2 Consistent formatting of this file is achieved with:
3 perl ./Porting/podtidy pod/perlrepository.pod
7 perlrepository - Using the Perl source repository
11 All of Perl's source code is kept centrally in a Git repository at
12 I<perl5.git.perl.org>. The repository contains many Perl revisions from
13 Perl 1 onwards and all the revisions from Perforce, the version control
14 system we were using previously. This repository is accessible in
17 The full repository takes up about 80MB of disk space. A check out of
18 the blead branch (that is, the main development branch, which contains
19 bleadperl, the development version of perl 5) takes up about 160MB of
20 disk space (including the repository). A build of bleadperl takes up
21 about 200MB (including the repository and the check out).
23 =head1 GETTING ACCESS TO THE REPOSITORY
25 =head2 READ ACCESS VIA THE WEB
27 You may access the repository over the web. This allows you to browse
28 the tree, see recent commits, subscribe to RSS feeds for the changes,
29 search for particular commits and more. You may access it at:
31 http://perl5.git.perl.org/perl.git
33 A mirror of the repository is found at:
35 http://github.com/github/perl
37 =head2 READ ACCESS VIA GIT
39 You will need a copy of Git for your computer. You can fetch a copy of
40 the repository using the Git protocol (which uses port 9418):
42 git clone git://perl5.git.perl.org/perl.git perl-git
44 This clones the repository and makes a local copy in the F<perl-git>
47 If your local network does not allow you to use port 9418, then you can
48 fetch a copy of the repository over HTTP (this is slower):
50 git clone http://perl5.git.perl.org/perl.git perl-http
52 This clones the repository and makes a local copy in the F<perl-http>
55 =head2 WRITE ACCESS TO THE REPOSITORY
57 If you are a committer, then you can fetch a copy of the repository
58 that you can push back on with:
60 git clone ssh://perl5.git.perl.org/perl.git perl-ssh
62 This clones the repository and makes a local copy in the F<perl-ssh>
65 If you cloned using the git protocol, which is faster than ssh, then
66 you will need to modify your config in order to enable pushing. Edit
67 F<.git/config> where you will see something like:
70 url = git://perl5.git.perl.org/perl.git
72 change that to something like this:
75 url = ssh://perl5.git.perl.org/perl.git
77 You can also set up your user name and e-mail address. For example
79 % git config user.name "Leon Brocard"
80 % git config user.email acme@astray.com
82 It is also possible to keep C<origin> as a git remote, and add a new
83 remote for ssh access:
85 % git remote add camel perl5.git.perl.org:/perl.git
87 This allows you to update your local repository by pulling from
88 C<origin>, which is faster and doesn't require you to authenticate, and
89 to push your changes back with the C<camel> remote:
94 The C<fetch> command just updates the C<camel> refs, as the objects
95 themselves should have been fetched when pulling from C<origin>.
97 =head2 A NOTE ON CAMEL AND DROMEDARY
99 The committers have SSH access to the two servers that serve
100 C<perl5.git.perl.org>. One is C<perl5.git.perl.org> itself (I<camel>),
101 which is the 'master' repository. The second one is
102 C<users.perl5.git.perl.org> (I<dromedary>), which can be used for
103 general testing and development. Dromedary syncs the git tree from
104 camel every few minutes, you should not push there. Both machines also
105 have a full CPAN mirror in /srv/CPAN, please use this. To share files
106 with the general public, dromedary serves your ~/public_html/ as
107 C<http://users.perl5.git.perl.org/~yourlogin/>
109 These hosts have fairly strict firewalls to the outside. Outgoing, only
110 rsync, ssh and git are allowed. For http and ftp, you can use
111 http://webproxy:3128 as proxy. Incoming, the firewall tries to detect
112 attacks and blocks IP addresses with suspicious activity. This
113 sometimes (but very rarely) has false positives and you might get
114 blocked. The quickest way to get unblocked is to notify the admins.
116 These two boxes are owned, hosted, and operated by booking.com. You can
117 reach the sysadmins in #p5p on irc.perl.org or via mail to
118 C<perl5-porters@perl.org>
120 =head1 OVERVIEW OF THE REPOSITORY
122 Once you have changed into the repository directory, you can inspect
125 After a clone the repository will contain a single local branch, which
126 will be the current branch as well, as indicated by the asterisk.
131 Using the -a switch to C<branch> will also show the remote tracking
132 branches in the repository:
140 The branches that begin with "origin" correspond to the "git remote"
141 that you cloned from (which is named "origin"). Each branch on the
142 remote will be exactly tracked by theses branches. You should NEVER do
143 work on these remote tracking branches. You only ever do work in a
144 local branch. Local branches can be configured to automerge (on pull)
145 from a designated remote tracking branch. This is the case with the
146 default branch C<blead> which will be configured to merge from the
147 remote tracking branch C<origin/blead>.
149 You can see recent commits:
153 And pull new changes from the repository, and update your local
154 repository (must be clean first)
158 Assuming we are on the branch C<blead> immediately after a pull, this
159 command would be more or less equivalent to:
162 % git merge origin/blead
164 In fact if you want to update your local repository without touching
165 your working directory you do:
169 And if you want to update your remote-tracking branches for all defined
170 remotes simultaneously you can do
174 Neither of these last two commands will update your working directory,
175 however both will update the remote-tracking branches in your
178 To switch to another branch:
180 % git checkout origin/maint-5.8-dor
182 To make a local branch of a remote branch:
184 % git checkout -b maint-5.10 origin/maint-5.10
186 To switch back to blead:
190 =head2 FINDING OUT YOUR STATUS
192 The most common git command you will use will probably be
196 This command will produce as output a description of the current state
197 of the repository, including modified files and unignored untracked
198 files, and in addition it will show things like what files have been
199 staged for the next commit, and usually some useful information about
200 how to change things. For instance the following:
204 # Your branch is ahead of 'origin/blead' by 1 commit.
206 # Changes to be committed:
207 # (use "git reset HEAD <file>..." to unstage)
209 # modified: pod/perlrepository.pod
211 # Changed but not updated:
212 # (use "git add <file>..." to update what will be committed)
214 # modified: pod/perlrepository.pod
217 # (use "git add <file>..." to include in what will be committed)
219 # deliberate.untracked
221 This shows that there were changes to this document staged for commit,
222 and that there were further changes in the working directory not yet
223 staged. It also shows that there was an untracked file in the working
224 directory, and as you can see shows how to change all of this. It also
225 shows that there is one commit on the working branch C<blead> which has
226 not been pushed to the C<origin> remote yet. B<NOTE>: that this output
227 is also what you see as a template if you do not provide a message to
230 Assuming we commit all the mentioned changes above:
232 % git commit -a -m'explain git status and stuff about remotes'
233 Created commit daf8e63: explain git status and stuff about remotes
234 1 files changed, 83 insertions(+), 3 deletions(-)
236 We can re-run git status and see something like this:
240 # Your branch is ahead of 'origin/blead' by 2 commits.
243 # (use "git add <file>..." to include in what will be committed)
245 # deliberate.untracked
246 nothing added to commit but untracked files present (use "git add" to track)
249 When in doubt, before you do anything else, check your status and read
250 it carefully, many questions are answered directly by the git status
253 =head1 SUBMITTING A PATCH
255 If you have a patch in mind for Perl, you should first get a copy of
258 % git clone git://perl5.git.perl.org/perl.git perl-git
260 Then change into the directory:
264 Alternatively, if you already have a Perl repository, you should ensure
265 that you're on the I<blead> branch, and your repository is up to date:
270 It's preferable to patch against the latest blead version, since this
271 is where new development occurs for all changes other than critical bug
272 fixes. Critical bug fix patches should be made against the relevant
273 maint branches, or should be submitted with a note indicating all the
274 branches where the fix should be applied.
276 Now that we have everything up to date, we need to create a temporary
277 new branch for these changes and switch into it:
279 % git checkout -b orange
281 which is the short form of
284 % git checkout orange
286 Then make your changes. For example, if Leon Brocard changes his name
287 to Orange Brocard, we should change his name in the AUTHORS file:
289 % perl -pi -e 's{Leon Brocard}{Orange Brocard}' AUTHORS
291 You can see what files are changed:
295 # Changes to be committed:
296 # (use "git reset HEAD <file>..." to unstage)
301 And you can see the changes:
304 diff --git a/AUTHORS b/AUTHORS
305 index 293dd70..722c93e 100644
308 @@ -541,7 +541,7 @@ Lars Hecking <lhecking@nmrc.ucc.ie>
309 Laszlo Molnar <laszlo.molnar@eth.ericsson.se>
310 Leif Huhn <leif@hale.dkstat.com>
311 Len Johnson <lenjay@ibm.net>
312 -Leon Brocard <acme@astray.com>
313 +Orange Brocard <acme@astray.com>
314 Les Peters <lpeters@aol.net>
315 Lesley Binks <lesley.binks@gmail.com>
316 Lincoln D. Stein <lstein@cshl.org>
318 Now commit your change locally:
320 % git commit -a -m 'Rename Leon Brocard to Orange Brocard'
321 Created commit 6196c1d: Rename Leon Brocard to Orange Brocard
322 1 files changed, 1 insertions(+), 1 deletions(-)
324 You can examine your last commit with:
328 and if you are not happy with either the description or the patch
329 itself you can fix it up by editing the files once more and then issue:
331 % git commit -a --amend
333 Now you should create a patch file for all your local changes:
335 % git format-patch origin
336 0001-Rename-Leon-Brocard-to-Orange-Brocard.patch
338 You should now send an email to perl5-porters@perl.org with a
339 description of your changes, and include this patch file as an
340 attachment. (See the next section for how to configure and use git to
341 send these emails for you.)
343 If you want to delete your temporary branch, you may do so with:
346 % git branch -d orange
347 error: The branch 'orange' is not an ancestor of your current HEAD.
348 If you are sure you want to delete it, run 'git branch -D orange'.
349 % git branch -D orange
350 Deleted branch orange.
352 =head2 Using git to send patch emails
354 In your ~/git/perl repository, set the destination email to the
355 perl5-porters mailing list.
357 $ git config sendemail.to perl5-porters@perl.org
359 Then you can use git directly to send your patch emails:
361 $ git send-email 0001-Rename-Leon-Brocard-to-Orange-Brocard.patch
363 You may need to set some configuration variables for your particular
364 email service provider. For example, to set your global git config to
365 send email via a gmail account:
367 $ git config --global sendemail.smtpserver smtp.gmail.com
368 $ git config --global sendemail.smtpssl 1
369 $ git config --global sendemail.smtpuser YOURUSERNAME@gmail.com
371 With this configuration, you will be prompted for your gmail password
372 when you run 'git send-email'. You can also configure
373 C<sendemail.smtppass> with your password if you don't care about having
374 your password in the .gitconfig file.
376 =head2 A note on derived files
378 Be aware that many files in the distribution are derivative--avoid
379 patching them, because git won't see the changes to them, and the build
380 process will overwrite them. Patch the originals instead. Most
381 utilities (like perldoc) are in this category, i.e. patch
382 utils/perldoc.PL rather than utils/perldoc. Similarly, don't create
383 patches for files under $src_root/ext from their copies found in
384 $install_root/lib. If you are unsure about the proper location of a
385 file that may have gotten copied while building the source
386 distribution, consult the C<MANIFEST>.
390 What should we recommend about binary files now? Do we need anything?
392 =head2 Getting your patch accepted
394 The first thing you should include with your patch is a description of
395 the problem that the patch corrects. If it is a code patch (rather
396 than a documentation patch) you should also include a small test case
397 that illustrates the bug (a patch to an existing test file is
400 If you are submitting a code patch there are several other things that
405 =item Comments, Comments, Comments
407 Be sure to adequately comment your code. While commenting every line
408 is unnecessary, anything that takes advantage of side effects of
409 operators, that creates changes that will be felt outside of the
410 function being patched, or that others may find confusing should be
411 documented. If you are going to err, it is better to err on the side
412 of adding too many comments than too few.
416 In general, please follow the particular style of the code you are
419 In particular, follow these general guidelines for patching Perl
422 8-wide tabs (no exceptions!)
423 4-wide indents for code, 2-wide indents for nested CPP #defines
424 try hard not to exceed 79-columns
426 uncuddled elses and "K&R" style for indenting control constructs
427 no C++ style (//) comments
428 mark places that need to be revisited with XXX (and revisit often!)
429 opening brace lines up with "if" when conditional spans multiple
430 lines; should be at end-of-line otherwise
431 in function definitions, name starts in column 0 (return value is on
433 single space after keywords that are followed by parens, no space
434 between function name and following paren
435 avoid assignments in conditionals, but if they're unavoidable, use
436 extra paren, e.g. "if (a && (b = c)) ..."
437 "return foo;" rather than "return(foo);"
438 "if (!foo) ..." rather than "if (foo == FALSE) ..." etc.
442 When submitting a patch you should make every effort to also include an
443 addition to perl's regression tests to properly exercise your patch.
444 Your testsuite additions should generally follow these guidelines
445 (courtesy of Gurusamy Sarathy <gsar@activestate.com>):
447 Know what you're testing. Read the docs, and the source.
448 Tend to fail, not succeed.
449 Interpret results strictly.
450 Use unrelated features (this will flush out bizarre interactions).
451 Use non-standard idioms (otherwise you are not testing TIMTOWTDI).
452 Avoid using hardcoded test numbers whenever possible (the
453 EXPECTED/GOT found in t/op/tie.t is much more maintainable,
454 and gives better failure reports).
455 Give meaningful error messages when a test fails.
456 Avoid using qx// and system() unless you are testing for them. If you
457 do use them, make sure that you cover _all_ perl platforms.
458 Unlink any temporary files you create.
459 Promote unforeseen warnings to errors with $SIG{__WARN__}.
460 Be sure to use the libraries and modules shipped with the version
461 being tested, not those that were already installed.
462 Add comments to the code explaining what you are testing for.
463 Make updating the '1..42' string unnecessary. Or make sure that
465 Test _all_ behaviors of a given operator, library, or function:
466 - All optional arguments
467 - Return values in various contexts (boolean, scalar, list, lvalue)
468 - Use both global and lexical variables
469 - Don't forget the exceptional, pathological cases.
473 =head1 ACCEPTING A PATCH
475 If you have received a patch file generated using the above section,
476 you should try out the patch.
478 First we need to create a temporary new branch for these changes and
481 % git checkout -b experimental
483 Patches that were formatted by C<git format-patch> are applied with
486 % git am 0001-Rename-Leon-Brocard-to-Orange-Brocard.patch
487 Applying Rename Leon Brocard to Orange Brocard
489 If just a raw diff is provided, it is also possible use this two-step
492 % git apply bugfix.diff
493 % git commit -a -m "Some fixing" --author="That Guy <that.guy@internets.com>"
495 Now we can inspect the change:
498 commit b1b3dab48344cff6de4087efca3dbd63548ab5e2
499 Author: Leon Brocard <acme@astray.com>
500 Date: Fri Dec 19 17:02:59 2008 +0000
502 Rename Leon Brocard to Orange Brocard
504 diff --git a/AUTHORS b/AUTHORS
505 index 293dd70..722c93e 100644
508 @@ -541,7 +541,7 @@ Lars Hecking <lhecking@nmrc.ucc.ie>
509 Laszlo Molnar <laszlo.molnar@eth.ericsson.se>
510 Leif Huhn <leif@hale.dkstat.com>
511 Len Johnson <lenjay@ibm.net>
512 -Leon Brocard <acme@astray.com>
513 +Orange Brocard <acme@astray.com>
514 Les Peters <lpeters@aol.net>
515 Lesley Binks <lesley.binks@gmail.com>
516 Lincoln D. Stein <lstein@cshl.org>
518 If you are a committer to Perl and you think the patch is good, you can
519 then merge it into blead then push it out to the main repository:
522 % git merge experimental
525 If you want to delete your temporary branch, you may do so with:
528 % git branch -d experimental
529 error: The branch 'experimental' is not an ancestor of your current HEAD.
530 If you are sure you want to delete it, run 'git branch -D experimental'.
531 % git branch -D experimental
532 Deleted branch experimental.
534 =head1 CLEANING A WORKING DIRECTORY
536 The command C<git clean> can with varying arguments be used as a
537 replacement for C<make clean>.
539 To reset your working directory to a pristine condition you can do:
543 However, be aware this will delete ALL untracked content. You can use
547 to remove all ignored untracked files, such as build and test
548 byproduct, but leave any manually created files alone.
550 If you only want to cancel some uncommitted edits, you can use C<git
551 checkout> and give it a list of files to be reverted, or C<git checkout
552 -f> to revert them all.
554 If you want to cancel one or several commits, you can use C<git reset>.
558 C<git> provides a built-in way to determine, with a binary search in
559 the history, which commit should be blamed for introducing a given bug.
561 Suppose that we have a script F<~/testcase.pl> that exits with C<0>
562 when some behaviour is correct, and with C<1> when it's faulty. We need
563 an helper script that automates building C<perl> and running the
569 # If you can use ccache, add -Dcc=ccache\ gcc -Dld=gcc to the Configure line
570 sh Configure -des -Dusedevel -Doptimize="-g"
571 test -f config.sh || exit 125
572 # Correct makefile for newer GNU gcc
573 perl -ni -we 'print unless /<(?:built-in|command)/' makefile x2p/makefile
574 # if you just need miniperl, replace test_prep with miniperl
576 [ -x ./perl ] || exit 125
577 ./perl -Ilib ~/testcase.pl
579 [ $ret -gt 127 ] && ret=127
583 This script may return C<125> to indicate that the corresponding commit
584 should be skipped. Otherwise, it returns the status of
587 We first enter in bisect mode with:
591 For example, if the bug is present on C<HEAD> but wasn't in 5.10.0,
592 C<git> will learn about this when you enter:
595 % git bisect good perl-5.10.0
596 Bisecting: 853 revisions left to test after this
598 This results in checking out the median commit between C<HEAD> and
599 C<perl-5.10.0>. We can then run the bisecting process with:
601 % git bisect run ~/run
603 When the first bad commit is isolated, C<git bisect> will tell you so:
605 ca4cfd28534303b82a216cfe83a1c80cbc3b9dc5 is first bad commit
606 commit ca4cfd28534303b82a216cfe83a1c80cbc3b9dc5
607 Author: Dave Mitchell <davem@fdisolutions.com>
608 Date: Sat Feb 9 14:56:23 2008 +0000
610 [perl #49472] Attributes + Unknown Error
615 You can peek into the bisecting process with C<git bisect log> and
616 C<git bisect visualize>. C<git bisect reset> will get you out of bisect
619 Please note that the first C<good> state must be an ancestor of the
620 first C<bad> state. If you want to search for the commit that I<solved>
621 some bug, you have to negate your test case (i.e. exit with C<1> if OK
622 and C<0> if not) and still mark the lower bound as C<good> and the
623 upper as C<bad>. The "first bad commit" has then to be understood as
624 the "first commit where the bug is solved".
626 C<git help bisect> has much more information on how you can tweak your
629 =head1 SUBMITTING A PATCH VIA GITHUB
631 GitHub is a website that makes it easy to fork and publish projects
632 with Git. First you should set up a GitHub account and log in.
634 Perl's git repository is mirrored on GitHub at this page:
636 http://github.com/github/perl/tree/blead
638 Visit the page and click the "fork" button. This clones the Perl git
639 repository for you and provides you with "Your Clone URL" from which
642 % git clone git@github.com:USERNAME/perl.git perl-github
644 We shall make the same patch as above, creating a new branch:
647 % git remote add upstream git://github.com/github/perl.git
648 % git pull upstream blead
649 % git checkout -b orange
650 % perl -pi -e 's{Leon Brocard}{Orange Brocard}' AUTHORS
651 % git commit -a -m 'Rename Leon Brocard to Orange Brocard'
652 % git push origin orange
654 The orange branch has been pushed to GitHub, so you should now send an
655 email to perl5-porters@perl.org with a description of your changes and
656 the following information:
658 http://github.com/USERNAME/perl/tree/orange
659 git@github.com:USERNAME/perl.git branch orange
661 =head1 MERGING FROM A BRANCH VIA GITHUB
663 If someone has provided a branch via GitHub and you are a committer,
664 you should use the following in your perl-ssh directory:
666 % git remote add dandv git://github.com/dandv/perl.git
669 Now you can see the differences between the branch and blead:
671 % git diff dandv/blead
673 And you can see the commits:
675 % git log dandv/blead
677 If you approve of a specific commit, you can cherry pick it:
679 % git cherry-pick 3adac458cb1c1d41af47fc66e67b49c8dec2323f
681 Or you could just merge the whole branch if you like it all:
683 % git merge dandv/blead
685 And then push back to the repository:
690 =head1 TOPIC BRANCHES AND REWRITING HISTORY
692 Individual committers should create topic branches under
693 B<yourname>/B<some_descriptive_name>. Other committers should check
694 with a topic branch's creator before making any change to it.
696 If you are not the creator of B<yourname>/B<some_descriptive_name>, you
697 might sometimes find that the original author has edited the branch's
698 history. There are lots of good reasons for this. Sometimes, an author
699 might simply be rebasing the branch onto a newer source point.
700 Sometimes, an author might have found an error in an early commit which
701 they wanted to fix before merging the branch to blead.
703 Currently the master repository is configured to forbid
704 non-fast-forward merges. This means that the branches within can not
705 be rebased and pushed as a single step.
707 The only way you will ever be allowed to rebase or modify the history
708 of a pushed branch is to delete it and push it as a new branch under
709 the same name. Please think carefully about doing this. It may be
710 better to sequentially rename your branches so that it is easier for
711 others working with you to cherry-pick their local changes onto the new
712 version. (XXX: needs explanation).
714 If you want to rebase a personal topic branch, you will have to delete
715 your existing topic branch and push as a new version of it. You can do
716 this via the following formula (see the explanation about C<refspec>'s
717 in the git push documentation for details) after you have rebased your
721 $ git checkout $user/$topic
723 $ git rebase origin/blead
725 # then "delete-and-push"
726 $ git push origin :$user/$topic
727 $ git push origin $user/$topic
729 B<NOTE:> it is forbidden at the repository level to delete any of the
730 "primary" branches. That is any branch matching
731 C<m!^(blead|maint|perl)!>. Any attempt to do so will result in git
732 producing an error like this:
734 $ git push origin :blead
735 *** It is forbidden to delete blead/maint branches in this repository
736 error: hooks/update exited with error code 1
737 error: hook declined to update refs/heads/blead
738 To ssh://perl5.git.perl.org/perl
739 ! [remote rejected] blead (hook declined)
740 error: failed to push some refs to 'ssh://perl5.git.perl.org/perl'
742 As a matter of policy we do B<not> edit the history of the blead and
743 maint-* branches. If a typo (or worse) sneaks into a commit to blead or
744 maint-*, we'll fix it in another commit. The only types of updates
745 allowed on these branches are "fast-forward's", where all history is
748 Annotated tags in the canonical perl.git repository will never be
749 deleted or modified. Think long and hard about whether you want to push
750 a local tag to perl.git before doing so. (Pushing unannotated tags is
753 =head1 COMMITTING TO MAINTENANCE VERSIONS
755 Maintenance versions should only be altered to add critical bug fixes.
757 To commit to a maintenance version of perl, you need to create a local
760 % git checkout --track -b maint-5.005 origin/maint-5.005
762 This creates a local branch named C<maint-5.005>, which tracks the
763 remote branch C<origin/maint-5.005>. Then you can pull, commit, merge
766 You can also cherry-pick commits from blead and another branch, by
767 using the C<git cherry-pick> command. It is recommended to use the
768 B<-x> option to C<git cherry-pick> in order to record the SHA1 of the
769 original commit in the new commit message.
773 The perl history contains one mistake which was not caught in the
774 conversion -- a merge was recorded in the history between blead and
775 maint-5.10 where no merge actually occurred. Due to the nature of git,
776 this is now impossible to fix in the public repository. You can remove
777 this mis-merge locally by adding the following line to your
778 C<.git/info/grafts> file:
780 296f12bbbbaa06de9be9d09d3dcf8f4528898a49 434946e0cb7a32589ed92d18008aaa1d88515930
782 It is particularly important to have this graft line if any bisecting
783 is done in the area of the "merge" in question.
787 The git documentation, accessible via C<git help command>.