bison/README-hacking.md

This file attempts to describe the rules to use when hacking Bison.
Don't put this file into the distribution.

Everything related to the development of Bison is on Savannah:
http://savannah.gnu.org/projects/bison/.


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

## 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 commit message.

## Bug reports
If somebody reports a new bug, mention his name in the commit message and in
the test case you write.  Put him into THANKS.

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.



Hacking
=======

## Visible Changes
Which include serious bug fixes, must be mentioned in NEWS.

## Translations
Only user visible strings are to be translated: error messages, bits of the
.output file etc.  This excludes impossible error messages (comparable to
assert/abort), and all the --trace output which is meant for the maintainers
only.

## Coding Style
Do not add horizontal tab characters to any file in Bison's repository
except where required.  For example, do not use tabs to format C code.
However, make files, ChangeLog, and some regular expressions require tabs.
Also, test cases might need to contain tabs to check that Bison properly
processes tabs in its input.

### Bison
Follow the GNU Coding Standards.

Don't reinvent the wheel: we use gnulib, which features many components.
Actually, Bison has legacy code that we should replace with gnulib modules
(e.g., many adhoc implementations of lists).

### Skeletons
We try to use the "typical" coding style for each language.

#### C/C++
Follow the GNU Coding Standards.

The `glr.c` skeleton was implemented with `camlCase`.  We are migrating it
to `snake_case`.  Because we are standardizing the code, it is currently
inconsistent.

Use `YYFOO` and `yyfoo` for entities that are exposed to the user.  They are
part of our contract with the users wrt backward compatibility.

Use `YY_FOO` and `yy_foo` for private matters.  Users should not use them,
we are free to change them without fear of backward compatibility issues.

Use `*_t` for types, especially for `yy*_t` in which case we shouldn't worry
about the C standard introducing such a name.

In C++, use `*_type` for type aliases.

#### Java
We follow https://www.oracle.com/technetwork/java/codeconventions-150003.pdf
and https://google.github.io/styleguide/javaguide.html.  Unfortunately at
some point some GNU Coding Style was installed in Java, but it's an error.
So we should for instance stop putting spaces in function calls.  Because we
are standardizing the code, it is currently inconsistent.

Use a 2-space indentation (Google) rather than 4 (Oracle).

## Commit Messages
Imitate the style we use.  Use `git log` to get sources of inspiration.

## Debugging
Bison supports tracing of its various steps, via the `--trace` option.
Since it is not meant for the end user, it is not displayed by `bison
--help`, nor is it documented in the manual.  Instead, run `bison
--trace=help`.



Working from the Repository
===========================

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:

- Autoconf <http://www.gnu.org/software/autoconf/>
- Automake <http://www.gnu.org/software/automake/>
- Flex <http://www.gnu.org/software/flex/>
- Gettext <http://www.gnu.org/software/gettext/>
- Graphviz <http://www.graphviz.org>
- Gzip <http://www.gnu.org/software/gzip/>
- Help2man <http://www.gnu.org/software/help2man/>
- Perl <http://www.cpan.org/>
- Rsync <http://samba.anu.edu.au/rsync/>
- Tar <http://www.gnu.org/software/tar/>
- Texinfo <http://www.gnu.org/software/texinfo/>

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

If you're using a GNU/Linux distribution, the easiest way to install the
above packages depends on your system.  The following shell command should
work for Debian-based systems such as Ubuntu:

    sudo apt-get install \
      autoconf automake autopoint flex graphviz help2man texinfo valgrind

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.
Note, however, that when gnulib is updated, running './bootstrap' again
might be needed.

## 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

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

    $ ./bootstrap

Bootstrapping updates the submodules to the versions registered in the
top-level directory.  To change gnulib, first check out the version you want
in `gnulib`, then commit this change in Bison's repository, and finally run
bootstrap.

If it fails with missing symbols (e.g., `error: possibly undefined macro:
AC_PROG_GNU_M4`), you are likely to have forgotten the submodule
initialization part.  To recover from it, run `git reset --hard HEAD`, and
restart with the submodule initialization.  Otherwise, 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

If you have git at version 1.8.2 or later, the command

    $ git submodule update --recursive --remote

will be useful for updating to the latest version of all submodules.

Under earlier versions, use of submodules make things somewhat different
because git does not yet support recursive operations: submodules must be
taken care of explicitly.

### 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 repository 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 commit ...

For a suggestion of what gnulib commit might be stable enough for a formal
release, see the ChangeLog in the latest gnulib snapshot at
http://erislabs.net/ianb/projects/gnulib/.

The Autoconf files we use are currently:
- m4/m4.m4
- lib/m4sugar/m4sugar.m4
- lib/m4sugar/foreach.m4

These files don't change very often in Autoconf, so it should be relatively
straight-forward to examine the differences in order to decide whether to
update.



Test Suite
==========

## make check
Consume without moderation.  It is composed of two kinds of tests: the
examples, and the main test suite.

### The Examples
In examples/, there is a number of ready-to-use examples (see
examples/README.md).  These examples have small test suites run by `make
check`.  The test results are in local `*.log` files (e.g.,
`$build/examples/c/calc/calc.log`).

### The Main Test Suite
The main test suite, in tests/, is written on top of GNU Autotest, which is
part of Autoconf.  Run `info autoconf 'Using Autotest'` to read the
documentation, not only about how to write tests, but also where are the
logs, how to read them etc.

The main test suite generates a log for each test (e.g.,
`$build/tests/testsuite.dir/004/testsuite.log` for test #4), and a main log
file in `$build/tests/testsuite.log`.  The latter is meant for end users: it
contains lots of details that should help diagnosing issues, including build
issues.  The per-test logs are more convenient when working locally.

#### TESTSUITEFLAGS
To run just the main test suite, run `make check-local`.

The default is for make check-local to run all tests sequentially.  This can
be very time consuming when checking repeatedly or on slower setups.  This
can be sped up in two ways:

Using -j, in a make-like fashion, for example:

    $ make check-local TESTSUITEFLAGS='-j8'

Actually, when using GNU Make, TESTSUITEFLAGS defaults to the -jN passed to
it, so you may simply run

    $ make check-local -j8

Running only the tests of a certain category, as specified in the AT files
with AT_KEYWORDS([[category]]). Categories include:
- c++, for c++ parsers
- deprec, for tests concerning deprecated constructs.
- glr, for glr parsers
- java, for java parsers
- report, for automaton dumps

To get a list of all the tests (and their keywords for -k), run

    $ ./tests/testsuite -l

To run a specific set of tests, use -k (for "keyword"). For example:

    $ make check-local TESTSUITEFLAGS='-k c++'

Both can be combined.

    $ make check-local TESTSUITEFLAGS='-j8 -k c++'

To rerun the tests that failed:

    $ make recheck -j5

#### Updating the Expectations
Sometimes some changes have a large impact on the test suite (e.g., when we
added the `[-Wother]` part to all the warnings).  Part of the update can be
done with a crude tool: `build-aux/update-test`.

Once you ran the test suite, and therefore have many `testsuite.log` files,
run, from the source tree:

    $ ./build-aux/update-test $build/tests/testsuite.dir/*/testsuite.log

where `$build` would be your build tree.  This will hopefully update most
tests.  Re-run the test suite.  It might be interesting to run `update-test`
again, since some early failures may stop latter tests from being run.  Yet
at some point, you'll have to fix remaining issues by hand...


## make maintainer-check-valgrind
This target uses valgrind both to check bison, and the generated parsers.

This is not mature on Mac OS X.  First, Valgrind does support the way bison
calls m4, so Valgrind cannot be used to check bison on Mac OS X.

Second, there are many errors that come from the platform itself, not from
bison.  build-aux/darwin11.4.0.valgrind addresses some of them.

Third, valgrind issues warnings such as:

    --99312:0:syswrap- WARNING: Ignoring sigreturn( ..., UC_RESET_ALT_STACK );

which cause the test to fail uselessly.  It is hard to ignore these errors
with a major overhaul of the way instrumentation is performed in the test
suite.  So currently, do not try to run valgrind on Mac OS X.

## Release checks
Try to run the test suite with more severe conditions before a
release:

- Configure the package with --enable-gcc-warnings, so that one checks that
  1. Bison compiles cleanly, 2. the parsers it produces compile cleanly too.

- Maybe build with -DGNULIB_POSIXCHECK, which suggests gnulib modules that
  can fix portability issues.  See if you really want to pay attention to
  its warnings; there's no need to obey blindly to it
  (<http://lists.gnu.org/archive/html/bison-patches/2012-05/msg00057.html>).

- Check with `make syntax-check` if there are issues diagnosed by gnulib.

- run `make maintainer-check` which:
  - runs `valgrind -q bison` to run Bison under Valgrind.
  - runs the parsers under Valgrind.
  - runs the test suite with G++ as C compiler...

- run `make maintainer-check-push`, which runs `make maintainer-check` while
  activating the push implementation and its pull interface wrappers in many
  test cases that were originally written to exercise only the pull
  implementation.  This makes certain the push implementation can perform
  every task the pull implementation can.

- run `make maintainer-check-xml`, which runs `make maintainer-check` while
  checking Bison's XML automaton report for every working grammar passed to
  Bison in the test suite.  The check just diffs the output of Bison's
  included XSLT style sheets with the output of --report=all and --graph.

- running `make maintainer-check-release` takes care of running
  maintainer-check, maintainer-check-push and maintainer-check-xml.

- Change tests/atlocal/CFLAGS to add your preferred options.

- Test with a very recent version of GCC for both C and C++.  Testing with
  older versions that are still in use is nice too.

## gnulib
To run tests on gnulib components (e.g., on bitset):

    cd gnulib
    ./gnulib-tool --test bitset-tests

possibly within a specified environment:

    CC='gcc-mp-8 -fsanitize=undefined' ./gnulib-tool --test bitset-tests

To be able to run the tests several times, and to use symlinks instead of
copies so that one can update the origin gnulib directory and immediately
re-run the tests, run:

    ./gnulib-tool --symlink --create-test --dir=/tmp/gnutest bitset-tests
    cd /tmp/gnutest
    ./configure -C CC='gcc-mp-8 -fsanitize=undefined' CFLAGS='-ggdb'
    make check



Release Procedure
=================

This section needs to be updated to take into account features from gnulib.
In particular, be sure to read README-release.

## Update the submodules.  See above.

## Update maintainer tools, such as Autoconf.  See above.

## Try to get the *.pot files to the Translation Project at least one
week before a stable release, to give them time to translate them.  Before
generating the *.pot files, make sure that po/POTFILES.in and
runtime-po/POTFILES.in list all files with translatable strings.  This
helps: `grep -l '\<_(' *`.

## Tests
See above.

## Update the foreign files
Running `./bootstrap` in the top level should update them all for you.  This
covers PO files too.  Sometimes a PO file contains problems that causes it
to be rejected by recent Gettext releases; please report these to the
Translation Project.

## Update README
Make sure the information in README is current.  Most notably, make sure it
recommends a version of GNU M4 that is compatible with the latest Bison
sources.

## Check copyright years.
We update years in copyright statements throughout Bison once at the start
of every year by running `make update-copyright`.  However, before a
release, it's good to verify that it's actually been run.  Besides the
copyright statement for each Bison file, check the copyright statements that
the skeletons insert into generated parsers, and check all occurrences of
`PACKAGE_COPYRIGHT_YEAR` in configure.ac.

## Update NEWS, commit and tag.
See do-release-commit-and-tag in README-release.  For a while, we used beta
names such as `2.6_rc1`.  Now that we use gnulib in the release procedure,
we must use `2.5.90`, which has the additional benefit of being properly
sorted in `git tag -l`.

## make alpha, beta, or stable
See README-release.

## Upload
There are two ways to upload the tarballs to the GNU servers: using gnupload
(from gnulib), or by hand.  Obviously prefer the former.  But in either
case, be sure to read the following paragraph.

### Setup
You need `gnupg`.

Make sure your public key has been uploaded at least to keys.gnupg.net.  You
can upload it with:

  gpg --keyserver keys.gnupg.net --send-keys F125BDF3

where F125BDF3 should be replaced with your key ID.

### Using gnupload
You need `ncftp`.

At the end `make stable` (or alpha/beta) will display the procedure to run.
Just copy and paste it in your shell.

### By hand

The generic GNU upload procedure is at
http://www.gnu.org/prep/maintain/maintain.html#Automated-FTP-Uploads.

Follow the instructions there to register your information so you're permitted
to upload.

Here's a brief reminder of how to roll the tarballs and upload them:

### make distcheck
### gpg -b bison-2.3b.tar.gz
### In a file named `bison-2.3b.tar.gz.directive`, type:

    version: 1.1
    directory: bison
    filename: bison-2.3b.tar.gz

### gpg --clearsign bison-2.3b.tar.gz.directive
### ftp ftp-upload.gnu.org # Log in as anonymous.
### cd /incoming/alpha # cd /incoming/ftp for full release.
### put bison-2.3b.tar.gz # This can take a while.
### put bison-2.3b.tar.gz.sig
### put bison-2.3b.tar.gz.directive.asc
### Repeat all these steps for bison-2.3b.tar.xz.

## Update Bison manual on www.gnu.org.

The instructions below are obsolete, and left in case one would like to run
the commands by hand.  Today, one just needs to run

    $ make web-manual-update

See README-release.

### You need a non-anonymous checkout of the web pages directory.

    $ cvs -d YOUR_USERID@cvs.savannah.gnu.org:/web/bison checkout bison

### Get familiar with the instructions for web page maintainers.
http://www.gnu.org/server/standards/readme_index.html
http://www.gnu.org/server/standards/README.software.html
especially the note about symlinks.

### Build the web pages.
Assuming BISON_CHECKOUT refers to a checkout of the Bison dir, and
BISON_WWW_CHECKOUT refers to the web directory created above, do:

    $ cd $BISON_CHECKOUT/doc
    $ make stamp-vti
    $ ../build-aux/gendocs.sh -o "$BISON_WWW_CHECKOUT/manual" \
      bison "Bison - GNU parser generator"
    $ cd $BISON_WWW_CHECKOUT

Verify that the result looks sane.

### Commit the modified and the new files.

### Remove old files.
Find the files which have not been overwritten (because they belonged to
sections that have been removed or renamed):

     $ cd manual/html_node
     $ ls -lt

Remove these files and commit their removal to CVS.  For each of these
files, add a line to the file .symlinks.  This will ensure that hyperlinks
to the removed files will redirect to the entire manual; this is better than
a 404 error.

## Announce
The "make release" command just created a template,
`$HOME/announce-bison-X.Y`.  Otherwise, to generate it, run:

    make RELEASE_TYPE=alpha gpg_key_ID=F125BDF3 announcement

where alpha can be replaced by `beta` or `table` and F125BDF3 should be
replaced with your key ID.

Complete/fix the announcement file.  The generated list of recipients
(info-gnu@gnu.org, bison-announce@gnu.org, bug-bison@gnu.org,
help-bison@gnu.org, bison-patches@gnu.org, and
coordinator@translationproject.org) is appropriate for a stable release or a
"serious beta".  For any other release, drop at least info-gnu@gnu.org.  For
an example of how to fill out the rest of the template, search the mailing
list archives for the most recent release announcement.

For a stable release, send the same announcement on the comp.compilers
newsgroup by sending email to compilers@iecc.com.  Do not make any Cc as the
moderator will throw away anything cross-posted or Cc'ed.  It really needs
to be a separate message.

## Prepare NEWS
So that developers don't accidentally add new items to the old NEWS entry,
create a new empty entry in line 3 (without the two leading spaces):

  * Noteworthy changes in release ?.? (????-??-??) [?]

Push these changes.

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