Begin bowing to public pressure toward an open blead;

[perl5.git] / Porting / release_managers_guide.pod

=head1 NAME

release_managers_guide - Releasing a new version of perl 5.x

As of August 2009, this file is mostly complete, although it is missing
some detail on doing a major release (e.g. 5.10.0 -> 5.12.0). Note that
things change at each release, so there may be new things not covered
here, or tools may need updating.

=head1 SYNOPSIS

This document describes the series of tasks required - some automatic, some
manual - to produce a perl release of some description, be that a snaphot,
release candidate, or final, numbered release of maint or blead.

The release process has traditionally been executed by the current
pumpking. Blead releases from 5.11.0 forward are made each month on the
20th by a non-pumpking release engineer.  The release engineer roster
and schedule can be found in Porting/release_schedule.pod.

This document both helps as a check-list for the release engineer 
and is a base for ideas on how the various tasks could be automated 
or distributed.

The outline of a typical release cycle is as follows:

    (5.10.1 is released, and post-release actions have been done)

    ...time passes...

    an occasional snapshot is released, that still identifies itself as
        5.10.1

    ...time passes...

    a few weeks before the release, a number of steps are performed,
        including bumping the version to 5.10.2

    ...a few weeks passes...

    perl-5.10.2-RC1 is released

    perl-5.10.2 is released

    post-release actions are performed, including creating new
        perl5103delta.pod

    ... the cycle continues ...

=head1 DETAILS

Some of the tasks described below apply to all four types of 
release of Perl. (snapshot, RC, final release of maint, final 
release of blead). Some of these tasks apply only to a subset
of these release types.  If a step does not apply to a given 
type of release, you will see a notation to that effect at
the beginning of the step.

=head2 Release types

=over 4

=item Snapshot

A snapshot is intended to encourage in-depth testing from time-to-time,
for example after a key point in the stabilisation of a branch. It
requires fewer steps than a full release, and the version number of perl in
the tarball will usually be the same as that of the previous release.

=item Release Candidate (RC)

A release candidate is an attempt to produce a tarball that is a close as
possible to the final release. Indeed, unless critical faults are found
during the RC testing, the final release will be identical to the RC
barring a few minor fixups (updating the release date in F<perlhist.pod>,
removing the RC status from F<patchlevel.h>, etc). If faults are found,
then the fixes should be put into a new release candidate, never directly
into a final release.

=item Stable/Maint release

At this point you should have a working release candidate with few or no
changes since.

It's essentially the same procedure as for making a release candidate, but
with a whole bunch of extra post-release steps.

=item Blead release

It's essentially the same procedure as for making a release candidate, but
with a whole bunch of extra post-release steps.

=back

=head2 Prerequisites

Before you can make an official release of perl, there are a few
hoops you need to jump through:

=over 4

=item PAUSE account

I<SKIP this step for SNAPSHOT>

Make sure you have a PAUSE account suitable for uploading a perl release.
If you don't have a PAUSE account, then request one:

    https://pause.perl.org/pause/query?ACTION=request_id

Check that your account is allowed to upload perl distros: goto
L<https://pause.perl.org/>, login, then select 'upload file to CPAN'; there
should be a "For pumpkings only: Send a CC" tickbox.  If not, ask Andreas
König to add your ID to the list of people allowed to upload something
called perl.  You can find Andreas' email address at:

    https://pause.perl.org/pause/query?ACTION=pause_04imprint

=item search.cpan.org

Make sure that search.cpan.org knows that you're allowed to upload
perl distros. Contact Graham Barr to make sure that you're on the right
list.

=item CPAN mirror

Some release engineering steps require a full mirror of the CPAN.
Work to fall back to using a remote mirror via HTTP is incomplete
but ongoing. (No, a minicpan mirror is not sufficient)

=item git checkout and commit bit

You will need a working C<git> installation, checkout of the perl
git repository and perl commit bit.  For information about working
with perl and git, see F<pod/perlrepository.pod>.

If you are not yet a perl committer, you won't be able to make a
release.  Have a chat with whichever evil perl porter tried to talk
you into the idea in the first place to figure out the best way to
resolve the issue.


=item Quotation for release announcement epigraph

I<SKIP this step for SNAPSHOT and RC>

For a numbered blead or maint release of perl, you will need a quotation 
to use as an epigraph to your release announcement.  (There's no harm
in having one for a snapshot, but it's not required).


=back


=head2 Building a release - advance actions

The work of building a release candidate for a numbered release of
perl generally starts several weeks before the first release candidate.
Some of the following steps should be done regularly, but all I<must> be
done in the run up to a release.

=over 4

=item *

I<You MAY SKIP this step for SNAPSHOT>

Ensure that dual-life CPAN modules are synchronised with CPAN.  Basically,
run the following:

    $ ./perl -Ilib Porting/core-cpan-diff -a -o /tmp/corediffs

to see any inconsistencies between the core and CPAN versions of distros,
then fix the core, or cajole CPAN authors as appropriate. See also the
C<-d> and C<-v> options for more detail.  You'll probably want to use the
C<-c cachedir> option to avoid repeated CPAN downloads.

To see which core distro versions differ from the current CPAN versions:

    $ ./perl -Ilib Porting/core-cpan-diff -x -a

If you are making a maint release, run C<core-cpan-diff> on both blead and
maint, then diff the two outputs. Compare this with what you expect, and if
necessary, fix things up. For example, you might think that both blead
and maint are synchronised with a particular CPAN module, but one might
have some extra changes. 

=item *

I<You MAY SKIP this step for SNAPSHOT>

Ensure dual-life CPAN modules are stable, which comes down to:

    for each module that fails its regression tests on $current
        did it fail identically on $previous?
        if yes, "SEP" (Somebody Else's Problem)
        else work out why it failed (a bisect is useful for this)

    attempt to group failure causes

    for each failure cause
        is that a regression?
        if yes, figure out how to fix it
            (more code? revert the code that broke it)
        else
            (presumably) it's relying on something un-or-under-documented
            should the existing behaviour stay?
                yes - goto "regression"
                no - note it in perldelta as a significant bugfix
                (also, try to inform the module's author)

=item *

I<You MAY SKIP this step for SNAPSHOT>

Similarly, monitor the smoking of core tests, and try to fix.

=item *

I<You MAY SKIP this step for SNAPSHOT>

Similarly, monitor the smoking of perl for compiler warnings, and try to
fix.

=item *

I<You MAY SKIP this step for SNAPSHOT>

Run F<Porting/cmpVERSION.pl> to compare the current source tree with the
previous version to check for for modules that have identical version
numbers but different contents, e.g.:

     $ cd ~/some-perl-root
     $ ./perl -Ilib Porting/cmpVERSION.pl -xd ~/my_perl-tarballs/perl-5.10.0 .

then bump the version numbers of any non-dual-life modules that have
changed since the previous release, but which still have the old version
number. If there is more than one maintenance branch (e.g. 5.8.x, 5.10.x),
then compare against both.

Note that some of the files listed may be generated (e.g. copied from ext/
to lib/, or a script like lib/lib_pm.PL is run to produce lib/lib.pm);
make sure you edit the correct file!

Once all version numbers have been bumped, re-run the checks.

Then run again without the -x option, to check that dual-life modules are
also sensible.

     $ ./perl -Ilib Porting/cmpVERSION.pl -d ~/my_perl-tarballs/perl-5.10.0 .

=item *

I<You MAY SKIP this step for SNAPSHOT>

Get perldelta in a mostly finished state.

Read  F<Porting/how_to_write_a_perldelta.pod>, and try to make sure that
every section it lists is, if necessary, populated and complete. Copy
edit the whole document.

=item *

I<You MUST SKIP this step for SNAPSHOT>

A week or two before the first release candidate, bump the perl version
number (e.g. from 5.10.0 to 5.10.1), to allow sufficient time for testing
and smoking with the target version built into the perl executable. For
subsequent release candidates and the final release, it it not necessary
to bump the version further.

There is a tool to semi-automate this process. It works in two stages.
First, it generates a list of suggested changes, which you review and
edit; then you feed this list back and it applies the edits. So, first
scan the source directory looking for likely candidates. The command line
arguments are the old and new version numbers, and -s means scan:

    $ Porting/bump-perl-version -s 5.10.0 5.10.1 > /tmp/scan

This produces a file containing a list of suggested edits, e.g.:

    NetWare/Makefile

       89: -MODULE_DESC     = "Perl 5.10.0 for NetWare"
           +MODULE_DESC     = "Perl 5.10.1 for NetWare"

i.e. in the file F<NetWare/Makefile>, line 89 would be changed as shown.
Review the file carefully, and delete any -/+ line pairs that you don't
want changing. You can also edit just the C<+> line to change the
suggested replacement text. Remember that this tool is largely just
grepping for '5.10.0' or whatever, so it will generate false positives. Be
careful not change text like "this was fixed in 5.10.0"! Then run:

    $ Porting/bump-perl-version -u < /tmp/scan

which will update all the files shown.

Be particularly careful with F<INSTALL>, which contains a mixture of
C<5.10.0>-type strings, some of which need bumping on every release, and
some of which need to be left unchanged. Also note that this tool
currently only detects a single substitution per line: so in particular,
this line in README.vms needs special handling:

    rename perl-5^.10^.1.dir perl-5_10_1.dir

Commit your changes:

    $ git st
        $ git diff
          B<review the delta carefully>

    $ git commit -a -m 'Bump the perl version in various places for 5.x.y'

When the version number is bumped, you should also update Module::CoreList (as
described below in L<"Building a release - on the day">) to reflect the new
version number.

=item *

I<You MUST SKIP this step for SNAPSHOT>

Review and update INSTALL to account for the change in version number;
in particular, the "Coexistence with earlier versions of perl 5" section.

=item *

I<You MUST SKIP this step for SNAPSHOT>

Update the F<Changes> file to contain the git log command which would show
all the changes in this release. You will need assume the existence of a
not-yet created tag for the forthcoming release; e.g.

    git log ... perl-5.10.0..perl-5.12.0

Due to warts in the perforce-to-git migration, some branches require extra
exclusions to avoid other branches being pulled in. Make sure you have the
correct incantation: replace the not-yet-created tag with C<HEAD> and see
if C<git log> produces roughly the right number of commits across roughly the
right time period (you may find C<git log --pretty=oneline | wc> useful).

=item *

Check some more build configurations. The check that setuid builds and
installs is for < 5.11.0 only.

    $ sh Configure -Dprefix=/tmp/perl-5.x.y  -Uinstallusrbinperl \
        -Duseshrplib -Dd_dosuid
    $ make
    $ LD_LIBRARY_PATH=`pwd` make test     # or similar for useshrplib

    $ make suidperl
    $ su -c 'make install'
    $ ls -l .../bin/sperl
    -rws--x--x 1 root root 69974 2009-08-22 21:55 .../bin/sperl

(Then delete the installation directory.)

XXX think of other configurations that need testing.

=item *

I<You MAY SKIP this step for SNAPSHOT>

Update F<AUTHORS>, using the C<Porting/checkAUTHORS.pl> script, and if
necessary, update the script to include new alias mappings for porters
already in F<AUTHORS>

    $ git log --pretty=fuller | perl Porting/checkAUTHORS.pl --acknowledged AUTHORS -

=back

=head2 Building a release - on the day

This section describes the actions required to make a release (or snapshot
etc) that are performed on the actual day.

=over 4

=item *

Review all the items in the previous section,
L<"Building a release - advance actions"> to ensure they are all done and
up-to-date.

=item *

I<You MAY SKIP this step for SNAPSHOT>

Re-read the perldelta to try to find any embarrassing typos and thinkos;
remove any C<TODO> or C<XXX> flags; update the "Known Problems" section
with any serious issues for which fixes are not going to happen now; and
run through pod and spell checkers, e.g.

    $ podchecker -warnings -warnings pod/perl5101delta.pod
    $ spell pod/perl5101delta.pod

Also, you may want to generate and view an HTML version of it to check
formatting, e.g.

    $ perl pod/pod2html pod/perl5101delta.pod > /tmp/perl5101delta.html

=item *

Make sure you have a gitwise-clean perl directory (no modified files,
unpushed commits etc):

    $ git status

=item *

If not already built, Configure and build perl so that you have a Makefile
and porting tools:

    $ ./Configure -Dusedevel -des && make

=item *

Check that files managed by F<regen.pl> and friends are up to date. From
within your working directory:

    $ git status
    $ make regen
    $ make regen_perly
    $ git status

If any of the files managed by F<regen.pl> have changed, then you should
re-make perl to check that it's okay, then commit the updated versions:

    $ git commit -a -m 'make regen; make regen_perly'

=item *

Rebuild META.yml:

    $ rm META.yml
    $ make META.yml
    $ git diff

XXX it would be nice to make Porting/makemeta use regen_lib.pl
to get the same 'update the file if its changed' functionality
we get with 'make regen' etc.

Commit META.yml if it has changed:

    $ git commit -m 'Update META.yml' META.yml

=item *

I<You MUST SKIP this step for SNAPSHOT>

Update C<Module::Corelist> with module version data for the new release.

Note that if this is a maint release, you should run the following actions
from the maint directory, but commit the C<Corelist.pm> changes in
I<blead> and subsequently cherry-pick it.

F<corelist.pl> uses ftp.funet.fi to verify information about dual-lived
modules on CPAN. It can use a full, local CPAN mirror or fall back
to C<wget> or C<curl> to fetch only package metadata remotely. (If you're
on Win32, then installing Cygwin is one way to have commands like C<wget>
and C<curl> available.)

(If you'd prefer to have a full CPAN mirror, see 
http://www.cpan.org/misc/cpan-faq.html#How_mirror_CPAN)

Then change to your perl checkout, and if necessary,

    $ make perl

If this not the first update for this version (e.g. if it was updated
when the version number was originally bumped), first edit
F<dist/Module-CoreList/lib/Module/CoreList.pm> to delete the existing
entries for this version from the C<%released> and C<%version> hashes:
they will have a key like C<5.010001> for 5.10.1.

XXX the edit-in-place functionality of Porting/corelist.pl should
be fixed to handle this automatically.

Then, If you have a local CPAN mirror, run:

    $ ./perl -Ilib Porting/corelist.pl ~/my-cpan-mirror

Otherwise, run:

    $ ./perl -Ilib Porting/corelist.pl cpan

This will chug for a while, possibly reporting various warnings about
badly-indexed CPAN modules unrelated to the modules actually in core.
Assuming all goes well, it will update
F<dist/Module-CoreList/lib/Module/CoreList.pm>.

Check that file over carefully:

    $ git diff dist/Module-CoreList/lib/Module/CoreList.pm

If necessary, bump C<$VERSION> (there's no need to do this for
every RC; in RC1, bump the version to a new clean number that will
appear in the final release, and leave as-is for the later RCs and final).

Edit the version number in the new C<< 'Module::CoreList' => 'X.YZ' >>
entry, as that is likely to reflect the previous version number.

Also edit Module::CoreList's new version number in its F<Changes> file and
in its F<META.yml> file.

In addition, if this is a final release (rather than a release candidate):

=over 4 

=item *

Update this version's entry in the C<%released> hash with today's date.

=item *

Make sure that the script has correctly updated the C<CAVEATS> section

=back

Finally, commit the new version of Module::CoreList:
(unless this is for maint; in which case commit it blead first, then
cherry-pick it back).

    $ git commit -m 'Update Module::CoreList for 5.x.y' dist/Module-CoreList/lib/Module/CoreList.pm

=item *

Check that the manifest is sorted and correct:

    $ make manisort
    $ make distclean
    $ git clean -xdf # This shouldn't be necessary if distclean is correct
    $ perl Porting/manicheck
    $ git status

        XXX manifest _sorting_ is now checked with make test_porting

Commit MANIFEST if it has changed:

    $ git commit -m 'Update MANIFEST' MANIFEST

=item *

I<You MUST SKIP this step for SNAPSHOT>

Add an entry to F<pod/perlhist.pod> with the current date, e.g.:

    David    5.10.1-RC1    2009-Aug-06

Make sure that the correct pumpking is listed in the left-hand column, and
if this is the first release under the stewardship of a new pumpking, make
sure that his or her name is listed in the section entitled
C<THE KEEPERS OF THE PUMPKIN>.

Be sure to commit your changes:

    $ git commit -m 'add new release to perlhist' pod/perlhist.pod

=item *

I<You MUST SKIP this step for SNAPSHOT>

Update F<patchlevel.h> to add a C<-RC1>-or-whatever string; or, if this is
a final release, remove it. For example:

     static const char * const local_patches[] = {
             NULL
    +        ,"RC1"
             PERL_GIT_UNPUSHED_COMMITS /* do not remove this line */

Be sure to commit your change:

    $ git commit -m 'bump version to RCnnn' patchlevel.h

=item *

Build perl, then make sure it passes its own test suite, and installs:

    $ git clean -xdf
    $ ./Configure -des -Dprefix=/tmp/perl-5.x.y-pretest

    # or if it's an odd-numbered version:
    $ ./Configure -des -Dusedevel -Dprefix=/tmp/perl-5.x.y-pretest

    $ make test install

=item *

Check that the output of C</tmp/perl-5.x.y-pretest/bin/perl -v> and
C</tmp/perl-5.x.y-pretest/bin/perl -V> are as expected,
especially as regards version numbers, patch and/or RC levels, and @INC
paths. Note that as they have been been built from a git working
directory, they will still identify themselves using git tags and
commits.

Then delete the temporary installation.

=item *

If this is maint release, make sure F<Porting/mergelog> is saved and
committed.

=item *

Push all your recent commits:

    $ git push origin ....


=item *

I<You MUST SKIP this step for SNAPSHOT>

Tag the release (e.g.):

    $ git tag v5.11.0 -m'First release of the v5.11 series!'

(Adjust the syntax appropriately if you're working on Win32, i.e. use
C<-m "..."> rather than C<-m'...'>.)

It is VERY important that from this point forward, you not push
your git changes to the Perl master repository.  If anything goes
wrong before you publish your newly-created tag, you can delete
and recreate it.  Once you push your tag, we're stuck with it
and you'll need to use a new version number for your release.

=item *

Create a tarball. Use the C<-s> option to specify a suitable suffix for
the tarball and directory name:

    $ cd root/of/perl/tree
    $ make distclean
    $ git clean -xdf            # make sure perl and git agree on files
    $ git status                # and there's nothing lying around

    $ perl Porting/makerel -b -s `git describe` # for a snapshot
    $ perl Porting/makerel -b -s RC1            # for a release candidate
    $ perl Porting/makerel -b                   # for a final release

This creates the  directory F<../perl-x.y.z-RC1> or similar, copies all
the MANIFEST files into it, sets the correct permissions on them,
adds DOS line endings to some, then tars it up as
F<../perl-x.y.z-RC1.tar.gz>. With C<-b>, it also creates a C<tar.bz2> file.


XXX if we go for extra tags and branches stuff, then add the extra details
here

=item *

Clean up the temporary directory, e.g.

    $ rm -rf ../perl-x.y.z-RC1

=item *

Copy the tarballs (.gz and possibly .bz2) to a web server somewhere you
have access to.

=item *

Download the tarball to some other machine. For a release candidate, 
you really want to test your tarball on two or more different platforms
and architectures. The #p5p IRC channel on irc.perl.org is a good place
to find willing victims.

=item *

Check that basic configuration and tests work on each test machine:

    $ ./Configure -des && make all test

=item *

Check that the test harness and install work on each test machine:

    $ make distclean
    $ ./Configure -des -Dprefix=/install/path && make all test_harness install
    $ cd /install/path

=item *

Check that the output of C<perl -v> and C<perl -V> are as expected,
especially as regards version numbers, patch and/or RC levels, and @INC
paths. 

Note that the results may be different without a F<.git/> directory,
which is why you should test from the tarball.

=item *

Run the Installation Verification Procedure utility:

    $ bin/perlivp
    ...
    All tests successful.
    $

=item *

Compare the pathnames of all installed files with those of the previous
release (i.e. against the last installed tarball on this branch which you
have previously verified using this same procedure). In particular, look
for files in the wrong place, or files no longer included which should be.
For example, suppose the about-to-be-released version is 5.10.1 and the
previous is 5.10.0:

    cd installdir-5.10.0/
    find . -type f | perl -pe's/5\.10\.0/5.10.1/g' | sort > /tmp/f1
    cd installdir-5.10.1/
    find . -type f | sort > /tmp/f2
    diff -u /tmp/f[12]

=item *

Bootstrap the CPAN client on the clean install:

    $ bin/perl -MCPAN -e'shell' 

(Use C<... -e "shell"> instead on Win32. You probably also need a set of
Unix command-line tools available for CPAN to function correctly without
Perl alternatives like LWP installed. Cygwin is an obvious choice.)

=item *

Try installing a popular CPAN module that's reasonably complex and that
has dependencies; for example:

    CPAN> install Inline
    CPAN> quit

Check that your perl can run this:

    $ bin/perl -lwe 'use Inline C => "int f() { return 42;} "; print f'
    42
    $

(Use C<... -lwe "use ..."> instead on Win32.)

=item *

Bootstrap the CPANPLUS client on the clean install:

    $ bin/cpanp

(Again, on Win32 you'll need something like Cygwin installed, but make sure
that you don't end up with its various F<bin/cpan*> programs being found on
the PATH before those of the Perl that you're trying to test.)

=item *

Install an XS module, for example:

    CPAN Terminal> i DBI
    CPAN Terminal> quit
    $ bin/perl -MDBI -e 1
    $

=item *

I<If you're building a SNAPSHOT, you should STOP HERE>

=item *

Check that the C<perlbug> utility works. Try the following:

    $ bin/perlbug
    ...
    Subject: test bug report
    Local perl administrator [yourself]: 
    Editor [vi]: 
    Module: 
    Category [core]: 
    Severity [low]: 
    (edit report)
    Action (Send/Display/Edit/Subject/Save to File): f
    Name of file to save message in [perlbug.rep]: 
    Action (Send/Display/Edit/Subject/Save to File): q

and carefully examine the output (in F<perlbug.rep]>), especially
the "Locally applied patches" section. If everything appears okay, then
delete the file, and try it again, this time actually submitting the bug
report. Check that it shows up, then remember to close it!

=item *

Wait for the smoke tests to catch up with the commit which this release is
based on (or at least the last commit of any consequence).

Then check that the smoke tests pass (particularly on Win32). If not, go
back and fix things.


=item *

Once smoking is okay, upload it to PAUSE. This is the point of no return.
If anything goes wrong after this point, you will need to re-prepare
a new release with a new minor version or RC number.

    https://pause.perl.org/

(Login, then select 'Upload a file to CPAN')

If your workstation is not connected to a high-bandwidth,
high-reliability connection to the Internet, you should probably use the
"GET URL" feature (rather than "HTTP UPLOAD") to have PAUSE retrieve the
new release from wherever you put it for testers to find it.  This will
eliminate anxious gnashing of teeth while you wait to see if your
15 megabyte HTTP upload successfully completes across your slow, twitchy
cable modem.  You can make use of your home directory on dromedary for
this purpose: F<http://users.perl5.git.perl.org/~USERNAME> maps to
F</home/USERNAME/public_html>, where F<USERNAME> is your login account
on dromedary.  I<Remember>: if your upload is partially successful, you
may need to contact a PAUSE administrator or even bump the version of perl.

Upload both the .gz and .bz2 versions of the tarball.

Wait until you receive notification emails from the PAUSE indexer
confirming that your uploads have been successfully indexed.  Do not
proceed any further until you are sure that the indexing of your uploads
has been successful.

=item *

Now that you've shipped the new perl release to PAUSE, it's
time to publish the tag you created earlier to the public git repo (e.g.):

    $ git push origin tag v5.11.0

=item *

Disarm the F<patchlevel.h> change; for example,

     static const char * const local_patches[] = {
             NULL
    -        ,"RC1"
             PERL_GIT_UNPUSHED_COMMITS /* do not remove this line */

Be sure to commit your change:

    $ git commit -m 'disarm RCnnn bump' patchlevel.h
    $ git push origin ....


=item *

Mail p5p to announce your new release, with a quote you prepared earlier.

=item *

Wait 24 hours or so, then post the announcement to use.perl.org.
(if you don't have access rights to post news, ask someone like Rafael to
do it for you.)

=item *

Check http://www.cpan.org/src/ to see if the new tarballs have appeared.
They should appear automatically, but if they don't then ask Jarkko to look
into it, since his scripts must have broken.

=item *

I<You MUST SKIP this step for RC, BLEAD>

Ask Jarkko to update the descriptions of which tarballs are current in
http://www.cpan.org/src/README.html, and Rafael to update
http://dev.perl.org/perl5/

=item *

I<You MUST SKIP this step for RC>

Remind the current maintainer of C<Module::CoreList> to push a new release
to CPAN.

=item *

I<You MUST SKIP this step for RC>

Bump the perlXYZdelta version number.

First, create a new empty perlNNNdelta.pod file for the current release + 1;
see F<Porting/how_to_write_a_perldelta.pod>.

You should be able to do this by just copying in a skeleton template and
then doing a quick fix up of the version numbers, e.g.

    $ cp -i Porting/perldelta_template.pod pod/perl5102delta.pod
    $ (edit it)
    $ git add pod/perl5102delta.pod

Edit F<pod.lst>: add the new entry, flagged as 'D', and unflag the previous
entry from being 'D'; for example:

    -D perl5101delta                Perl changes in version 5.10.1
    +D perl5102delta                Perl changes in version 5.10.2
    +  perl5101delta                Perl changes in version 5.10.1

Run C<perl pod/buildtoc --build-all> to update the F<perldelta> version in
the following files:

    MANIFEST
    Makefile.SH
    pod.lst
    pod/perl.pod
    vms/descrip_mms.template
    win32/Makefile
    win32/makefile.mk
    win32/pod.mak

Then manually edit (F<vms/descrip_mms.template> to bump the version
in the following entry:

    [.pod]perldelta.pod : [.pod]perl5101delta.pod

XXX this previous step needs to fixed to automate it in pod/buildtoc.

Manually update references to the perlNNNdelta version in these files:

    INSTALL
    README

Edit the previous delta file to change the C<NAME> from C<perldelta>
to C<perlNNNdelta>.

These two lists of files probably aren't exhaustive; do a recursive grep
on the previous filename to look for suitable candidates that may have
been missed.

Finally, commit:

    $ git commit -a -m 'create perlXXXdelta'

At this point you may want  to compare the commit with a previous bump to
see if they look similar. See commit ca8de22071 for an example of a
previous version bump.

=item *

I<You MUST SKIP this step for RC, BLEAD>

If this was a maint release, then edit F<Porting/mergelog> to change
all the C<d> (deferred) flags to C<.> (needs review).

=item *

I<You MUST SKIP this step for BLEAD>

If this was the first release candidate for a major release of maint
(5.x.0 where x is even), then create a new maint branch based on the
commit tagged as the current release and bump the version in the blead
branch in git, e.g. 5.12.0 to 5.13.0.

[ XXX probably lots more stuff to do, including perldelta,
C<lib/feature.pm> ]

Assuming you're using git 1.7.x or newer:

    $ git checkout -b maint-5.12
    $ git push origin -u maint-5.12

=item *

I<You MUST SKIP this step for RC, BLEAD>

Copy the perlNNNdelta.pod for this release into the other branches; for
example:

    $ cp -i ../5.10.x/pod/perl5101delta.pod pod/    # for example
    $ git add pod/perl5101delta.pod

Edit F<pod.lst> to add an entry for the file, e.g.:

    perl5101delta               Perl changes in version 5.10.1

Then rebuild various files:

    $ perl pod/buildtoc --build-all

Finally, commit:

    $ git commit -a -m 'add perlXXXdelta'

=item *

Make sure any recent F<pod/perlhist.pod> entries are copied to
F<perlhist.pod> on other branches; typically the RC* and final entries,
e.g.

          5.8.9-RC1     2008-Nov-10
          5.8.9-RC2     2008-Dec-06
          5.8.9         2008-Dec-14

=item *

I<You MUST RETIRE to your preferred PUB, CAFE or SEASIDE VILLA for some
much-needed rest and relaxation>.

Thanks for releasing perl!

=back

=head1 SOURCE

Based on
http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/2009-05/msg00608.html,
plus a whole bunch of other sources, including private correspondence.

=cut