dpkg-buildflags: support debian/buildflags

This file is for use by package maintainers. Since the call to
dpkg-buildflags might be hidden by packaging helpers, it's a good
idea to offer a simple way for package maintainers to extend
the set of flags returned. Otherwise each package helper must provide
its own way to extend the compilation flags.

debian/changelog

@@ -62,6 +62,9 @@ dpkg (1.16.1) UNRELEASED; urgency=low
     to be clearer. Closes: #608260
   * dpkg-buildpackage no longer exports the compiler flags. Closes: #560070
     Packages must directly call dpkg-buildflags to retrieve them.
+  * dpkg-buildflags parses a supplementary configuration file under the
+    control of the package maintainer: debian/buildflags (or the corresponding
+    architecture/os specific variants).
 
   [ Guillem Jover ]
   * Install deb-src-control(5) man pages in dpkg-dev. Closes: #620520

man/dpkg-buildflags.1

@@ -1,4 +1,4 @@
-.TH dpkg\-buildflags 1 "2010-07-29" "Debian Project" "dpkg suite"
+.TH dpkg\-buildflags 1 "2011-07-07" "Debian Project" "dpkg suite"
 .SH NAME
 dpkg\-buildflags \- returns build flags to use during package build
 .
@@ -19,6 +19,12 @@ for the current user with \fB$XDG_CONFIG_HOME/dpkg/buildflags.conf\fP
 where \fB$XDG_CONFIG_HOME\fP defaults to \fB$HOME/.config\fP;
 .IP 3.
 temporarily by the user with environment variables (see section \fBENVIRONMENT\fP).
+.IP 4.
+by the package maintainer with one of the following files (the first found
+is used): \fBdebian/buildflags.\fP\fIarch\fP, \fBdebian/buildflags.\fP\fIos\fP,
+\fBdebian/buildflags\fP. The \fIarch\fP substitution corresponds to the
+DEB_HOST_ARCH variable returned by \fBdpkg\-architecture\fP while \fIos\fP
+corresponds to DEB_HOST_ARCH_OS.
 .P
 The configuration files can contain two types of directives:
 .TP
@@ -107,6 +113,9 @@ System wide configuration file.
 .TP
 .BR $XDG_CONFIG_HOME/dpkg/buildflags.conf " or " $HOME/.config/dpkg/buildflags.conf
 User configuration file.
+.TP
+\fBdebian/buildflags.\fIarch\fP, \fBdebian/buildflags.\fIos\fP, \fBdebian/buildflags\fP
+Package maintainer configuration file.
 .SH ENVIRONMENT
 Those environment variables should not be set by official packages, they
 are meant for users who are recompiling a Debian package and would like to
@@ -121,7 +130,7 @@ This variable can be used to append supplementary options to the value
 returned for the given \fIflag\fP.
 .
 .SH AUTHOR
-Copyright \(co 2010 Rapha\[:e]l Hertzog
+Copyright \(co 2010-2011 Rapha\[:e]l Hertzog
 .sp
 This is free software; see the GNU General Public Licence version 2 or
 later for copying conditions. There is NO WARRANTY.

scripts/Dpkg/BuildFlags.pm

@@ -1,4 +1,4 @@
-# Copyright © 2010 Raphaël Hertzog <hertzog@debian.org>
+# Copyright © 2010-2011 Raphaël Hertzog <hertzog@debian.org>
 #
 # This program is free software; you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -18,11 +18,12 @@ package Dpkg::BuildFlags;
 use strict;
 use warnings;
 
-our $VERSION = "1.00";
+our $VERSION = "1.01";
 
 use Dpkg::Gettext;
 use Dpkg::BuildOptions;
 use Dpkg::ErrorHandling;
+use Dpkg::Path qw(find_build_file);
 use Dpkg::Vendor qw(run_vendor_hook);
 
 =encoding utf8
@@ -134,11 +135,26 @@ sub load_environment_config {
     }
 }
 
+=item $bf->load_package_config()
+
+Update flags based on directives stored in debian/buildflags
+and associated arch-specific variants.
+
+=cut
+
+sub load_package_config {
+    my ($self) = @_;
+    my $config = find_build_file("debian/buildflags");
+    if (defined $config) {
+        $self->update_from_conffile($config, undef);
+    }
+}
+
 =item $bf->load_config()
 
-Call successively load_system_config(), load_user_config() and
-load_environment_config() to update the default build flags
-defined by the vendor.
+Call successively load_system_config(), load_user_config(),
+load_environment_config() and load_package_config() to update the default
+build flags defined by the vendor.
 
 =cut
 
@@ -147,24 +163,26 @@ sub load_config {
     $self->load_system_config();
     $self->load_user_config();
     $self->load_environment_config();
+    $self->load_package_config();
 }
 
 =item $bf->set($flag, $value, $source)
 
-Update the build flag $flag with value $value and record its origin as $source.
+Update the build flag $flag with value $value and record its origin as
+$source (if defined).
 
 =cut
 
 sub set {
     my ($self, $flag, $value, $src) = @_;
     $self->{flags}->{$flag} = $value;
-    $self->{origin}->{$flag} = $src;
+    $self->{origin}->{$flag} = $src if defined $src;
 }
 
 =item $bf->append($flag, $value, $source)
 
 Append the options listed in $value to the current value of the flag $flag.
-Record its origin as $source.
+Record its origin as $source (if defined).
 
 =cut
 
@@ -175,7 +193,7 @@ sub append {
     } else {
         $self->{flags}->{$flag} = $value;
     }
-    $self->{origin}->{$flag} = $src;
+    $self->{origin}->{$flag} = $src if defined $src;
 }
 
 =item $bf->update_from_conffile($file, $source)
@@ -183,7 +201,7 @@ sub append {
 Update the current build flags based on the configuration directives
 contained in $file. See dpkg-buildflags(1) for the format of the directives.
 
-$source is the origin recorded for any build flag set or modified.
+If defined, $source is the origin recorded for any build flag set or modified.
 
 =cut
 
@@ -261,6 +279,13 @@ sub list {
 
 =back
 
+=head1 CHANGES
+
+=head2 Version 1.01
+
+New method: $bf->load_package_config(). This method is called last as part
+of load_config().
+
 =head1 AUTHOR
 
 Raphaël Hertzog <hertzog@debian.org>