Known-bad candidate versions are not an upgrade option

If we have a negative dependency to deal with we prefer to install an
upgrade rather than remove the current version. That is why we split the
method rather explicitly in two in 57df273 but there is a case we didn't
react to: If we have seen the candidate before as a "satisfier" of this
negative dependency there is no point in trying to upgrade to it later
on. We keep that info by candidate discard if we can, but even if we
can't we can at least keep that info around locally.

This "fixes" (or would hide) the problem described in 04a020d as well as
you don't have to discard installations you never make.

1 files changed, 9 insertions, 1 deletions

diff --git a/apt-pkg/depcache.cc b/apt-pkg/depcache.cc
index 02a80b2e8..39e30a38d 100644
--- a/apt-pkg/depcache.cc
+++ b/apt-pkg/depcache.cc
@@ -1221,6 +1221,7 @@ static bool MarkInstall_RemoveConflictsIfNotUpgradeable(pkgDepCache &Cache, bool
       If the candidate is effected try to keep current and discard candidate
       If the current is effected try upgrading to candidate or remove it */
    bool failedToRemoveSomething = false;
+   APT::PackageVector badCandidate;
    for (auto const &D : toRemove)
    {
       for (auto const &Ver : getAllPossibleSolutions(Cache, D, D, APT::CacheSetHelper::CANDIDATE, true))
@@ -1241,6 +1242,8 @@ static bool MarkInstall_RemoveConflictsIfNotUpgradeable(pkgDepCache &Cache, bool
 	       if (Pkg->CurrentVer == 0)
 		  Cache.MarkProtected(Pkg);
 	    }
+	    else
+	       badCandidate.push_back(Pkg);
 	 }
 	 else if (not MarkInstall_MarkDeleteForNotUpgradeable(Cache, DebugAutoInstall, PV, Depth, Pkg, propagateProctected))
 	 {
@@ -1249,11 +1252,14 @@ static bool MarkInstall_RemoveConflictsIfNotUpgradeable(pkgDepCache &Cache, bool
 	       break;
 	 }
       }
+      if (failedToRemoveSomething && not propagateProctected && not FromUser)
+	 break;
       for (auto const &Ver : getAllPossibleSolutions(Cache, D, D, APT::CacheSetHelper::INSTALLED, true))
       {
 	 auto const Pkg = Ver.ParentPkg();
 	 auto &State = Cache[Pkg];
-	 if (State.CandidateVer != Ver && State.CandidateVer != nullptr)
+	 if (State.CandidateVer != Ver && State.CandidateVer != nullptr &&
+	     std::find(badCandidate.cbegin(), badCandidate.cend(), Pkg) == badCandidate.end())
 	    toUpgrade.push_back(Pkg);
 	 else if (not MarkInstall_MarkDeleteForNotUpgradeable(Cache, DebugAutoInstall, PV, Depth, Pkg, propagateProctected))
 	 {
@@ -1262,6 +1268,8 @@ static bool MarkInstall_RemoveConflictsIfNotUpgradeable(pkgDepCache &Cache, bool
 	       break;
 	 }
       }
+      if (failedToRemoveSomething && not propagateProctected && not FromUser)
+	 break;
    }
    toRemove.clear();
    return not failedToRemoveSomething;