This is a live mirror of the Perl 5 development currently hosted at https://github.com/perl/perl5
[perl #82702] Fix commit message internal link.
[perl5.git] / pod / perlrepository.pod
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1=encoding utf8
2
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3=for comment
4Consistent formatting of this file is achieved with:
5 perl ./Porting/podtidy pod/perlrepository.pod
6
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7=head1 NAME
8
9perlrepository - Using the Perl source repository
10
11=head1 SYNOPSIS
12
dc3c3040 13All of Perl's source code is kept centrally in a Git repository at
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14I<perl5.git.perl.org>. The repository contains many Perl revisions from
15Perl 1 onwards and all the revisions from Perforce, the version control
16system we were using previously. This repository is accessible in
17different ways.
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18
19The full repository takes up about 80MB of disk space. A check out of
7f4ffa9d 20the blead branch (that is, the main development branch, which contains
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21bleadperl, the development version of perl 5) takes up about 160MB of
22disk space (including the repository). A build of bleadperl takes up
23about 200MB (including the repository and the check out).
d7dd28b6 24
ba336be1 25=head1 Getting access to the repository
d7dd28b6 26
ba336be1 27=head2 Read access via the web
d7dd28b6 28
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29You may access the repository over the web. This allows you to browse
30the tree, see recent commits, subscribe to RSS feeds for the changes,
31search for particular commits and more. You may access it at:
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32
33 http://perl5.git.perl.org/perl.git
34
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35A mirror of the repository is found at:
36
45b194c5 37 http://github.com/mirrors/perl
dc3c3040 38
ba336be1 39=head2 Read access via Git
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40
41You will need a copy of Git for your computer. You can fetch a copy of
42the repository using the Git protocol (which uses port 9418):
43
e0b2b458 44 % git clone git://perl5.git.perl.org/perl.git perl-git
d7dd28b6 45
f755e97d 46This clones the repository and makes a local copy in the F<perl-git>
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47directory.
48
49If your local network does not allow you to use port 9418, then you can
cf5e7595 50fetch a copy of the repository over HTTP (this is at least 4x slower):
d7dd28b6 51
e0b2b458 52 % git clone http://perl5.git.perl.org/perl.git perl-http
d7dd28b6 53
f755e97d 54This clones the repository and makes a local copy in the F<perl-http>
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55directory.
56
ba336be1 57=head2 Write access to the repository
d7dd28b6 58
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59If you are a committer, then you can fetch a copy of the repository
60that you can push back on with:
d7dd28b6 61
e0b2b458 62 % git clone ssh://perl5.git.perl.org/perl.git perl-ssh
d7dd28b6 63
8f718e95 64This clones the repository and makes a local copy in the F<perl-ssh>
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65directory.
66
c26da522 67If you cloned using the git protocol, which is faster than ssh, then
11ed6e28 68you will need to modify the URL for the origin remote to enable
77db6475 69pushing. To do that edit F<.git/config> with git-config(1) like this:
1a0f15d5 70
e0b2b458 71 % git config remote.origin.url ssh://perl5.git.perl.org/perl.git
d7dd28b6 72
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73You can also set up your user name and e-mail address. Most people do
74this once globally in their F<~/.gitconfig> by doing something like:
184487f0 75
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76 % git config --global user.name "Ævar Arnfjörð Bjarmason"
77 % git config --global user.email avarab@gmail.com
78
79However if you'd like to override that just for perl then execute then
80execute something like the following in F<perl-git>:
81
82 % git config user.email avar@cpan.org
184487f0 83
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84It is also possible to keep C<origin> as a git remote, and add a new
85remote for ssh access:
f6c12373 86
dc3c3040 87 % git remote add camel perl5.git.perl.org:/perl.git
f6c12373 88
6acba58e 89This allows you to update your local repository by pulling from
f755e97d 90C<origin>, which is faster and doesn't require you to authenticate, and
6acba58e 91to push your changes back with the C<camel> remote:
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92
93 % git fetch camel
94 % git push camel
95
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96The C<fetch> command just updates the C<camel> refs, as the objects
97themselves should have been fetched when pulling from C<origin>.
f6c12373 98
ba336be1 99=head2 A note on camel and dromedary
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100
101The committers have SSH access to the two servers that serve
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102C<perl5.git.perl.org>. One is C<perl5.git.perl.org> itself (I<camel>),
103which is the 'master' repository. The second one is
104C<users.perl5.git.perl.org> (I<dromedary>), which can be used for
105general testing and development. Dromedary syncs the git tree from
106camel every few minutes, you should not push there. Both machines also
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107have a full CPAN mirror in /srv/CPAN, please use this. To share files
108with the general public, dromedary serves your ~/public_html/ as
333f8875 109C<http://users.perl5.git.perl.org/~yourlogin/>
b47aa495 110
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111These hosts have fairly strict firewalls to the outside. Outgoing, only
112rsync, ssh and git are allowed. For http and ftp, you can use
113http://webproxy:3128 as proxy. Incoming, the firewall tries to detect
114attacks and blocks IP addresses with suspicious activity. This
115sometimes (but very rarely) has false positives and you might get
116blocked. The quickest way to get unblocked is to notify the admins.
117
118These two boxes are owned, hosted, and operated by booking.com. You can
119reach the sysadmins in #p5p on irc.perl.org or via mail to
120C<perl5-porters@perl.org>
121
ba336be1 122=head1 Overview of the repository
d7dd28b6 123
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124Once you have changed into the repository directory, you can inspect
125it.
d7dd28b6 126
39219fd3 127After a clone the repository will contain a single local branch, which
50eca761 128will be the current branch as well, as indicated by the asterisk.
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129
130 % git branch
131 * blead
132
f755e97d 133Using the -a switch to C<branch> will also show the remote tracking
6acba58e 134branches in the repository:
39219fd3 135
d9847473 136 % git branch -a
09081495 137 * blead
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138 origin/HEAD
139 origin/blead
140 ...
141
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142The branches that begin with "origin" correspond to the "git remote"
143that you cloned from (which is named "origin"). Each branch on the
144remote will be exactly tracked by theses branches. You should NEVER do
145work on these remote tracking branches. You only ever do work in a
146local branch. Local branches can be configured to automerge (on pull)
147from a designated remote tracking branch. This is the case with the
148default branch C<blead> which will be configured to merge from the
149remote tracking branch C<origin/blead>.
39219fd3 150
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151You can see recent commits:
152
c2cf2042 153 % git log
d7dd28b6 154
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155And pull new changes from the repository, and update your local
156repository (must be clean first)
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157
158 % git pull
09081495 159
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160Assuming we are on the branch C<blead> immediately after a pull, this
161command would be more or less equivalent to:
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162
163 % git fetch
164 % git merge origin/blead
165
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166In fact if you want to update your local repository without touching
167your working directory you do:
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168
169 % git fetch
170
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171And if you want to update your remote-tracking branches for all defined
172remotes simultaneously you can do
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173
174 % git remote update
175
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176Neither of these last two commands will update your working directory,
177however both will update the remote-tracking branches in your
178repository.
39219fd3 179
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180To make a local branch of a remote branch:
181
182 % git checkout -b maint-5.10 origin/maint-5.10
183
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184To switch back to blead:
185
186 % git checkout blead
c2cf2042 187
ba336be1 188=head2 Finding out your status
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189
190The most common git command you will use will probably be
191
192 % git status
193
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194This command will produce as output a description of the current state
195of the repository, including modified files and unignored untracked
196files, and in addition it will show things like what files have been
197staged for the next commit, and usually some useful information about
198how to change things. For instance the following:
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199
200 $ git status
201 # On branch blead
202 # Your branch is ahead of 'origin/blead' by 1 commit.
203 #
204 # Changes to be committed:
205 # (use "git reset HEAD <file>..." to unstage)
206 #
207 # modified: pod/perlrepository.pod
208 #
209 # Changed but not updated:
210 # (use "git add <file>..." to update what will be committed)
211 #
212 # modified: pod/perlrepository.pod
213 #
214 # Untracked files:
215 # (use "git add <file>..." to include in what will be committed)
216 #
217 # deliberate.untracked
218
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219This shows that there were changes to this document staged for commit,
220and that there were further changes in the working directory not yet
221staged. It also shows that there was an untracked file in the working
222directory, and as you can see shows how to change all of this. It also
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223shows that there is one commit on the working branch C<blead> which has
224not been pushed to the C<origin> remote yet. B<NOTE>: that this output
225is also what you see as a template if you do not provide a message to
226C<git commit>.
7f6effc7 227
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228Assuming that you'd like to commit all the changes you've just made as
229a a single atomic unit, run this command:
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230
231 % git commit -a
232
233(That C<-a> tells git to add every file you've changed to this commit.
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234New files aren't automatically added to your commit when you use
235C<commit -a> If you want to add files or to commit some, but not all of
236your changes, have a look at the documentation for C<git add>.)
bdaf0bc6 237
e9360695 238Git will start up your favorite text editor, so that you can craft a
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239commit message for your change. See L</Commit message> below for more
240information about what makes a good commit message.
241
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242Once you've finished writing your commit message and exited your
243editor, git will write your change to disk and tell you something like
244this:
7f6effc7 245
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246 Created commit daf8e63: explain git status and stuff about remotes
247 1 files changed, 83 insertions(+), 3 deletions(-)
248
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249
250If you re-run C<git status>, you should see something like this:
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251
252 % git status
253 # On branch blead
254 # Your branch is ahead of 'origin/blead' by 2 commits.
255 #
256 # Untracked files:
257 # (use "git add <file>..." to include in what will be committed)
258 #
259 # deliberate.untracked
260 nothing added to commit but untracked files present (use "git add" to track)
261
39219fd3 262
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263When in doubt, before you do anything else, check your status and read
264it carefully, many questions are answered directly by the git status
265output.
39219fd3 266
ba336be1 267=head1 Submitting a patch
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268
269If you have a patch in mind for Perl, you should first get a copy of
270the repository:
271
272 % git clone git://perl5.git.perl.org/perl.git perl-git
273
274Then change into the directory:
275
276 % cd perl-git
277
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278Alternatively, if you already have a Perl repository, you should ensure
279that you're on the I<blead> branch, and your repository is up to date:
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280
281 % git checkout blead
282 % git pull
283
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284It's preferable to patch against the latest blead version, since this
285is where new development occurs for all changes other than critical bug
286fixes. Critical bug fix patches should be made against the relevant
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287maint branches, or should be submitted with a note indicating all the
288branches where the fix should be applied.
a44f43ac 289
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290Now that we have everything up to date, we need to create a temporary
291new branch for these changes and switch into it:
b1fccde5 292
a9b05323 293 % git checkout -b orange
23f8d33e 294
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295which is the short form of
296
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297 % git branch orange
298 % git checkout orange
299
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300Creating a topic branch makes it easier for the maintainers to rebase
301or merge back into the master blead for a more linear history. If you
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302don't work on a topic branch the maintainer has to manually cherry pick
303your changes onto blead before they can be applied.
0c24b290 304
77db6475 305That'll get you scolded on perl5-porters, so don't do that. Be Awesome.
0c24b290 306
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307Then make your changes. For example, if Leon Brocard changes his name
308to Orange Brocard, we should change his name in the AUTHORS file:
309
310 % perl -pi -e 's{Leon Brocard}{Orange Brocard}' AUTHORS
311
312You can see what files are changed:
313
314 % git status
f755e97d 315 # On branch orange
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316 # Changes to be committed:
317 # (use "git reset HEAD <file>..." to unstage)
318 #
2699d634 319 # modified: AUTHORS
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320 #
321
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322And you can see the changes:
323
324 % git diff
325 diff --git a/AUTHORS b/AUTHORS
326 index 293dd70..722c93e 100644
327 --- a/AUTHORS
328 +++ b/AUTHORS
7df2e4bc 329 @@ -541,7 +541,7 @@ Lars Hecking <lhecking@nmrc.ucc.ie>
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330 Laszlo Molnar <laszlo.molnar@eth.ericsson.se>
331 Leif Huhn <leif@hale.dkstat.com>
332 Len Johnson <lenjay@ibm.net>
333 -Leon Brocard <acme@astray.com>
334 +Orange Brocard <acme@astray.com>
335 Les Peters <lpeters@aol.net>
336 Lesley Binks <lesley.binks@gmail.com>
337 Lincoln D. Stein <lstein@cshl.org>
338
77471e41 339For changes significant enough to warrant a F<pod/perldelta.pod> entry, the
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340porters would greatly appreciate it if you submit an entry along with your
341actual change. Significant changes include, but are not limited to:
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342
343=over 4
344
345=item *
346
347adding, deprecating, or removing core features
348
349=item *
350
351adding, deprecating, removing, or upgrading core or dual-life modules
352
353=item *
354
355adding new core tests
356
357=item *
358
359fixing security issues and user-visible bugs in the core
360
361=item *
362
507569bb 363changes that might break existing code, either on the perl or C level
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364
365=item *
366
367significant performance improvements
368
369=item *
370
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371adding, removing, or significantly changing documentation in the F<pod/>
372directory
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373
374=item *
375
376important platform-specific changes
377
378=back
379
507569bb 380Please make sure you add the perldelta entry to the right section within
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381F<pod/perldelta.pod>. More information on how to write good perldelta entries is
382available in the C<Style> section of F<Porting/how_to_write_a_perldelta.pod>.
383
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384Now commit your change locally:
385
dc3c3040 386 % git commit -a -m 'Rename Leon Brocard to Orange Brocard'
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387 Created commit 6196c1d: Rename Leon Brocard to Orange Brocard
388 1 files changed, 1 insertions(+), 1 deletions(-)
389
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390The C<-a> option is used to include all files that git tracks that you have
391changed. If at this time, you only want to commit some of the files you have
392worked on, you can omit the C<-a> and use the command C<S<git add I<FILE ...>>>
393before doing the commit. C<S<git add --interactive>> allows you to even just
394commit portions of files instead of all the changes in them.
395
396The C<-m> option is used to specify the commit message. If you omit it, git
397will open a text editor for you to compose the message interactively. This
398is useful when the changes are more complex than the sample given here, and,
399depending on the editor, to know that the first line of the commit message
400doesn't exceed the 50 character legal maximum.
401
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402You can examine your last commit with:
403
404 % git show HEAD
405
406and if you are not happy with either the description or the patch
c26da522 407itself you can fix it up by editing the files once more and then issue:
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408
409 % git commit -a --amend
410
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411Now you should create a patch file for all your local changes:
412
f15b1f22 413 % git format-patch -M origin..
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414 0001-Rename-Leon-Brocard-to-Orange-Brocard.patch
415
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416You should now send an email to to
417L<perlbug@perl.org|mailto:perlbug@perl.org> with a description of your
418changes, and include this patch file as an attachment. In addition to
77db6475 419being tracked by RT, mail to perlbug will automatically be forwarded to
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420perl5-porters (with manual moderation, so please be patient). You should only
421send patches to L<perl5-porters@perl.org|mailto:perl5-porters@perl.org>
422directly if the patch is not ready to be applied, but intended for discussion.
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423
424See the next section for how to configure and use git to send these
425emails for you.
c2cf2042 426
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427If you want to delete your temporary branch, you may do so with:
428
429 % git checkout blead
430 % git branch -d orange
431 error: The branch 'orange' is not an ancestor of your current HEAD.
432 If you are sure you want to delete it, run 'git branch -D orange'.
433 % git branch -D orange
434 Deleted branch orange.
7df2e4bc 435
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436=head2 Using git to send patch emails
437
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438In your ~/git/perl repository, set the destination email to perl's bug
439tracker:
440
441 $ git config sendemail.to perlbug@perl.org
442
443Or maybe perl5-porters (discussed above):
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444
445 $ git config sendemail.to perl5-porters@perl.org
446
447Then you can use git directly to send your patch emails:
448
449 $ git send-email 0001-Rename-Leon-Brocard-to-Orange-Brocard.patch
450
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451You may need to set some configuration variables for your particular
452email service provider. For example, to set your global git config to
453send email via a gmail account:
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454
455 $ git config --global sendemail.smtpserver smtp.gmail.com
456 $ git config --global sendemail.smtpssl 1
457 $ git config --global sendemail.smtpuser YOURUSERNAME@gmail.com
458
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459With this configuration, you will be prompted for your gmail password
460when you run 'git send-email'. You can also configure
461C<sendemail.smtppass> with your password if you don't care about having
462your password in the .gitconfig file.
2d5f1d01 463
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464=head2 A note on derived files
465
466Be aware that many files in the distribution are derivative--avoid
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467patching them, because git won't see the changes to them, and the build
468process will overwrite them. Patch the originals instead. Most
469utilities (like perldoc) are in this category, i.e. patch
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470F<utils/perldoc.PL> rather than F<utils/perldoc>. Similarly, don't
471create patches for files under $src_root/ext from their copies found in
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472$install_root/lib. If you are unsure about the proper location of a
473file that may have gotten copied while building the source
474distribution, consult the C<MANIFEST>.
a44f43ac 475
6e2cec71 476=for XXX
6e2cec71 477What should we recommend about binary files now? Do we need anything?
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478
479=head2 Getting your patch accepted
480
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481If you are submitting a code patch there are several things that you
482need to do.
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483
484=over 4
485
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486=item Commit message
487
488As you craft each patch you intend to submit to the Perl core, it's
489important to write a good commit message.
490
1a5f98ea 491The first line of the commit message should be a short description and
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492should skip the full stop. It should be no longer than the subject line
493of an E-Mail, 50 characters being a good rule of thumb.
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494
495A lot of Git tools (Gitweb, GitHub, git log --pretty=oneline, ..) will
496only display the first line (cut off at 50 characters) when presenting
497commit summaries.
498
499The commit message should include description of the problem that the
500patch corrects or new functionality that the patch adds.
bdaf0bc6 501
bdaf0bc6 502As a general rule of thumb, your commit message should let a programmer
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503with a reasonable familiarity with the Perl core quickly understand
504what you were trying to do, how you were trying to do it and why the
505change matters to Perl.
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506
507=over 4
508
509=item What
510
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511Your commit message should describe what part of the Perl core you're
512changing and what you expect your patch to do.
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513
514=item Why
515
516Perhaps most importantly, your commit message should describe why the
517change you are making is important. When someone looks at your change
518in six months or six years, your intent should be clear. If you're
519deprecating a feature with the intent of later simplifying another bit
520of code, say so. If you're fixing a performance problem or adding a new
521feature to support some other bit of the core, mention that.
522
523=item How
524
525While it's not necessary for documentation changes, new tests or
526trivial patches, it's often worth explaining how your change works.
527Even if it's clear to you today, it may not be clear to a porter next
528month or next year.
529
530=back
531
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532A commit message isn't intended to take the place of comments in your
533code. Commit messages should describe the change you made, while code
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534comments should describe the current state of the code. If you've just
535implemented a new feature, complete with doc, tests and well-commented
536code, a brief commit message will often suffice. If, however, you've
537just changed a single character deep in the parser or lexer, you might
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538need to write a small novel to ensure that future readers understand
539what you did and why you did it.
540
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541=item Comments, Comments, Comments
542
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543Be sure to adequately comment your code. While commenting every line
544is unnecessary, anything that takes advantage of side effects of
a44f43ac 545operators, that creates changes that will be felt outside of the
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546function being patched, or that others may find confusing should be
547documented. If you are going to err, it is better to err on the side
548of adding too many comments than too few.
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549
550=item Style
551
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552In general, please follow the particular style of the code you are
553patching.
a44f43ac 554
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555In particular, follow these general guidelines for patching Perl
556sources:
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557
558 8-wide tabs (no exceptions!)
559 4-wide indents for code, 2-wide indents for nested CPP #defines
560 try hard not to exceed 79-columns
561 ANSI C prototypes
562 uncuddled elses and "K&R" style for indenting control constructs
563 no C++ style (//) comments
564 mark places that need to be revisited with XXX (and revisit often!)
565 opening brace lines up with "if" when conditional spans multiple
566 lines; should be at end-of-line otherwise
567 in function definitions, name starts in column 0 (return value is on
568 previous line)
569 single space after keywords that are followed by parens, no space
570 between function name and following paren
571 avoid assignments in conditionals, but if they're unavoidable, use
572 extra paren, e.g. "if (a && (b = c)) ..."
573 "return foo;" rather than "return(foo);"
574 "if (!foo) ..." rather than "if (foo == FALSE) ..." etc.
575
576=item Testsuite
577
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578If your patch changes code (rather than just changing documentation)
579you should also include one or more test cases which illustrate the bug
580you're fixing or validate the new functionality you're adding. In
581general, you should update an existing test file rather than create a
582new one.
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584Your testsuite additions should generally follow these guidelines
585(courtesy of Gurusamy Sarathy <gsar@activestate.com>):
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586
587 Know what you're testing. Read the docs, and the source.
588 Tend to fail, not succeed.
589 Interpret results strictly.
590 Use unrelated features (this will flush out bizarre interactions).
591 Use non-standard idioms (otherwise you are not testing TIMTOWTDI).
592 Avoid using hardcoded test numbers whenever possible (the
593 EXPECTED/GOT found in t/op/tie.t is much more maintainable,
594 and gives better failure reports).
595 Give meaningful error messages when a test fails.
596 Avoid using qx// and system() unless you are testing for them. If you
597 do use them, make sure that you cover _all_ perl platforms.
598 Unlink any temporary files you create.
599 Promote unforeseen warnings to errors with $SIG{__WARN__}.
600 Be sure to use the libraries and modules shipped with the version
601 being tested, not those that were already installed.
602 Add comments to the code explaining what you are testing for.
603 Make updating the '1..42' string unnecessary. Or make sure that
604 you update it.
605 Test _all_ behaviors of a given operator, library, or function:
606 - All optional arguments
607 - Return values in various contexts (boolean, scalar, list, lvalue)
608 - Use both global and lexical variables
609 - Don't forget the exceptional, pathological cases.
610
611=back
612
ba336be1 613=head1 Accepting a patch
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614
615If you have received a patch file generated using the above section,
616you should try out the patch.
617
618First we need to create a temporary new branch for these changes and
619switch into it:
620
a9b05323 621 % git checkout -b experimental
7df2e4bc 622
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623Patches that were formatted by C<git format-patch> are applied with
624C<git am>:
7df2e4bc 625
2af192ee 626 % git am 0001-Rename-Leon-Brocard-to-Orange-Brocard.patch
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627 Applying Rename Leon Brocard to Orange Brocard
628
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629If just a raw diff is provided, it is also possible use this two-step
630process:
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631
632 % git apply bugfix.diff
dc3c3040 633 % git commit -a -m "Some fixing" --author="That Guy <that.guy@internets.com>"
09645c26 634
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635Now we can inspect the change:
636
dc3c3040 637 % git show HEAD
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638 commit b1b3dab48344cff6de4087efca3dbd63548ab5e2
639 Author: Leon Brocard <acme@astray.com>
640 Date: Fri Dec 19 17:02:59 2008 +0000
641
642 Rename Leon Brocard to Orange Brocard
7df2e4bc 643
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644 diff --git a/AUTHORS b/AUTHORS
645 index 293dd70..722c93e 100644
646 --- a/AUTHORS
647 +++ b/AUTHORS
648 @@ -541,7 +541,7 @@ Lars Hecking <lhecking@nmrc.ucc.ie>
649 Laszlo Molnar <laszlo.molnar@eth.ericsson.se>
650 Leif Huhn <leif@hale.dkstat.com>
651 Len Johnson <lenjay@ibm.net>
652 -Leon Brocard <acme@astray.com>
653 +Orange Brocard <acme@astray.com>
654 Les Peters <lpeters@aol.net>
655 Lesley Binks <lesley.binks@gmail.com>
656 Lincoln D. Stein <lstein@cshl.org>
657
658If you are a committer to Perl and you think the patch is good, you can
75fb7651 659then merge it into blead then push it out to the main repository:
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660
661 % git checkout blead
d9847473 662 % git merge experimental
75fb7651 663 % git push
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664
665If you want to delete your temporary branch, you may do so with:
666
667 % git checkout blead
668 % git branch -d experimental
669 error: The branch 'experimental' is not an ancestor of your current HEAD.
670 If you are sure you want to delete it, run 'git branch -D experimental'.
671 % git branch -D experimental
672 Deleted branch experimental.
b0d36535 673
ba336be1 674=head1 Cleaning a working directory
b0d36535 675
6acba58e 676The command C<git clean> can with varying arguments be used as a
dc3c3040 677replacement for C<make clean>.
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678
679To reset your working directory to a pristine condition you can do:
680
e0b2b458 681 % git clean -dxf
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682
683However, be aware this will delete ALL untracked content. You can use
684
e0b2b458 685 % git clean -Xf
b0d36535 686
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687to remove all ignored untracked files, such as build and test
688byproduct, but leave any manually created files alone.
b0d36535 689
0549aefb 690If you only want to cancel some uncommitted edits, you can use C<git
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691checkout> and give it a list of files to be reverted, or C<git checkout
692-f> to revert them all.
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693
694If you want to cancel one or several commits, you can use C<git reset>.
695
ba336be1 696=head1 Bisecting
d82a90c1 697
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698C<git> provides a built-in way to determine, with a binary search in
699the history, which commit should be blamed for introducing a given bug.
d82a90c1 700
6acba58e 701Suppose that we have a script F<~/testcase.pl> that exits with C<0>
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702when some behaviour is correct, and with C<1> when it's faulty. You
703need an helper script that automates building C<perl> and running the
6acba58e 704testcase:
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705
706 % cat ~/run
707 #!/bin/sh
708 git clean -dxf
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709
710 # If you get './makedepend: 1: Syntax error: Unterminated quoted
711 # string' when bisecting versions of perl older than 5.9.5 this hack
712 # will work around the bug in makedepend.SH which was fixed in
cfe91bfa 713 # version 96a8704c. Make sure to comment out `git checkout makedepend.SH'
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714 # below too.
715 git show blead:makedepend.SH > makedepend.SH
716
d82a90c1 717 # If you can use ccache, add -Dcc=ccache\ gcc -Dld=gcc to the Configure line
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718 # if Encode is not needed for the test, you can speed up the bisect by
719 # excluding it from the runs with -Dnoextensions=Encode
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720 sh Configure -des -Dusedevel -Doptimize="-g"
721 test -f config.sh || exit 125
722 # Correct makefile for newer GNU gcc
723 perl -ni -we 'print unless /<(?:built-in|command)/' makefile x2p/makefile
724 # if you just need miniperl, replace test_prep with miniperl
d7923bfe 725 make test_prep
68814ba4 726 [ -x ./perl ] || exit 125
d82a90c1 727 ./perl -Ilib ~/testcase.pl
c0d1ef72 728 ret=$?
7930c68b 729 [ $ret -gt 127 ] && ret=127
cfe91bfa 730 # git checkout makedepend.SH
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731 git clean -dxf
732 exit $ret
d82a90c1 733
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734This script may return C<125> to indicate that the corresponding commit
735should be skipped. Otherwise, it returns the status of
736F<~/testcase.pl>.
d82a90c1 737
bdaf0bc6 738You first enter in bisect mode with:
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739
740 % git bisect start
741
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742For example, if the bug is present on C<HEAD> but wasn't in 5.10.0,
743C<git> will learn about this when you enter:
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744
745 % git bisect bad
746 % git bisect good perl-5.10.0
747 Bisecting: 853 revisions left to test after this
748
6acba58e 749This results in checking out the median commit between C<HEAD> and
bdaf0bc6 750C<perl-5.10.0>. You can then run the bisecting process with:
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751
752 % git bisect run ~/run
753
754When the first bad commit is isolated, C<git bisect> will tell you so:
755
756 ca4cfd28534303b82a216cfe83a1c80cbc3b9dc5 is first bad commit
757 commit ca4cfd28534303b82a216cfe83a1c80cbc3b9dc5
758 Author: Dave Mitchell <davem@fdisolutions.com>
759 Date: Sat Feb 9 14:56:23 2008 +0000
760
9469eb4a 761 [perl #49472] Attributes + Unknown Error
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762 ...
763
764 bisect run success
765
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766You can peek into the bisecting process with C<git bisect log> and
767C<git bisect visualize>. C<git bisect reset> will get you out of bisect
768mode.
d82a90c1 769
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770Please note that the first C<good> state must be an ancestor of the
771first C<bad> state. If you want to search for the commit that I<solved>
772some bug, you have to negate your test case (i.e. exit with C<1> if OK
773and C<0> if not) and still mark the lower bound as C<good> and the
774upper as C<bad>. The "first bad commit" has then to be understood as
775the "first commit where the bug is solved".
d82a90c1 776
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777C<git help bisect> has much more information on how you can tweak your
778binary searches.
9d68b7ed 779
ba336be1 780=head1 Submitting a patch via GitHub
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781
782GitHub is a website that makes it easy to fork and publish projects
783with Git. First you should set up a GitHub account and log in.
784
785Perl's git repository is mirrored on GitHub at this page:
786
45b194c5 787 http://github.com/mirrors/perl/tree/blead
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788
789Visit the page and click the "fork" button. This clones the Perl git
790repository for you and provides you with "Your Clone URL" from which
791you should clone:
792
793 % git clone git@github.com:USERNAME/perl.git perl-github
794
bdaf0bc6 795The same patch as above, using github might look like this:
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796
797 % cd perl-github
edb9e29e 798 % git remote add upstream git://perl5.git.perl.org/perl.git
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799 % git pull upstream blead
800 % git checkout -b orange
801 % perl -pi -e 's{Leon Brocard}{Orange Brocard}' AUTHORS
dc3c3040 802 % git commit -a -m 'Rename Leon Brocard to Orange Brocard'
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803 % git push origin orange
804
805The orange branch has been pushed to GitHub, so you should now send an
705c800c 806email (see L</Submitting a patch>) with a description of your changes
64a8e22b 807and the following information:
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808
809 http://github.com/USERNAME/perl/tree/orange
fb60e745 810 git://github.com/USERNAME/perl.git branch orange
03050721 811
ba336be1 812=head1 Merging from a branch via GitHub
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813
814If someone has provided a branch via GitHub and you are a committer,
5c9c28c6 815you should use the following in your perl-ssh directory:
c26da522 816
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817 % git remote add avar git://github.com/avar/perl.git
818 % git fetch avar
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819
820Now you can see the differences between the branch and blead:
821
e98adcab 822 % git diff avar/orange
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823
824And you can see the commits:
825
e98adcab 826 % git log avar/orange
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827
828If you approve of a specific commit, you can cherry pick it:
829
e98adcab 830 % git cherry-pick 0c24b290ae02b2ab3304f51d5e11e85eb3659eae
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831
832Or you could just merge the whole branch if you like it all:
833
e98adcab 834 % git merge avar/orange
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835
836And then push back to the repository:
837
838 % git push
839
ce2a8773 840
ba336be1 841=head1 Topic branches and rewriting history
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842
843Individual committers should create topic branches under
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844B<yourname>/B<some_descriptive_name>. Other committers should check
845with a topic branch's creator before making any change to it.
ce2a8773 846
b16add97
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847The simplest way to create a remote topic branch that works on all
848versions of git is to push the current head as a new branch on the
849remote, then check it out locally:
850
851 $ branch="$yourname/$some_descriptive_name"
852 $ git push origin HEAD:$branch
853 $ git checkout -b $branch origin/$branch
854
855Users of git 1.7 or newer can do it in a more obvious manner:
856
857 $ branch="$yourname/$some_descriptive_name"
858 $ git checkout -b $branch
859 $ git push origin -u $branch
33e5002f 860
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861If you are not the creator of B<yourname>/B<some_descriptive_name>, you
862might sometimes find that the original author has edited the branch's
863history. There are lots of good reasons for this. Sometimes, an author
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864might simply be rebasing the branch onto a newer source point.
865Sometimes, an author might have found an error in an early commit which
866they wanted to fix before merging the branch to blead.
ce2a8773 867
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868Currently the master repository is configured to forbid
869non-fast-forward merges. This means that the branches within can not
870be rebased and pushed as a single step.
ce2a8773 871
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872The only way you will ever be allowed to rebase or modify the history
873of a pushed branch is to delete it and push it as a new branch under
874the same name. Please think carefully about doing this. It may be
875better to sequentially rename your branches so that it is easier for
876others working with you to cherry-pick their local changes onto the new
877version. (XXX: needs explanation).
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878
879If you want to rebase a personal topic branch, you will have to delete
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880your existing topic branch and push as a new version of it. You can do
881this via the following formula (see the explanation about C<refspec>'s
882in the git push documentation for details) after you have rebased your
883branch:
884
885 # first rebase
886 $ git checkout $user/$topic
887 $ git fetch
888 $ git rebase origin/blead
889
890 # then "delete-and-push"
891 $ git push origin :$user/$topic
892 $ git push origin $user/$topic
893
894B<NOTE:> it is forbidden at the repository level to delete any of the
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895"primary" branches. That is any branch matching
896C<m!^(blead|maint|perl)!>. Any attempt to do so will result in git
897producing an error like this:
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898
899 $ git push origin :blead
900 *** It is forbidden to delete blead/maint branches in this repository
901 error: hooks/update exited with error code 1
902 error: hook declined to update refs/heads/blead
333f8875 903 To ssh://perl5.git.perl.org/perl
2699d634 904 ! [remote rejected] blead (hook declined)
333f8875 905 error: failed to push some refs to 'ssh://perl5.git.perl.org/perl'
2699d634 906
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907As a matter of policy we do B<not> edit the history of the blead and
908maint-* branches. If a typo (or worse) sneaks into a commit to blead or
909maint-*, we'll fix it in another commit. The only types of updates
910allowed on these branches are "fast-forward's", where all history is
911preserved.
2699d634 912
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913Annotated tags in the canonical perl.git repository will never be
914deleted or modified. Think long and hard about whether you want to push
915a local tag to perl.git before doing so. (Pushing unannotated tags is
2699d634 916not allowed.)
ce2a8773 917
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918=head1 Committing to blead
919
920If you are a committer, you have the right to commit changes directly to
921the 'blead' branch, which will become the next production release of Perl.
922
923Before pushing I<any> local change to blead, it's incredibly important
924that you do a few things, lest other committers come after you with
925pitchforks and torches:
926
927=over
928
929=item *
930
3f76ddee 931Make sure you have a good commit message. See L</Commit message> elsewhere in
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932this document
933
934=item *
935
936Run the test suite. You might not think that one typo fix would break
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937a test file. You'd be wrong. Here's an example of where not running the
938suite caused problems. A patch was submitted that added a couple of
939tests to an existing .t. It couldn't possibly affect anything else, so
940no need to test beyond the single affected .t, right? But, the
941submitter's email address had changed since the last of their
942submissions, and this caused other tests to fail. Running the test
943target given in the next item would have caught this problem.
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944
945=item *
946
947If you don't run the full test suite, at least C<make test_porting>.
948This will run basic sanity checks. To see which sanity checks, have a
949look in F<t/porting>.
950
951=back
952
ba336be1 953=head1 Committing to maintenance versions
9d68b7ed 954
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955Maintenance versions should only be altered to add critical bug fixes,
956see L<perlpolicy>.
7f4ffa9d 957
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958To commit to a maintenance version of perl, you need to create a local
959tracking branch:
960
961 % git checkout --track -b maint-5.005 origin/maint-5.005
962
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963This creates a local branch named C<maint-5.005>, which tracks the
964remote branch C<origin/maint-5.005>. Then you can pull, commit, merge
965and push as before.
b0d36535 966
f755e97d 967You can also cherry-pick commits from blead and another branch, by
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968using the C<git cherry-pick> command. It is recommended to use the
969B<-x> option to C<git cherry-pick> in order to record the SHA1 of the
970original commit in the new commit message.
f755e97d 971
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972Before pushing any change to a maint version, make sure you've satisfied
973the steps in L</Committing to blead> above.
974
ba336be1 975=head1 Grafts
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976
977The perl history contains one mistake which was not caught in the
ac036724 978conversion: a merge was recorded in the history between blead and
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979maint-5.10 where no merge actually occurred. Due to the nature of git,
980this is now impossible to fix in the public repository. You can remove
981this mis-merge locally by adding the following line to your
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982C<.git/info/grafts> file:
983
984 296f12bbbbaa06de9be9d09d3dcf8f4528898a49 434946e0cb7a32589ed92d18008aaa1d88515930
985
986It is particularly important to have this graft line if any bisecting
987is done in the area of the "merge" in question.
988
041325d6 989=head1 SEE ALSO
bdaf0bc6 990
041325d6 991=over
bdaf0bc6 992
705c800c 993=item *
041325d6 994
705c800c
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995The git documentation, accessible via the C<git help> command
996
997=item *
998
999L<perlpolicy> - Perl core development policy
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1000
1001=back
f755e97d 1002
041325d6 1003=cut