Deperecate a symbol only when the history of version matches.

When merging symbols in a SymbolFile, a symbol is deprecated when it has
disappeared from the new set of symbols. However when the new set of
symbols dates back to before the current one, deprecating doesn't make
sense. This patch corrects this behaviour. Also add a test to verify that
symbols got correctly marked as deprecated.

scripts/Dpkg/Shlibs/SymbolFile.pm

@@ -223,10 +223,14 @@ sub merge_symbols {
     }
 
     # Scan all symbols in the file and mark as deprecated those that are
-    # no more provided
+    # no more provided (only if the minver is bigger than the version where
+    # the symbol was introduced)
     foreach my $sym (keys %{$self->{objects}{$soname}{syms}}) {
 	if (! exists $dynsyms{$sym}) {
-	    $self->{objects}{$soname}{syms}{$sym}{deprecated} = $minver;
+	    my $info = $self->{objects}{$soname}{syms}{$sym};
+	    if (vercmp($minver, $info->{minver}) > 0) {
+		$self->{objects}{$soname}{syms}{$sym}{deprecated} = $minver;
+	    }
 	}
     }
 }
@@ -256,11 +260,13 @@ sub get_dependency {
 }
 
 sub lookup_symbol {
-    my ($self, $name, $sonames) = @_;
+    my ($self, $name, $sonames, $inc_deprecated) = @_;
+    $inc_deprecated = 0 unless defined($inc_deprecated);
     foreach my $so (@{$sonames}) {
 	next if (! exists $self->{objects}{$so});
 	if (exists $self->{objects}{$so}{syms}{$name} and
-	    not $self->{objects}{$so}{syms}{$name}{deprecated})
+	    ($inc_deprecated or not
+	    $self->{objects}{$so}{syms}{$name}{deprecated}))
 	{
 	    my $dep_id = $self->{objects}{$so}{syms}{$name}{dep_id};
 	    return {

scripts/t/200_Dpkg_Shlibs.t

@@ -1,6 +1,6 @@
 # -*- mode: cperl;-*-
 
-use Test::More tests => 25;
+use Test::More tests => 26;
 
 use strict;
 use warnings;
@@ -79,6 +79,10 @@ ok( $sym_file_old->has_lost_symbols($sym_file), 'has lost symbols' );
 is( $sym_file_old->lookup_symbol('__bss_start@Base', ['libc.so.6']),
     undef, 'internal symbols are blacklisted');
 
+$sym = $sym_file->lookup_symbol('_errno@GLIBC_2.0', ['libc.so.6'], 1);
+is_deeply($sym, { 'minver' => '2.3.6.ds1-13', 'dep_id' => 0, 
+		  'deprecated' => '2.6-1', 'depends' => '', 
+		  'soname' => 'libc.so.6' }, 'deprecated symbol');
 
 use File::Temp;