HACKING - automake - Git at Google


            
            ================================================================

            
            = This file


            * This file attempts to describe the rules to use when hacking

            
              automake.


            ================================================================

            
            = Administrivia


            * The correct response to most actual bugs is to write a new test case

            
              which demonstrates the bug.  Then fix the bug, re-run the test suite,

            
              and check everything in.


            * If you incorporate a change from somebody on the net:

            
              First, if it is a large change, you must make sure they have signed the

            
              appropriate paperwork.

            
              Second, be sure to add their name and email address to THANKS


            * If a change fixes a test, mention the test in the ChangeLog entry.

            
              If a change fixes a bug registered in the Automake debbugs tracker,

            
              mention the bug number in the ChangeLog entry.


            * If somebody reports a new bug, mention his name in the ChangeLog entry

            
              and in the test case you write.  Put him into THANKS.


            * When documenting a non-trivial idiom or example in the manual, be

            
              sure to add a test case for it, and to reference such test case from

            
              a proper Texinfo comment.


            * Some files in the automake package are not owned by automake.  These

            
              files should never be edited here.  These files are

            
                  COPYING (from FSF),

            
                  INSTALL (autoconf-patches@gnu.org),

            
                  config.guess, config.sub (config-patches@gnu.org),

            
                  texinfo.tex (bug-texinfo@gnu.org),

            
              Most of them are updated before release with `make fetch'.


            * Changes other than bug fixes must be mentioned in NEWS.  Important

            
              bug fixes should be mentioned in NEWS, too.


            ================================================================

            
            = Naming


            * We've adopted the convention that internal AC_SUBSTs should be

            
              named with a leading `am__', and internally generated targets

            
              should be named with a leading `am--'.  This convention, although

            
              in place from at least February 2001, isn't yet universally used.

            
              But all new code should use it.


              We used to use `_am_' as the prefix for an internal AC_SUBST.

            
              However, it turns out that NEWS-OS 4.2R complains if a Makefile

            
              variable begins with `_'.  Yay for them.  I changed the target

            
              naming convention just to be safe.


            ================================================================

            
            = Editing `.am' files


            * Always use $(...) and not ${...}


            * Use `:', not `true'.  Use `exit 1', not `false'.


            * Use `##' comments liberally.  Comment anything even remotely

            
              unusual.


            * Never use basename or dirname.  Instead use sed.


            * Do not use `cd' within back-quotes, use `$(am__cd)' instead.

            
              Otherwise the directory name may be printed, depending on CDPATH.

            
              More generally, do not ever use plain `cd' together with a relative

            
              directory that does not start with a dot, or you might end up in one

            
              computed with CDPATH.


            * For install and uninstall rules, if a loop is required, it should be

            
              silent.  Then the body of the loop itself should print each

            
              "important" command it runs.  The printed commands should be preceded

            
              by a single space.


            ================================================================

            
            = Editing automake.in and aclocal.in


            * Indent using GNU style.  For historical reasons, the perl code

            
              contains portions indented using Larry Wall's style (perl-mode's

            
              default), and other portions using the GNU style (cperl-mode's

            
              default).  Write new code using GNU style.


            * Don't use & for function calls, unless required.

            
              The use of & prevents prototypes from being checked.

            
              Just as above, don't change massively all the code to strip the

            
              &, just convert the old code as you work on it, and write new

            
              code without.


            ================================================================

            
            = Working with git


            * To regenerate dependent files created by aclocal and automake,

            
              use the `bootstrap' script.  It uses the code from the source

            
              tree, so the resulting files (aclocal.m4 and Makefile.in) should

            
              be the same as you would get if you install this version of

            
              automake and use it to generate those files.  Be sure to have the

            
              latest stable version of Autoconf installed.  If such version is

            
              not installed as "autoconf", pass it explicitly (along with the

            
              accompanying "autom4te") when calling `bootstrap' and `configure'.

            
              For example:

            
                $ AUTOCONF=autoconf2.68 AUTOM4TE=autom4te2.68 ./bootstrap

            
                $ ./configure AUTOCONF=autoconf2.68 AUTOM4TE=autom4te2.68


            * Dependent files aclocal.m4, configure and Makefile.in in all

            
              directories should be up to date in the git repository, so that

            
              the changes in them can be easily noticed and analyzed.


            * The git tree currently carries a number of branches: master for the

            
              current development, and release branches named branch-X.Y.  The maint

            
              branch serves as common ground for both master and the active release

            
              branches.  Changes intended for both should be applied to maint, which

            
              should then be merged to release branches and master, of course after

            
              suitable testing.  It is advisable to merge only after a set of related

            
              commits have been applied.


            * Example work flow for patches to maint:


              # 1. Checkout the "maint" branch:

            
              git checkout maint


              # 2. Apply the patch(es) with "git am" (or create them with $EDITOR):

            
              git am -3 0*.patch

            
              # 2a. Run required tests, if any ...


              # 3. Merge maint into branch-1.11:

            
              git checkout branch-1.11

            
              git merge maint

            
              # 3a. Run required tests, if any ...


              # 4. Redo steps 3 and 3a for master:

            
              git checkout master

            
              git merge maint

            
              # testing ...


              # 5. Push the maint and master branches:

            
              git push --dry-run origin maint branch-1.11 master

            
              # if all seems ok, then actually push:

            
              git push origin maint branch-1.11 master


            * When fixing a bug (especially a long-standing one), it may be useful

            
              to commit the fix to a new temporary branch based off the commit that

            
              introduced the bug.  Then this "bugfix branch" can be merged into all

            
              the active branches descending from the buggy commit.  This offers a

            
              simple way to fix the bug consistently and effectively.


            * When referring to older commits, use 'git describe' output as pointer.


            * There may be a number of longer-lived feature branches for new developments.

            
              They should be based off of a common ancestor of all active branches to

            
              which the feature should or might be merged later.  The next branch may

            
              serve as common ground for feature merging and testing, should they not

            
              be ready for master yet.


            * For merges from branches other than maint, prefer 'git merge --log' over

            
              plain 'git merge', so that a later 'git log' gives an indication of which

            
              actual patches were merged even when they don't appear early in the list.


            * master and release branches should not be rewound, i.e., should always

            
              fast-forward, except maybe for privacy issues.  The maint branch should not

            
              be rewound except maybe after retiring a release branch or a new stable

            
              release.  For next, and for feature branches, the announcement for the

            
              branch should document rewinding policy.


            * In order for rebasing and merging of ChangeLog entries to work seamlessly,

            
              install and configure git-merge-changelog, currently available as gnulib

            
              module.


            ================================================================

            
            = Test suite


            * Use "make check" and "make maintainer-check" liberally.


            * Make sure each test file is executable.


            * Use `keep_testdirs=yes' to keep test directories for successful

            
              tests also.


            * Use perl coverage information to ensure your new code is thoroughly

            
              tested by your new tests.


            * See file `tests/README' for more information.


            ================================================================

            
            = Release procedure


            * The steps outlined here are meant to be followed for alpha and stable

            
              releases as well.  Where differences are expected, they will be

            
              explicitly described.


            * Fetch new versions of the files that are maintained by the FSF.

            
              Commit.  Unfortunately you need an FSF account to do this.

            
              (You can also use `make fetch', but that is still woefully incomplete.)


            * Update NEWS.


            * Update the version number in configure.ac.

            
              (The idea is that every other alpha number will be a net release.

            
              The repository will always have its own "odd" number so we can easily

            
              distinguish net and repo versions.)


            * Update ChangeLog.


            * Run this:

            
              ./bootstrap && ./configure && make && make check && make distcheck


            * Run `make release-stats' if release statistics in doc/automake.texi

            
              have not been updated yet.


            * Run `make git-release'.

            
              This will run "make dist" to create the tarballs, commit the last

            
              NEWS/configure.ac/ChangeLog changes, tag the repository, sign

            
              the tarballs, and upload them.

            
              Use `make GNUPLOADFLAGS="--user key" git-release' to sign with

            
              a non-default key.


            * Update version number in configure.ac to next alpha number.

            
              Re-run ./bootstrap and commit.


            * Don't forget to `git push' your changes so they appear in the public

            
              git tree.


            * For stable releases, update the manuals at www.gnu.org:

            
              - Generate manuals:

            
                cd doc

            
                wget "http://savannah.gnu.org/cgi-bin/viewcvs/~checkout~/texinfo/texinfo/util/gendocs.sh"

            
                wget "http://savannah.gnu.org/cgi-bin/viewcvs/~checkout~/texinfo/texinfo/util/gendocs_template"

            
                sh ./gendocs.sh --email bug-automake@gnu.org automake "GNU Automake"

            
              - copy manuals recursively to web cvs,

            
              - commit.

            
              - Check for link errors, fix them, recheck until convergence:

            
                <http://validator.w3.org/checklink>


            * Send the announcement at least to <autotools-announce@gnu.org> and

            
              <automake@gnu.org>.  If the release is a stable one, the announcement

            
              must also go to <info-gnu@gnu.org>; if it is an alpha or beta release,

            
              announcement should be sent also to <platform-testers@gnu.org>, to

            
              maximize the possibility of early testing on exotic or proprietary

            
              systems.  Finally, copy the announcement into the NEWS feed at

            
              <https://savannah.gnu.org/projects/automake>.


            -----


            Copyright (C) 2003, 2007, 2008, 2010, 2011 Free Software Foundation,

            
            Inc.


            This program is free software; you can redistribute it and/or modify

            
            it under the terms of the GNU General Public License as published by

            
            the Free Software Foundation; either version 2, or (at your option)

            
            any later version.


            This program is distributed in the hope that it will be useful,

            
            but WITHOUT ANY WARRANTY; without even the implied warranty of

            
            MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

            
            GNU General Public License for more details.


            You should have received a copy of the GNU General Public License

            
            along with this program.  If not, see <http://www.gnu.org/licenses/>.


            Local Variables:

            
            mode: text

            
            End:
	================================================================
	= This file

	* This file attempts to describe the rules to use when hacking
	automake.

	================================================================
	= Administrivia

	* The correct response to most actual bugs is to write a new test case
	which demonstrates the bug. Then fix the bug, re-run the test suite,
	and check everything in.

	* If you incorporate a change from somebody on the net:
	First, if it is a large change, you must make sure they have signed the
	appropriate paperwork.
	Second, be sure to add their name and email address to THANKS

	* If a change fixes a test, mention the test in the ChangeLog entry.
	If a change fixes a bug registered in the Automake debbugs tracker,
	mention the bug number in the ChangeLog entry.

	* If somebody reports a new bug, mention his name in the ChangeLog entry
	and in the test case you write. Put him into THANKS.

	* When documenting a non-trivial idiom or example in the manual, be
	sure to add a test case for it, and to reference such test case from
	a proper Texinfo comment.

	* Some files in the automake package are not owned by automake. These
	files should never be edited here. These files are
	COPYING (from FSF),
	INSTALL (autoconf-patches@gnu.org),
	config.guess, config.sub (config-patches@gnu.org),
	texinfo.tex (bug-texinfo@gnu.org),
	Most of them are updated before release with `make fetch'.

	* Changes other than bug fixes must be mentioned in NEWS. Important
	bug fixes should be mentioned in NEWS, too.

	================================================================
	= Naming

	* We've adopted the convention that internal AC_SUBSTs should be
	named with a leading `am__', and internally generated targets
	should be named with a leading `am--'. This convention, although
	in place from at least February 2001, isn't yet universally used.
	But all new code should use it.

	We used to use `_am_' as the prefix for an internal AC_SUBST.
	However, it turns out that NEWS-OS 4.2R complains if a Makefile
	variable begins with `_'. Yay for them. I changed the target
	naming convention just to be safe.

	================================================================
	= Editing `.am' files

	* Always use $(...) and not ${...}

	* Use `:', not `true'. Use `exit 1', not `false'.

	* Use `##' comments liberally. Comment anything even remotely
	unusual.

	* Never use basename or dirname. Instead use sed.

	* Do not use `cd' within back-quotes, use `$(am__cd)' instead.
	Otherwise the directory name may be printed, depending on CDPATH.
	More generally, do not ever use plain `cd' together with a relative
	directory that does not start with a dot, or you might end up in one
	computed with CDPATH.

	* For install and uninstall rules, if a loop is required, it should be
	silent. Then the body of the loop itself should print each
	"important" command it runs. The printed commands should be preceded
	by a single space.

	================================================================
	= Editing automake.in and aclocal.in

	* Indent using GNU style. For historical reasons, the perl code
	contains portions indented using Larry Wall's style (perl-mode's
	default), and other portions using the GNU style (cperl-mode's
	default). Write new code using GNU style.

	* Don't use & for function calls, unless required.
	The use of & prevents prototypes from being checked.
	Just as above, don't change massively all the code to strip the
	&, just convert the old code as you work on it, and write new
	code without.

	================================================================
	= Working with git

	* To regenerate dependent files created by aclocal and automake,
	use the `bootstrap' script. It uses the code from the source
	tree, so the resulting files (aclocal.m4 and Makefile.in) should
	be the same as you would get if you install this version of
	automake and use it to generate those files. Be sure to have the
	latest stable version of Autoconf installed. If such version is
	not installed as "autoconf", pass it explicitly (along with the
	accompanying "autom4te") when calling `bootstrap' and `configure'.
	For example:
	$ AUTOCONF=autoconf2.68 AUTOM4TE=autom4te2.68 ./bootstrap
	$ ./configure AUTOCONF=autoconf2.68 AUTOM4TE=autom4te2.68

	* Dependent files aclocal.m4, configure and Makefile.in in all
	directories should be up to date in the git repository, so that
	the changes in them can be easily noticed and analyzed.

	* The git tree currently carries a number of branches: master for the
	current development, and release branches named branch-X.Y. The maint
	branch serves as common ground for both master and the active release
	branches. Changes intended for both should be applied to maint, which
	should then be merged to release branches and master, of course after
	suitable testing. It is advisable to merge only after a set of related
	commits have been applied.

	* Example work flow for patches to maint:

	# 1. Checkout the "maint" branch:
	git checkout maint

	# 2. Apply the patch(es) with "git am" (or create them with $EDITOR):
	git am -3 0*.patch
	# 2a. Run required tests, if any ...

	# 3. Merge maint into branch-1.11:
	git checkout branch-1.11
	git merge maint
	# 3a. Run required tests, if any ...

	# 4. Redo steps 3 and 3a for master:
	git checkout master
	git merge maint
	# testing ...

	# 5. Push the maint and master branches:
	git push --dry-run origin maint branch-1.11 master
	# if all seems ok, then actually push:
	git push origin maint branch-1.11 master

	* When fixing a bug (especially a long-standing one), it may be useful
	to commit the fix to a new temporary branch based off the commit that
	introduced the bug. Then this "bugfix branch" can be merged into all
	the active branches descending from the buggy commit. This offers a
	simple way to fix the bug consistently and effectively.

	* When referring to older commits, use 'git describe' output as pointer.

	* There may be a number of longer-lived feature branches for new developments.
	They should be based off of a common ancestor of all active branches to
	which the feature should or might be merged later. The next branch may
	serve as common ground for feature merging and testing, should they not
	be ready for master yet.

	* For merges from branches other than maint, prefer 'git merge --log' over
	plain 'git merge', so that a later 'git log' gives an indication of which
	actual patches were merged even when they don't appear early in the list.

	* master and release branches should not be rewound, i.e., should always
	fast-forward, except maybe for privacy issues. The maint branch should not
	be rewound except maybe after retiring a release branch or a new stable
	release. For next, and for feature branches, the announcement for the
	branch should document rewinding policy.

	* In order for rebasing and merging of ChangeLog entries to work seamlessly,
	install and configure git-merge-changelog, currently available as gnulib
	module.

	================================================================
	= Test suite

	* Use "make check" and "make maintainer-check" liberally.

	* Make sure each test file is executable.

	* Use `keep_testdirs=yes' to keep test directories for successful
	tests also.

	* Use perl coverage information to ensure your new code is thoroughly
	tested by your new tests.

	* See file `tests/README' for more information.

	================================================================
	= Release procedure

	* The steps outlined here are meant to be followed for alpha and stable
	releases as well. Where differences are expected, they will be
	explicitly described.

	* Fetch new versions of the files that are maintained by the FSF.
	Commit. Unfortunately you need an FSF account to do this.
	(You can also use `make fetch', but that is still woefully incomplete.)

	* Update NEWS.

	* Update the version number in configure.ac.
	(The idea is that every other alpha number will be a net release.
	The repository will always have its own "odd" number so we can easily
	distinguish net and repo versions.)

	* Update ChangeLog.

	* Run this:
	./bootstrap && ./configure && make && make check && make distcheck

	* Run `make release-stats' if release statistics in doc/automake.texi
	have not been updated yet.

	* Run `make git-release'.
	This will run "make dist" to create the tarballs, commit the last
	NEWS/configure.ac/ChangeLog changes, tag the repository, sign
	the tarballs, and upload them.
	Use `make GNUPLOADFLAGS="--user key" git-release' to sign with
	a non-default key.

	* Update version number in configure.ac to next alpha number.
	Re-run ./bootstrap and commit.

	* Don't forget to `git push' your changes so they appear in the public
	git tree.

	* For stable releases, update the manuals at www.gnu.org:
	- Generate manuals:
	cd doc
	wget "http://savannah.gnu.org/cgi-bin/viewcvs/~checkout~/texinfo/texinfo/util/gendocs.sh"
	wget "http://savannah.gnu.org/cgi-bin/viewcvs/~checkout~/texinfo/texinfo/util/gendocs_template"
	sh ./gendocs.sh --email bug-automake@gnu.org automake "GNU Automake"
	- copy manuals recursively to web cvs,
	- commit.
	- Check for link errors, fix them, recheck until convergence:
	<http://validator.w3.org/checklink>

	* Send the announcement at least to <autotools-announce@gnu.org> and
	<automake@gnu.org>. If the release is a stable one, the announcement
	must also go to <info-gnu@gnu.org>; if it is an alpha or beta release,
	announcement should be sent also to <platform-testers@gnu.org>, to
	maximize the possibility of early testing on exotic or proprietary
	systems. Finally, copy the announcement into the NEWS feed at
	<https://savannah.gnu.org/projects/automake>.

	-----

	Copyright (C) 2003, 2007, 2008, 2010, 2011 Free Software Foundation,
	Inc.

	This program is free software; you can redistribute it and/or modify
	it under the terms of the GNU General Public License as published by
	the Free Software Foundation; either version 2, or (at your option)
	any later version.

	This program is distributed in the hope that it will be useful,
	but WITHOUT ANY WARRANTY; without even the implied warranty of
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	GNU General Public License for more details.

	You should have received a copy of the GNU General Public License
	along with this program. If not, see <http://www.gnu.org/licenses/>.

	Local Variables:
	mode: text
	End: