Stop using polymorphic comparison when comparing switch_selections

master_changes.md

@@ -107,6 +107,7 @@ users)
 ## Shell
 
 ## Internal
+  * Stop using polymorphic comparison when comparing `OpamTypes.switch_selections` [#6102 @kit-ty-kate]
 
 ## Internal: Windows
 
@@ -151,5 +152,6 @@ users)
 ## opam-solver
 
 ## opam-format
+  * Add `OpamTypesBase.switch_selections_{compare,equal}`: proper comparison functions for `OpamTypes.switch_selections` [#6102 @kit-ty-kate]
 
 ## opam-core

src/format/opamTypesBase.ml

@@ -332,3 +332,16 @@ let string_of_path_format = function
 let char_of_separator = function
   | SSemiColon -> ';'
   | SColon -> ':'
+
+let switch_selections_compare x
+    {sel_installed; sel_roots; sel_compiler; sel_pinned} =
+  let cmp = OpamPackage.Set.compare x.sel_installed sel_installed in
+  if cmp <> 0 then cmp else
+    let cmp = OpamPackage.Set.compare x.sel_roots sel_roots in
+    if cmp <> 0 then cmp else
+      let cmp = OpamPackage.Set.compare x.sel_compiler sel_compiler in
+      if cmp <> 0 then cmp else
+        OpamPackage.Set.compare x.sel_pinned sel_pinned
+
+let switch_selections_equal x y =
+  switch_selections_compare x y = 0

src/format/opamTypesBase.mli

@@ -112,3 +112,8 @@ val raw_of_op: euok_writeable env_update_op_kind -> OpamParserTypes.FullPos.env_
 (* Path transformers & separator functions *)
 val string_of_path_format: path_format -> string
 val char_of_separator: separator -> char
+
+(** Comparators **)
+(* Switch selections *)
+val switch_selections_compare : switch_selections -> switch_selections -> int
+val switch_selections_equal : switch_selections -> switch_selections -> bool

src/state/opamSwitchAction.ml

@@ -188,7 +188,10 @@ let update_switch_state ?installed ?installed_roots ?reinstall ?pinned st =
   in
   let st = { st with compiler_packages } in
   if not OpamStateConfig.(!r.dryrun) then (
-    if OpamSwitchState.selections st <> old_selections then write_selections st;
+    if not (OpamTypesBase.switch_selections_equal
+              (OpamSwitchState.selections st)
+              old_selections) then
+      write_selections st;
     if not (OpamPackage.Set.equal reinstall0 reinstall) then
       OpamFile.PkgList.write
         (OpamPath.Switch.reinstall st.switch_global.root st.switch)

src/state/opamUpdate.ml

@@ -464,7 +464,7 @@ let dev_packages st ?autolock ?(working_dir=OpamPackage.Set.empty) packages =
   (* The following is needed for pinned packages that may have changed
      version *)
   let selections1 = OpamSwitchState.selections st in
-  if selections0 <> selections1 then
+  if not (OpamTypesBase.switch_selections_equal selections0 selections1) then
     OpamFile.SwitchSelections.write
       (OpamPath.Switch.selections st.switch_global.root st.switch)
       selections1;