Fix bugs with autoremove

- restriction to the cone of mentionned packages was broken
- the command could cause conflicts in the case of orphan packages; when we only
  do removals that won't lead to rebuilds, as is the case with autoremove
  without argument, we can actually just ignore orphans (with argument, only
  keep orphans within the reverse dep cone, as usual).

Author: AltGr

Diff for: .ocamlinit

@@ -1,4 +1,5 @@
 #use "topfind";;
+#use "down.top";;
 #require "opam-client";;
 
 OpamClientConfig.opam_init ();;

Diff for: master_changes.md

@@ -19,7 +19,8 @@ New option/command/subcommand are prefixed with ◈.
   * The stdout of `pre-` and `post-session` hooks is now propagated to the user [#4382 @AltGr - fix #4359]
 
 ## Remove
-  *
+  * Fix `opam remove --autoremove <PKG>` to not autoremove unrelated packages
+  * Fix cases where `opam remove -a` could trigger conflicts in the presence of orphan packages
 
 ## Switch
   * Fix `--update-invariant` when removing or changing package name [#4360 @AltGr - fix #4353]

Diff for: src/client/opamClient.ml

@@ -1261,10 +1261,10 @@ let remove_t ?ask ~autoremove ~force atoms t =
     (slog OpamFormula.string_of_atoms) atoms;
 
   let t, full_orphans, orphan_versions =
-    let changes =
-      if autoremove then None
-      else Some (OpamSwitchState.packages_of_atoms t atoms) in
-    orphans ?changes t
+    if atoms = [] then t, OpamPackage.Set.empty, OpamPackage.Set.empty
+    else
+    let changes = OpamSwitchState.packages_of_atoms t atoms in
+    orphans ~changes t
   in
 
   let nothing_to_do = ref true in
@@ -1306,7 +1306,7 @@ let remove_t ?ask ~autoremove ~force atoms t =
     let to_keep =
       (if autoremove then t.installed_roots %% t.installed else t.installed)
       ++ universe.u_base
-      -- to_remove -- full_orphans -- orphan_versions
+      -- to_remove
     in
     let to_keep =
       OpamSolver.dependencies ~build:true ~post:true
@@ -1318,10 +1318,10 @@ let remove_t ?ask ~autoremove ~force atoms t =
     let requested = OpamPackage.names_of_packages packages in
     let to_remove =
       if autoremove then
-        let to_remove = t.installed -- to_keep in
-        if atoms = [] then to_remove
+        let to_remove1 = t.installed -- to_keep in
+        if atoms = [] then to_remove1
         else (* restrict to the dependency cone of removed pkgs *)
-          to_remove %%
+          to_remove1 %%
           (OpamSolver.dependencies ~build:true ~post:true
              ~depopts:true ~installed:true universe to_remove)
       else to_remove in

Diff for: src/state/opamSwitchState.ml

@@ -314,7 +314,6 @@ let load lock_kind gt rt switch =
   let opams =
     OpamPackage.Map.union (fun _ x -> x) repos_package_index pinned_opams
   in
-  let packages = OpamPackage.keys opams in
   let available_packages =
     lazy (compute_available_packages gt switch switch_config
             ~pinned ~opams)
@@ -324,6 +323,7 @@ let load lock_kind gt rt switch =
        computing availability *)
     OpamPackage.Map.union (fun _ x -> x) installed_opams opams
   in
+  let packages = OpamPackage.keys opams in
   let installed_without_def =
     OpamPackage.Set.fold (fun nv nodef ->
         if OpamPackage.Map.mem nv installed_opams then nodef else