Use roslyn API to display extended completion and fix quirks with scripts/top of file (dotnet#9165)

* Use roslyn API to show unopened namespace in extended completion

* Properly add open decls when at the top of a file

Author: cartermp

Common/RoslynHelpers.fs

@@ -187,19 +187,30 @@ module internal OpenDeclarationHelper =
 
         let getLineStr line = sourceText.Lines.[line].ToString().Trim()
         let pos = ParsedInput.adjustInsertionPoint getLineStr ctx
-        let docLine = pos.Line - 1
+        let docLine = Line.toZ pos.Line
         let lineStr = (String.replicate pos.Column " ") + "open " + ns
-        let sourceText = sourceText |> insert docLine lineStr
+
+        // If we're at the top of a file (e.g., F# script) then add a newline before adding the open declaration
+        let sourceText =
+            if docLine = 0 then
+                sourceText
+                |> insert docLine Environment.NewLine
+                |> insert docLine lineStr
+            else
+                sourceText |> insert docLine lineStr
+
         // if there's no a blank line between open declaration block and the rest of the code, we add one
         let sourceText = 
             if sourceText.Lines.[docLine + 1].ToString().Trim() <> "" then 
                 sourceText |> insert (docLine + 1) ""
             else sourceText
+
         let sourceText =
             // for top level module we add a blank line between the module declaration and first open statement
             if (pos.Column = 0 || ctx.ScopeKind = ScopeKind.Namespace) && docLine > 0
                 && not (sourceText.Lines.[docLine - 1].ToString().Trim().StartsWith "open") then
                     sourceText |> insert docLine ""
             else sourceText
+
         sourceText, minPos |> Option.defaultValue 0
 

Completion/CompletionProvider.fs

@@ -143,10 +143,10 @@ type internal FSharpCompletionProvider
 
             declarationItems |> Array.iteri (fun number declarationItem ->
                 let glyph = Tokenizer.FSharpGlyphToRoslynGlyph (declarationItem.Glyph, declarationItem.Accessibility)
-                let name =
+                let namespaceName =
                     match declarationItem.NamespaceToOpen with
-                    | Some namespaceToOpen -> sprintf "%s (open %s)" declarationItem.Name namespaceToOpen
-                    | _ -> declarationItem.Name
+                    | Some namespaceToOpen -> namespaceToOpen
+                    | _ -> null // Icky, but this is how roslyn handles it
 
                 let filterText =
                     match declarationItem.NamespaceToOpen, declarationItem.Name.Split '.' with
@@ -157,8 +157,14 @@ type internal FSharpCompletionProvider
                     | _, idents -> Array.last idents
 
                 let completionItem = 
-                    FSharpCommonCompletionItem.Create(name, null, rules = getRules intellisenseOptions.ShowAfterCharIsTyped, glyph = Nullable glyph, filterText = filterText)
-                                        .AddProperty(FullNamePropName, declarationItem.FullName)
+                    FSharpCommonCompletionItem.Create(
+                        declarationItem.Name,
+                        null,
+                        rules = getRules intellisenseOptions.ShowAfterCharIsTyped,
+                        glyph = Nullable glyph,
+                        filterText = filterText,
+                        inlineDescription = namespaceName)
+                        .AddProperty(FullNamePropName, declarationItem.FullName)
 
                 let completionItem =
                     match declarationItem.Kind with
@@ -167,7 +173,7 @@ type internal FSharpCompletionProvider
                     | _ -> completionItem
 
                 let completionItem =
-                    if name <> declarationItem.NameInCode then
+                    if declarationItem.Name <> declarationItem.NameInCode then
                         completionItem.AddProperty(NameInCodePropName, declarationItem.NameInCode)
                     else completionItem