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
13 from Perl 1 onwards and all the revisions from Perforce, the version
14 control system we were using previously. This repository is accessible
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 you will need to
66 modify your config in order to enable pushing. Edit F<.git/config>
67 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
312 % git commit -a --amend
314 Now you should create a patch file for all your local changes:
316 % git format-patch origin
317 0001-Rename-Leon-Brocard-to-Orange-Brocard.patch
319 You should now send an email to perl5-porters@perl.org with a
320 description of your changes, and include this patch file as an
323 If you want to delete your temporary branch, you may do so with:
326 % git branch -d orange
327 error: The branch 'orange' is not an ancestor of your current HEAD.
328 If you are sure you want to delete it, run 'git branch -D orange'.
329 % git branch -D orange
330 Deleted branch orange.
332 =head2 A note on derived files
334 Be aware that many files in the distribution are derivative--avoid
335 patching them, because git won't see the changes to them, and the build
336 process will overwrite them. Patch the originals instead. Most
337 utilities (like perldoc) are in this category, i.e. patch
338 utils/perldoc.PL rather than utils/perldoc. Similarly, don't create
339 patches for files under $src_root/ext from their copies found in
340 $install_root/lib. If you are unsure about the proper location of a
341 file that may have gotten copied while building the source
342 distribution, consult the C<MANIFEST>.
344 =head2 A note on binary files
346 Since the patch(1) utility cannot deal with binary files, it's
347 important that you either avoid the use of binary files in your patch,
348 generate the files dynamically, or that you encode any binary files
349 using the F<uupacktool.pl> utility.
351 Assuming you needed to include a gzip-encoded file for a module's test
352 suite, you might do this as follows using the F<uupacktool.pl> utility:
354 $ perl uupacktool.pl -v -p -D lib/Some/Module/t/src/t.gz
355 Writing lib/Some/Module/t/src/t.gz into lib/Some/Module/t/src/t.gz.packed
357 This will replace the C<t.gz> file with an encoded counterpart. During
358 C<make test>, before any tests are run, perl's Makefile will restore
359 all the C<.packed> files mentioned in the MANIFEST to their original
360 name. This means that the test suite does not need to be aware of this
361 packing scheme and will not need to be altered.
363 =head2 Getting your patch accepted
365 The first thing you should include with your patch is a description of
366 the problem that the patch corrects. If it is a code patch (rather
367 than a documentation patch) you should also include a small test case
368 that illustrates the bug (a patch to an existing test file is
371 If you are submitting a code patch there are several other things that
376 =item Comments, Comments, Comments
378 Be sure to adequately comment your code. While commenting every line
379 is unnecessary, anything that takes advantage of side effects of
380 operators, that creates changes that will be felt outside of the
381 function being patched, or that others may find confusing should be
382 documented. If you are going to err, it is better to err on the side
383 of adding too many comments than too few.
387 In general, please follow the particular style of the code you are
390 In particular, follow these general guidelines for patching Perl
393 8-wide tabs (no exceptions!)
394 4-wide indents for code, 2-wide indents for nested CPP #defines
395 try hard not to exceed 79-columns
397 uncuddled elses and "K&R" style for indenting control constructs
398 no C++ style (//) comments
399 mark places that need to be revisited with XXX (and revisit often!)
400 opening brace lines up with "if" when conditional spans multiple
401 lines; should be at end-of-line otherwise
402 in function definitions, name starts in column 0 (return value is on
404 single space after keywords that are followed by parens, no space
405 between function name and following paren
406 avoid assignments in conditionals, but if they're unavoidable, use
407 extra paren, e.g. "if (a && (b = c)) ..."
408 "return foo;" rather than "return(foo);"
409 "if (!foo) ..." rather than "if (foo == FALSE) ..." etc.
413 When submitting a patch you should make every effort to also include an
414 addition to perl's regression tests to properly exercise your patch.
415 Your testsuite additions should generally follow these guidelines
416 (courtesy of Gurusamy Sarathy <gsar@activestate.com>):
418 Know what you're testing. Read the docs, and the source.
419 Tend to fail, not succeed.
420 Interpret results strictly.
421 Use unrelated features (this will flush out bizarre interactions).
422 Use non-standard idioms (otherwise you are not testing TIMTOWTDI).
423 Avoid using hardcoded test numbers whenever possible (the
424 EXPECTED/GOT found in t/op/tie.t is much more maintainable,
425 and gives better failure reports).
426 Give meaningful error messages when a test fails.
427 Avoid using qx// and system() unless you are testing for them. If you
428 do use them, make sure that you cover _all_ perl platforms.
429 Unlink any temporary files you create.
430 Promote unforeseen warnings to errors with $SIG{__WARN__}.
431 Be sure to use the libraries and modules shipped with the version
432 being tested, not those that were already installed.
433 Add comments to the code explaining what you are testing for.
434 Make updating the '1..42' string unnecessary. Or make sure that
436 Test _all_ behaviors of a given operator, library, or function:
437 - All optional arguments
438 - Return values in various contexts (boolean, scalar, list, lvalue)
439 - Use both global and lexical variables
440 - Don't forget the exceptional, pathological cases.
444 =head1 ACCEPTING A PATCH
446 If you have received a patch file generated using the above section,
447 you should try out the patch.
449 First we need to create a temporary new branch for these changes and
452 % git checkout -b experimental
454 Patches that were formatted by C<git format-patch> are applied with
457 % git am 0001-Rename-Leon-Brocard-to-Orange-Brocard.patch
458 Applying Rename Leon Brocard to Orange Brocard
460 If just a raw diff is provided, it is also possible use this two-step
463 % git apply bugfix.diff
464 % git commit -a -m "Some fixing" --author="That Guy <that.guy@internets.com>"
466 Now we can inspect the change:
469 commit b1b3dab48344cff6de4087efca3dbd63548ab5e2
470 Author: Leon Brocard <acme@astray.com>
471 Date: Fri Dec 19 17:02:59 2008 +0000
473 Rename Leon Brocard to Orange Brocard
475 diff --git a/AUTHORS b/AUTHORS
476 index 293dd70..722c93e 100644
479 @@ -541,7 +541,7 @@ Lars Hecking <lhecking@nmrc.ucc.ie>
480 Laszlo Molnar <laszlo.molnar@eth.ericsson.se>
481 Leif Huhn <leif@hale.dkstat.com>
482 Len Johnson <lenjay@ibm.net>
483 -Leon Brocard <acme@astray.com>
484 +Orange Brocard <acme@astray.com>
485 Les Peters <lpeters@aol.net>
486 Lesley Binks <lesley.binks@gmail.com>
487 Lincoln D. Stein <lstein@cshl.org>
489 If you are a committer to Perl and you think the patch is good, you can
490 then merge it into blead then push it out to the main repository:
493 % git merge experimental
496 If you want to delete your temporary branch, you may do so with:
499 % git branch -d experimental
500 error: The branch 'experimental' is not an ancestor of your current HEAD.
501 If you are sure you want to delete it, run 'git branch -D experimental'.
502 % git branch -D experimental
503 Deleted branch experimental.
505 =head1 CLEANING A WORKING DIRECTORY
507 The command C<git clean> can with varying arguments be used as a
508 replacement for C<make clean>.
510 To reset your working directory to a pristine condition you can do:
514 However, be aware this will delete ALL untracked content. You can use
518 to remove all ignored untracked files, such as build and test
519 byproduct, but leave any manually created files alone.
521 If you only want to cancel some uncommitted edits, you can use C<git
522 checkout> and give it a list of files to be reverted, or C<git
523 checkout -f> to revert them all.
525 If you want to cancel one or several commits, you can use C<git reset>.
529 C<git> provides a built-in way to determine, with a binary search in
530 the history, which commit should be blamed for introducing a given bug.
532 Suppose that we have a script F<~/testcase.pl> that exits with C<0>
533 when some behaviour is correct, and with C<1> when it's faulty. We need
534 an helper script that automates building C<perl> and running the
540 # If you can use ccache, add -Dcc=ccache\ gcc -Dld=gcc to the Configure line
541 sh Configure -des -Dusedevel -Doptimize="-g" || exit 125
543 ./perl -Ilib ~/testcase.pl
545 This script may return C<125> to indicate that the corresponding commit
546 should be skipped. Otherwise, it returns the status of
549 We first enter in bisect mode with:
553 For example, if the bug is present on C<HEAD> but wasn't in 5.10.0,
554 C<git> will learn about this when you enter:
557 % git bisect good perl-5.10.0
558 Bisecting: 853 revisions left to test after this
560 This results in checking out the median commit between C<HEAD> and
561 C<perl-5.10.0>. We can then run the bisecting process with:
563 % git bisect run ~/run
565 When the first bad commit is isolated, C<git bisect> will tell you so:
567 ca4cfd28534303b82a216cfe83a1c80cbc3b9dc5 is first bad commit
568 commit ca4cfd28534303b82a216cfe83a1c80cbc3b9dc5
569 Author: Dave Mitchell <davem@fdisolutions.com>
570 Date: Sat Feb 9 14:56:23 2008 +0000
572 [perl #49472] Attributes + Unknown Error
577 You can peek into the bisecting process with C<git bisect log> and
578 C<git bisect visualize>. C<git bisect reset> will get you out of bisect
581 Please note that the first C<good> state must be an ancestor of the
582 first C<bad> state. If you want to search for the commit that I<solved>
583 some bug, you have to negate your test case (i.e. exit with C<1> if OK
584 and C<0> if not) and still mark the lower bound as C<good> and the
585 upper as C<bad>. The "first bad commit" has then to be understood as
586 the "first commit where the bug is solved".
588 C<git help bisect> has much more information on how you can tweak your
591 =head1 SUBMITTING A PATCH VIA GITHUB
593 GitHub is a website that makes it easy to fork and publish projects
594 with Git. First you should set up a GitHub account and log in.
596 Perl's git repository is mirrored on GitHub at this page:
598 http://github.com/github/perl/tree/blead
600 Visit the page and click the "fork" button. This clones the Perl git
601 repository for you and provides you with "Your Clone URL" from which
604 % git clone git@github.com:USERNAME/perl.git perl-github
606 We shall make the same patch as above, creating a new branch:
609 % git remote add upstream git://github.com/github/perl.git
610 % git pull upstream blead
611 % git checkout -b orange
612 % perl -pi -e 's{Leon Brocard}{Orange Brocard}' AUTHORS
613 % git commit -a -m 'Rename Leon Brocard to Orange Brocard'
614 % git push origin orange
616 The orange branch has been pushed to GitHub, so you should now send an
617 email to perl5-porters@perl.org with a description of your changes and
618 the following information:
620 http://github.com/USERNAME/perl/tree/orange
621 git@github.com:USERNAME/perl.git branch orange
623 =head1 COMMITTING TO MAINTENANCE VERSIONS
625 To commit to a maintenance version of perl, you need to create a local
628 % git checkout --track -b maint-5.005 origin/maint-5.005
630 This creates a local branch named C<maint-5.005>, which tracks the
631 remote branch C<origin/maint-5.005>. Then you can pull, commit, merge
634 You can also cherry-pick commits from blead and another branch, by
635 using the C<git cherry-pick> command. It is recommended to use the
636 B<-x> option to C<git cherry-pick> in order to record the SHA1 of the
637 original commit in the new commit message.
641 The git documentation, accessible via C<git help command>.