Dpkg::Vendor::Debian: Add support for a reproducible feature area

Signed-off-by: Guillem Jover <guillem@debian.org>

debian/changelog

@@ -45,6 +45,8 @@ dpkg (1.17.14) UNRELEASED; urgency=low
       build flags propagation. Closes: #628516
   * Pass DEB_BUILD_OPTIONS to dpkg-buildflags in buildflags.mk, required to
     get noopt to work at all, for example.
+  * Add a new dpkg-buildflags reproducible feature area:
+    Thanks to Paul Wise <pabs@debian.org>. Closes: #762683
 
   [ Raphaël Hertzog ]
   * Explain better in deb-triggers(5) why interest/activate-noawait should be

man/dpkg-buildflags.1

@@ -135,8 +135,8 @@ the flag is set/modified by an environment-specific configuration.
 .TP
 .BI \-\-query\-features " area"
 Print the features enabled for a given area. The only currently recognized
-areas are \fBqa\fP and \fBhardening\fP, see the \fBFEATURE AREAS\fP section
-for more details.
+areas are \fBqa\fP, \fBreproducible\fP and \fBhardening\fP,
+see the \fBFEATURE AREAS\fP section for more details.
 Exits with 0 if the area is known otherwise exits with 1.
 .IP
 The output is in RFC822 format, with one section per feature.
@@ -338,6 +338,11 @@ architectures (most notably i386) can see performance losses of up to
 15% in very text-segment-heavy application workloads; most workloads
 see less than 1%. Architectures with more general registers (e.g. amd64)
 do not see as high a worst-case penalty.
+.SS Reproducibility
+The compile-time options detailed below can be used to help improve
+build reproducibility or provide additional warning messages during
+compilation. Except as noted below, these are enabled by default for
+architectures that support them.
 .
 .SH ENVIRONMENT
 There are 2 sets of environment variables doing the same operations, the

scripts/Dpkg/Vendor/Debian.pm

@@ -68,6 +68,7 @@ sub run_hook {
 	}
     } elsif ($hook eq 'update-buildflags') {
 	$self->_add_qa_flags(@params);
+	$self->_add_reproducible_flags(@params);
 	$self->_add_hardening_flags(@params);
     } else {
         return $self->SUPER::run_hook($hook, @params);
@@ -145,6 +146,22 @@ sub _add_qa_flags {
     }
 }
 
+sub _add_reproducible_flags {
+    my ($self, $flags) = @_;
+
+    # Default feature states.
+    my %use_feature = (
+    );
+
+    # Adjust features based on user or maintainer's desires.
+    $self->_parse_feature_area('reproducible', \%use_feature);
+
+    # Store the feature usage.
+    while (my ($feature, $enabled) = each %use_feature) {
+       $flags->set_feature('reproducible', $feature, $enabled);
+    }
+}
+
 sub _add_hardening_flags {
     my ($self, $flags) = @_;
     my $arch = get_host_arch();