dpkg-gencontrol: use the new Dpkg::Deps module to rewrite the dependencies

Normal dependency fields are rewritten by order of importance and simplified
by taking into account the dependencies already parsed. The dependencies are
also sorted to have a more predictable output (which is easier to compare in
a debdiff output).

The other relation (non-dependency) fields are simplified as unions
instead of intersections.

scripts/dpkg-gencontrol.pl

@@ -10,6 +10,7 @@ use Dpkg::Gettext;
 use Dpkg::ErrorHandling qw(warning error failure unknown internerr syserr
                            subprocerr usageerr);
 use Dpkg::Arch qw(get_host_arch debarch_eq debarch_is);
+use Dpkg::Deps qw(@pkg_dep_fields %dep_field_type);
 
 push(@INC,$dpkglibdir);
 require 'controllib.pl';
@@ -17,7 +18,6 @@ require 'controllib.pl';
 our %substvar;
 our (%f, %fi);
 our %p2i;
-our @pkg_dep_fields;
 our $sourcepackage;
 
 textdomain("dpkg-dev");
@@ -226,16 +226,43 @@ init_substvar_arch();
 # Process dependency fields in a second pass, now that substvars have been
 # initialized.
 
-for $_ (keys %fi) {
-    my $v = $fi{$_};
+my $facts = Dpkg::Deps::KnownFacts->new();
+$facts->add_installed_package($f{'Package'}, $f{'Version'});
+if (exists $fi{"C$myindex Provides"}) {
+    my $provides = Dpkg::Deps::parse(substvars($fi{"C$myindex Provides"}),
+                                     reduce_arch => 1, union => 1);
+    if (defined $provides) {
+	foreach my $subdep ($provides->get_deps()) {
+	    if ($subdep->isa('Dpkg::Deps::Simple')) {
+		$facts->add_provided_package($subdep->{package},
+                        $subdep->{relation}, $subdep->{version},
+                        $f{'Package'});
+	    }
+	}
+    }
+}
 
-    if (s/^C$myindex //) {
-        if (exists($pkg_dep_fields{$_})) {
-           my $dep = parsedep(substvars($v), 1, 1);
-            error(_g("error occurred while parsing %s"), $_)
-                unless defined $dep;
-            $f{$_}= showdep($dep, 0);
-        }
+my (@seen_deps);
+foreach my $field (@pkg_dep_fields) {
+    my $key = "C$myindex $field";
+    if (exists $fi{$key}) {
+	my $dep;
+	if ($dep_field_type{$field} eq 'normal') {
+	    $dep = Dpkg::Deps::parse(substvars($fi{$key}), use_arch => 1,
+                                     reduce_arch => 1);
+	    error(_g("error occurred while parsing %s"), $_) unless defined $dep;
+	    $dep->simplify_deps($facts, @seen_deps);
+	    # Remember normal deps to simplify even further weaker deps
+	    push @seen_deps, $dep if $dep_field_type{$field} eq 'normal';
+	} else {
+	    $dep = Dpkg::Deps::parse(substvars($fi{$key}), use_arch => 1,
+                                     reduce_arch => 1, union => 1);
+	    error(_g("error occurred while parsing %s"), $_) unless defined $dep;
+	    $dep->simplify_deps($facts);
+	}
+	$dep->sort();
+	$f{$field} = $dep->dump();
+	delete $f{$field} unless $f{$field}; # Delete empty field
     }
 }