From 5b0af47d64862f58ec6663010b781c7cfb980b12 Mon Sep 17 00:00:00 2001
From: Paul Hebble <pjhebble@gmail.com>
Date: Tue, 10 Aug 2021 11:56:04 -0500
Subject: [PATCH] Don't prompt user to choose conflicting modules

---
 Core/Registry/AvailableModule.cs | 17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/Core/Registry/AvailableModule.cs b/Core/Registry/AvailableModule.cs
index 27b8aea111..51210617e5 100644
--- a/Core/Registry/AvailableModule.cs
+++ b/Core/Registry/AvailableModule.cs
@@ -131,10 +131,10 @@ private static bool DependsAndConflictsOK(CkanModule module, IEnumerable<CkanMod
                     }
                 }
             }
+            var othersMinusSelf = others.Where(m => m.identifier != module.identifier).Memoize();
             if (module.conflicts != null)
             {
                 // Skip self-conflicts (but catch other modules providing self)
-                var othersMinusSelf = others.Where(m => m.identifier != module.identifier).Memoize();
                 foreach (RelationshipDescriptor rel in module.conflicts)
                 {
                     // If any of the conflicts are present, fail
@@ -144,6 +144,21 @@ private static bool DependsAndConflictsOK(CkanModule module, IEnumerable<CkanMod
                     }
                 }
             }
+            // Check reverse conflicts so user isn't prompted to choose modules that will error out immediately
+            var selfArray = new CkanModule[] { module };
+            foreach (CkanModule other in othersMinusSelf)
+            {
+                if (other.conflicts != null)
+                {
+                    foreach (RelationshipDescriptor rel in other.conflicts)
+                    {
+                        if (rel.MatchesAny(selfArray, null, null))
+                        {
+                            return false;
+                        }
+                    }
+                }
+            }
             return true;
         }