solver3: Only hide ver->pkg clauses, not pkg->ver version selection ones

Particularly as Helmut pointed out we need to show which version we
selected for install if there is only one but there is a versioned
conflicts.

Reported-By: Helmut Grohne <helmut@subdivi.de> on IRC

3 files changed, 45 insertions, 6 deletions

diff --git a/apt-pkg/solver3.cc b/apt-pkg/solver3.cc
index cebface27..4030b9de1 100644
--- a/apt-pkg/solver3.cc
+++ b/apt-pkg/solver3.cc
@@ -249,8 +249,17 @@ std::string APT::Solver::Clause::toString(pkgCache &cache, bool pretty) const
 	 out.append(" | ");
       }
    }
-   else if (group == Group::SelectVersion && negative)
+   else if (pretty && group == Group::SelectVersion && negative)
       out.append(" conflicts with other versions of itself");
+   else if (pretty && group == Group::SelectVersion && reason.Pkg()) {
+      out.append(solutions.size() > 1 ? " is available in versions " : " is available in version ");
+      for (auto var : solutions) {
+	 assert(var.Ver());
+	 if (var != solutions.front())
+	    out.append(", ");
+	 out.append(var.Ver(cache).VerStr());
+      }
+   }
    else
    {
       out.append(" -> ");
@@ -349,8 +358,9 @@ std::string APT::Solver::LongWhyStr(Var var, bool decision, const Clause *rclaus
       }
    };
 
-   // Version selection clauses like pkg=ver -> pkg or pkg -> pkg=ver are irrelevant for the user, skip them
-   if (decision && rclause && rclause->group == Group::SelectVersion)
+   // Inverse version selection clauses that select the package if the version is selected,
+   // such as pkg=ver -> pkg, are irrelevant for the user, skip them
+   if (var.Pkg() && decision && rclause && rclause->group == Group::SelectVersion)
    {
       var = rclause->reason;
       rclause = (*this)[var].reason;
@@ -398,7 +408,7 @@ std::string APT::Solver::LongWhyStr(Var var, bool decision, const Clause *rclaus
    {
       auto const &state = (*this)[*it];
       // Don't print version selection clauses
-      if (state.reason && state.reason->group == Group::SelectVersion)
+      if (it->Pkg() && state.reason && state.reason->group == Group::SelectVersion)
       {
 	 --i;
 	 continue;
diff --git a/test/integration/test-bug-612557-garbage-upgrade b/test/integration/test-bug-612557-garbage-upgrade
index a001c4385..00bc9ac2d 100755
--- a/test/integration/test-bug-612557-garbage-upgrade
+++ b/test/integration/test-bug-612557-garbage-upgrade
@@ -23,9 +23,10 @@ testfailuremsg "E: Unable to satisfy dependencies. Reached two conflicting decis
       1. python-uno:i386=1:3.3.0-2 is selected as an upgrade
       2. python-uno:i386=1:3.3.0-2 Depends libreoffice-common
       3. libreoffice-common:i386 Conflicts openoffice.org-common
-   2. openoffice.org-common:i386 is selected for install because:
+   2. openoffice.org-common:i386=1:3.2.1-11+squeeze2 is selected for install because:
       1. openoffice.org-emailmerge:i386 is selected for install
-      2. openoffice.org-emailmerge:i386 PreDepends openoffice.org-common" aptget --trivial-only install python-uno --solver 3.0
+      2. openoffice.org-emailmerge:i386 PreDepends openoffice.org-common
+      3. openoffice.org-common:i386 is available in version 1:3.2.1-11+squeeze2" aptget --trivial-only install python-uno --solver 3.0
 testfailureequal 'Reading package lists...
 Building dependency tree...
 Reading state information...
diff --git a/test/integration/test-solver3-show-version-selection b/test/integration/test-solver3-show-version-selection
new file mode 100755
index 000000000..c4d23eccf
--- /dev/null
+++ b/test/integration/test-solver3-show-version-selection
@@ -0,0 +1,28 @@
+#!/bin/sh
+set -e
+
+TESTDIR="$(readlink -f "$(dirname "$0")")"
+. "$TESTDIR/framework"
+setupenvironment
+configarchitecture 'amd64' 's390x'
+
+insertpackage 'unstable' 'sbuild-build-depends-main-dummy' 's390x' '0.invalid.0' 'Depends: libgstreamer1.0-dev'
+insertpackage 'unstable' 'libgstreamer1.0-dev' 's390x' '1.25.90-2' 'Depends: libc6 (>= 2.34)'
+insertpackage 'unstable' 'libc6' 's390x' '14.2.0-17' 'Depends: libgcc-s1'
+insertpackage 'unstable' 'libgcc-s1' 's390x' '14.2.0-17' 'Multi-Arch: same'
+insertpackage 'installed,unstable' 'libgcc-s1' 'amd64' '14.2.0-18' 'Multi-Arch: same'
+
+setupaptarchive
+
+testfailuremsg "E: Unable to satisfy dependencies. Reached two conflicting decisions:
+   1. libc6:s390x is selected for install because:
+      1. sbuild-build-depends-main-dummy:s390x=0.invalid.0 is selected for install
+      2. sbuild-build-depends-main-dummy:s390x Depends libgstreamer1.0-dev:s390x
+      3. libgstreamer1.0-dev:s390x Depends libc6:s390x (>= 2.34)
+   2. libc6:s390x Depends libgcc-s1:s390x
+      but none of the choices are installable:
+      - libgcc-s1:s390x is not selected for install because:
+        1. libgcc-s1:amd64 is selected for install
+        2. libgcc-s1:amd64 is available in version 14.2.0-18
+        3. libgcc-s1:s390x Breaks libgcc-s1 (!= 14.2.0-17)" apt install sbuild-build-depends-main-dummy --solver 3.0
+