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GitHub's mirror is now at mirrors/perl, not github/perl
[perl5.git] / pod / perlrepository.pod
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1=for comment
2Consistent formatting of this file is achieved with:
3 perl ./Porting/podtidy pod/perlrepository.pod
4
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5=head1 NAME
6
7perlrepository - Using the Perl source repository
8
9=head1 SYNOPSIS
10
dc3c3040 11All of Perl's source code is kept centrally in a Git repository at
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12I<perl5.git.perl.org>. The repository contains many Perl revisions from
13Perl 1 onwards and all the revisions from Perforce, the version control
14system we were using previously. This repository is accessible in
15different ways.
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16
17The full repository takes up about 80MB of disk space. A check out of
7f4ffa9d 18the blead branch (that is, the main development branch, which contains
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19bleadperl, the development version of perl 5) takes up about 160MB of
20disk space (including the repository). A build of bleadperl takes up
21about 200MB (including the repository and the check out).
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22
23=head1 GETTING ACCESS TO THE REPOSITORY
24
25=head2 READ ACCESS VIA THE WEB
26
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27You may access the repository over the web. This allows you to browse
28the tree, see recent commits, subscribe to RSS feeds for the changes,
29search for particular commits and more. You may access it at:
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30
31 http://perl5.git.perl.org/perl.git
32
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33A mirror of the repository is found at:
34
f9bcfeac 35 http://github.com/mirrors/perl
dc3c3040 36
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37=head2 READ ACCESS VIA GIT
38
39You will need a copy of Git for your computer. You can fetch a copy of
40the repository using the Git protocol (which uses port 9418):
41
e0b2b458 42 % git clone git://perl5.git.perl.org/perl.git perl-git
d7dd28b6 43
f755e97d 44This clones the repository and makes a local copy in the F<perl-git>
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45directory.
46
47If your local network does not allow you to use port 9418, then you can
cf5e7595 48fetch a copy of the repository over HTTP (this is at least 4x slower):
d7dd28b6 49
e0b2b458 50 % git clone http://perl5.git.perl.org/perl.git perl-http
d7dd28b6 51
f755e97d 52This clones the repository and makes a local copy in the F<perl-http>
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53directory.
54
55=head2 WRITE ACCESS TO THE REPOSITORY
56
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57If you are a committer, then you can fetch a copy of the repository
58that you can push back on with:
d7dd28b6 59
e0b2b458 60 % git clone ssh://perl5.git.perl.org/perl.git perl-ssh
d7dd28b6 61
8f718e95 62This clones the repository and makes a local copy in the F<perl-ssh>
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63directory.
64
c26da522 65If you cloned using the git protocol, which is faster than ssh, then
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66you will need to modify the URL for the origin remote to enable
67pushing. To do that edit F<.git/config> with L<git-config(1)> like
68this:
1a0f15d5 69
e0b2b458 70 % git config remote.origin.url ssh://perl5.git.perl.org/perl.git
d7dd28b6 71
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72You can also set up your user name and e-mail address. Most people do
73this once globally in their F<~/.gitconfig> by doing something like:
184487f0 74
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75 % git config --global user.name "Ævar Arnfjörð Bjarmason"
76 % git config --global user.email avarab@gmail.com
77
78However if you'd like to override that just for perl then execute then
79execute something like the following in F<perl-git>:
80
81 % git config user.email avar@cpan.org
184487f0 82
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83It is also possible to keep C<origin> as a git remote, and add a new
84remote for ssh access:
f6c12373 85
dc3c3040 86 % git remote add camel perl5.git.perl.org:/perl.git
f6c12373 87
6acba58e 88This allows you to update your local repository by pulling from
f755e97d 89C<origin>, which is faster and doesn't require you to authenticate, and
6acba58e 90to push your changes back with the C<camel> remote:
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91
92 % git fetch camel
93 % git push camel
94
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95The C<fetch> command just updates the C<camel> refs, as the objects
96themselves should have been fetched when pulling from C<origin>.
f6c12373 97
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98=head2 A NOTE ON CAMEL AND DROMEDARY
99
100The committers have SSH access to the two servers that serve
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101C<perl5.git.perl.org>. One is C<perl5.git.perl.org> itself (I<camel>),
102which is the 'master' repository. The second one is
103C<users.perl5.git.perl.org> (I<dromedary>), which can be used for
104general testing and development. Dromedary syncs the git tree from
105camel every few minutes, you should not push there. Both machines also
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106have a full CPAN mirror in /srv/CPAN, please use this. To share files
107with the general public, dromedary serves your ~/public_html/ as
333f8875 108C<http://users.perl5.git.perl.org/~yourlogin/>
b47aa495 109
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110These hosts have fairly strict firewalls to the outside. Outgoing, only
111rsync, ssh and git are allowed. For http and ftp, you can use
112http://webproxy:3128 as proxy. Incoming, the firewall tries to detect
113attacks and blocks IP addresses with suspicious activity. This
114sometimes (but very rarely) has false positives and you might get
115blocked. The quickest way to get unblocked is to notify the admins.
116
117These two boxes are owned, hosted, and operated by booking.com. You can
118reach the sysadmins in #p5p on irc.perl.org or via mail to
119C<perl5-porters@perl.org>
120
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121=head1 OVERVIEW OF THE REPOSITORY
122
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123Once you have changed into the repository directory, you can inspect
124it.
d7dd28b6 125
39219fd3 126After a clone the repository will contain a single local branch, which
50eca761 127will be the current branch as well, as indicated by the asterisk.
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128
129 % git branch
130 * blead
131
f755e97d 132Using the -a switch to C<branch> will also show the remote tracking
6acba58e 133branches in the repository:
39219fd3 134
d9847473 135 % git branch -a
09081495 136 * blead
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137 origin/HEAD
138 origin/blead
139 ...
140
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141The branches that begin with "origin" correspond to the "git remote"
142that you cloned from (which is named "origin"). Each branch on the
143remote will be exactly tracked by theses branches. You should NEVER do
144work on these remote tracking branches. You only ever do work in a
145local branch. Local branches can be configured to automerge (on pull)
146from a designated remote tracking branch. This is the case with the
147default branch C<blead> which will be configured to merge from the
148remote tracking branch C<origin/blead>.
39219fd3 149
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150You can see recent commits:
151
c2cf2042 152 % git log
d7dd28b6 153
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154And pull new changes from the repository, and update your local
155repository (must be clean first)
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156
157 % git pull
09081495 158
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159Assuming we are on the branch C<blead> immediately after a pull, this
160command would be more or less equivalent to:
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161
162 % git fetch
163 % git merge origin/blead
164
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165In fact if you want to update your local repository without touching
166your working directory you do:
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167
168 % git fetch
169
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170And if you want to update your remote-tracking branches for all defined
171remotes simultaneously you can do
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172
173 % git remote update
174
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175Neither of these last two commands will update your working directory,
176however both will update the remote-tracking branches in your
177repository.
39219fd3 178
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179To switch to another branch:
180
181 % git checkout origin/maint-5.8-dor
182
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183To make a local branch of a remote branch:
184
185 % git checkout -b maint-5.10 origin/maint-5.10
186
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187To switch back to blead:
188
189 % git checkout blead
c2cf2042 190
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191=head2 FINDING OUT YOUR STATUS
192
193The most common git command you will use will probably be
194
195 % git status
196
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197This command will produce as output a description of the current state
198of the repository, including modified files and unignored untracked
199files, and in addition it will show things like what files have been
200staged for the next commit, and usually some useful information about
201how to change things. For instance the following:
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202
203 $ git status
204 # On branch blead
205 # Your branch is ahead of 'origin/blead' by 1 commit.
206 #
207 # Changes to be committed:
208 # (use "git reset HEAD <file>..." to unstage)
209 #
210 # modified: pod/perlrepository.pod
211 #
212 # Changed but not updated:
213 # (use "git add <file>..." to update what will be committed)
214 #
215 # modified: pod/perlrepository.pod
216 #
217 # Untracked files:
218 # (use "git add <file>..." to include in what will be committed)
219 #
220 # deliberate.untracked
221
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222This shows that there were changes to this document staged for commit,
223and that there were further changes in the working directory not yet
224staged. It also shows that there was an untracked file in the working
225directory, and as you can see shows how to change all of this. It also
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226shows that there is one commit on the working branch C<blead> which has
227not been pushed to the C<origin> remote yet. B<NOTE>: that this output
228is also what you see as a template if you do not provide a message to
229C<git commit>.
7f6effc7 230
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231Assuming that you'd like to commit all the changes you've just made as a
232a single atomic unit, run this command:
233
234 % git commit -a
235
236(That C<-a> tells git to add every file you've changed to this commit.
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237New files aren't automatically added to your commit when you use C<commit
238-a> If you want to add files or to commit some, but not all of your
239changes, have a look at the documentation for C<git add>.)
bdaf0bc6 240
e9360695 241Git will start up your favorite text editor, so that you can craft a
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242commit message for your change. See L</Commit message> below for more
243information about what makes a good commit message.
244
245Once you've finished writing your commit message and exited your editor,
246git will write your change to disk and tell you something like this:
7f6effc7 247
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248 Created commit daf8e63: explain git status and stuff about remotes
249 1 files changed, 83 insertions(+), 3 deletions(-)
250
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251
252If you re-run C<git status>, you should see something like this:
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253
254 % git status
255 # On branch blead
256 # Your branch is ahead of 'origin/blead' by 2 commits.
257 #
258 # Untracked files:
259 # (use "git add <file>..." to include in what will be committed)
260 #
261 # deliberate.untracked
262 nothing added to commit but untracked files present (use "git add" to track)
263
39219fd3 264
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265When in doubt, before you do anything else, check your status and read
266it carefully, many questions are answered directly by the git status
267output.
39219fd3 268
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269=head1 SUBMITTING A PATCH
270
271If you have a patch in mind for Perl, you should first get a copy of
272the repository:
273
274 % git clone git://perl5.git.perl.org/perl.git perl-git
275
276Then change into the directory:
277
278 % cd perl-git
279
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280Alternatively, if you already have a Perl repository, you should ensure
281that you're on the I<blead> branch, and your repository is up to date:
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282
283 % git checkout blead
284 % git pull
285
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286It's preferable to patch against the latest blead version, since this
287is where new development occurs for all changes other than critical bug
288fixes. Critical bug fix patches should be made against the relevant
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289maint branches, or should be submitted with a note indicating all the
290branches where the fix should be applied.
a44f43ac 291
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292Now that we have everything up to date, we need to create a temporary
293new branch for these changes and switch into it:
b1fccde5 294
a9b05323 295 % git checkout -b orange
23f8d33e 296
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297which is the short form of
298
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299 % git branch orange
300 % git checkout orange
301
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302Creating a topic branch makes it easier for the maintainers to rebase
303or merge back into the master blead for a more linear history. If you
304don't work on a topic branch the maintainer has to manually cherry
305pick your changes onto blead before they can be applied.
306
307That'll get you scolded on perl5-porters, so don't do that. Be
308Awesome.
309
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310Then make your changes. For example, if Leon Brocard changes his name
311to Orange Brocard, we should change his name in the AUTHORS file:
312
313 % perl -pi -e 's{Leon Brocard}{Orange Brocard}' AUTHORS
314
315You can see what files are changed:
316
317 % git status
f755e97d 318 # On branch orange
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319 # Changes to be committed:
320 # (use "git reset HEAD <file>..." to unstage)
321 #
2699d634 322 # modified: AUTHORS
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323 #
324
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325And you can see the changes:
326
327 % git diff
328 diff --git a/AUTHORS b/AUTHORS
329 index 293dd70..722c93e 100644
330 --- a/AUTHORS
331 +++ b/AUTHORS
7df2e4bc 332 @@ -541,7 +541,7 @@ Lars Hecking <lhecking@nmrc.ucc.ie>
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333 Laszlo Molnar <laszlo.molnar@eth.ericsson.se>
334 Leif Huhn <leif@hale.dkstat.com>
335 Len Johnson <lenjay@ibm.net>
336 -Leon Brocard <acme@astray.com>
337 +Orange Brocard <acme@astray.com>
338 Les Peters <lpeters@aol.net>
339 Lesley Binks <lesley.binks@gmail.com>
340 Lincoln D. Stein <lstein@cshl.org>
341
342Now commit your change locally:
343
dc3c3040 344 % git commit -a -m 'Rename Leon Brocard to Orange Brocard'
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345 Created commit 6196c1d: Rename Leon Brocard to Orange Brocard
346 1 files changed, 1 insertions(+), 1 deletions(-)
347
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348You can examine your last commit with:
349
350 % git show HEAD
351
352and if you are not happy with either the description or the patch
c26da522 353itself you can fix it up by editing the files once more and then issue:
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354
355 % git commit -a --amend
356
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357Now you should create a patch file for all your local changes:
358
2af192ee 359 % git format-patch origin
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360 0001-Rename-Leon-Brocard-to-Orange-Brocard.patch
361
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362You should now send an email to either perlbug@perl.org or
363perl5-porters@perl.org with a description of your changes, and include
364this patch file as an attachment. The perlbug address is preferred,
365but use perl5-porters for patches intended for discussion.
366
367See the next section for how to configure and use git to send these
368emails for you.
c2cf2042 369
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370If you want to delete your temporary branch, you may do so with:
371
372 % git checkout blead
373 % git branch -d orange
374 error: The branch 'orange' is not an ancestor of your current HEAD.
375 If you are sure you want to delete it, run 'git branch -D orange'.
376 % git branch -D orange
377 Deleted branch orange.
7df2e4bc 378
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379=head2 Using git to send patch emails
380
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381In your ~/git/perl repository, set the destination email to perl's bug
382tracker:
383
384 $ git config sendemail.to perlbug@perl.org
385
386Or maybe perl5-porters (discussed above):
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387
388 $ git config sendemail.to perl5-porters@perl.org
389
390Then you can use git directly to send your patch emails:
391
392 $ git send-email 0001-Rename-Leon-Brocard-to-Orange-Brocard.patch
393
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394You may need to set some configuration variables for your particular
395email service provider. For example, to set your global git config to
396send email via a gmail account:
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397
398 $ git config --global sendemail.smtpserver smtp.gmail.com
399 $ git config --global sendemail.smtpssl 1
400 $ git config --global sendemail.smtpuser YOURUSERNAME@gmail.com
401
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402With this configuration, you will be prompted for your gmail password
403when you run 'git send-email'. You can also configure
404C<sendemail.smtppass> with your password if you don't care about having
405your password in the .gitconfig file.
2d5f1d01 406
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407=head2 A note on derived files
408
409Be aware that many files in the distribution are derivative--avoid
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410patching them, because git won't see the changes to them, and the build
411process will overwrite them. Patch the originals instead. Most
412utilities (like perldoc) are in this category, i.e. patch
413utils/perldoc.PL rather than utils/perldoc. Similarly, don't create
414patches for files under $src_root/ext from their copies found in
415$install_root/lib. If you are unsure about the proper location of a
416file that may have gotten copied while building the source
417distribution, consult the C<MANIFEST>.
a44f43ac 418
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419As a special case, several files are regenerated by 'make regen' if
420your patch alters C<embed.fnc>. These are needed for compilation, but
421are included in the distribution so that you can build perl without
422needing another perl to generate the files. You must test with these
423regenerated files, but it is preferred that you instead note that
424'make regen is needed' in both the email and the commit message, and
425submit your patch without them. If you're submitting a series of
426patches, it might be best to submit the regenerated changes
427immediately after the source-changes that caused them, so as to have
428as little effect as possible on the bisectability of your patchset.
429
6e2cec71 430=for XXX
a44f43ac 431
6e2cec71 432What should we recommend about binary files now? Do we need anything?
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433
434=head2 Getting your patch accepted
435
bdaf0bc6 436If you are submitting a code patch there are several things that
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437you need to do.
438
439=over 4
440
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441=item Commit message
442
443As you craft each patch you intend to submit to the Perl core, it's
444important to write a good commit message.
445
446Your commit message should start with a description of the problem that
447the patch corrects or new functionality that the patch adds.
448
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449As a general rule of thumb, your commit message should let a programmer
450with a reasonable familiarity with the Perl core quickly understand what
451you were trying to do, how you were trying to do it and why the change
452matters to Perl.
453
454=over 4
455
456=item What
457
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458Your commit message should describe what part of the Perl core you're
459changing and what you expect your patch to do.
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460
461=item Why
462
463Perhaps most importantly, your commit message should describe why the
464change you are making is important. When someone looks at your change
465in six months or six years, your intent should be clear. If you're
466deprecating a feature with the intent of later simplifying another bit
467of code, say so. If you're fixing a performance problem or adding a new
468feature to support some other bit of the core, mention that.
469
470=item How
471
472While it's not necessary for documentation changes, new tests or
473trivial patches, it's often worth explaining how your change works.
474Even if it's clear to you today, it may not be clear to a porter next
475month or next year.
476
477=back
478
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479A commit message isn't intended to take the place of comments in your
480code. Commit messages should describe the change you made, while code
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481comments should describe the current state of the code. If you've just
482implemented a new feature, complete with doc, tests and well-commented
483code, a brief commit message will often suffice. If, however, you've
484just changed a single character deep in the parser or lexer, you might
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485need to write a small novel to ensure that future readers understand
486what you did and why you did it.
487
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488=item Comments, Comments, Comments
489
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490Be sure to adequately comment your code. While commenting every line
491is unnecessary, anything that takes advantage of side effects of
a44f43ac 492operators, that creates changes that will be felt outside of the
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493function being patched, or that others may find confusing should be
494documented. If you are going to err, it is better to err on the side
495of adding too many comments than too few.
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496
497=item Style
498
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499In general, please follow the particular style of the code you are
500patching.
a44f43ac 501
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502In particular, follow these general guidelines for patching Perl
503sources:
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504
505 8-wide tabs (no exceptions!)
506 4-wide indents for code, 2-wide indents for nested CPP #defines
507 try hard not to exceed 79-columns
508 ANSI C prototypes
509 uncuddled elses and "K&R" style for indenting control constructs
510 no C++ style (//) comments
511 mark places that need to be revisited with XXX (and revisit often!)
512 opening brace lines up with "if" when conditional spans multiple
513 lines; should be at end-of-line otherwise
514 in function definitions, name starts in column 0 (return value is on
515 previous line)
516 single space after keywords that are followed by parens, no space
517 between function name and following paren
518 avoid assignments in conditionals, but if they're unavoidable, use
519 extra paren, e.g. "if (a && (b = c)) ..."
520 "return foo;" rather than "return(foo);"
521 "if (!foo) ..." rather than "if (foo == FALSE) ..." etc.
522
523=item Testsuite
524
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525If your patch changes code (rather than just changing documentation) you
526should also include one or more test cases which illustrate the bug you're
527fixing or validate the new functionality you're adding. In general,
528you should update an existing test file rather than create a new one.
529
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530Your testsuite additions should generally follow these guidelines
531(courtesy of Gurusamy Sarathy <gsar@activestate.com>):
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532
533 Know what you're testing. Read the docs, and the source.
534 Tend to fail, not succeed.
535 Interpret results strictly.
536 Use unrelated features (this will flush out bizarre interactions).
537 Use non-standard idioms (otherwise you are not testing TIMTOWTDI).
538 Avoid using hardcoded test numbers whenever possible (the
539 EXPECTED/GOT found in t/op/tie.t is much more maintainable,
540 and gives better failure reports).
541 Give meaningful error messages when a test fails.
542 Avoid using qx// and system() unless you are testing for them. If you
543 do use them, make sure that you cover _all_ perl platforms.
544 Unlink any temporary files you create.
545 Promote unforeseen warnings to errors with $SIG{__WARN__}.
546 Be sure to use the libraries and modules shipped with the version
547 being tested, not those that were already installed.
548 Add comments to the code explaining what you are testing for.
549 Make updating the '1..42' string unnecessary. Or make sure that
550 you update it.
551 Test _all_ behaviors of a given operator, library, or function:
552 - All optional arguments
553 - Return values in various contexts (boolean, scalar, list, lvalue)
554 - Use both global and lexical variables
555 - Don't forget the exceptional, pathological cases.
556
557=back
558
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559=head1 ACCEPTING A PATCH
560
561If you have received a patch file generated using the above section,
562you should try out the patch.
563
564First we need to create a temporary new branch for these changes and
565switch into it:
566
a9b05323 567 % git checkout -b experimental
7df2e4bc 568
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569Patches that were formatted by C<git format-patch> are applied with
570C<git am>:
7df2e4bc 571
2af192ee 572 % git am 0001-Rename-Leon-Brocard-to-Orange-Brocard.patch
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573 Applying Rename Leon Brocard to Orange Brocard
574
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575If just a raw diff is provided, it is also possible use this two-step
576process:
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577
578 % git apply bugfix.diff
dc3c3040 579 % git commit -a -m "Some fixing" --author="That Guy <that.guy@internets.com>"
09645c26 580
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581Now we can inspect the change:
582
dc3c3040 583 % git show HEAD
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584 commit b1b3dab48344cff6de4087efca3dbd63548ab5e2
585 Author: Leon Brocard <acme@astray.com>
586 Date: Fri Dec 19 17:02:59 2008 +0000
587
588 Rename Leon Brocard to Orange Brocard
7df2e4bc 589
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590 diff --git a/AUTHORS b/AUTHORS
591 index 293dd70..722c93e 100644
592 --- a/AUTHORS
593 +++ b/AUTHORS
594 @@ -541,7 +541,7 @@ Lars Hecking <lhecking@nmrc.ucc.ie>
595 Laszlo Molnar <laszlo.molnar@eth.ericsson.se>
596 Leif Huhn <leif@hale.dkstat.com>
597 Len Johnson <lenjay@ibm.net>
598 -Leon Brocard <acme@astray.com>
599 +Orange Brocard <acme@astray.com>
600 Les Peters <lpeters@aol.net>
601 Lesley Binks <lesley.binks@gmail.com>
602 Lincoln D. Stein <lstein@cshl.org>
603
604If you are a committer to Perl and you think the patch is good, you can
75fb7651 605then merge it into blead then push it out to the main repository:
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606
607 % git checkout blead
d9847473 608 % git merge experimental
75fb7651 609 % git push
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610
611If you want to delete your temporary branch, you may do so with:
612
613 % git checkout blead
614 % git branch -d experimental
615 error: The branch 'experimental' is not an ancestor of your current HEAD.
616 If you are sure you want to delete it, run 'git branch -D experimental'.
617 % git branch -D experimental
618 Deleted branch experimental.
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619
620=head1 CLEANING A WORKING DIRECTORY
621
6acba58e 622The command C<git clean> can with varying arguments be used as a
dc3c3040 623replacement for C<make clean>.
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624
625To reset your working directory to a pristine condition you can do:
626
e0b2b458 627 % git clean -dxf
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628
629However, be aware this will delete ALL untracked content. You can use
630
e0b2b458 631 % git clean -Xf
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633to remove all ignored untracked files, such as build and test
634byproduct, but leave any manually created files alone.
b0d36535 635
0549aefb 636If you only want to cancel some uncommitted edits, you can use C<git
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637checkout> and give it a list of files to be reverted, or C<git checkout
638-f> to revert them all.
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639
640If you want to cancel one or several commits, you can use C<git reset>.
641
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642=head1 BISECTING
643
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644C<git> provides a built-in way to determine, with a binary search in
645the history, which commit should be blamed for introducing a given bug.
d82a90c1 646
6acba58e 647Suppose that we have a script F<~/testcase.pl> that exits with C<0>
bdaf0bc6 648when some behaviour is correct, and with C<1> when it's faulty. You need
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649an helper script that automates building C<perl> and running the
650testcase:
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651
652 % cat ~/run
653 #!/bin/sh
654 git clean -dxf
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655
656 # If you get './makedepend: 1: Syntax error: Unterminated quoted
657 # string' when bisecting versions of perl older than 5.9.5 this hack
658 # will work around the bug in makedepend.SH which was fixed in
659 # version 96a8704c. Make sure to comment out `git co makedepend.SH'
660 # below too.
661 git show blead:makedepend.SH > makedepend.SH
662
d82a90c1 663 # If you can use ccache, add -Dcc=ccache\ gcc -Dld=gcc to the Configure line
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664 # if Encode is not needed for the test, you can speed up the bisect by
665 # excluding it from the runs with -Dnoextensions=Encode
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666 sh Configure -des -Dusedevel -Doptimize="-g"
667 test -f config.sh || exit 125
668 # Correct makefile for newer GNU gcc
669 perl -ni -we 'print unless /<(?:built-in|command)/' makefile x2p/makefile
670 # if you just need miniperl, replace test_prep with miniperl
d7923bfe 671 make test_prep
68814ba4 672 [ -x ./perl ] || exit 125
d82a90c1 673 ./perl -Ilib ~/testcase.pl
c0d1ef72 674 ret=$?
7930c68b 675 [ $ret -gt 127 ] && ret=127
a4583001 676 # git co makedepend.SH
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677 git clean -dxf
678 exit $ret
d82a90c1 679
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680This script may return C<125> to indicate that the corresponding commit
681should be skipped. Otherwise, it returns the status of
682F<~/testcase.pl>.
d82a90c1 683
bdaf0bc6 684You first enter in bisect mode with:
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685
686 % git bisect start
687
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688For example, if the bug is present on C<HEAD> but wasn't in 5.10.0,
689C<git> will learn about this when you enter:
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690
691 % git bisect bad
692 % git bisect good perl-5.10.0
693 Bisecting: 853 revisions left to test after this
694
6acba58e 695This results in checking out the median commit between C<HEAD> and
bdaf0bc6 696C<perl-5.10.0>. You can then run the bisecting process with:
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697
698 % git bisect run ~/run
699
700When the first bad commit is isolated, C<git bisect> will tell you so:
701
702 ca4cfd28534303b82a216cfe83a1c80cbc3b9dc5 is first bad commit
703 commit ca4cfd28534303b82a216cfe83a1c80cbc3b9dc5
704 Author: Dave Mitchell <davem@fdisolutions.com>
705 Date: Sat Feb 9 14:56:23 2008 +0000
706
9469eb4a 707 [perl #49472] Attributes + Unknown Error
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708 ...
709
710 bisect run success
711
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712You can peek into the bisecting process with C<git bisect log> and
713C<git bisect visualize>. C<git bisect reset> will get you out of bisect
714mode.
d82a90c1 715
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716Please note that the first C<good> state must be an ancestor of the
717first C<bad> state. If you want to search for the commit that I<solved>
718some bug, you have to negate your test case (i.e. exit with C<1> if OK
719and C<0> if not) and still mark the lower bound as C<good> and the
720upper as C<bad>. The "first bad commit" has then to be understood as
721the "first commit where the bug is solved".
d82a90c1 722
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723C<git help bisect> has much more information on how you can tweak your
724binary searches.
9d68b7ed 725
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726=head1 SUBMITTING A PATCH VIA GITHUB
727
728GitHub is a website that makes it easy to fork and publish projects
729with Git. First you should set up a GitHub account and log in.
730
731Perl's git repository is mirrored on GitHub at this page:
732
f9bcfeac 733 http://github.com/mirrors/perl/tree/blead
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734
735Visit the page and click the "fork" button. This clones the Perl git
736repository for you and provides you with "Your Clone URL" from which
737you should clone:
738
739 % git clone git@github.com:USERNAME/perl.git perl-github
740
bdaf0bc6 741The same patch as above, using github might look like this:
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742
743 % cd perl-github
edb9e29e 744 % git remote add upstream git://perl5.git.perl.org/perl.git
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745 % git pull upstream blead
746 % git checkout -b orange
747 % perl -pi -e 's{Leon Brocard}{Orange Brocard}' AUTHORS
dc3c3040 748 % git commit -a -m 'Rename Leon Brocard to Orange Brocard'
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749 % git push origin orange
750
751The orange branch has been pushed to GitHub, so you should now send an
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752email (see L</SUBMITTING A PATCH>) with a description of your changes
753and the following information:
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754
755 http://github.com/USERNAME/perl/tree/orange
756 git@github.com:USERNAME/perl.git branch orange
757
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758=head1 MERGING FROM A BRANCH VIA GITHUB
759
760If someone has provided a branch via GitHub and you are a committer,
5c9c28c6 761you should use the following in your perl-ssh directory:
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762
763 % git remote add dandv git://github.com/dandv/perl.git
fe442cc0 764 % git fetch dandv
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765
766Now you can see the differences between the branch and blead:
767
768 % git diff dandv/blead
769
770And you can see the commits:
771
772 % git log dandv/blead
773
774If you approve of a specific commit, you can cherry pick it:
775
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776 % git cherry-pick 3adac458cb1c1d41af47fc66e67b49c8dec2323f
777
778Or you could just merge the whole branch if you like it all:
779
780 % git merge dandv/blead
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781
782And then push back to the repository:
783
784 % git push
785
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786
787=head1 TOPIC BRANCHES AND REWRITING HISTORY
788
789Individual committers should create topic branches under
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790B<yourname>/B<some_descriptive_name>. Other committers should check
791with a topic branch's creator before making any change to it.
ce2a8773 792
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793The simplest way to create a remote topic branch that works on all
794versions of git is to push the current head as a new branch on the
795remote, then check it out locally:
796
797 $ branch="$yourname/$some_descriptive_name"
798 $ git push origin HEAD:$branch
799 $ git checkout -b $branch origin/$branch
800
801Users of git 1.7 or newer can do it in a more obvious manner:
802
803 $ branch="$yourname/$some_descriptive_name"
804 $ git checkout -b $branch
805 $ git push origin -u $branch
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807If you are not the creator of B<yourname>/B<some_descriptive_name>, you
808might sometimes find that the original author has edited the branch's
809history. There are lots of good reasons for this. Sometimes, an author
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810might simply be rebasing the branch onto a newer source point.
811Sometimes, an author might have found an error in an early commit which
812they wanted to fix before merging the branch to blead.
ce2a8773 813
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814Currently the master repository is configured to forbid
815non-fast-forward merges. This means that the branches within can not
816be rebased and pushed as a single step.
ce2a8773 817
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818The only way you will ever be allowed to rebase or modify the history
819of a pushed branch is to delete it and push it as a new branch under
820the same name. Please think carefully about doing this. It may be
821better to sequentially rename your branches so that it is easier for
822others working with you to cherry-pick their local changes onto the new
823version. (XXX: needs explanation).
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824
825If you want to rebase a personal topic branch, you will have to delete
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826your existing topic branch and push as a new version of it. You can do
827this via the following formula (see the explanation about C<refspec>'s
828in the git push documentation for details) after you have rebased your
829branch:
830
831 # first rebase
832 $ git checkout $user/$topic
833 $ git fetch
834 $ git rebase origin/blead
835
836 # then "delete-and-push"
837 $ git push origin :$user/$topic
838 $ git push origin $user/$topic
839
840B<NOTE:> it is forbidden at the repository level to delete any of the
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841"primary" branches. That is any branch matching
842C<m!^(blead|maint|perl)!>. Any attempt to do so will result in git
843producing an error like this:
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844
845 $ git push origin :blead
846 *** It is forbidden to delete blead/maint branches in this repository
847 error: hooks/update exited with error code 1
848 error: hook declined to update refs/heads/blead
333f8875 849 To ssh://perl5.git.perl.org/perl
2699d634 850 ! [remote rejected] blead (hook declined)
333f8875 851 error: failed to push some refs to 'ssh://perl5.git.perl.org/perl'
2699d634 852
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853As a matter of policy we do B<not> edit the history of the blead and
854maint-* branches. If a typo (or worse) sneaks into a commit to blead or
855maint-*, we'll fix it in another commit. The only types of updates
856allowed on these branches are "fast-forward's", where all history is
857preserved.
2699d634 858
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859Annotated tags in the canonical perl.git repository will never be
860deleted or modified. Think long and hard about whether you want to push
861a local tag to perl.git before doing so. (Pushing unannotated tags is
2699d634 862not allowed.)
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9469eb4a 864=head1 COMMITTING TO MAINTENANCE VERSIONS
9d68b7ed 865
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866Maintenance versions should only be altered to add critical bug fixes.
867
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868To commit to a maintenance version of perl, you need to create a local
869tracking branch:
870
871 % git checkout --track -b maint-5.005 origin/maint-5.005
872
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873This creates a local branch named C<maint-5.005>, which tracks the
874remote branch C<origin/maint-5.005>. Then you can pull, commit, merge
875and push as before.
b0d36535 876
f755e97d 877You can also cherry-pick commits from blead and another branch, by
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878using the C<git cherry-pick> command. It is recommended to use the
879B<-x> option to C<git cherry-pick> in order to record the SHA1 of the
880original commit in the new commit message.
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882=head1 GRAFTS
883
884The perl history contains one mistake which was not caught in the
ac036724 885conversion: a merge was recorded in the history between blead and
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886maint-5.10 where no merge actually occurred. Due to the nature of git,
887this is now impossible to fix in the public repository. You can remove
888this mis-merge locally by adding the following line to your
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889C<.git/info/grafts> file:
890
891 296f12bbbbaa06de9be9d09d3dcf8f4528898a49 434946e0cb7a32589ed92d18008aaa1d88515930
892
893It is particularly important to have this graft line if any bisecting
894is done in the area of the "merge" in question.
895
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896
897
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898=head1 SEE ALSO
899
900The git documentation, accessible via C<git help command>.
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