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/gitroot/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/gitroot/perl.git
77 NOTE: there are symlinks set up so that the /gitroot is optional and
78 since SSH is the default protocol you can actually shorten the "url" to
79 C<perl5.git.perl.org:/perl.git>.
81 You can also set up your user name and e-mail address. For example
83 % git config user.name "Leon Brocard"
84 % git config user.email acme@astray.com
86 It is also possible to keep C<origin> as a git remote, and add a new
87 remote for ssh access:
89 % git remote add camel perl5.git.perl.org:/perl.git
91 This allows you to update your local repository by pulling from
92 C<origin>, which is faster and doesn't require you to authenticate, and
93 to push your changes back with the C<camel> remote:
98 The C<fetch> command just updates the C<camel> refs, as the objects
99 themselves should have been fetched when pulling from C<origin>.
101 The committers have access to 2 servers that serve perl5.git.perl.org.
102 One is camel.booking.com, which is the 'master' repository. The
103 perl5.git.perl.org IP address also lives on this machine. The second
104 one is dromedary.booking.com, which can be used for general testing and
105 development. Dromedary syncs the git tree from camel every few minutes,
106 you should not push there. Both machines also have a full CPAN mirror.
107 To share files with the general public, dromedary serves your
108 ~/public_html/ as http://users.perl5.git.perl.org/~yourlogin/
110 =head1 OVERVIEW OF THE REPOSITORY
112 Once you have changed into the repository directory, you can inspect
115 After a clone the repository will contain a single local branch, which
116 will be the current branch as well, as indicated by the asterisk.
121 Using the -a switch to C<branch> will also show the remote tracking
122 branches in the repository:
130 The branches that begin with "origin" correspond to the "git remote"
131 that you cloned from (which is named "origin"). Each branch on the
132 remote will be exactly tracked by theses branches. You should NEVER do
133 work on these remote tracking branches. You only ever do work in a
134 local branch. Local branches can be configured to automerge (on pull)
135 from a designated remote tracking branch. This is the case with the
136 default branch C<blead> which will be configured to merge from the
137 remote tracking branch C<origin/blead>.
139 You can see recent commits:
143 And pull new changes from the repository, and update your local
144 repository (must be clean first)
148 Assuming we are on the branch C<blead> immediately after a pull, this
149 command would be more or less equivalent to:
152 % git merge origin/blead
154 In fact if you want to update your local repository without touching
155 your working directory you do:
159 And if you want to update your remote-tracking branches for all defined
160 remotes simultaneously you can do
164 Neither of these last two commands will update your working directory,
165 however both will update the remote-tracking branches in your
168 To switch to another branch:
170 % git checkout origin/maint-5.8-dor
172 To make a local branch of a remote branch:
174 % git checkout -b maint-5.10 origin/maint-5.10
176 To switch back to blead:
180 =head2 FINDING OUT YOUR STATUS
182 The most common git command you will use will probably be
186 This command will produce as output a description of the current state
187 of the repository, including modified files and unignored untracked
188 files, and in addition it will show things like what files have been
189 staged for the next commit, and usually some useful information about
190 how to change things. For instance the following:
194 # Your branch is ahead of 'origin/blead' by 1 commit.
196 # Changes to be committed:
197 # (use "git reset HEAD <file>..." to unstage)
199 # modified: pod/perlrepository.pod
201 # Changed but not updated:
202 # (use "git add <file>..." to update what will be committed)
204 # modified: pod/perlrepository.pod
207 # (use "git add <file>..." to include in what will be committed)
209 # deliberate.untracked
211 This shows that there were changes to this document staged for commit,
212 and that there were further changes in the working directory not yet
213 staged. It also shows that there was an untracked file in the working
214 directory, and as you can see shows how to change all of this. It also
215 shows that there is one commit on the working branch C<blead> which has
216 not been pushed to the C<origin> remote yet. B<NOTE>: that this output
217 is also what you see as a template if you do not provide a message to
220 Assuming we commit all the mentioned changes above:
222 % git commit -a -m'explain git status and stuff about remotes'
223 Created commit daf8e63: explain git status and stuff about remotes
224 1 files changed, 83 insertions(+), 3 deletions(-)
226 We can re-run git status and see something like this:
230 # Your branch is ahead of 'origin/blead' by 2 commits.
233 # (use "git add <file>..." to include in what will be committed)
235 # deliberate.untracked
236 nothing added to commit but untracked files present (use "git add" to track)
239 When in doubt, before you do anything else, check your status and read
240 it carefully, many questions are answered directly by the git status
243 =head1 SUBMITTING A PATCH
245 If you have a patch in mind for Perl, you should first get a copy of
248 % git clone git://perl5.git.perl.org/perl.git perl-git
250 Then change into the directory:
254 Alternatively, if you already have a Perl repository, you should ensure
255 that you're on the I<blead> branch, and your repository is up to date:
260 It's preferable to patch against the latest blead version, since this
261 is where new development occurs for all changes other than critical bug
262 fixes. Critical bug fix patches should be made against the relevant
263 maint branches, or should be submitted with a note indicating all the
264 branches where the fix should be applied.
266 Now that we have everything up to date, we need to create a temporary
267 new branch for these changes and switch into it:
269 % git checkout -b orange
271 which is the short form of
274 % git checkout orange
276 Then make your changes. For example, if Leon Brocard changes his name
277 to Orange Brocard, we should change his name in the AUTHORS file:
279 % perl -pi -e 's{Leon Brocard}{Orange Brocard}' AUTHORS
281 You can see what files are changed:
285 # Changes to be committed:
286 # (use "git reset HEAD <file>..." to unstage)
291 And you can see the changes:
294 diff --git a/AUTHORS b/AUTHORS
295 index 293dd70..722c93e 100644
298 @@ -541,7 +541,7 @@ Lars Hecking <lhecking@nmrc.ucc.ie>
299 Laszlo Molnar <laszlo.molnar@eth.ericsson.se>
300 Leif Huhn <leif@hale.dkstat.com>
301 Len Johnson <lenjay@ibm.net>
302 -Leon Brocard <acme@astray.com>
303 +Orange Brocard <acme@astray.com>
304 Les Peters <lpeters@aol.net>
305 Lesley Binks <lesley.binks@gmail.com>
306 Lincoln D. Stein <lstein@cshl.org>
308 Now commit your change locally:
310 % git commit -a -m 'Rename Leon Brocard to Orange Brocard'
311 Created commit 6196c1d: Rename Leon Brocard to Orange Brocard
312 1 files changed, 1 insertions(+), 1 deletions(-)
314 You can examine your last commit with:
318 and if you are not happy with either the description or the patch
319 itself you can fix it up by editing the files once more and then issue:
321 % git commit -a --amend
323 Now you should create a patch file for all your local changes:
325 % git format-patch origin
326 0001-Rename-Leon-Brocard-to-Orange-Brocard.patch
328 You should now send an email to perl5-porters@perl.org with a
329 description of your changes, and include this patch file as an
330 attachment. (See the next section for how to configure and use
331 git to send these emails for you.)
333 If you want to delete your temporary branch, you may do so with:
336 % git branch -d orange
337 error: The branch 'orange' is not an ancestor of your current HEAD.
338 If you are sure you want to delete it, run 'git branch -D orange'.
339 % git branch -D orange
340 Deleted branch orange.
342 =head2 Using git to send patch emails
344 In your ~/git/perl repository, set the destination email to the perl5-porters
347 $ git config sendemail.to perl5-porters@perl.org
349 Then you can use git directly to send your patch emails:
351 $ git send-email 0001-Rename-Leon-Brocard-to-Orange-Brocard.patch
353 You may need to set some configuration variables for your particular email
354 service provider. For example, to set your global git config to send email via
357 $ git config --global sendemail.smtpserver smtp.gmail.com
358 $ git config --global sendemail.smtpssl 1
359 $ git config --global sendemail.smtpuser YOURUSERNAME@gmail.com
361 With this configuration, you will be prompted for your gmail password when you
362 run 'git send-email'. You can also configure C<sendemail.smtppass> with your
363 password if you don't care about having your password in the .gitconfig file.
365 =head2 A note on derived files
367 Be aware that many files in the distribution are derivative--avoid
368 patching them, because git won't see the changes to them, and the build
369 process will overwrite them. Patch the originals instead. Most
370 utilities (like perldoc) are in this category, i.e. patch
371 utils/perldoc.PL rather than utils/perldoc. Similarly, don't create
372 patches for files under $src_root/ext from their copies found in
373 $install_root/lib. If you are unsure about the proper location of a
374 file that may have gotten copied while building the source
375 distribution, consult the C<MANIFEST>.
379 What should we recommend about binary files now? Do we need anything?
381 =head2 Getting your patch accepted
383 The first thing you should include with your patch is a description of
384 the problem that the patch corrects. If it is a code patch (rather
385 than a documentation patch) you should also include a small test case
386 that illustrates the bug (a patch to an existing test file is
389 If you are submitting a code patch there are several other things that
394 =item Comments, Comments, Comments
396 Be sure to adequately comment your code. While commenting every line
397 is unnecessary, anything that takes advantage of side effects of
398 operators, that creates changes that will be felt outside of the
399 function being patched, or that others may find confusing should be
400 documented. If you are going to err, it is better to err on the side
401 of adding too many comments than too few.
405 In general, please follow the particular style of the code you are
408 In particular, follow these general guidelines for patching Perl
411 8-wide tabs (no exceptions!)
412 4-wide indents for code, 2-wide indents for nested CPP #defines
413 try hard not to exceed 79-columns
415 uncuddled elses and "K&R" style for indenting control constructs
416 no C++ style (//) comments
417 mark places that need to be revisited with XXX (and revisit often!)
418 opening brace lines up with "if" when conditional spans multiple
419 lines; should be at end-of-line otherwise
420 in function definitions, name starts in column 0 (return value is on
422 single space after keywords that are followed by parens, no space
423 between function name and following paren
424 avoid assignments in conditionals, but if they're unavoidable, use
425 extra paren, e.g. "if (a && (b = c)) ..."
426 "return foo;" rather than "return(foo);"
427 "if (!foo) ..." rather than "if (foo == FALSE) ..." etc.
431 When submitting a patch you should make every effort to also include an
432 addition to perl's regression tests to properly exercise your patch.
433 Your testsuite additions should generally follow these guidelines
434 (courtesy of Gurusamy Sarathy <gsar@activestate.com>):
436 Know what you're testing. Read the docs, and the source.
437 Tend to fail, not succeed.
438 Interpret results strictly.
439 Use unrelated features (this will flush out bizarre interactions).
440 Use non-standard idioms (otherwise you are not testing TIMTOWTDI).
441 Avoid using hardcoded test numbers whenever possible (the
442 EXPECTED/GOT found in t/op/tie.t is much more maintainable,
443 and gives better failure reports).
444 Give meaningful error messages when a test fails.
445 Avoid using qx// and system() unless you are testing for them. If you
446 do use them, make sure that you cover _all_ perl platforms.
447 Unlink any temporary files you create.
448 Promote unforeseen warnings to errors with $SIG{__WARN__}.
449 Be sure to use the libraries and modules shipped with the version
450 being tested, not those that were already installed.
451 Add comments to the code explaining what you are testing for.
452 Make updating the '1..42' string unnecessary. Or make sure that
454 Test _all_ behaviors of a given operator, library, or function:
455 - All optional arguments
456 - Return values in various contexts (boolean, scalar, list, lvalue)
457 - Use both global and lexical variables
458 - Don't forget the exceptional, pathological cases.
462 =head1 ACCEPTING A PATCH
464 If you have received a patch file generated using the above section,
465 you should try out the patch.
467 First we need to create a temporary new branch for these changes and
470 % git checkout -b experimental
472 Patches that were formatted by C<git format-patch> are applied with
475 % git am 0001-Rename-Leon-Brocard-to-Orange-Brocard.patch
476 Applying Rename Leon Brocard to Orange Brocard
478 If just a raw diff is provided, it is also possible use this two-step
481 % git apply bugfix.diff
482 % git commit -a -m "Some fixing" --author="That Guy <that.guy@internets.com>"
484 Now we can inspect the change:
487 commit b1b3dab48344cff6de4087efca3dbd63548ab5e2
488 Author: Leon Brocard <acme@astray.com>
489 Date: Fri Dec 19 17:02:59 2008 +0000
491 Rename Leon Brocard to Orange Brocard
493 diff --git a/AUTHORS b/AUTHORS
494 index 293dd70..722c93e 100644
497 @@ -541,7 +541,7 @@ Lars Hecking <lhecking@nmrc.ucc.ie>
498 Laszlo Molnar <laszlo.molnar@eth.ericsson.se>
499 Leif Huhn <leif@hale.dkstat.com>
500 Len Johnson <lenjay@ibm.net>
501 -Leon Brocard <acme@astray.com>
502 +Orange Brocard <acme@astray.com>
503 Les Peters <lpeters@aol.net>
504 Lesley Binks <lesley.binks@gmail.com>
505 Lincoln D. Stein <lstein@cshl.org>
507 If you are a committer to Perl and you think the patch is good, you can
508 then merge it into blead then push it out to the main repository:
511 % git merge experimental
514 If you want to delete your temporary branch, you may do so with:
517 % git branch -d experimental
518 error: The branch 'experimental' is not an ancestor of your current HEAD.
519 If you are sure you want to delete it, run 'git branch -D experimental'.
520 % git branch -D experimental
521 Deleted branch experimental.
523 =head1 CLEANING A WORKING DIRECTORY
525 The command C<git clean> can with varying arguments be used as a
526 replacement for C<make clean>.
528 To reset your working directory to a pristine condition you can do:
532 However, be aware this will delete ALL untracked content. You can use
536 to remove all ignored untracked files, such as build and test
537 byproduct, but leave any manually created files alone.
539 If you only want to cancel some uncommitted edits, you can use C<git
540 checkout> and give it a list of files to be reverted, or C<git checkout
541 -f> to revert them all.
543 If you want to cancel one or several commits, you can use C<git reset>.
547 C<git> provides a built-in way to determine, with a binary search in
548 the history, which commit should be blamed for introducing a given bug.
550 Suppose that we have a script F<~/testcase.pl> that exits with C<0>
551 when some behaviour is correct, and with C<1> when it's faulty. We need
552 an helper script that automates building C<perl> and running the
558 # If you can use ccache, add -Dcc=ccache\ gcc -Dld=gcc to the Configure line
559 sh Configure -des -Dusedevel -Doptimize="-g"
560 test -f config.sh || exit 125
561 # Correct makefile for newer GNU gcc
562 perl -ni -we 'print unless /<(?:built-in|command)/' makefile x2p/makefile
563 # if you just need miniperl, replace test_prep with miniperl
565 [ -x ./perl ] || exit 125
566 ./perl -Ilib ~/testcase.pl
568 [ $ret -gt 127 ] && ret=127
572 This script may return C<125> to indicate that the corresponding commit
573 should be skipped. Otherwise, it returns the status of
576 We first enter in bisect mode with:
580 For example, if the bug is present on C<HEAD> but wasn't in 5.10.0,
581 C<git> will learn about this when you enter:
584 % git bisect good perl-5.10.0
585 Bisecting: 853 revisions left to test after this
587 This results in checking out the median commit between C<HEAD> and
588 C<perl-5.10.0>. We can then run the bisecting process with:
590 % git bisect run ~/run
592 When the first bad commit is isolated, C<git bisect> will tell you so:
594 ca4cfd28534303b82a216cfe83a1c80cbc3b9dc5 is first bad commit
595 commit ca4cfd28534303b82a216cfe83a1c80cbc3b9dc5
596 Author: Dave Mitchell <davem@fdisolutions.com>
597 Date: Sat Feb 9 14:56:23 2008 +0000
599 [perl #49472] Attributes + Unknown Error
604 You can peek into the bisecting process with C<git bisect log> and
605 C<git bisect visualize>. C<git bisect reset> will get you out of bisect
608 Please note that the first C<good> state must be an ancestor of the
609 first C<bad> state. If you want to search for the commit that I<solved>
610 some bug, you have to negate your test case (i.e. exit with C<1> if OK
611 and C<0> if not) and still mark the lower bound as C<good> and the
612 upper as C<bad>. The "first bad commit" has then to be understood as
613 the "first commit where the bug is solved".
615 C<git help bisect> has much more information on how you can tweak your
618 =head1 SUBMITTING A PATCH VIA GITHUB
620 GitHub is a website that makes it easy to fork and publish projects
621 with Git. First you should set up a GitHub account and log in.
623 Perl's git repository is mirrored on GitHub at this page:
625 http://github.com/github/perl/tree/blead
627 Visit the page and click the "fork" button. This clones the Perl git
628 repository for you and provides you with "Your Clone URL" from which
631 % git clone git@github.com:USERNAME/perl.git perl-github
633 We shall make the same patch as above, creating a new branch:
636 % git remote add upstream git://github.com/github/perl.git
637 % git pull upstream blead
638 % git checkout -b orange
639 % perl -pi -e 's{Leon Brocard}{Orange Brocard}' AUTHORS
640 % git commit -a -m 'Rename Leon Brocard to Orange Brocard'
641 % git push origin orange
643 The orange branch has been pushed to GitHub, so you should now send an
644 email to perl5-porters@perl.org with a description of your changes and
645 the following information:
647 http://github.com/USERNAME/perl/tree/orange
648 git@github.com:USERNAME/perl.git branch orange
650 =head1 MERGING FROM A BRANCH VIA GITHUB
652 If someone has provided a branch via GitHub and you are a committer,
653 you should use the following in your perl-ssh directory:
655 % git remote add dandv git://github.com/dandv/perl.git
658 Now you can see the differences between the branch and blead:
660 % git diff dandv/blead
662 And you can see the commits:
664 % git log dandv/blead
666 If you approve of a specific commit, you can cherry pick it:
668 % git cherry-pick 3adac458cb1c1d41af47fc66e67b49c8dec2323f
670 Or you could just merge the whole branch if you like it all:
672 % git merge dandv/blead
674 And then push back to the repository:
679 =head1 TOPIC BRANCHES AND REWRITING HISTORY
681 Individual committers should create topic branches under
682 B<yourname>/B<some_descriptive_name>. Other committers should check with
683 a topic branch's creator before making any change to it.
685 If you are not the creator of B<yourname>/B<some_descriptive_name>, you
686 might sometimes find that the original author has edited the branch's
687 history. There are lots of good reasons for this. Sometimes, an author
688 might simply be rebasing the branch onto a newer source point. Sometimes,
689 an author might have found an error in an early commit which they wanted
690 to fix before merging the branch to blead.
692 Currently the master repository is configured to forbid non-fast-forward
693 merges. This means that the branches within can not be rebased and
694 pushed as a single step.
696 The only way you will ever be allowed to rebase or modify the history of
697 a pushed branch is to delete it and push it as a new branch under the same
698 name. Please think carefully about doing this. It may be better to sequentially
699 rename your branches so that it is easier for others working with you to
700 cherry-pick their local changes onto the new version. (XXX: needs
703 If you want to rebase a personal topic branch, you will have to delete
704 your existing topic branch and push as a new version of it. You can do
705 this via the following formula (see the explanation about C<refspec>'s
706 in the git push documentation for details) after you have rebased your
710 $ git checkout $user/$topic
712 $ git rebase origin/blead
714 # then "delete-and-push"
715 $ git push origin :$user/$topic
716 $ git push origin $user/$topic
718 B<NOTE:> it is forbidden at the repository level to delete any of the
719 "primary" branches. That is any branch matching C<m!^(blead|maint|perl)!>.
720 Any attempt to do so will result in git producing an error like this:
722 $ git push origin :blead
723 *** It is forbidden to delete blead/maint branches in this repository
724 error: hooks/update exited with error code 1
725 error: hook declined to update refs/heads/blead
726 To ssh://camel.booking.com/perl
727 ! [remote rejected] blead (hook declined)
728 error: failed to push some refs to 'ssh://camel.booking.com/perl'
730 As a matter of policy we do B<not> edit the history of the blead and maint-*
731 branches. If a typo (or worse) sneaks into a commit to blead or maint-*, we'll
732 fix it in another commit. The only types of updates allowed on these
733 branches are "fast-forward's", where all history is preserved.
735 Annotated tags in the canonical perl.git repository will never be deleted
736 or modified. Think long and hard about whether you want to push a local
737 tag to perl.git before doing so. (Pushing unannotated tags is
740 =head1 COMMITTING TO MAINTENANCE VERSIONS
742 Maintenance versions should only be altered to add critical bug fixes.
744 To commit to a maintenance version of perl, you need to create a local
747 % git checkout --track -b maint-5.005 origin/maint-5.005
749 This creates a local branch named C<maint-5.005>, which tracks the
750 remote branch C<origin/maint-5.005>. Then you can pull, commit, merge
753 You can also cherry-pick commits from blead and another branch, by
754 using the C<git cherry-pick> command. It is recommended to use the
755 B<-x> option to C<git cherry-pick> in order to record the SHA1 of the
756 original commit in the new commit message.
760 The perl history contains one mistake which was not caught in the
761 conversion -- a merge was recorded in the history between blead and
762 maint-5.10 where no merge actually occurred. Due to the nature of
763 git, this is now impossible to fix in the public repository. You can
764 remove this mis-merge locally by adding the following line to your
765 C<.git/info/grafts> file:
767 296f12bbbbaa06de9be9d09d3dcf8f4528898a49 434946e0cb7a32589ed92d18008aaa1d88515930
769 It is particularly important to have this graft line if any bisecting
770 is done in the area of the "merge" in question.
774 The git documentation, accessible via C<git help command>.