Fix (at least some of the) empty conflict explanations

ocaml · Jan 19, 2022 · 64cf433 · 64cf433
1 parent b77f6d4
commit 64cf433
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diff --git a/master_changes.md b/master_changes.md
@@ -160,6 +160,7 @@ users)
 ## Client
   * Check whether the repository might need updating more often [#4935 @kit-ty-kate]
   * ✘ It is no longer possible to process actions on packages that depend on a package that was removed upstream [#4969 @altgr]
+  * Fix (at least some of the) empty conflict explanations [#4982 @kit-ty-kate]
 
 ## Internal
   * Add license and lowerbounds to opam files [#4714 @kit-ty-kate]

diff --git a/src/solver/opamCudf.ml b/src/solver/opamCudf.ml
@@ -854,7 +854,10 @@ let extract_explanations packages cudfnv2opam reasons : explanation list =
               Map.update pkg (CS.union chain) CS.empty acc
             in
             let ds = get deps p in
-            let dsc = ds %% all_conflicting in
+            let dsc = match Hashtbl.length missing with
+              | 0 -> ds (* Hack to fix https://github.com/ocaml/opam/issues/4373. We should try to do better at some point *)
+              | _ -> ds %% all_conflicting
+            in
             if not (Set.is_empty dsc) then
               dsc ++ seen1, Set.fold append_to_chains (dsc -- seen1) new_chains
             else