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 disk
20 space (including the repository). A build of bleadperl takes up about 200MB
21 (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. One is
102 camel.booking.com, which is the 'master' repository. The perl5.git.perl.org IP
103 address also lives on this machine. The second one is dromedary.booking.com,
104 which can be used for general testing and development. Dromedary syncs the git
105 tree from camel every few minutes, you should not push there. Both machines
106 also have a full CPAN mirror. To share files with the general public, dromedary
107 serves your ~/public_html/ as http://users.perl5.git.perl.org/~yourlogin/
109 =head1 OVERVIEW OF THE REPOSITORY
111 Once you have changed into the repository directory, you can inspect
114 After a clone the repository will contain a single local branch, which
115 will be the current branch as well, as indicated by the asterisk.
120 Using the -a switch to C<branch> will also show the remote tracking
121 branches in the repository:
129 The branches that begin with "origin" correspond to the "git remote"
130 that you cloned from (which is named "origin"). Each branch on the
131 remote will be exactly tracked by theses branches. You should NEVER do
132 work on these remote tracking branches. You only ever do work in a
133 local branch. Local branches can be configured to automerge (on pull)
134 from a designated remote tracking branch. This is the case with the
135 default branch C<blead> which will be configured to merge from the
136 remote tracking branch C<origin/blead>.
138 You can see recent commits:
142 And pull new changes from the repository, and update your local
143 repository (must be clean first)
147 Assuming we are on the branch C<blead> immediately after a pull, this
148 command would be more or less equivalent to:
151 % git merge origin/blead
153 In fact if you want to update your local repository without touching
154 your working directory you do:
158 And if you want to update your remote-tracking branches for all defined
159 remotes simultaneously you can do
163 Neither of these last two commands will update your working directory,
164 however both will update the remote-tracking branches in your
167 To switch to another branch:
169 % git checkout origin/maint-5.8-dor
171 To make a local branch of a remote branch:
173 % git checkout -b maint-5.10 origin/maint-5.10
175 To switch back to blead:
179 =head2 FINDING OUT YOUR STATUS
181 The most common git command you will use will probably be
185 This command will produce as output a description of the current state
186 of the repository, including modified files and unignored untracked
187 files, and in addition it will show things like what files have been
188 staged for the next commit, and usually some useful information about
189 how to change things. For instance the following:
193 # Your branch is ahead of 'origin/blead' by 1 commit.
195 # Changes to be committed:
196 # (use "git reset HEAD <file>..." to unstage)
198 # modified: pod/perlrepository.pod
200 # Changed but not updated:
201 # (use "git add <file>..." to update what will be committed)
203 # modified: pod/perlrepository.pod
206 # (use "git add <file>..." to include in what will be committed)
208 # deliberate.untracked
210 This shows that there were changes to this document staged for commit,
211 and that there were further changes in the working directory not yet
212 staged. It also shows that there was an untracked file in the working
213 directory, and as you can see shows how to change all of this. It also
214 shows that there is one commit on the working branch C<blead> which has
215 not been pushed to the C<origin> remote yet. B<NOTE>: that this output
216 is also what you see as a template if you do not provide a message to
219 Assuming we commit all the mentioned changes above:
221 % git commit -a -m'explain git status and stuff about remotes'
222 Created commit daf8e63: explain git status and stuff about remotes
223 1 files changed, 83 insertions(+), 3 deletions(-)
225 We can re-run git status and see something like this:
229 # Your branch is ahead of 'origin/blead' by 2 commits.
232 # (use "git add <file>..." to include in what will be committed)
234 # deliberate.untracked
235 nothing added to commit but untracked files present (use "git add" to track)
238 When in doubt, before you do anything else, check your status and read
239 it carefully, many questions are answered directly by the git status
242 =head1 SUBMITTING A PATCH
244 If you have a patch in mind for Perl, you should first get a copy of
247 % git clone git://perl5.git.perl.org/perl.git perl-git
249 Then change into the directory:
253 Alternatively, if you already have a Perl repository, you should ensure
254 that you're on the I<blead> branch, and your repository is up to date:
259 It's preferable to patch against the latest blead version, since
260 this is where new development occurs for all changes other than critical
261 bug fixes. Critical bug fix patches should be made against the relevant
262 maint branches, or should be submitted with a note indicating all the
263 branches where the fix should be applied.
265 Now that we have everything up to date, we need to create a temporary
266 new branch for these changes and switch into it:
268 % git checkout -b orange
270 which is the short form of
273 % git checkout orange
275 Then make your changes. For example, if Leon Brocard changes his name
276 to Orange Brocard, we should change his name in the AUTHORS file:
278 % perl -pi -e 's{Leon Brocard}{Orange Brocard}' AUTHORS
280 You can see what files are changed:
284 # Changes to be committed:
285 # (use "git reset HEAD <file>..." to unstage)
290 And you can see the changes:
293 diff --git a/AUTHORS b/AUTHORS
294 index 293dd70..722c93e 100644
297 @@ -541,7 +541,7 @@ Lars Hecking <lhecking@nmrc.ucc.ie>
298 Laszlo Molnar <laszlo.molnar@eth.ericsson.se>
299 Leif Huhn <leif@hale.dkstat.com>
300 Len Johnson <lenjay@ibm.net>
301 -Leon Brocard <acme@astray.com>
302 +Orange Brocard <acme@astray.com>
303 Les Peters <lpeters@aol.net>
304 Lesley Binks <lesley.binks@gmail.com>
305 Lincoln D. Stein <lstein@cshl.org>
307 Now commit your change locally:
309 % git commit -a -m 'Rename Leon Brocard to Orange Brocard'
310 Created commit 6196c1d: Rename Leon Brocard to Orange Brocard
311 1 files changed, 1 insertions(+), 1 deletions(-)
313 You can examine your last commit with:
317 and if you are not happy with either the description or the patch
318 itself you can fix it up by editing the files once more and then issue:
320 % git commit -a --amend
322 Now you should create a patch file for all your local changes:
324 % git format-patch origin
325 0001-Rename-Leon-Brocard-to-Orange-Brocard.patch
327 You should now send an email to perl5-porters@perl.org with a
328 description of your changes, and include this patch file as an
331 If you want to delete your temporary branch, you may do so with:
334 % git branch -d orange
335 error: The branch 'orange' is not an ancestor of your current HEAD.
336 If you are sure you want to delete it, run 'git branch -D orange'.
337 % git branch -D orange
338 Deleted branch orange.
340 =head2 A note on derived files
342 Be aware that many files in the distribution are derivative--avoid
343 patching them, because git won't see the changes to them, and the build
344 process will overwrite them. Patch the originals instead. Most
345 utilities (like perldoc) are in this category, i.e. patch
346 utils/perldoc.PL rather than utils/perldoc. Similarly, don't create
347 patches for files under $src_root/ext from their copies found in
348 $install_root/lib. If you are unsure about the proper location of a
349 file that may have gotten copied while building the source
350 distribution, consult the C<MANIFEST>.
352 =head2 A note on binary files
354 Since the patch(1) utility cannot deal with binary files, it's
355 important that you either avoid the use of binary files in your patch,
356 generate the files dynamically, or that you encode any binary files
357 using the F<uupacktool.pl> utility.
359 Assuming you needed to include a gzip-encoded file for a module's test
360 suite, you might do this as follows using the F<uupacktool.pl> utility:
362 $ perl uupacktool.pl -v -p -D lib/Some/Module/t/src/t.gz
363 Writing lib/Some/Module/t/src/t.gz into lib/Some/Module/t/src/t.gz.packed
365 This will replace the C<t.gz> file with an encoded counterpart. During
366 C<make test>, before any tests are run, perl's Makefile will restore
367 all the C<.packed> files mentioned in the MANIFEST to their original
368 name. This means that the test suite does not need to be aware of this
369 packing scheme and will not need to be altered.
371 =head2 Getting your patch accepted
373 The first thing you should include with your patch is a description of
374 the problem that the patch corrects. If it is a code patch (rather
375 than a documentation patch) you should also include a small test case
376 that illustrates the bug (a patch to an existing test file is
379 If you are submitting a code patch there are several other things that
384 =item Comments, Comments, Comments
386 Be sure to adequately comment your code. While commenting every line
387 is unnecessary, anything that takes advantage of side effects of
388 operators, that creates changes that will be felt outside of the
389 function being patched, or that others may find confusing should be
390 documented. If you are going to err, it is better to err on the side
391 of adding too many comments than too few.
395 In general, please follow the particular style of the code you are
398 In particular, follow these general guidelines for patching Perl
401 8-wide tabs (no exceptions!)
402 4-wide indents for code, 2-wide indents for nested CPP #defines
403 try hard not to exceed 79-columns
405 uncuddled elses and "K&R" style for indenting control constructs
406 no C++ style (//) comments
407 mark places that need to be revisited with XXX (and revisit often!)
408 opening brace lines up with "if" when conditional spans multiple
409 lines; should be at end-of-line otherwise
410 in function definitions, name starts in column 0 (return value is on
412 single space after keywords that are followed by parens, no space
413 between function name and following paren
414 avoid assignments in conditionals, but if they're unavoidable, use
415 extra paren, e.g. "if (a && (b = c)) ..."
416 "return foo;" rather than "return(foo);"
417 "if (!foo) ..." rather than "if (foo == FALSE) ..." etc.
421 When submitting a patch you should make every effort to also include an
422 addition to perl's regression tests to properly exercise your patch.
423 Your testsuite additions should generally follow these guidelines
424 (courtesy of Gurusamy Sarathy <gsar@activestate.com>):
426 Know what you're testing. Read the docs, and the source.
427 Tend to fail, not succeed.
428 Interpret results strictly.
429 Use unrelated features (this will flush out bizarre interactions).
430 Use non-standard idioms (otherwise you are not testing TIMTOWTDI).
431 Avoid using hardcoded test numbers whenever possible (the
432 EXPECTED/GOT found in t/op/tie.t is much more maintainable,
433 and gives better failure reports).
434 Give meaningful error messages when a test fails.
435 Avoid using qx// and system() unless you are testing for them. If you
436 do use them, make sure that you cover _all_ perl platforms.
437 Unlink any temporary files you create.
438 Promote unforeseen warnings to errors with $SIG{__WARN__}.
439 Be sure to use the libraries and modules shipped with the version
440 being tested, not those that were already installed.
441 Add comments to the code explaining what you are testing for.
442 Make updating the '1..42' string unnecessary. Or make sure that
444 Test _all_ behaviors of a given operator, library, or function:
445 - All optional arguments
446 - Return values in various contexts (boolean, scalar, list, lvalue)
447 - Use both global and lexical variables
448 - Don't forget the exceptional, pathological cases.
452 =head1 ACCEPTING A PATCH
454 If you have received a patch file generated using the above section,
455 you should try out the patch.
457 First we need to create a temporary new branch for these changes and
460 % git checkout -b experimental
462 Patches that were formatted by C<git format-patch> are applied with
465 % git am 0001-Rename-Leon-Brocard-to-Orange-Brocard.patch
466 Applying Rename Leon Brocard to Orange Brocard
468 If just a raw diff is provided, it is also possible use this two-step
471 % git apply bugfix.diff
472 % git commit -a -m "Some fixing" --author="That Guy <that.guy@internets.com>"
474 Now we can inspect the change:
477 commit b1b3dab48344cff6de4087efca3dbd63548ab5e2
478 Author: Leon Brocard <acme@astray.com>
479 Date: Fri Dec 19 17:02:59 2008 +0000
481 Rename Leon Brocard to Orange Brocard
483 diff --git a/AUTHORS b/AUTHORS
484 index 293dd70..722c93e 100644
487 @@ -541,7 +541,7 @@ Lars Hecking <lhecking@nmrc.ucc.ie>
488 Laszlo Molnar <laszlo.molnar@eth.ericsson.se>
489 Leif Huhn <leif@hale.dkstat.com>
490 Len Johnson <lenjay@ibm.net>
491 -Leon Brocard <acme@astray.com>
492 +Orange Brocard <acme@astray.com>
493 Les Peters <lpeters@aol.net>
494 Lesley Binks <lesley.binks@gmail.com>
495 Lincoln D. Stein <lstein@cshl.org>
497 If you are a committer to Perl and you think the patch is good, you can
498 then merge it into blead then push it out to the main repository:
501 % git merge experimental
504 If you want to delete your temporary branch, you may do so with:
507 % git branch -d experimental
508 error: The branch 'experimental' is not an ancestor of your current HEAD.
509 If you are sure you want to delete it, run 'git branch -D experimental'.
510 % git branch -D experimental
511 Deleted branch experimental.
513 =head1 CLEANING A WORKING DIRECTORY
515 The command C<git clean> can with varying arguments be used as a
516 replacement for C<make clean>.
518 To reset your working directory to a pristine condition you can do:
522 However, be aware this will delete ALL untracked content. You can use
526 to remove all ignored untracked files, such as build and test
527 byproduct, but leave any manually created files alone.
529 If you only want to cancel some uncommitted edits, you can use C<git
530 checkout> and give it a list of files to be reverted, or C<git checkout
531 -f> to revert them all.
533 If you want to cancel one or several commits, you can use C<git reset>.
537 C<git> provides a built-in way to determine, with a binary search in
538 the history, which commit should be blamed for introducing a given bug.
540 Suppose that we have a script F<~/testcase.pl> that exits with C<0>
541 when some behaviour is correct, and with C<1> when it's faulty. We need
542 an helper script that automates building C<perl> and running the
548 # If you can use ccache, add -Dcc=ccache\ gcc -Dld=gcc to the Configure line
549 sh Configure -des -Dusedevel -Doptimize="-g"
550 test -f config.sh || exit 125
551 # Correct makefile for newer GNU gcc
552 perl -ni -we 'print unless /<(?:built-in|command)/' makefile x2p/makefile
553 # if you just need miniperl, replace test_prep with miniperl
555 -x ./perl || exit 125
556 ./perl -Ilib ~/testcase.pl
561 This script may return C<125> to indicate that the corresponding commit
562 should be skipped. Otherwise, it returns the status of
565 We first enter in bisect mode with:
569 For example, if the bug is present on C<HEAD> but wasn't in 5.10.0,
570 C<git> will learn about this when you enter:
573 % git bisect good perl-5.10.0
574 Bisecting: 853 revisions left to test after this
576 This results in checking out the median commit between C<HEAD> and
577 C<perl-5.10.0>. We can then run the bisecting process with:
579 % git bisect run ~/run
581 When the first bad commit is isolated, C<git bisect> will tell you so:
583 ca4cfd28534303b82a216cfe83a1c80cbc3b9dc5 is first bad commit
584 commit ca4cfd28534303b82a216cfe83a1c80cbc3b9dc5
585 Author: Dave Mitchell <davem@fdisolutions.com>
586 Date: Sat Feb 9 14:56:23 2008 +0000
588 [perl #49472] Attributes + Unknown Error
593 You can peek into the bisecting process with C<git bisect log> and
594 C<git bisect visualize>. C<git bisect reset> will get you out of bisect
597 Please note that the first C<good> state must be an ancestor of the
598 first C<bad> state. If you want to search for the commit that I<solved>
599 some bug, you have to negate your test case (i.e. exit with C<1> if OK
600 and C<0> if not) and still mark the lower bound as C<good> and the
601 upper as C<bad>. The "first bad commit" has then to be understood as
602 the "first commit where the bug is solved".
604 C<git help bisect> has much more information on how you can tweak your
607 =head1 SUBMITTING A PATCH VIA GITHUB
609 GitHub is a website that makes it easy to fork and publish projects
610 with Git. First you should set up a GitHub account and log in.
612 Perl's git repository is mirrored on GitHub at this page:
614 http://github.com/github/perl/tree/blead
616 Visit the page and click the "fork" button. This clones the Perl git
617 repository for you and provides you with "Your Clone URL" from which
620 % git clone git@github.com:USERNAME/perl.git perl-github
622 We shall make the same patch as above, creating a new branch:
625 % git remote add upstream git://github.com/github/perl.git
626 % git pull upstream blead
627 % git checkout -b orange
628 % perl -pi -e 's{Leon Brocard}{Orange Brocard}' AUTHORS
629 % git commit -a -m 'Rename Leon Brocard to Orange Brocard'
630 % git push origin orange
632 The orange branch has been pushed to GitHub, so you should now send an
633 email to perl5-porters@perl.org with a description of your changes and
634 the following information:
636 http://github.com/USERNAME/perl/tree/orange
637 git@github.com:USERNAME/perl.git branch orange
639 =head1 MERGING FROM A BRANCH VIA GITHUB
641 If someone has provided a branch via GitHub and you are a committer,
642 you should use the following in your perl-ssh directory:
644 % git remote add dandv git://github.com/dandv/perl.git
647 Now you can see the differences between the branch and blead:
649 % git diff dandv/blead
651 And you can see the commits:
653 % git log dandv/blead
655 If you approve of a specific commit, you can cherry pick it:
657 % git cherry-pick 3adac458cb1c1d41af47fc66e67b49c8dec2323f
659 Or you could just merge the whole branch if you like it all:
661 % git merge dandv/blead
663 And then push back to the repository:
667 =head1 COMMITTING TO MAINTENANCE VERSIONS
669 Maintenance versions should only be altered to add critical bug fixes.
671 To commit to a maintenance version of perl, you need to create a local
674 % git checkout --track -b maint-5.005 origin/maint-5.005
676 This creates a local branch named C<maint-5.005>, which tracks the
677 remote branch C<origin/maint-5.005>. Then you can pull, commit, merge
680 You can also cherry-pick commits from blead and another branch, by
681 using the C<git cherry-pick> command. It is recommended to use the
682 B<-x> option to C<git cherry-pick> in order to record the SHA1 of the
683 original commit in the new commit message.
687 The git documentation, accessible via C<git help command>.