=encoding UTF-8

=head1 NAME

debhelper-compat-upgrade-checklist - Upgrade checklist for supported debhelper compat levels

=head1 SYNOPSIS

This document is an upgrade checklist of all the supported debhelper compat levels. It also
lists all the supported debhelper compat levels.

The B<dh_assistant compat-upgrade-checklist> command can provide a package specific upgrade
checklist from compat 7 and up (requires B<debhelper/13.25> or later). Its main limitation
is accuracy of its heuristics. Please review the documentation of L<dh_assistant(1)> for
details.

Information about how to declare the compat level is in L<debhelper(7)/COMPATIBILITY LEVELS>.

If you are upgrading from a (now) obsolete compat level, then please refer to
L<debhelper-obsolete-compat(7)>.

=head1 DESCRIPTION

=head2 Upgrade checklist for supported compatibility levels

These are the available compatibility levels:

=over 4

=item v15

This compatibility level is still open for development; use with caution.

Changes from v14 are:

=over 8

=item -

The B<single-binary> add-on for B<dh> is no longer implicitly activated by
source packages that have a single B<Package> stanza in F<debian/control>. If
the package needs the short-cuts for single-binary packages, it must explicitly
activate the B<single-binary> add-in.

This can be done via a B<Build-Depends> on B<dh-sequence-single-binary>.

Any B<--without single-binary> passed to B<dh> to avoid the warning in compat 14
can now be removed to simplify F<debian/rules> without triggering the warning.

=item -

It is now an error to use package-less versions of debhelper configuration files
when there are 2 or more binary packages listed in F<debian/control> in
most cases.  Legacy files should be renamed to F<< debian/I<package>.foo >>
(from F<debian/foo>) where I<package> is the first binary package listed in
F<debian/control>.

The primary exception to this change are files such as F<debian/changelog>,
F<debian/NEWS>, and F<debian/copyright>, where the same file is used for all
packages by default.  These cases will remain unchanged.

=item -

It is now an error to use a packaging file without the package prefix for
B<--name> even if the source package only produces one binary package. As example,
if you had a F<debian/bar.service> with the following snippet in F<debian/rules>:

 override_dh_installsystemd:
    dh_installsystemd -p foo --name bar

Then you need to rename F<debian/bar.service> to F<debian/foo.bar.service>.

=back

=item v14

This compatibility level is still open for development; use with caution.

Changes from v13 are:

=over 8

=item -

The B<dh_installmodules> and B<dh_installpam> tools will now install their
configuration files under F<< /usr/lib/modprobe.d/I<package> >> and
F<< /usr/lib/pam.d/I<package> >> instead of their respective directory under
F<< /etc >>.

Please consider using the "rm_conffile" feature from L<dh_installdeb(1)> to
ensure the proper removal of previous modprobe and PAM files.

=item -

Packages using the B<dh> sequencer should be aware the following changes:

=over 4

=item -

The order and placement has changed for B<dh_strip_nondeterminism>,
B<dh_compress>, and B<dh_fixperm>. Previously, these three commands
were run in the listed order between B<dh_installxfonts> and
B<dh_missing>.

Their new placement is after B<dh_missing> (arch:all) or
B<dh_shlibdeps> (arch:any) and before B<dh_installdeb>. Additionally,
their new order is B<dh_fixperms>, B<dh_strip_nondeterminism>, and
then B<dh_compress>.

This change may require updates to third-party add-ons that use either
of these three commands as anchor or to hook targets for any of these
commands that made assumptions about the command order.

Additionally, B<dh_strip_nondeterminism> and B<dh_compress> plus any commands added
by third-party add-ons using these as anchors will no longer be able to rely on the
mode/ownership normalization by B<dh_fixperms>, which may expose bugs in the form
of incorrect mode or ownership in the resulting binary package.

Please file any such bugs against the relevant tool. Feel free to include the
B<debhelper> maintainers in CC.

=item -

The tool B<dh_installsysusers> is now included in the default sequence. This
helper tool will process systemd sysusers files.

=item -

The B<dh_installalternatives> tool will now be run after B<dh_link> rather than after
B<dh_installinitramfs> in the default B<dh> sequence.

=item -

The B<dh_dwz> command has been removed from the default sequence. If it is still desired,
add B<dh-sequence-dwz> to B<Build-Depends-Arch> or run it in
B<execute_before_dh_strip-arch> with B<-a> to get the closest emulation of the previous
behavior.

Note: The B<dh_dwz> command will cause a lot of differences in the generated debug symbols.
If you use B<diffoscope> as part of your compat upgrade checks, you may want to temporarily
use B<dh_dwz> to keep the delta reviewable while upgrading and then remove B<dh_dwz>
afterwards.

=item -

Use of the B<dh_gconf> command in override and hook targets now causes
an error.  The B<dh_gconf> command has been a no-op for years and was
removed in debhelper 13.4.

=item -

A new tool called B<dh_computeautosubstvars> has been added and is now run immediately
before B<dh_gencontrol>. If you inject commands before B<dh_gencontrol>
(either via hook targets or third-party sequence add-on), consider moving them
to after B<dh_installdeb> instead as the new tool generally assumes no more changes
will occur between it is called and B<dh_gencontrol> is called.

Notable exception to this assumption if you have to tweak substvars per
L<https://lists.debian.org/debian-devel/2024/03/msg00030.html>.

=item -

I<< This item only applies to source packages that have exactly one B<Package> stanza in F<debian/control>. >>

The B<dh_auto_install> command now unconditionally uses B<--destdir=debian/tmp> by default. The special-case
for source packages building a single binary package is now moved to B<single-binary> B<dh> addon. Note, this
add-on is activated by default in compat 14 but not in compat 15 (see next bullet item).

=item -

I<< This item only applies to source packages that have exactly one B<Package> stanza in F<debian/control>. >>

The B<dh> sequencer will warn if the B<single-binary> addon is implicitly activated to
warn maintainers of the pending compat 15 change in B<dh_auto_install>. The implicit
activation is a transitional feature to reduce the changes of risks with this change.
In compat 15, the implicit activation will no longer trigger.

Maintainers are urged to either explicitly activate the B<single-binary> addon to
preserve the existing behaviour (e.g., by adding B<dh-sequence-single-binary> to
Build-Depends), or explicitly passing B<--destdir> to B<dh_auto_install> if used and
then passing B<--without single-binary> to B<dh> (the latter to silence the warning).

The rationale for this change is to avoid "surprises" when adding a second binary package
later.  Previously, debhelper would silently change behaviour often resulting in empty
binary packages being uploaded to the archive by mistake. With the new behaviour,
the B<single-binary> addon will detect the mismatch and warn the maintainer of what is
about to happen.

=back

=item -

The B<dh_installsystemduser> tool will default to enabling systemd user units,
start them on installation, restart them on upgrades and stop them on uninstalling
the package.

=item -

The B<dh_gencontrol> tool now automatically applies relationship substvars to
relevant fields. That means that many substvars such as B<${misc:Depends}>
and B<${shlibs:Depends}> no longer need to be explicitly mentioned in
F<debian/control>. This applies to any substvar named after a field that
the installed version of B<dpkg> considers a relation or dependency-like
field. At the time of writing, the list consists of:

=over 4

=item -

Pre-Depends

=item -

Depends

=item -

Recommends

=item -

Suggests

=item -

Enhances

=item -

Conflicts

=item -

Breaks

=item -

Replaces

=item -

Provides

=item -

Built-Using

=item -

Static-Built-Using

=back

This means that B<Depends: foo, ${misc:Depends}> in F<debian/control> can
now be reduced to B<Depends: foo> and B<Depends: ${misc:Depends}, ${shlibs:Depends}>
can be removed entirely as examples of how the feature works.

Note that other substvars such as B<${binary:Version}> are unaffected by
this change and should still be used explicitly as necessary. Additionally,
for B<Essential: yes> packages that manually promoted B<${shlibs:Depends}>
into B<Pre-Depends> field, B<dh_shlibdeps> will handle this automatically
as well (see the next compat item).

See L<https://lists.debian.org/debian-devel/2024/02/msg00230.html> for the
details of this proposal. The summary in
L<https://lists.debian.org/debian-devel/2024/03/msg00030.html> also covers
when the substvars need tweaking.  The most common case involves using
the B<-d> option from B<dpkg-shlibdeps> possibly via B<dh_shlibdeps>.

Note: This change will cause false-positives from an unfixed
L<lintian(1)>. Please check L<https://bugs.debian.org/1067653> for
L<lintian(1)> support for this change.

Finally, B<debhelper> also applies this feature the substvars for the
following fields due to implementation details:

=over 4

=item -

Commands

See L<#638517|https://bugs.debian.org/638517> for what the field is used for.

=back


=item -

The B<dh_shlibdeps> tool now defaults to using B<${shlibs:Pre-Depends}> for
packages that are B<Essential: yes>.

Note due to the B<dh_gencontrol> change above, any package using B<dh_gencontrol>
will not have to do anything for this migration.

=item -

When running B<dh_auto_install>, B<debhelper> provided build systems will now ensure
all paths in the B<destdir> have minimal user permissions (B<chmod -R u+rwX>) to avoid
weird I<permission denied> errors during builds.

Third-party provided debhelper build systems are recommended to support this as well.
This can be done by running

     $this->ensure_minimal_permissions($destdir) if not compat(13);

in the B<debhelper> Buildsystem code from their B<sub install> implementation after
the upstream code has been run.

If you are not using B<dh_auto_install> and you run into weird I<permission denied>
errors, you can often solve this by running B<chmod -R u+rwX DIRECTORY> after running
the install target from the upstream build system.

Please take care to check if your package has any special cases for permissions where
files or directories for some reason must not have the "user write bit" set. Known
cases are B<*.ali> files and B</etc/sudoers.d>, which B<dh_fixperms> will fix up by
default.

The problem with uncommon permissions have always been present in theory. However, it
has become considerable more visible with B<dh_fixperms> being run later in the
sequence as of compat 14 and with the move to remove B<fakeroot> by default (which
papered over some of these issues). This change is aimed at mitigating the problem.

=item -

The debhelper configuration files are subject to the following changes:

=over 4

=item -

It now triggers a warning to use package-less versions of debhelper configuration
files when there are 2 or more binary packages listed in F<debian/control> in
most cases.  Legacy files should be renamed to F<< debian/I<package>.foo >>
(from F<debian/foo>) where I<package> is the first binary package listed in
F<debian/control>.

The primary exception to this change are files such as F<debian/changelog>,
F<debian/NEWS>, and F<debian/copyright>, where the same file is used for all
packages by default.  These cases will remain unchanged.  The debhelper tool
using the files will trigger warnings on usage.

In compat 15 (or later), this is changed to an error.

=item -

It now triggers a warning to use a packaging file without the package prefix for
B<--name> even if the source package only produces one binary package. As example,
if you had a F<debian/bar.service> with the following snippet in F<debian/rules>:

 override_dh_installsystemd:
    dh_installsystemd -p foo --name bar

Then you need to rename F<debian/bar.service> to F<debian/foo.bar.service>.

In compat 15 (or later), this is changed to an error.

=item -

The default look up rules for B<Dh_Lib> based tools now assume that configuration
files are no longer named (B<--name>) nor support architecture restrictions by default.
If you work with a third-party debhelper-like tool and need support for either of these
features, please file a bug against the tool asking it to declare its configuration
file with the relevant options in its B<pkgfile> call.

Note that B<debhelper> itself tweaked its rules for most of its tools as well based on
analysis of usage via B<codesearch.debian.org>. Should you be relying on a feature like
architecture restrictions for a given config file that is no longer supported, please
file a feature request for the use-case and it might be restored.

=back

=item -

Packages using the B<cmake> build system should be aware of the following changes:

=over 4

=item -

The B<cmake> buildsystem now passes
B<-DCMAKE_BUILD_RPATH_USE_ORIGIN=ON> to L<cmake(1)> to avoid some
reproducibility issues.

=item -

The B<cmake> build system now sets the B<ASMFLAGS> environment variable when it is unset
and B<ASFLAGS> is present. The former name (B<ASMFLAGS>) is the name B<cmake> expects,
while the latter (B<ASFLAGS>) is the name that L<dpkg-buildpackage(1)> uses.

=item -

The B<cmake> build systems now use B<cmake --install> instead of B<make install>
in the L<dh_auto_install(1)> call.  Any override of B<dh_auto_install> that
passes extra parameters to the upstream build system should be reviewed.

=back

=item -

Packages using the B<meson> build system should be aware of the following changes:

=over 4

=item -

The B<meson> build system now passes B<--auto-features=enabled> to B<meson>.

=item -

The B<meson+ninja> build system now use B<meson install> instead of B<ninja install>
in the L<dh_auto_install(1)> call.  Any override of B<dh_auto_install> that
passes extra parameters to the upstream build system should be reviewed.

=back

=item -

The F<debian/compat> file is no longer accepted as a source for specifying the
debhelper compat level. Put the compat level in the B<X-DH-Compat> field of
the B<Source> stanza of F<debian/control>.

Note to avoid breaking packages that already migrated to compat 14 immediately,
while it was experimental this change is first enforced when compat 14 becomes
stable.

=item -

The tool B<dh_installtmpfiles> now runs with B<--remove> on package removal, and
B<--purge> on package purge. systemd v256 is required for the latter.

=item -

The B<dh_lintian> tool no longer accepts architecture specific overrides files
for packages with B<Multi-Arch: same> in F<debian/control>, since these would
not be co-installable. Instances affected by this error should migrate to
L<lintian(1)> architecture specific overrides.

=back

=item v13

This is the recommended mode of operation.

Changes from v12 are:

=over 8

=item -

The B<meson+ninja> build system now uses B<meson test> instead of
B<ninja test> when running the test suite.  Any override of
B<dh_auto_test> that passes extra parameters to upstream test runner
should be reviewed as B<meson test> is not command line compatible
with B<ninja test>.

=item -

All debhelper like tools based on the official debhelper library
(including B<dh> and the official B<dh_*> tools) no longer accepts
abbreviated command parameters.  At the same time, B<dh> now
optimizes out calls to redundant B<dh_*> helpers even when passed
long command line options.

=item -

The ELF related debhelper tools (B<dh_dwz>, B<dh_strip>,
B<dh_makeshlibs>, B<dh_shlibdeps>) are now only run for arch dependent
packages by default (i.e. they are excluded from B<*-indep> targets
and are passed B<-a> by default). If you need them for B<*-indep>
targets, you can add an explicit Build-Depends on
B<dh-sequence-elf-tools>.

=item -

The third-party B<gradle> build system (from B<gradle-debian-helper>
package) now runs the upstream-provided test suite automatically.  To
suppress such behavior, override B<dh_auto_test>.

=item -

The B<dh_installman> tool now aborts if it sees conflicting
definitions of a manpage.  This typically happens if the upstream
build system is installing a compressed version and the package lists
an uncompressed version of the manpage in F<<
debian/I<package>.manpages >>.  Often the easiest fix is to remove the
manpage from F<< debian/I<package>.manpages >> (assuming both versions
are identical).

=item -

The B<dh_auto_*> helpers now reset the environment variable B<HOME>
and the common B<XDG_*> variables.  Please see description of the
environment variables in L<debhelper(1)/ENVIRONMENT> for how this is handled.

I<This feature changed between debhelper 13 and debhelper 13.2.>

=item -

The B<dh> command will now error if an override or hook target for an
obsolete command are present in F<debian/rules>
(e.g. B<override_dh_systemd_enable:>).

=item -

The B<dh_missing> command will now default to B<--fail-missing>.  This
can be reverted to a non-fatal warning by explicitly passing
B<--list-missing> like it was in compat 12.

If you do not want the warning either, please omit the call to
B<dh_missing>.  If you use the B<dh> command sequencer, then you can
do this by inserting an empty override target in the
F<debian/rules> file of the relevant package.  As an example:

    # Disable dh_missing
    override_dh_missing:

=item -

The B<dh> command sequencer now runs B<dh_installtmpfiles> in the
default sequence.  The B<dh_installtmpfiles> takes over handling of
tmpfiles.d configuration files.  Related functionality in
B<dh_installsystemd> is now disabled.

Note that B<dh_installtmpfiles> responds to
F<< debian/I<package>.tmpfiles >> where B<dh_installsystemd> used
a name without the trailing "s".

=item -

Many B<dh_*> tools now support limited variable expansion via the
B<${foo}> syntax.  In many cases, this can be used to reference paths
that contain either spaces or L<dpkg-architecture(1)> values.  While
this can reduce the need for L<dh-exec(1)> in some cases, it is B<not>
a replacement L<dh-exec(1)> in general.  If you need filtering,
renaming, etc., the package will still need L<dh-exec(1)>.

Please see L</Substitutions in debhelper config files> for syntax and
available substitution variables.  To B<dh_*> tool writers, substitution
expansion occurs as a part of the B<filearray> and B<filedoublearray>
functions.

=item -

The B<dh> command sequencer will now skip all hook and override targets
for B<dh_auto_test>, B<dh_dwz> and B<dh_strip> when B<DEB_BUILD_OPTIONS>
lists the relevant B<nocheck> / B<nostrip> options.

Any package relying on these targets to always be run should instead
move relevant logic out of those targets.  E.g. non-test related
packaging code from B<override_dh_auto_test> would have to be moved to
B<execute_after_dh_auto_build> or B<execute_before_dh_auto_install>.

=item -

The B<cmake> buildsystem now passes B<-DCMAKE_SKIP_INSTALL_ALL_DEPENDENCY=ON>
to L<cmake(1)> to speed up automatic installation process. If for some reason
you need previous behavior, override the flag:

    dh_auto_configure -- -DCMAKE_SKIP_INSTALL_ALL_DEPENDENCY=OFF ...

=back

=item v12

Changes from v11 are:

=over 8

=item -

The B<dh_makeshlibs> tool now generates shlibs files with versioned
dependency by default.  This means that B<-VUpstream-Version>
(a.k.a. B<-V>) is now the default.

If an unversioned dependency in the shlibs file is wanted, this can be
obtained by passing B<-VNone> instead.  However, please see
L<dh_makeshlibs(1)> for the caveat of unversioned dependencies.

=item -

The B<-s> (B<--same-arch>) option is removed.  Please use B<-a> (B<--arch>) instead.

=item -

Invoking B<dh_clean -k> now causes an error instead of a deprecation
warning.

=item -

The B<--no-restart-on-upgrade> option in B<dh_installinit> has been removed.
Please use the new name B<--no-stop-on-upgrade>

=item -

There was a bug in the B<doit> (and similar) functions from
L<Debian::Debhelper::Dh_Lib> that made them spawn a shell in one
particular circumstance.  This bug is now removed and will cause
helpers that rely on the bug to fail with a "command not found"-error.

=item -

The B<--list-missing> and B<--fail-missing> in B<dh_install> has been
removed.  Please use B<dh_missing> and its corresponding options,
which can also see the files installed by other helpers.

=item -

The B<dh_installinit> helper no longer installs configuration for
the upstart init system.  Instead, it will abort the build if it
finds an old upstart configuration file.  The error is there to
remind the package maintainer to ensure the proper removal of the
conffiles shipped in previous versions of the package (if any).

=item -

The B<dh_installdeb> tool will do basic validation of some
L<dpkg-maintscript-helper(1)> commands and will error out if the
commands appear to be invalid.

=item -

The B<dh_missing> tool will now default to B<--list-missing>.

=item -

The B<dh_makeshlibs> tool will now only pass libraries to L<dpkg-gensymbols(1)>
if the ELF binary has a SONAME (containing ".so").

=item -

The B<dh_compress> tool no longer compresses examples (i.e. anything installed
in F<</usr/share/doc/I<package>/examples>>.)

=item -

The standard sequence in B<dh> now includes B<dh_dwz> and
B<dh_installinitramfs> by default.  This makes the B<dwz> and
B<installinitramfs> sequences obsolete and they will now fail with an
error.  If you want to skip these commands, then please insert an
empty override target for them in F<debian/rules>
(e.g. I<override_dh_dwz:>)

=item -

The build systems B<meson> and B<autoconf> no longer explicitly set
the B<--libexecdir> variable and thus relies on the build system
default - which should be B</usr/libexec> (per FHS 3.0, adopted in
Debian Policy 4.1.5).

If a particular upstream package does not use the correct default, the
parameter can often be passed manually via L<dh_auto_configure(1)>.  E.g.
via the following example:

    override_dh_auto_configure:
    	dh_auto_configure -- --libexecdir=/usr/libexec

Note the B<--> before the B<--libexecdir> parameter.

=item -

B<Retroactively removed in debhelper/13.5>:

The B<dh_installdeb> tool would no longer install the maintainer provided
F<conffiles> file as it was deemed unnecessary.  However, the
B<remove-on-upgrade> from dpkg/1.20 made the file relevant again and
B<dh_installdeb> now installs it again in compat levels 12+.

=item -

The B<dh_installsystemd> tool no longer relies on B<dh_installinit> for
handling systemd services that have a sysvinit alternative.  Both tools
must now be used in such a case to ensure the service is properly started
under both sysvinit and systemd.

If you have an override for B<dh_installinit> (e.g. to call it with
B<--no-start>) then you will probably need one for
B<dh_installsystemd> as well now.

This change makes B<dh_installinit> inject a I<misc:Pre-Depends> for
B<< init-system-helpers (>= 1.54~) >>.  Please ensure that the package
lists B<${misc:Pre-Depends}> in its B<Pre-Depends> field before
upgrading to compat 12.

=item -

The third-party B<dh_golang> tool (from B<dh-golang> package) now defaults on
honoring B<DH_GOLANG_EXCLUDES> variable for source installation in -dev
packages and not only during the building process. Please set
B<DH_GOLANG_EXCLUDES_ALL> to false to revert to the previous behaviour. See
B<Debian::Debhelper::Buildsystem::golang(3pm)> for details and examples.

=item -

B<dh_installsystemduser> is now included in the B<dh> standard
sequence by default.

=item -

The B<python-distutils> buildsystem is now removed.  Please use the
third-party build system B<pybuild> instead.

=back

=item v11

This mode is discouraged.

The compat 11 is discouraged for new packages as it suffers from
feature interaction between L<dh_installinit> and L<dh_installsystemd>
causing services to not run correctly in some cases.  Please consider
using compatibility mode 10 or 12 instead.  More details about the
issue are available in Debian#887904 and
L<https://lists.debian.org/debian-release/2019/04/msg01442.html>.

Changes from v10 are:

=over 8

=item -

B<dh_installinit> no longer installs F<service> or F<tmpfile> files,
nor generates maintainer scripts for those files.  Please use the new
B<dh_installsystemd> helper.

=item -

The B<dh_systemd_enable> and B<dh_systemd_start> helpers have been
replaced by the new B<dh_installsystemd> helper.  For the same reason,
the B<systemd> sequence for B<dh> has also been removed.  If you need
to disable the B<dh_installsystemd> helper tool, please use an empty
override target.

Please note that the B<dh_installsystemd> tool has a slightly
different behaviour in some cases (e.g. when using the B<--name>
parameter).

=item -

B<dh_installdirs> no longer creates debian/I<package> directories
unless explicitly requested (or it has to create a subdirectory in
it).

The vast majority of all packages will be unaffected by this change.

=item -

The B<makefile> buildsystem now passes B<INSTALL="install
--strip-program=true"> to L<make(1)>.  Derivative buildsystems
(e.g. B<configure> or B<cmake>) are unaffected by this change.

=item -

The B<autoconf> buildsystem now passes B<--runstatedir=/run> to
F<./configure>.

=item -

The B<cmake> buildsystem now passes
B<-DCMAKE_INSTALL_RUNSTATEDIR=/run> to L<cmake(1)>.

=item -

B<dh_installman> will now prefer detecting the language from the
path name rather than the extension.

=item -

B<dh_auto_install> will now only create the destination
directory it needs.  Previously, it would create the package build
directory for all packages.  This will not affect packages that only
build with debhelper commands, but it may expose bugs in commands not
included in debhelper.

=item -

The helpers B<dh_installdocs>, B<dh_installexamples>, B<dh_installinfo>,
and B<dh_installman> now error out if their config has a pattern that
does not match anything or reference a path that does not exist.

Known exceptions include building with the B<nodoc> profile, where the
above tools will silently permit failed matches where the patterns
are used to specify documentation.

=item -

The helpers B<dh_installdocs>, B<dh_installexamples>, B<dh_installinfo>,
and B<dh_installman> now accept the parameter B<--sourcedir> with same
meaning as B<dh_install>. Furthermore, they now also fall back to
F<debian/tmp> like B<dh_install>.

Migration note: A bug in debhelper 11 up to 11.1.5 made
B<dh_installinfo> incorrectly ignore B<--sourcedir>.

=item -

The B<perl-makemaker> and B<perl-build> build systems no longer pass
B<-I.> to perl.  Packages that rely on this behavior can often use the
B<PERL5LIB> environment variable as a substitute.  E.g. by adding
B<export PERL5LIB=.> in their debian/rules file (or similar).

=item -

The B<PERL_USE_UNSAFE_INC> environment variable is no longer set by
B<dh> or any of the B<dh_auto_*> tools.  It was added as a temporary
work around to avoid a lot of packages failing to build at the same
time.

Note this item will eventually become obsolete as upstream intends
to drop support for the B<PERL_USE_UNSAFE_INC> environment variable.
When perl drops support for it, then this variable will be removed
retroactively from existing compat levels as well.

=item -

The B<dh_makeshlibs> helper will now exit with an error if objdump
returns a non-zero exit from analysing a given file.

=item -

The B<dh_installdocs> and B<dh_installexamples> tools may now install
I<most> of the documentation in a different path to comply with the
recommendation from Debian policy §12.3 (since version 3.9.7).

Note that if a given source package only contains a single binary
package in F<debian/control> or none of the packages are I<-doc>
packages, then this change is not relevant for that source package and
you can skip to the next change.

By default, these tools will now attempt to determine a "main package
for the documentation" (called a I<doc-main-package> from here on) for
every I<-doc> package.  If they find such a I<doc-main-package>, they
will now install the documentation into the path F<<
/usr/share/doc/I<doc-main-package> >> in the given doc package.
I.e. the path can change but the documentation is still shipped in the
I<-doc> package.

The B<--doc-main-package> option can be used when the auto-detection
is insufficient or to reset the path to its previous value if there is
a reason to diverge from Debian policy recommendation.

Some documentation will not be affected by this change.  These
exceptions include the copyright file, changelog files, README.Debian,
etc.  These files will still be installed in the path F<<
/usr/share/doc/I<package> >>.

=item -

The B<dh_strip> and B<dh_shlibdeps> tools no longer uses filename
patterns to determine which files to process.  Instead, they open the
file and look for an ELF header to determine if a given file is an
shared object or an ELF executable.

This change may cause the tools to process more files than previously.

=back

=item v10

Changes from v9 are:

=over 8

=item -

B<dh_installinit> will no longer installs a file named debian/I<package>
as an init script.

=item -

B<dh_installdocs> will error out if it detects links created with
--link-doc between packages of architecture "all" and non-"all" as it
breaks binNMUs.

=item -

B<dh_installdeb> no longer installs a maintainer-provided
debian/I<package>.shlibs file.  This is now done by B<dh_makeshlibs>
instead.

=item -

B<dh_installwm> refuses to create a broken package if no man page
can be found (required to register for the x-window-manager alternative).

=item -

Debhelper will default to B<--parallel> for all buildsystems that
support parallel building.  This can be disabled by using either
B<--no-parallel> or passing B<--max-parallel> with a value of 1.

=item -

The B<dh> command will not accept any of the deprecated "manual
sequence control" parameters (B<--before>, B<--after>, etc.).  Please
use override targets instead.

B<Retroactively applied to earlier compat levels>: B<dh> no longer
accepts any of these since debhelper/12.4.

=item -

The B<dh> command will no longer use log files to track which commands
have been run.  The B<dh> command I<still> keeps track of whether it
already ran the "build" sequence and skip it if it did.

The main effects of this are:

=over 4

=item -

With this, it is now easier to debug the I<install> or/and I<binary>
sequences because they can now trivially be re-run (without having to
do a full "clean and rebuild" cycle)

=item -

The main caveat is that B<dh_*> now only keeps track of what happened
in a single override target.  When all the calls to a given B<dh_cmd>
command happens in the same override target everything will work as
before.

Example of where it can go wrong:

  override_dh_foo:
    dh_foo -pmy-pkg

  override_dh_bar:
    dh_bar
    dh_foo --remaining

In this case, the call to B<dh_foo --remaining> will I<also> include
I<my-pkg>, since B<dh_foo -pmy-pkg> was run in a separate override
target.  This issue is not limited to B<--remaining>, but also includes
B<-a>, B<-i>, etc.

=back

=item -

The B<dh_installdeb> command now shell-escapes the lines in the
F<maintscript> config file.  This was the original intent but it did
not work properly and packages have begun to rely on the incomplete
shell escaping (e.g. quoting file names).

=item -

The B<dh_installinit> command now defaults to
B<--restart-after-upgrade>.  For packages needing the previous
behaviour, please use B<--no-restart-after-upgrade>.

=item -

The B<autoreconf> sequence is now enabled by default.  Please pass
B<--without autoreconf> to B<dh> if this is not desirable for a given
package

=item -

The B<systemd> sequence is now enabled by default.  Please pass
B<--without systemd> to B<dh> if this is not desirable for a given
package.

=item -

B<Retroactively removed>: B<dh> no longer creates the package build
directory when skipping running debhelper commands. This will not
affect packages that only build with debhelper commands, but it may
expose bugs in commands not included in debhelper.

This compatibility feature had a bug since its inception in
debhelper/9.20130516 that made it fail to apply in compat 9 and
earlier.  As there has been no reports of issues caused by this bug in
those ~5 years, this item have been removed rather than fixed.

=back

=item v9

Changes from v8 are:

=over 8

=item -

Multiarch support. In particular, B<dh_auto_configure> passes
multiarch directories to B<autoconf> in --libdir and --libexecdir.

=item -

dh is aware of the usual dependencies between targets in debian/rules.
So, "dh binary" will run any build, build-arch, build-indep, install,
etc targets that exist in the rules file. There's no need to define an
explicit binary target with explicit dependencies on the other targets.

=item -

B<dh_strip> compresses debugging symbol files to reduce the installed
size of -dbg packages.

=item -

B<dh_auto_configure> does not include the source package name
in --libexecdir when using B<autoconf>.

=item -

B<dh> does not default to enabling --with=python-support

(Obsolete: As the B<dh_pysupport> tool was removed from Debian
stretch.  Since debhelper/10.3, B<dh> no longer enables this sequence
add-on regardless of compat level)

=item -

All of the B<dh_auto_>I<*> debhelper programs and B<dh> set
environment variables listed by B<dpkg-buildflags>, unless
they are already set.

=item -

B<dh_auto_configure> passes B<dpkg-buildflags> CFLAGS, CPPFLAGS, and
LDFLAGS to perl F<Makefile.PL> and F<Build.PL>

=item -

B<dh_strip> puts separated debug symbols in a location based on their
build-id.

=item -

Executable debhelper config files are run and their output used as the
configuration.

=back

This mode is deprecated.

=item v8

Changes from v7 are:

=over 8

=item -

Commands will fail rather than warning when they are passed unknown options.

=item -

B<dh_makeshlibs> will run B<dpkg-gensymbols> on all shared libraries that it
generates shlibs files for. So B<-X> can be used to exclude libraries.
Also, libraries in unusual locations that B<dpkg-gensymbols> would not
have processed before will be passed to it, a behavior change that
can cause some packages to fail to build.

=item -

B<dh> requires the sequence to run be specified as the first parameter, and
any switches come after it. Ie, use "B<dh $@ --foo>", not "B<dh --foo $@>".

=item -

B<dh_auto_>I<*> prefer to use Perl's B<Module::Build> in preference to F<Makefile.PL>.

=back

This mode is deprecated.

=item v7

This mode is deprecated.

This is the lowest supported compatibility level.

If you are upgrading from an earlier compatibility level, please
review L<debhelper-obsolete-compat(7)>.

=back

=head1 SEE ALSO

=over 4

=item L<debhelper-obsolete-compat(7)>

Upgrading from a (now) obsolete compatibility level? This document covers the
upgrade checklist up to the earliest supported level.

=item L<debhelper(7)>

General information about the debhelper framework. This document also covers
how to declare your chosen debhelper compat level.

=back

=head1 AUTHORS

Niels Thykier <niels@thykier.net>

Joey Hess

=cut
