is no way to create 'something.h'.

We fixed this problem in a later release by further massaging the
output of 'gcc' to include a dummy dependency for each header file.

File: automake-history.info, Node: Dependencies for the User, Next: Techniques for Dependencies, Prev: Dependencies As Side Effects, Up: Dependency Tracking Evolution

2.3 Dependencies for the User
=============================

Description
-----------

The bugs associated with 'make dist', over time, became a real problem.
Packages using Automake were being built on a large number of platforms,
and were becoming increasingly complex. Broken dependencies were
distributed in "portable" 'Makefile.in's, leading to user complaints.
Also, the requirement for 'gcc' and GNU 'make' was a constant source of
bug reports. The next implementation of dependency tracking aimed to
remove these problems.

We realized that the only truly reliable way to automatically track
dependencies was to do it when the package itself was built. This meant
discovering a method portable to any version of make and any compiler.
Also, we wanted to preserve what we saw as the best point of the second
implementation: dependency computation as a side effect of compilation.

In the end we found that most modern make implementations support
some form of include directive. Also, we wrote a wrapper script that
let us abstract away differences between dependency tracking methods for
compilers. For instance, some compilers cannot generate dependencies as
a side effect of compilation. In this case we simply have the script
run the compiler twice. Currently our wrapper script ('depcomp') knows
about twelve different compilers (including a "compiler" that simply
invokes 'makedepend' and then the real compiler, which is assumed to be
a standard Unix-like C compiler with no way to do dependency tracking).

Bugs
----

* Running a wrapper script for each compilation slows down the build.
* Many users don't really care about precise dependencies.
* This implementation, like every other automatic dependency tracking
scheme in common use today (indeed, every one we've ever heard of),
suffers from the "duplicated new header" bug.

This bug occurs because dependency tracking tools, such as the
compiler, only generate dependencies on the successful opening of a
file, and not on every probe.

Suppose for instance that the compiler searches three directories
for a given header, and that the header is found in the third
directory. If the programmer erroneously adds a header file with
the same name to the first directory, then a clean rebuild from
scratch could fail (suppose the new header file is buggy), whereas
an incremental rebuild will succeed.

What has happened here is that people have a misunderstanding of
what a dependency is. Tool writers think a dependency encodes
information about which files were read by the compiler. However,
a dependency must actually encode information about what the
compiler tried to do.

This problem is not serious in practice. Programmers typically do
not use the same name for a header file twice in a given project.
(At least, not in C or C++. This problem may be more troublesome
in Java.) This problem is easy to fix, by modifying dependency
generators to record every probe, instead of every successful open.

* Since Automake generates dependencies as a side effect of
compilation, there is a bootstrapping problem when header files are
generated by running a program. The problem is that, the first
time the build is done, there is no way by default to know that the
headers are required, so make might try to run a compilation for
which the headers have not yet been built.

This was also a problem in the previous dependency tracking
implementation.

The current fix is to use 'BUILT_SOURCES' to list built headers
(*note Sources: (automake)Sources.). This causes them to be built
before any other build rules are run. This is unsatisfactory as a
general solution, however in practice it seems sufficient for most
actual programs.

This code is used since Automake 1.5.

In GCC 3.0, we managed to convince the maintainers to add special
command-line options to help Automake more efficiently do its job. We
hoped this would let us avoid the use of a wrapper script when
Automake's automatic dependency tracking was used with 'gcc'.

Unfortunately, this code doesn't quite do what we want. In
particular, it removes the dependency file if the compilation fails;
we'd prefer that it instead only touch the file in any way if the
compilation succeeds.

Nevertheless, since Automake 1.7, when a recent 'gcc' is detected at
'configure' time, we inline the dependency-generation code and do not
use the 'depcomp' wrapper script. This makes compilations faster for
those using this compiler (probably our primary user base). The
counterpart is that because we have to encode two compilation rules in
'Makefile' (with or without 'depcomp'), the produced 'Makefile's are
larger.

File: automake-history.info, Node: Techniques for Dependencies, Prev: Dependencies for the User, Up: Dependency Tracking Evolution

2.4 Techniques for Computing Dependencies
=========================================

There are actually several ways for a build tool like Automake to cause
tools to generate dependencies.

'makedepend'
This was a commonly-used method in the past. The idea is to run a
special program over the source and have it generate dependency
information. Traditional implementations of 'makedepend' are not
completely precise; ordinarily they were conservative and
discovered too many dependencies.
The tool
An obvious way to generate dependencies is to simply write the tool
so that it can generate the information needed by the build tool.
This is also the most portable method. Many compilers have an
option to generate dependencies. Unfortunately, not all tools
provide such an option.
The file system
It is possible to write a special file system that tracks opens,
reads, writes, etc, and then feed this information back to the
build tool. 'clearmake' does this. This is a very powerful
technique, as it doesn't require cooperation from the tool.
Unfortunately it is also very difficult to implement and also not
practical in the general case.
'LD_PRELOAD'
Rather than use the file system, one could write a special library
to intercept 'open' and other syscalls. This technique is also
quite powerful, but unfortunately it is not portable enough for use
in 'automake'.

* Menu:

* Recommendations for Tool Writers::
* Future Directions for Dependencies::

File: automake-history.info, Node: Recommendations for Tool Writers, Next: Future Directions for Dependencies, Up: Techniques for Dependencies

2.4.1 Recommendations for Tool Writers
--------------------------------------

We think that every compilation tool ought to be able to generate
dependencies as a side effect of compilation. Furthermore, at least
while 'make'-based tools are nearly universally in use (at least in the
free software community), the tool itself should generate dummy
dependencies for header files, to avoid the deleted header file bug.
Finally, the tool should generate a dependency for each probe, instead
of each successful file open, in order to avoid the duplicated new
header bug.

File: automake-history.info, Node: Future Directions for Dependencies, Prev: Recommendations for Tool Writers, Up: Techniques for Dependencies

2.4.2 Future Directions for Dependencies
----------------------------------------

Currently, only languages and compilers understood by Automake can have
dependency tracking enabled. We would like to see if it is practical
(and worthwhile) to let this support be extended by the user to
languages unknown to Automake.

File: automake-history.info, Node: Releases, Next: Copying This Manual, Prev: Dependency Tracking Evolution, Up: Top

3 Release Statistics
********************

The following table (inspired by 'perlhist(1)') quantifies the evolution
of Automake using these metrics:

Date, Rel
The date and version of the release.
am
The number of lines of the 'automake' script.
acl
The number of lines of the 'aclocal' script.
pm
The number of lines of the 'Perl' supporting modules.
'*.am'
The number of lines of the 'Makefile' fragments. The number in
parentheses is the number of files.
m4
The number of lines (and files) of Autoconf macros.
doc
The number of pages of the documentation (the Postscript version).
t
The number of test cases in the test suite. Of those, the number
in parentheses is the number of generated test cases.

Date Rel am acl pm '*.am' m4 doc t
------------------------------------------------------------------------------------
1994-09-19 CVS 141 299 (24)
1994-11-05 CVS 208 332 (28)
1995-11-23 0.20 533 458 (35) 9
1995-11-26 0.21 613 480 (36) 11
1995-11-28 0.22 1116 539 (38) 12
1995-11-29 0.23 1240 541 (38) 12
1995-12-08 0.24 1462 504 (33) 14
1995-12-10 0.25 1513 511 (37) 15
1996-01-03 0.26 1706 438 (36) 16
1996-01-03 0.27 1706 438 (36) 16
1996-01-13 0.28 1964 934 (33) 16
1996-02-07 0.29 2299 936 (33) 17
1996-02-24 0.30 2544 919 (32) 85 (1) 20 9
1996-03-11 0.31 2877 919 (32) 85 (1) 29 17
1996-04-27 0.32 3058 921 (31) 85 (1) 30 26
1996-05-18 0.33 3110 926 (31) 105 (1) 30 35
1996-05-28 1.0 3134 973 (32) 105 (1) 30 38
1997-06-22 1.2 6089 385 1294 (36) 592 (20) 37 126
1998-04-05 1.3 6415 422 1470 (39) 741 (23) 39 156
1999-01-14 1.4 7240 426 1591 (40) 734 (20) 51 197
2001-05-08 1.4-p1 7251 426 1591 (40) 734 (20) 51 197
2001-05-24 1.4-p2 7268 439 1591 (40) 734 (20) 49 197
2001-06-07 1.4-p3 7312 439 1591 (40) 734 (20) 49 197
2001-06-10 1.4-p4 7321 439 1591 (40) 734 (20) 49 198
2001-07-15 1.4-p5 7228 426 1596 (40) 734 (20) 51 198
2001-08-23 1.5 8016 475 600 2654 (39) 1166 (29) 63 327
2002-03-05 1.6 8465 475 1136 2732 (39) 1603 (27) 66 365
2002-04-11 1.6.1 8544 475 1136 2741 (39) 1603 (27) 66 372
2002-06-14 1.6.2 8575 475 1136 2800 (39) 1609 (27) 67 386
2002-07-28 1.6.3 8600 475 1153 2809 (39) 1609 (27) 67 391
2002-07-28 1.4-p6 7332 455 1596 (40) 735 (20) 49 197
2002-09-25 1.7 9189 471 1790 2965 (39) 1606 (28) 73 430
2002-10-16 1.7.1 9229 475 1790 2977 (39) 1606 (28) 73 437
2002-12-06 1.7.2 9334 475 1790 2988 (39) 1606 (28) 77 445
2003-02-20 1.7.3 9389 475 1790 3023 (39) 1651 (29) 84 448
2003-04-23 1.7.4 9429 475 1790 3031 (39) 1644 (29) 85 458
2003-05-18 1.7.5 9429 475 1790 3033 (39) 1645 (29) 85 459
2003-07-10 1.7.6 9442 475 1790 3033 (39) 1660 (29) 85 461
2003-09-07 1.7.7 9443 475 1790 3041 (39) 1660 (29) 90 467
2003-10-07 1.7.8 9444 475 1790 3041 (39) 1660 (29) 90 468
2003-11-09 1.7.9 9444 475 1790 3048 (39) 1660 (29) 90 468
2003-12-10 1.8 7171 585 7730 3236 (39) 1666 (31) 104 521
2004-01-11 1.8.1 7217 663 7726 3287 (39) 1686 (31) 104 525
2004-01-12 1.8.2 7217 663 7726 3288 (39) 1686 (31) 104 526
2004-03-07 1.8.3 7214 686 7735 3303 (39) 1695 (31) 111 530
2004-04-25 1.8.4 7214 686 7736 3310 (39) 1701 (31) 112 531
2004-05-16 1.8.5 7240 686 7736 3299 (39) 1701 (31) 112 533
2004-07-28 1.9 7508 715 7794 3352 (40) 1812 (32) 115 551
2004-08-11 1.9.1 7512 715 7794 3354 (40) 1812 (32) 115 552
2004-09-19 1.9.2 7512 715 7794 3354 (40) 1812 (32) 132 554
2004-11-01 1.9.3 7507 718 7804 3354 (40) 1812 (32) 134 556
2004-12-18 1.9.4 7508 718 7856 3361 (40) 1811 (32) 140 560
2005-02-13 1.9.5 7523 719 7859 3373 (40) 1453 (32) 142 562
2005-07-10 1.9.6 7539 699 7867 3400 (40) 1453 (32) 144 570
2006-10-15 1.10 7859 1072 8024 3512 (40) 1496 (34) 172 604
2008-01-19 1.10.1 7870 1089 8025 3520 (40) 1499 (34) 173 617
2008-11-23 1.10.2 7882 1089 8027 3540 (40) 1509 (34) 176 628
2009-05-17 1.11 8721 1092 8289 4164 (42) 1714 (37) 181 732 (20)

File: automake-history.info, Node: Copying This Manual, Prev: Releases, Up: Top

Appendix A Copying This Manual
******************************

* Menu:

* GNU Free Documentation License:: License for copying this manual

File: automake-history.info, Node: GNU Free Documentation License, Up: Copying This Manual

A.1 GNU Free Documentation License
==================================

Version 1.3, 3 November 2008

Everyone is permitted to copy and distribute verbatim copies
of this license document, but changing it is not allowed.

0. PREAMBLE

The purpose of this License is to make a manual, textbook, or other
functional and useful document "free" in the sense of freedom: to
assure everyone the effective freedom to copy and redistribute it,
with or without modifying it, either commercially or
noncommercially. Secondarily, this License preserves for the
author and publisher a way to get credit for their work, while not
being considered responsible for modifications made by others.

This License is a kind of "copyleft", which means that derivative
works of the document must themselves be free in the same sense.
It complements the GNU General Public License, which is a copyleft
license designed for free software.

We have designed this License in order to use it for manuals for
free software, because free software needs free documentation: a
free program should come with manuals providing the same freedoms
that the software does. But this License is not limited to
software manuals; it can be used for any textual work, regardless
of subject matter or whether it is published as a printed book. We
recommend this License principally for works whose purpose is
instruction or reference.

1. APPLICABILITY AND DEFINITIONS

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A "Modified Version" of the Document means any work containing the
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A "Secondary Section" is a named appendix or a front-matter section
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The "Invariant Sections" are certain Secondary Sections whose
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Preserve the Title of the section, and preserve in the section
all the substance and tone of each of the contributor
acknowledgements and/or dedications given therein.

L. Preserve all the Invariant Sections of the Document, unaltered
in their text and in their titles. Section numbers or the
equivalent are not considered part of the section titles.

M. Delete any section Entitled "Endorsements". Such a section
may not be included in the Modified Version.

N. Do not retitle any existing section to be Entitled
"Endorsements" or to conflict in title with any Invariant
Section.

O. Preserve any Warranty Disclaimers.

If the Modified Version includes new front-matter sections or
appendices that qualify as Secondary Sections and contain no
material copied from the Document, you may at your option designate
some or all of these sections as invariant. To do this, add their
titles to the list of Invariant Sections in the Modified Version's
license notice. These titles must be distinct from any other
section titles.

You may add a section Entitled "Endorsements", provided it contains
nothing but endorsements of your Modified Version by various
parties--for example, statements of peer review or that the text
has been approved by an organization as the authoritative
definition of a standard.

You may add a passage of up to five words as a Front-Cover Text,
and a passage of up to 25 words as a Back-Cover Text, to the end of
the list of Cover Texts in the Modified Version. Only one passage
of Front-Cover Text and one of Back-Cover Text may be added by (or
through arrangements made by) any one entity. If the Document
already includes a cover text for the same cover, previously added
by you or by arrangement made by the same entity you are acting on
behalf of, you may not add another; but you may replace the old
one, on explicit permission from the previous publisher that added
the old one.

The author(s) and publisher(s) of the Document do not by this
License give permission to use their names for publicity for or to
assert or imply endorsement of any Modified Version.

5. COMBINING DOCUMENTS

You may combine the Document with other documents released under
this License, under the terms defined in section 4 above for
modified versions, provided that you include in the combination all
of the Invariant Sections of all of the original documents,
unmodified, and list them all as Invariant Sections of your
combined work in its license notice, and that you preserve all
their Warranty Disclaimers.

The combined work need only contain one copy of this License, and
multiple identical Invariant Sections may be replaced with a single
copy. If there are multiple Invariant Sections with the same name
but different contents, make the title of each such section unique
by adding at the end of it, in parentheses, the name of the
original author or publisher of that section if known, or else a
unique number. Make the same adjustment to the section titles in
the list of Invariant Sections in the license notice of the
combined work.

In the combination, you must combine any sections Entitled
"History" in the various original documents, forming one section
Entitled "History"; likewise combine any sections Entitled
"Acknowledgements", and any sections Entitled "Dedications". You
must delete all sections Entitled "Endorsements."

6. COLLECTIONS OF DOCUMENTS

You may make a collection consisting of the Document and other
documents released under this License, and replace the individual
copies of this License in the various documents with a single copy
that is included in the collection, provided that you follow the
rules of this License for verbatim copying of each of the documents
in all other respects.

You may extract a single document from such a collection, and
distribute it individually under this License, provided you insert
a copy of this License into the extracted document, and follow this
License in all other respects regarding verbatim copying of that
document.

7. AGGREGATION WITH INDEPENDENT WORKS

A compilation of the Document or its derivatives with other
separate and independent documents or works, in or on a volume of a
storage or distribution medium, is called an "aggregate" if the
copyright resulting from the compilation is not used to limit the
legal rights of the compilation's users beyond what the individual
works permit. When the Document is included in an aggregate, this
License does not apply to the other works in the aggregate which
are not themselves derivative works of the Document.

If the Cover Text requirement of section 3 is applicable to these
copies of the Document, then if the Document is less than one half
of the entire aggregate, the Document's Cover Texts may be placed
on covers that bracket the Document within the aggregate, or the
electronic equivalent of covers if the Document is in electronic
form. Otherwise they must appear on printed covers that bracket
the whole aggregate.

8. TRANSLATION

Translation is considered a kind of modification, so you may
distribute translations of the Document under the terms of section
4. Replacing Invariant Sections with translations requires special
permission from their copyright holders, but you may include
translations of some or all Invariant Sections in addition to the
original versions of these Invariant Sections. You may include a
translation of this License, and all the license notices in the
Document, and any Warranty Disclaimers, provided that you also
include the original English version of this License and the
original versions of those notices and disclaimers. In case of a
disagreement between the translation and the original version of
this License or a notice or disclaimer, the original version will
prevail.

If a section in the Document is Entitled "Acknowledgements",
"Dedications", or "History", the requirement (section 4) to
Preserve its Title (section 1) will typically require changing the
actual title.

9. TERMINATION

You may not copy, modify, sublicense, or distribute the Document
except as expressly provided under this License. Any attempt
otherwise to copy, modify, sublicense, or distribute it is void,
and will automatically terminate your rights under this License.

However, if you cease all violation of this License, then your
license from a particular copyright holder is reinstated (a)
provisionally, unless and until the copyright holder explicitly and
finally terminates your license, and (b) permanently, if the
copyright holder fails to notify you of the violation by some
reasonable means prior to 60 days after the cessation.

Moreover, your license from a particular copyright holder is
reinstated permanently if the copyright holder notifies you of the
violation by some reasonable means, this is the first time you have
received notice of violation of this License (for any work) from
that copyright holder, and you cure the violation prior to 30 days
after your receipt of the notice.

Termination of your rights under this section does not terminate
the licenses of parties who have received copies or rights from you
under this License. If your rights have been terminated and not
permanently reinstated, receipt of a copy of some or all of the
same material does not give you any rights to use it.

10. FUTURE REVISIONS OF THIS LICENSE

The Free Software Foundation may publish new, revised versions of
the GNU Free Documentation License from time to time. Such new
versions will be similar in spirit to the present version, but may
differ in detail to address new problems or concerns. See
<https://www.gnu.org/copyleft/>.

Each version of the License is given a distinguishing version
number. If the Document specifies that a particular numbered
version of this License "or any later version" applies to it, you
have the option of following the terms and conditions either of
that specified version or of any later version that has been
published (not as a draft) by the Free Software Foundation. If the
Document does not specify a version number of this License, you may
choose any version ever published (not as a draft) by the Free
Software Foundation. If the Document specifies that a proxy can
decide which future versions of this License can be used, that
proxy's public statement of acceptance of a version permanently
authorizes you to choose that version for the Document.

11. RELICENSING

"Massive Multiauthor Collaboration Site" (or "MMC Site") means any
World Wide Web server that publishes copyrightable works and also
provides prominent facilities for anybody to edit those works. A
public wiki that anybody can edit is an example of such a server.
A "Massive Multiauthor Collaboration" (or "MMC") contained in the
site means any set of copyrightable works thus published on the MMC
site.

"CC-BY-SA" means the Creative Commons Attribution-Share Alike 3.0
license published by Creative Commons Corporation, a not-for-profit
corporation with a principal place of business in San Francisco,
California, as well as future copyleft versions of that license
published by that same organization.

"Incorporate" means to publish or republish a Document, in whole or
in part, as part of another Document.

An MMC is "eligible for relicensing" if it is licensed under this
License, and if all works that were first published under this
License somewhere other than this MMC, and subsequently
incorporated in whole or in part into the MMC, (1) had no cover
texts or invariant sections, and (2) were thus incorporated prior
to November 1, 2008.

The operator of an MMC Site may republish an MMC contained in the
site under CC-BY-SA on the same site at any time before August 1,
2009, provided the MMC is eligible for relicensing.

ADDENDUM: How to use this License for your documents
====================================================

To use this License in a document you have written, include a copy of
the License in the document and put the following copyright and license
notices just after the title page:

Copyright (C) YEAR YOUR NAME.
Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.3
or any later version published by the Free Software Foundation;
with no Invariant Sections, no Front-Cover Texts, and no Back-Cover
Texts. A copy of the license is included in the section entitled ``GNU
Free Documentation License''.

If you have Invariant Sections, Front-Cover Texts and Back-Cover
Texts, replace the "with...Texts." line with this:

with the Invariant Sections being LIST THEIR TITLES, with
the Front-Cover Texts being LIST, and with the Back-Cover Texts
being LIST.

If you have Invariant Sections without Cover Texts, or some other
combination of the three, merge those two alternatives to suit the
situation.

If your document contains nontrivial examples of program code, we
recommend releasing these examples in parallel under your choice of free
software license, such as the GNU General Public License, to permit
their use in free software.

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