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Alien::Build::Manual::User3Contributed Perl DocumeAlien::Build::Manual::FAQ(3)

NAME
       Alien::Build::Manual::FAQ - Frequently Asked Questions about
       Alien::Build

VERSION
       version 2.37

SYNOPSIS
	perldoc	Alien::Build::Manual::FAQ

DESCRIPTION
       This document serves to answer the most frequently asked	questions made
       by developers creating Alien modules using Alien::Build.

QUESTIONS
   What	is Alien, Alien::Base and Alien::Build?
       Alien in	a Perl namespace for defining dependencies in CPAN for
       libraries and tools which are not "native" to CPAN.  For	a manifesto
       style description of the	Why, and How see Alien.	 Alien::Base is	a base
       class for the Alien runtime.  Alien::Build is a tool for	probing	the
       operating system	for existing libraries and tools, and downloading,
       building	and installing packages.  alienfile is a recipe	format for
       describing how to probe,	download, build	and install a package.

   How do I build a package that uses build system
       autoconf

       Use the autoconf	plugin (Alien::Build::Plugin::Build::Autoconf).	 If
       your package provides a pkg-config ".pc"	file, then you can also	use
       the PkgConfig plugin (Alien::Build::Plugin::PkgConfig::Negotiate).

	use alienfile
	plugin PkgConfig => 'libfoo';
	share {
	  start_url => 'http://example.org/dist';
	  plugin Download => (
	    version => qr/libfoo-([0-9\.])\.tar\.gz$/,
	  );
	  plugin Extract => 'tar.gz';
	  plugin 'Build::Autoconf';
	};

       If you need to provide custom flags to configure, you can do that too:

	share {
	  plugin 'Build::Autoconf';
	  build	[
	    '%{configure} --disable-shared --enable-foo',
	    '%{make}',
	    '%{make} install',
	  ];
	};

       If your package requires	GNU Make, use "%{gmake}" instead of "%{make}".

       autoconf-like

       If you see an error like	this:

	Unknown	option "--with-pic".

       It is because the autoconf plugin uses the "--with-pic" option by
       default,	since it makes sense most of the time, and autoconf usually
       ignores options that it does not	recognize.  Some autoconf style	build
       systems fail when they see an option that they do not recognize.	 You
       can turn	this behavior off for these packages:

	plugin 'Build::Autoconf' => (
	  with_pic => 0,
	);

       Another thing about the autoconf	plugin is that it uses "DESTDIR" to do
       a double	staged install.	 If you	see an error like "nothing was
       installed into destdir",	that means that	your package does not support
       "DESTDIR".  You should instead use the MSYS plugin and use a command
       sequence	to do the build	like this:

	share {
	  plugin 'Build::MSYS';
	  build	[
	    # explicitly running configure with	"sh" will make sure that
	    # it works on windows as well as UNIX.
	    'sh	configure --prefix=%{.install.prefix} --disable-shared',
	    '%{make}',
	    '%{make} install',
	  ];
	};

       CMake

       There is	an alien Alien::cmake3 that provides "cmake" 3.x or better (It
       is preferred to the older Alien::CMake).	 Though	it is recommended that
       you use the "cmake" (Alien::Build::Plugin::Build::CMake)	plugin instead
       of using	Alien::cmake3.

	use alienfile;

	share {
	  plugin 'Build::CMake';
	  build	[
	    # this is the default build	step, if you do	not specify one.
	    [ '%{cmake}',
		@{ meta->prop->{plugin_build_cmake}->{args} },
		# ... put extra	cmake args here	...
		'.'
	    ],
	    '%{make}',
	    '%{make} install',
	  ];
	};

       vanilla Makefiles

       Alien::Build provides a helper ("%{make}") for the "make" that is used
       by Perl and ExtUtils::MakeMaker (EUMM).	Unfortunately the "make"
       supported by Perl and EUMM on Windows ("nmake" and "dmake") are not
       widely supported	by most	open source projects.  (Thankfully recent
       perls and EUMM support GNU Make on windows now).

       You can use the "make" plugin (Alien::Build::Plugin::Build::Make) to
       tell the	Alien::Build system know which make the	project	that you are
       alienizing requires.

	plugin 'Build::Make' =>	'umake';
	# umake	makes %{make} either GNU Make or BSD Make on Unix and GNU Make on Windows.
	build {
	  build	[
	    # You can use the Perl config compiler and cflags using the	%{perl.config...} helper
	    [ '%{make}', 'CC=%{perl.config.cc}', 'CFLAGS=%{perl.config.cccdlflags} %{perl.config.optimize}' ],
	    [ '%{make}', 'install', 'PREFIX=%{.install.prefix}'	],
	  ],
	};

       Some open source	projects require GNU Make, and you can specify that,
       and Alien::gmake	will be	pulled in on platforms that do not already
       have it.

	plugin 'Build::Make' =>	'gmake';
	...

   How do I probe for a	package	that uses pkg-config
       Use the "pkg-config" plugin
       (Alien::Build::Plugin::PkgConfig::Negotiate):

	use alienfile;
	plugin 'PkgConfig' => (
	  pkg_name => 'libfoo',
	);

       It will probe for a system version of the library.  It will also	add
       the appropriate "version" "cflags" and "libs" properties	on either a
       "system"	or "share" install.

   How do I specify a minimum or exact version requirement for packages	that
       use pkg-config?
       The various pkg-config plugins all support atleast_version,
       exact_version and maximum_version fields, which have the	same meaning
       as the "pkg-config" command line	interface:

	use alienfile;

	plugin 'PkgConfig', pkg_name =>	foo, atleast_version =>	'1.2.3';

       or

	use alienfile;

	plugin 'PkgConfig', pkg_name =>	foo, exact_version => '1.2.3';

   How to create an Alien module for a packages	that do	not support pkg-
       config?
       Packages	that provide a configuration script

       Many packages provide a command that you	can use	to get the appropriate
       version,	compiler and linker flags.  For	those packages you can just
       use the commands	in your	alienfile.  Something like this:

	use alienfile;

	probe [	'foo-config --version' ];

	share {
	  ...

	  build	[
	    '%{make} PREFIX=%{.runtime.prefix}',
	    '%{amek} install PREFIX=%{.runtime.prefix}',
	  ];
	};

	gather [
	  [ 'foo-config', '--version', \'%{.runtime.version}' ],
	  [ 'foo-config', '--cflags',  \'%{.runtime.cflags}'  ],
	  [ 'foo-config', '--libs',    \'%{.runtime.libs}'    ],
	];

       Packages	that require a compile test

       Some packages just expect you do	know that "-lfoo" will work.  For
       those you can use the "cbuilder"	plugin
       (Alien::Build::Plugin::Probe::CBuilder.

	use alienfile;
	plugin 'Probe::CBuilder' => (
	  cflags => '-I/opt/libfoo/include',
	  libs	 => '-L/opt/libfoo/lib -lfoo',
	);

	share {
	  ...
	  gather sub {
	    my($build) = @_;
	    my $prefix = $build->runtime_prop->{prefix};
	    $build->runtime_prop->{cflags} = "-I$prefix/include	";
	    $build->runtime_prop->{libs}   = "-L$prefix/lib -lfoo ";
	  };
	}

       This plugin will	build a	small program with these flags and test	that
       it works.  (There are also options to provide a program that can	make
       simple tests to ensure the library works).  If the probe	works, it will
       set the compiler	and linker flags.  (There are also options for
       extracting the version from the test program).  If you do a share
       install you will	need to	set the	compiler and linker flags yourself in
       the gather step,	if you aren't using a build plugin that	will do	that
       for you.

   Can/Should I	write a	tool oriented Alien module?
       Certainly.  The original	intent was to provide libraries, but tools are
       also quite doable using the Alien::Build	toolset.  A good example of
       how to do this is Alien::nasm.  You will	want to	use the
       'Probe::CommandLine':

	use alienfile;

	plugin 'Probe::CommandLine' => (
	  command => 'gzip',
	);

   How do I test my package once it is built (before it	is installed)?
       Use Test::Alien.	 It has	extensive documentation, and integrates	nicely
       with Alien::Base.

   How do I patch packages that	need alterations?
       If you have a diff file you can use patch:

	use alienfile;

	probe sub { 'share' }; # replace with appropriate probe

	share {
	  ...
	  patch	[ '%{patch} -p1	< %{.install.patch}/mypatch.diff' ];
	  build	[ ... ]	;
	}

	...

       You can also patch using	Perl if	that is	easier:

	use alienfile;

	probe sub { 'share' };

	share {
	  ...
	  patch	sub {
	    my($build) = @_;
	    # make changes to source prior to build
	  };
	  build	[ ... ];
	};

   The flags that a plugin produces are	wrong!
       Sometimes, the compiler or linker flags that the	PkgConfig plugin comes
       up with are not quite right.  (Frequently this is actually because a
       package maintainer is providing a broken	".pc" file).  (Other plugins
       may also	have problems).	 You could replace the plugin's	"gather" step
       but a better way	is to provide a	subroutine callback to be called after
       the gather stage	is complete.  You can do this with the alienfile
       "after" directive:

	use alienfile;

	plugin 'PlgConfig' => 'libfoo';

	share {
	  ...
	  after	'gather' => sub	{
	    my($build) = @_;
	    $build->runtime_prop->{libs}	.= " -lbar";	    # libfoo also requires libbar
	    $build->runtime_prop->{libs_static}	.= " -lbar -lbaz";  # libfoo also requires libbaz under	static linkage
	  };
	};

       Sometimes you only need to do this on certain platforms.	 You can
       adjust the logic	based on $^O appropriately.

	use alienfile;

	plugin 'PlgConfig' => 'libfoo';

	share {
	  ...
	  after	'gather' => sub	{
	    my($build) = @_;
	    if($^O eq 'MSWin32') {
	      $build->runtime_prop->{libs} .= "	-lpsapi";
	    }
	  };
	};

   "cannot open	shared object file" trying to load XS
       The error looks something like this:

	t/acme_alien_dontpanic2.t ....... 1/?
	# Failed test 'xs'
	# at t/acme_alien_dontpanic2.t line 13.
	#   XSLoader failed
	#     Can't load '/home/cip/.cpanm/work/1581635869.456/Acme-Alien-DontPanic2-2.0401/_alien/tmp/test-alien-lyiQNX/auto/Test/Alien/XS/ Mod0/Mod0.so' for module Test::Alien::XS::Mod0: libdontpanic.so.0:	cannot open shared object file:	No such	file or	directory at /opt /perl/5.30.1/lib/5.30.1/x86_64-linux/DynaLoader.pm line 193.
	#  at /home/cip/perl5/lib/perl5/Test/Alien.pm line 414.
	# Compilation failed in	require	at /home/cip/perl5/lib/perl5/Test/Alien.pm line	414.
	# BEGIN	failed--compilation aborted at /home/cip/perl5/lib/perl5/Test/Alien.pm line 414.
	t/acme_alien_dontpanic2.t ....... Dubious, test	returned 1 (wstat 256, 0x100)
	Failed 1/6 subtests
	t/acme_alien_dontpanic2__ffi.t .. ok

       This error happened at test time	for the	Alien, but depending on	your
       environment and Alien it	might happen later and the actual diagnostic
       wording might vary.

       This is usually because your XS or Alien	tries to use dynamic libraries
       instead of dynamic libraries.  Please consult the section about dynamic
       vs. static libraries in Alien::Build::Manual::AlienAuthor.  The TL;DR
       is that Alien::Build::Plugin::Gather::IsolateDynamic might help.	 If
       you are the Alien author	and the	package	you are	alienizing doesn't
       have a static option you	can use	Alien::Role::Dino, but please note the
       extended	set of caveats!

   599 Internal	Exception errors downloading packages from the internet
	Alien::Build::Plugin::Fetch::HTTPTiny> 599 Internal Exception fetching http://dist.libuv.org/dist/v1.15.0
	Alien::Build::Plugin::Fetch::HTTPTiny> exception: IO::Socket::SSL 1.42 must be installed for https support
	Alien::Build::Plugin::Fetch::HTTPTiny> exception: Net::SSLeay 1.49 must	be installed for https support
	Alien::Build::Plugin::Fetch::HTTPTiny> An attempt at a SSL URL https was made, but your	HTTP::Tiny does	not appear to be able to use https.
	Alien::Build::Plugin::Fetch::HTTPTiny> Please see: https://metacpan.org/pod/Alien::Build::Manual::FAQ#599-Internal-Exception-errors-downloading-packages-from-the-internet
	error fetching http://dist.libuv.org/dist/v1.15.0: 599 Internal	Exception at /Users/ollisg/.perlbrew/libs/perl-5.26.0@test1/lib/perl5/Alien/Build/Plugin/Fetch/HTTPTiny.pm line	68.

       (Older versions of Alien::Build produced	a less verbose more confusing
       version of this diagnostic).

       TL;DR, instead of this:

	share {
	  start_url => 'http://example.org/dist';
	  ...
	};

       do this:

	share {
	  start_url => 'https://example.org/dist';
	};

       If the website is going to redirect to a	secure URL anyway.

       The "599	Internal Exception" indicates an "internal" exception from
       HTTP::Tiny and is not a real HTTP status	code or	error.	This could
       mean a number of	different problems, but	most frequently	indicates that
       a SSL request was made without the required modules (Net::SSLeay	and
       IO::Socket::SSL).  Normally the
       Alien::Build::Plugin::Download::Negotiate and
       Alien::Build::Plugin::Fetch::HTTPTiny will make sure that the
       appropriate modules are added to	your prerequisites for you if you
       specify a "https" URL.  Some websites allow an initial request from
       "http" but then redirect	to "https".  If	you can	it is better to
       specify "https",	if you cannot, then you	can instead use	the "ssl"
       property	on either of those two plugins.

   Network fetch is turned off
       If you get an error like	this:

	Alien::Build> install type share requested or detected,	but network fetch is turned off
	Alien::Build> see see https://metacpan.org/pod/Alien::Build::Manual::FAQ#Network-fetch-is-turned-off

       This is because your environment	is setup not to	install	aliens that
       require the network.  You can turn network fetch	back on	by setting
       "ALIEN_INSTALL_NETWORK" to true,	or by unsetting	it.  This environment
       variable	is designed for	environments that don't	ever want to install
       aliens that require downloading source packages over the	internet.

   I would really prefer you not download stuff	off the	internet
       The idea	of Alien is to download	missing	packages and build them
       automatically to	make installing	easier.	 Some people may not like
       this, or	may even have security requirements that they not download
       random package over the internet	(caveat, downloading random stuff off
       of CPAN may not be any safer, so	make sure you audit all	of the open
       source software that you	use appropriately).  Another reason you	may
       not want	to download from the internet is if you	are packaging up an
       alien for an operating system vendor, which will	always want to use the
       system version of a library.  In	that situation you don't want
       Alien::Build to go off and download something from the internet because
       the probe failed	for some reason.

       This is easy to take care of, simply set	"ALIEN_INSTALL_TYPE" to
       "system"	and a build from source	code will never	be attempted.  On
       systems that do not provide system versions of the library or tool you
       will get	an error, allowing you to install the library, and retry the
       alien install.  You can also set	the environment	variable on just some
       aliens.

	% export ALIEN_INSTALL_TYPE=system  # for everyone

	% env ALIEN_INSTALL_TYPE=system	cpanm -v Alien::libfoo

   For testing I would like to test both system	and share installs!
       You can use the "ALIEN_INSTALL_TYPE" environment	variable.  It will
       force either a "share" or "system" install depending on how it is set.
       For travis you can do something like this:

	env:
	  matrix:
	    - ALIEN_INSTALL_TYPE=share
	    - ALIEN_INSTALL_TYPE=system

   How do I use	Alien::Build from Dist::Zilla?
       For creating Alien::Base	and Alien::Build based dist from Dist::Zilla
       you can use the dzil plugin Dist::Zilla::Plugin::AlienBuild.

   Cannot find either a	share directory	or a ConfigData	module
       If you see an error like	this:

	Cannot find either a share directory or	a ConfigData module for	Alien::libfoo.
	(Alien::libfoo loaded from lib/Alien/libfoo.pm)
	Please see https://metacpan.org/pod/distribution/Alien-Build/lib/Alien/Build/Manual/FAQ.pod#Cannot-find-either-a-share-directory-or-a-ConfigData-module
	Can't locate Alien/libfoo/ConfigData.pm	in @INC	(you may need to install the Alien::libfoo::ConfigData module) (@INC contains: ...)

       it means	you are	trying to use an Alien that hasn't been	properly
       installed.  An Alien::Base based	Alien needs to have either the share
       directory build during the install process or for older legacy
       Alien::Base::ModuleBuild	based Aliens, a	ConfigData module generated by
       Module::Build.

       This usually happens if you try to use an Alien module from the lib
       directory as part of the	Alien's	distribution.  You need	to build the
       alien and use "blib/lib"	instead	of "lib" or install the	alien and use
       the installed path.

       It is also possible that	your Alien installer is	not set	up correctly.
       Make sure your "Makefile.PL" is using Alien::Build::MM correctly.

   I have a question not listed	here!
       There are a number of forums available to people	working	on Alien,
       Alien::Base and Alien::Build modules:

       "#native" on irc.perl.org
	   This	is intended for	native interfaces in general so	is a good
	   place for questions about Alien generally or	Alien::Base and
	   Alien::Build	specifically.

       mailing list
	   The "perl5-alien" google group is intended for Alien	issues
	   generally, including	Alien::Base and	Alien::Build.

	   <https://groups.google.com/forum/#!forum/perl5-alien>

       Open a support ticket
	   If you have an issue	with Alie::Build itself, then please open a
	   support ticket on the project's GitHub issue	tracker.

	   <https://github.com/plicease/Alien-Build/issues>

SEE ALSO
       Alien::Build, Alien::Build::MM, Alien::Build::Plugin, alienfile

AUTHOR
       Author: Graham Ollis <plicease@cpan.org>

       Contributors:

       Diab Jerius (DJERIUS)

       Roy Storey (KIWIROY)

       Ilya Pavlov

       David Mertens (run4flat)

       Mark Nunberg (mordy, mnunberg)

       Christian Walde (Mithaldu)

       Brian Wightman (MidLifeXis)

       Zaki Mughal (zmughal)

       mohawk (mohawk2,	ETJ)

       Vikas N Kumar (vikasnkumar)

       Flavio Poletti (polettix)

       Salvador	FandiA+-o (salva)

       Gianni Ceccarelli (dakkar)

       Pavel Shaydo (zwon, trinitum)

       Kang-min	Liu (aao.ae<degree>, gugod)

       Nicholas	Shipp (nshp)

       Juan JuliA!n Merelo GuervA^3s (JJ)

       Joel Berger (JBERGER)

       Petr Pisar (ppisar)

       Lance Wicks (LANCEW)

       Ahmad Fatoum (a3f, ATHREEF)

       JosA(C) JoaquAn Atria (JJATRIA)

       Duke Leto (LETO)

       Shoichi Kaji (SKAJI)

       Shawn Laffan (SLAFFAN)

       Paul Evans (leonerd, PEVANS)

       HAYkon HA|gland (hakonhagland, HAKONH)

COPYRIGHT AND LICENSE
       This software is	copyright (c) 2011-2020	by Graham Ollis.

       This is free software; you can redistribute it and/or modify it under
       the same	terms as the Perl 5 programming	language system	itself.

perl v5.32.1			  2020-11-02	  Alien::Build::Manual::FAQ(3)

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