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 master branch, which contains bleadperl,
19 the development version of perl 5) takes up about 160MB of disk space
20 (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 =head1 OVERVIEW OF THE REPOSITORY
103 Once you have changed into the repository directory, you can inspect
106 After a clone the repository will contain a single local branch, which
107 will be the current branch as well, as indicated by the asterisk.
112 Using the -a switch to C<branch> will also show the remote tracking
113 branches in the repository:
121 The branches that begin with "origin" correspond to the "git remote"
122 that you cloned from (which is named "origin"). Each branch on the
123 remote will be exactly tracked by theses branches. You should NEVER do
124 work on these remote tracking branches. You only ever do work in a
125 local branch. Local branches can be configured to automerge (on pull)
126 from a designated remote tracking branch. This is the case with the
127 default branch C<blead> which will be configured to merge from the
128 remote tracking branch C<origin/blead>.
130 You can see recent commits:
134 And pull new changes from the repository, and update your local
135 repository (must be clean first)
139 Assuming we are on the branch C<blead> immediately after a pull, this
140 command would be more or less equivalent to:
143 % git merge origin/blead
145 In fact if you want to update your local repository without touching
146 your working directory you do:
150 And if you want to update your remote-tracking branches for all defined
151 remotes simultaneously you can do
155 Neither of these last two commands will update your working directory,
156 however both will update the remote-tracking branches in your
159 To switch to another branch:
161 % git checkout origin/maint-5.8-dor
163 To make a local branch of a remote branch:
165 % git checkout -b maint-5.10 origin/maint-5.10
167 To switch back to blead:
171 =head2 FINDING OUT YOUR STATUS
173 The most common git command you will use will probably be
177 This command will produce as output a description of the current state
178 of the repository, including modified files and unignored untracked
179 files, and in addition it will show things like what files have been
180 staged for the next commit, and usually some useful information about
181 how to change things. For instance the following:
185 # Your branch is ahead of 'origin/blead' by 1 commit.
187 # Changes to be committed:
188 # (use "git reset HEAD <file>..." to unstage)
190 # modified: pod/perlrepository.pod
192 # Changed but not updated:
193 # (use "git add <file>..." to update what will be committed)
195 # modified: pod/perlrepository.pod
198 # (use "git add <file>..." to include in what will be committed)
200 # deliberate.untracked
202 This shows that there were changes to this document staged for commit,
203 and that there were further changes in the working directory not yet
204 staged. It also shows that there was an untracked file in the working
205 directory, and as you can see shows how to change all of this. It also
206 shows that there is one commit on the working branch C<blead> which has
207 not been pushed to the C<origin> remote yet. B<NOTE>: that this output
208 is also what you see as a template if you do not provide a message to
211 Assuming we commit all the mentioned changes above:
213 % git commit -a -m'explain git status and stuff about remotes'
214 Created commit daf8e63: explain git status and stuff about remotes
215 1 files changed, 83 insertions(+), 3 deletions(-)
217 We can re-run git status and see something like this:
221 # Your branch is ahead of 'origin/blead' by 2 commits.
224 # (use "git add <file>..." to include in what will be committed)
226 # deliberate.untracked
227 nothing added to commit but untracked files present (use "git add" to track)
230 When in doubt, before you do anything else, check your status and read
231 it carefully, many questions are answered directly by the git status
234 =head1 SUBMITTING A PATCH
236 If you have a patch in mind for Perl, you should first get a copy of
239 % git clone git://perl5.git.perl.org/perl.git perl-git
241 Then change into the directory:
245 Alternatively, if you already have a Perl repository, you should ensure
246 that you're on the I<blead> branch, and your repository is up to date:
251 (It's preferable to patch against the latest blead version, since
252 patches are usually integrated from blead to the maintenance branches.
253 This does not apply, obviously, in the rare case where your patch is
254 specific to a maintaince release.)
256 Now that we have everything up to date, we need to create a temporary
257 new branch for these changes and switch into it:
259 % git checkout -b orange
261 which is the short form of
264 % git checkout orange
266 Then make your changes. For example, if Leon Brocard changes his name
267 to Orange Brocard, we should change his name in the AUTHORS file:
269 % perl -pi -e 's{Leon Brocard}{Orange Brocard}' AUTHORS
271 You can see what files are changed:
275 # Changes to be committed:
276 # (use "git reset HEAD <file>..." to unstage)
281 And you can see the changes:
284 diff --git a/AUTHORS b/AUTHORS
285 index 293dd70..722c93e 100644
288 @@ -541,7 +541,7 @@ Lars Hecking <lhecking@nmrc.ucc.ie>
289 Laszlo Molnar <laszlo.molnar@eth.ericsson.se>
290 Leif Huhn <leif@hale.dkstat.com>
291 Len Johnson <lenjay@ibm.net>
292 -Leon Brocard <acme@astray.com>
293 +Orange Brocard <acme@astray.com>
294 Les Peters <lpeters@aol.net>
295 Lesley Binks <lesley.binks@gmail.com>
296 Lincoln D. Stein <lstein@cshl.org>
298 Now commit your change locally:
300 % git commit -a -m 'Rename Leon Brocard to Orange Brocard'
301 Created commit 6196c1d: Rename Leon Brocard to Orange Brocard
302 1 files changed, 1 insertions(+), 1 deletions(-)
304 You can examine your last commit with:
308 and if you are not happy with either the description or the patch
309 itself you can fix it up by editing the files once more and then issue:
311 % git commit -a --amend
313 Now you should create a patch file for all your local changes:
315 % git format-patch origin
316 0001-Rename-Leon-Brocard-to-Orange-Brocard.patch
318 You should now send an email to perl5-porters@perl.org with a
319 description of your changes, and include this patch file as an
322 If you want to delete your temporary branch, you may do so with:
325 % git branch -d orange
326 error: The branch 'orange' is not an ancestor of your current HEAD.
327 If you are sure you want to delete it, run 'git branch -D orange'.
328 % git branch -D orange
329 Deleted branch orange.
331 =head2 A note on derived files
333 Be aware that many files in the distribution are derivative--avoid
334 patching them, because git won't see the changes to them, and the build
335 process will overwrite them. Patch the originals instead. Most
336 utilities (like perldoc) are in this category, i.e. patch
337 utils/perldoc.PL rather than utils/perldoc. Similarly, don't create
338 patches for files under $src_root/ext from their copies found in
339 $install_root/lib. If you are unsure about the proper location of a
340 file that may have gotten copied while building the source
341 distribution, consult the C<MANIFEST>.
343 =head2 A note on binary files
345 Since the patch(1) utility cannot deal with binary files, it's
346 important that you either avoid the use of binary files in your patch,
347 generate the files dynamically, or that you encode any binary files
348 using the F<uupacktool.pl> utility.
350 Assuming you needed to include a gzip-encoded file for a module's test
351 suite, you might do this as follows using the F<uupacktool.pl> utility:
353 $ perl uupacktool.pl -v -p -D lib/Some/Module/t/src/t.gz
354 Writing lib/Some/Module/t/src/t.gz into lib/Some/Module/t/src/t.gz.packed
356 This will replace the C<t.gz> file with an encoded counterpart. During
357 C<make test>, before any tests are run, perl's Makefile will restore
358 all the C<.packed> files mentioned in the MANIFEST to their original
359 name. This means that the test suite does not need to be aware of this
360 packing scheme and will not need to be altered.
362 =head2 Getting your patch accepted
364 The first thing you should include with your patch is a description of
365 the problem that the patch corrects. If it is a code patch (rather
366 than a documentation patch) you should also include a small test case
367 that illustrates the bug (a patch to an existing test file is
370 If you are submitting a code patch there are several other things that
375 =item Comments, Comments, Comments
377 Be sure to adequately comment your code. While commenting every line
378 is unnecessary, anything that takes advantage of side effects of
379 operators, that creates changes that will be felt outside of the
380 function being patched, or that others may find confusing should be
381 documented. If you are going to err, it is better to err on the side
382 of adding too many comments than too few.
386 In general, please follow the particular style of the code you are
389 In particular, follow these general guidelines for patching Perl
392 8-wide tabs (no exceptions!)
393 4-wide indents for code, 2-wide indents for nested CPP #defines
394 try hard not to exceed 79-columns
396 uncuddled elses and "K&R" style for indenting control constructs
397 no C++ style (//) comments
398 mark places that need to be revisited with XXX (and revisit often!)
399 opening brace lines up with "if" when conditional spans multiple
400 lines; should be at end-of-line otherwise
401 in function definitions, name starts in column 0 (return value is on
403 single space after keywords that are followed by parens, no space
404 between function name and following paren
405 avoid assignments in conditionals, but if they're unavoidable, use
406 extra paren, e.g. "if (a && (b = c)) ..."
407 "return foo;" rather than "return(foo);"
408 "if (!foo) ..." rather than "if (foo == FALSE) ..." etc.
412 When submitting a patch you should make every effort to also include an
413 addition to perl's regression tests to properly exercise your patch.
414 Your testsuite additions should generally follow these guidelines
415 (courtesy of Gurusamy Sarathy <gsar@activestate.com>):
417 Know what you're testing. Read the docs, and the source.
418 Tend to fail, not succeed.
419 Interpret results strictly.
420 Use unrelated features (this will flush out bizarre interactions).
421 Use non-standard idioms (otherwise you are not testing TIMTOWTDI).
422 Avoid using hardcoded test numbers whenever possible (the
423 EXPECTED/GOT found in t/op/tie.t is much more maintainable,
424 and gives better failure reports).
425 Give meaningful error messages when a test fails.
426 Avoid using qx// and system() unless you are testing for them. If you
427 do use them, make sure that you cover _all_ perl platforms.
428 Unlink any temporary files you create.
429 Promote unforeseen warnings to errors with $SIG{__WARN__}.
430 Be sure to use the libraries and modules shipped with the version
431 being tested, not those that were already installed.
432 Add comments to the code explaining what you are testing for.
433 Make updating the '1..42' string unnecessary. Or make sure that
435 Test _all_ behaviors of a given operator, library, or function:
436 - All optional arguments
437 - Return values in various contexts (boolean, scalar, list, lvalue)
438 - Use both global and lexical variables
439 - Don't forget the exceptional, pathological cases.
443 =head1 ACCEPTING A PATCH
445 If you have received a patch file generated using the above section,
446 you should try out the patch.
448 First we need to create a temporary new branch for these changes and
451 % git checkout -b experimental
453 Patches that were formatted by C<git format-patch> are applied with
456 % git am 0001-Rename-Leon-Brocard-to-Orange-Brocard.patch
457 Applying Rename Leon Brocard to Orange Brocard
459 If just a raw diff is provided, it is also possible use this two-step
462 % git apply bugfix.diff
463 % git commit -a -m "Some fixing" --author="That Guy <that.guy@internets.com>"
465 Now we can inspect the change:
468 commit b1b3dab48344cff6de4087efca3dbd63548ab5e2
469 Author: Leon Brocard <acme@astray.com>
470 Date: Fri Dec 19 17:02:59 2008 +0000
472 Rename Leon Brocard to Orange Brocard
474 diff --git a/AUTHORS b/AUTHORS
475 index 293dd70..722c93e 100644
478 @@ -541,7 +541,7 @@ Lars Hecking <lhecking@nmrc.ucc.ie>
479 Laszlo Molnar <laszlo.molnar@eth.ericsson.se>
480 Leif Huhn <leif@hale.dkstat.com>
481 Len Johnson <lenjay@ibm.net>
482 -Leon Brocard <acme@astray.com>
483 +Orange Brocard <acme@astray.com>
484 Les Peters <lpeters@aol.net>
485 Lesley Binks <lesley.binks@gmail.com>
486 Lincoln D. Stein <lstein@cshl.org>
488 If you are a committer to Perl and you think the patch is good, you can
489 then merge it into blead then push it out to the main repository:
492 % git merge experimental
495 If you want to delete your temporary branch, you may do so with:
498 % git branch -d experimental
499 error: The branch 'experimental' is not an ancestor of your current HEAD.
500 If you are sure you want to delete it, run 'git branch -D experimental'.
501 % git branch -D experimental
502 Deleted branch experimental.
504 =head1 CLEANING A WORKING DIRECTORY
506 The command C<git clean> can with varying arguments be used as a
507 replacement for C<make clean>.
509 To reset your working directory to a pristine condition you can do:
513 However, be aware this will delete ALL untracked content. You can use
517 to remove all ignored untracked files, such as build and test
518 byproduct, but leave any manually created files alone.
520 If you only want to cancel some uncommitted edits, you can use C<git
521 checkout> and give it a list of files to be reverted, or C<git checkout
522 -f> to revert them all.
524 If you want to cancel one or several commits, you can use C<git reset>.
528 C<git> provides a built-in way to determine, with a binary search in
529 the history, which commit should be blamed for introducing a given bug.
531 Suppose that we have a script F<~/testcase.pl> that exits with C<0>
532 when some behaviour is correct, and with C<1> when it's faulty. We need
533 an helper script that automates building C<perl> and running the
539 # If you can use ccache, add -Dcc=ccache\ gcc -Dld=gcc to the Configure line
540 sh Configure -des -Dusedevel -Doptimize="-g"
541 test -f config.sh || exit 125
542 # Correct makefile for newer GNU gcc
543 perl -ni -we 'print unless /<(?:built-in|command)/' makefile x2p/makefile
544 # if you just need miniperl, replace test_prep with miniperl
546 -x ./perl || exit 125
547 ./perl -Ilib ~/testcase.pl
552 This script may return C<125> to indicate that the corresponding commit
553 should be skipped. Otherwise, it returns the status of
556 We first enter in bisect mode with:
560 For example, if the bug is present on C<HEAD> but wasn't in 5.10.0,
561 C<git> will learn about this when you enter:
564 % git bisect good perl-5.10.0
565 Bisecting: 853 revisions left to test after this
567 This results in checking out the median commit between C<HEAD> and
568 C<perl-5.10.0>. We can then run the bisecting process with:
570 % git bisect run ~/run
572 When the first bad commit is isolated, C<git bisect> will tell you so:
574 ca4cfd28534303b82a216cfe83a1c80cbc3b9dc5 is first bad commit
575 commit ca4cfd28534303b82a216cfe83a1c80cbc3b9dc5
576 Author: Dave Mitchell <davem@fdisolutions.com>
577 Date: Sat Feb 9 14:56:23 2008 +0000
579 [perl #49472] Attributes + Unknown Error
584 You can peek into the bisecting process with C<git bisect log> and
585 C<git bisect visualize>. C<git bisect reset> will get you out of bisect
588 Please note that the first C<good> state must be an ancestor of the
589 first C<bad> state. If you want to search for the commit that I<solved>
590 some bug, you have to negate your test case (i.e. exit with C<1> if OK
591 and C<0> if not) and still mark the lower bound as C<good> and the
592 upper as C<bad>. The "first bad commit" has then to be understood as
593 the "first commit where the bug is solved".
595 C<git help bisect> has much more information on how you can tweak your
598 =head1 SUBMITTING A PATCH VIA GITHUB
600 GitHub is a website that makes it easy to fork and publish projects
601 with Git. First you should set up a GitHub account and log in.
603 Perl's git repository is mirrored on GitHub at this page:
605 http://github.com/github/perl/tree/blead
607 Visit the page and click the "fork" button. This clones the Perl git
608 repository for you and provides you with "Your Clone URL" from which
611 % git clone git@github.com:USERNAME/perl.git perl-github
613 We shall make the same patch as above, creating a new branch:
616 % git remote add upstream git://github.com/github/perl.git
617 % git pull upstream blead
618 % git checkout -b orange
619 % perl -pi -e 's{Leon Brocard}{Orange Brocard}' AUTHORS
620 % git commit -a -m 'Rename Leon Brocard to Orange Brocard'
621 % git push origin orange
623 The orange branch has been pushed to GitHub, so you should now send an
624 email to perl5-porters@perl.org with a description of your changes and
625 the following information:
627 http://github.com/USERNAME/perl/tree/orange
628 git@github.com:USERNAME/perl.git branch orange
630 =head1 MERGING FROM A BRANCH VIA GITHUB
632 If someone has provided a branch via GitHub and you are a committer,
633 you should use the following in your perl-ssh directory:
635 % git remote add dandv git://github.com/dandv/perl.git
638 Now you can see the differences between the branch and blead:
640 % git diff dandv/blead
642 And you can see the commits:
644 % git log dandv/blead
646 If you approve of a specific commit, you can cherry pick it:
648 % git cherry-pick 3adac458cb1c1d41af47fc66e67b49c8dec2323f
650 Or you could just merge the whole branch if you like it all:
652 % git merge dandv/blead
654 And then push back to the repository:
658 =head1 COMMITTING TO MAINTENANCE VERSIONS
660 To commit to a maintenance version of perl, you need to create a local
663 % git checkout --track -b maint-5.005 origin/maint-5.005
665 This creates a local branch named C<maint-5.005>, which tracks the
666 remote branch C<origin/maint-5.005>. Then you can pull, commit, merge
669 You can also cherry-pick commits from blead and another branch, by
670 using the C<git cherry-pick> command. It is recommended to use the
671 B<-x> option to C<git cherry-pick> in order to record the SHA1 of the
672 original commit in the new commit message.
676 The git documentation, accessible via C<git help command>.