doc: update README-hacking.

[bison.git] / README-hacking

-*- outline -*-

These notes intend to help people working on the checked-out sources.
These requirements do not apply when building from a distribution tarball.

* Requirements

We've opted to keep only the highest-level sources in the repository.
This eases our maintenance burden, (fewer merges etc.), but imposes more
requirements on anyone wishing to build from the just-checked-out sources.
For example, you have to use the latest stable versions of the maintainer
tools we depend upon, including:

- Automake <http://www.gnu.org/software/automake/>
- Autoconf <http://www.gnu.org/software/autoconf/>
- Flex <http://www.gnu.org/software/flex/>
- Gettext <http://www.gnu.org/software/gettext/>
- Gzip <http://www.gnu.org/software/gzip/>
- Perl <http://www.cpan.org/>
- Rsync <http://samba.anu.edu.au/rsync/>
- Tar <http://www.gnu.org/software/tar/>

Valgrind <http://valgrind.org/> is also highly recommended, if
Valgrind supports your architecture.

Bison is written using Bison grammars, so there are bootstrapping
issues.  The bootstrap script attempts to discover when the C code
generated from the grammars is out of date, and to bootstrap with an
out-of-date version of the C code, but the process is not foolproof.
Also, you may run into similar problems yourself if you modify Bison.

Only building the initial full source tree will be a bit painful.
Later, after synchronizing from the repository a plain `make' should
be sufficient.

* First checkout

Obviously, if you are reading these notes, you did manage to check out
this package from the repository.  For the record, you will find all the
relevant information on:

        http://savannah.gnu.org/git/?group=bison

Bison uses Git submodules: subscriptions to other Git repositories.
In particular it uses gnulib, the GNU portability library.  To ask Git
to perform the first checkout of the submodules, run

       $ git submodule update --init

Git submodule support is weak before versions 1.6 and later, you
should probably upgrade Git if your version is older.

The next step is to get other files needed to build, which are
extracted from other source packages:

        $ ./bootstrap

And there you are!  Just

        $ ./configure
        $ make
        $ make check

At this point, there should be no difference between your local copy,
and the master copy:

        $ git diff

should output no difference.

Enjoy!

* Updating

The use of submodules make things somewhat different because git does
not support recursive operations: submodules must be taken care of
explicitly by the user.

** Updating Bison

If you pull a newer version of a branch, say via `git pull', you might
import requests for updated submodules.  A simple `git diff' will
reveal if the current version of the submodule (i.e., the actual
contents of the gnulib directory) and the current request from the
subscriber (i.e., the reference of the version of gnulib that the
Bison reporitory requests) differ.  To upgrade the submodules (i.e.,
to check out the version that is actually requested by the subscriber,
run `git submodule update'.

        $ git pull
        $ git submodule update

** Updating a submodule
To update a submodule, say gnulib, do as follows:

Get the most recent version of the master branch from git.

        $ cd gnulib
        $ git fetch
        $ git checkout -b master --track origin/master

Make sure Bison can live with that version of gnulib.

        $ cd ..
        $ ./bootstrap
        $ make distcheck

Register your changes.

        $ git checkin ...

-----

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