From c94b507b92b3d833761f3e416d4d5bba709bf87f Mon Sep 17 00:00:00 2001
From: Julian Andres Klode <julian.klode@canonical.com>
Date: Thu, 15 Aug 2019 13:40:31 +0200
Subject: Add ?virtual pattern

This matches any package that does not have versions.
---
 apt-pkg/cachefilter-patterns.cc    | 2 ++
 apt-pkg/cachefilter-patterns.h     | 8 ++++++++
 doc/apt-patterns.7.xml             | 5 +++++
 test/integration/test-apt-patterns | 6 ++++++
 4 files changed, 21 insertions(+)

diff --git a/apt-pkg/cachefilter-patterns.cc b/apt-pkg/cachefilter-patterns.cc
index f078924ff..986faaf52 100644
--- a/apt-pkg/cachefilter-patterns.cc
+++ b/apt-pkg/cachefilter-patterns.cc
@@ -236,6 +236,8 @@ std::unique_ptr<APT::CacheFilter::Matcher> PatternParser::aPattern(std::unique_p
       return std::make_unique<APT::CacheFilter::TrueMatcher>();
    if (node->matches("?upgradable", 0, 0))
       return std::make_unique<Patterns::PackageIsUpgradable>(file);
+   if (node->matches("?virtual", 0, 0))
+      return std::make_unique<Patterns::PackageIsVirtual>();
    if (node->matches("?x-name-fnmatch", 1, 1))
       return std::make_unique<APT::CacheFilter::PackageNameMatchesFnmatch>(aWord(node->arguments[0]));
 
diff --git a/apt-pkg/cachefilter-patterns.h b/apt-pkg/cachefilter-patterns.h
index 993839425..d37da815f 100644
--- a/apt-pkg/cachefilter-patterns.h
+++ b/apt-pkg/cachefilter-patterns.h
@@ -221,6 +221,14 @@ struct PackageIsUpgradable : public PackageMatcher
       return Pkg->CurrentVer != 0 && (*Cache)[Pkg].Upgradable();
    }
 };
+
+struct PackageIsVirtual : public PackageMatcher
+{
+   bool operator()(pkgCache::PkgIterator const &Pkg) override
+   {
+      return Pkg->VersionList == 0;
+   }
+};
 } // namespace Patterns
 } // namespace Internal
 } // namespace APT
diff --git a/doc/apt-patterns.7.xml b/doc/apt-patterns.7.xml
index 2eda77b55..efd4293dc 100644
--- a/doc/apt-patterns.7.xml
+++ b/doc/apt-patterns.7.xml
@@ -99,6 +99,11 @@
      <varlistentry><term><code>?upgradable</code></term>
      <listitem><para>Selects packages that can be upgraded (have a newer candidate).</para></listitem>
      </varlistentry>
+     <varlistentry><term><code>?virtual</code></term>
+     <listitem><para>Selects all virtual packages; that is packages without a version.
+      These exist when they are referenced somewhere in the archive,
+      for example because something depends on that name.</para></listitem>
+     </varlistentry>
    </variablelist>
  </refsect1>
 
diff --git a/test/integration/test-apt-patterns b/test/integration/test-apt-patterns
index c75793e55..92c76edd1 100755
--- a/test/integration/test-apt-patterns
+++ b/test/integration/test-apt-patterns
@@ -161,6 +161,12 @@ testsuccessequal "Listing...
 not-obsolete/unstable 2.0 i386 [upgradable from: 1.0]
 N: There is 1 additional version. Please use the '-a' switch to see it" apt list '?upgradable'
 
+testsuccessequal "Package: does-not-exist
+State: not a real package (virtual)
+N: Can't select candidate version from package does-not-exist as it has no candidate
+N: Can't select versions from package 'does-not-exist' as it is purely virtual
+N: No packages found" apt show '?virtual'
+
 testsuccessequal "Listing..." apt list '?x-name-fnmatch(1)'
 testsuccessequal "Listing...
 automatic1/now 1.0 i386 [installed,local]
-- 
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