Bug#647227: lintian: create separate tag for packages that could benefit from "build-arch"/"build-indep"

[Niels Thykier <niels@thykier.net>]

Package: lintian
Severity: wishlist
Tags: patch

Hi,

As I suggested in #629385, lintian could be used to detect packages
that could benefit from having the recommended build-arch and
build-indep packages.

The technical details are in the attached patch; though the tag
info (and possibly the name) could use some attention.

Also I am not sure it makes sense to make this an "important/possible"
tag.  For the purpose of finding the relevant packages to update/NMU
any severity would do.

~Niels

diff --git a/checks/rules b/checks/rules
index 0c88104..decdae0 100644
--- a/checks/rules
+++ b/checks/rules
@@ -110,6 +110,8 @@ sub run {
 my $pkg = shift;
 my $type = shift;
 my $info = shift;
+my $proc = shift;
+my $group = shift;
 
 my $rules = $info->debfiles('rules');
 
@@ -359,14 +361,28 @@ while (<RULES>) {
 close RULES;
 
 unless ($includes) {
+    my $rec = 0;
     # Make sure all the required rules were seen.
     for my $target (sort keys %required) {
         tag 'debian-rules-missing-required-target', $target
             unless $seen{$target};
     }
     for my $target (sort keys %recommended) {
-        tag 'debian-rules-missing-recommended-target', $target
-            unless $seen{$target};
+        unless ($seen{$target}) {
+            tag 'debian-rules-missing-recommended-target', $target;
+            $rec++;
+        }
+    }
+
+    if ($rec) {
+        my $all = 0;
+        my $notall = 0;
+        foreach my $p ($group->get_processables) {
+            next if $p->pkg_type eq 'source' or $p->pkg_type eq 'changes';
+            $all++ if $p->pkg_arch eq 'all';
+            $notall++ if $p->pkg_arch ne 'all';
+        }
+        tag 'package-would-benefit-from-build-arch-targets' if $all && $notall;
     }
 }
 
diff --git a/checks/rules.desc b/checks/rules.desc
index 99f73de..291cb62 100644
--- a/checks/rules.desc
+++ b/checks/rules.desc
@@ -212,3 +212,9 @@ Info: The rules files appear to be reading or modifying a variable not
  can be used by users, who wants to re-compile debian packages with
  special (or non-standard) build flags.
 
+Tag: package-would-benefit-from-build-arch-targets
+Severity: important
+Certainty: possible
+Ref: #629385, https://wiki.debian.org/ReleaseGoals/BuildArchTarget
+Info: Please add a build-arch and build-indep target.
+