Dedupe opens

Author: brianrourkeboll

src/Compiler/Service/ServiceAnalysis.fs

@@ -278,7 +278,7 @@ module UnusedOpens =
 
     /// Filter out the open statements whose contents are referred to somewhere in the symbol uses.
     /// Async to allow cancellation.
-    let filterOpenStatements (symbolUses1: FSharpSymbolUse[], symbolUses2: FSharpSymbolUse[]) openStatements =
+    let filterOpenStatements (symbolUses1: FSharpSymbolUse[], symbolUses2: FSharpSymbolUse[]) (openStatements: OpenStatement[]) =
         async {
             // the key is a namespace or module, the value is a list of FSharpSymbolUse range of symbols defined in the
             // namespace or module. So, it's just symbol uses ranges grouped by namespace or module where they are _defined_.
@@ -297,17 +297,13 @@ module UnusedOpens =
                     | _ -> ()
                 | _ -> ()
 
-            // We want to check them from last to first.
-            // See https://github.com/dotnet/fsharp/issues/16226
-            let reversedOpenStatements = openStatements |> List.ofArray |> List.rev
+            let openStatements =
+                openStatements
+                |> List.ofArray
+                |> List.distinctBy (_.OpenedGroups >> List.map (_.OpenedModules >> Array.map _.Entity))
 
             let! results =
-                filterOpenStatementsIncremental
-                    symbolUses2
-                    symbolUsesRangesByDeclaringEntity
-                    reversedOpenStatements
-                    (Dictionary(entityHash))
-                    []
+                filterOpenStatementsIncremental symbolUses2 symbolUsesRangesByDeclaringEntity openStatements (Dictionary(entityHash)) []
 
             return results |> List.map (fun os -> os.Range)
         }