Ignore expression code fix

.editorconfig

@@ -23,3 +23,6 @@ fsharp_max_array_or_list_width=80
 fsharp_max_dot_get_expression_width=80
 fsharp_max_function_binding_width=80
 fsharp_max_value_binding_width=80
+
+[src/FsAutoComplete/CodeFixes/*.fs]
+fsharp_experimental_keep_indent_in_branch = true

src/FsAutoComplete/CodeFixes/IgnoreExpression.fs

@@ -0,0 +1,96 @@
+module FsAutoComplete.CodeFix.IgnoreExpression
+
+open FSharp.Compiler.Syntax
+open FSharp.Compiler.SyntaxTrivia
+open FSharp.Compiler.Text
+open FSharp.UMX
+open FsToolkit.ErrorHandling
+open Ionide.LanguageServerProtocol.Types
+open FsAutoComplete.CodeFix.Types
+open FsAutoComplete
+open FsAutoComplete.LspHelpers
+
+let title = "Ignore expression"
+
+let fix (getParseResultsForFile: GetParseResultsForFile) : CodeFix =
+  Run.ifDiagnosticByCode (set [ "20" ]) (fun diagnostic (codeActionParams: CodeActionParams) ->
+    asyncResult {
+      let fileName = codeActionParams.TextDocument.GetFilePath() |> Utils.normalizePath
+      let fcsPos = protocolPosToPos codeActionParams.Range.Start
+      let mDiag = protocolRangeToRange (UMX.untag fileName) diagnostic.Range
+
+      // Only do single line for now
+      if mDiag.StartLine <> mDiag.EndLine then
+        return []
+      else
+
+      let! (parseAndCheckResults: ParseAndCheckResults, _line: string, sourceText: IFSACSourceText) =
+        getParseResultsForFile fileName fcsPos
+
+      let mExprOpt =
+        (fcsPos, parseAndCheckResults.GetParseResults.ParseTree)
+        ||> ParsedInput.tryPick (fun path node ->
+          match node with
+          | SyntaxNode.SynExpr(e) when Range.equals mDiag e.Range -> Some(path, e)
+          | _ -> None)
+
+      match mExprOpt with
+      | None -> return []
+      | Some(path, expr) ->
+
+      let needsParentheses =
+        // expr |> ignore
+        let exprInPipe =
+          let lineNumber = expr.Range.StartLine
+
+          let mkRangeInFile (offset: int) (length: int) : range =
+            Range.mkRange
+              expr.Range.FileName
+              (Position.mkPos lineNumber (expr.Range.EndColumn + offset))
+              (Position.mkPos lineNumber (expr.Range.EndColumn + offset + length))
+
+          let mPipe = mkRangeInFile 2 2
+          let mIgnore = mkRangeInFile 5 6
+
+          SynExpr.App(
+            ExprAtomicFlag.NonAtomic,
+            false,
+            SynExpr.App(
+              ExprAtomicFlag.NonAtomic,
+              true,
+              SynExpr.LongIdent(
+                false,
+                SynLongIdent(
+                  [ FSharp.Compiler.Syntax.Ident("op_PipeRight", mPipe) ],
+                  [],
+                  [ Some(IdentTrivia.OriginalNotation "|>") ]
+                ),
+                None,
+                mPipe
+              ),
+              expr, // The expr that will now be piped into ignore.
+              Range.unionRanges expr.Range mPipe
+            ),
+            SynExpr.Ident(FSharp.Compiler.Syntax.Ident("ignore", mIgnore)),
+            Range.unionRanges expr.Range mIgnore
+          )
+
+        SynExpr.shouldBeParenthesizedInContext sourceText.GetLineString path exprInPipe
+
+      let newText =
+        let currentText = sourceText.GetSubTextFromRange expr.Range
+
+        if not needsParentheses then
+          $"%s{currentText} |> ignore"
+        else
+          $"(%s{currentText}) |> ignore"
+
+      return
+        [ { SourceDiagnostic = None
+            Title = title
+            File = codeActionParams.TextDocument
+            Edits =
+              [| { Range = fcsRangeToLsp expr.Range
+                   NewText = newText } |]
+            Kind = FixKind.Fix } ]
+    })

src/FsAutoComplete/CodeFixes/IgnoreExpression.fsi

@@ -0,0 +1,6 @@
+module FsAutoComplete.CodeFix.IgnoreExpression
+
+open FsAutoComplete.CodeFix.Types
+
+val title: string
+val fix: getParseResultsForFile: GetParseResultsForFile -> CodeFix

src/FsAutoComplete/LspServers/AdaptiveServerState.fs

@@ -1925,7 +1925,8 @@ type AdaptiveState(lspClient: FSharpLspClient, sourceTextFactory: ISourceTextFac
          AddTypeAliasToSignatureFile.fix forceGetFSharpProjectOptions tryGetParseAndCheckResultsForFile
          UpdateTypeAbbreviationInSignatureFile.fix tryGetParseAndCheckResultsForFile
          AddBindingToSignatureFile.fix forceGetFSharpProjectOptions tryGetParseAndCheckResultsForFile
-         ReplaceLambdaWithDotLambda.fix getLanguageVersion tryGetParseAndCheckResultsForFile |])
+         ReplaceLambdaWithDotLambda.fix getLanguageVersion tryGetParseAndCheckResultsForFile
+         IgnoreExpression.fix tryGetParseAndCheckResultsForFile |])
 
   let forgetDocument (uri: DocumentUri) =
     async {

test/FsAutoComplete.Tests.Lsp/CodeFixTests/IgnoreExpressionTests.fs

@@ -0,0 +1,61 @@
+module private FsAutoComplete.Tests.CodeFixTests.IgnoreExpressionTests
+
+open Expecto
+open Helpers
+open Utils.ServerTests
+open Utils.CursorbasedTests
+open FsAutoComplete.CodeFix
+
+let tests state =
+  serverTestList (nameof IgnoreExpression) state defaultConfigDto None (fun server ->
+    [ let selectCodeFix = CodeFix.withTitle IgnoreExpression.title
+
+      testCaseAsync "ignore constant"
+      <| CodeFix.check
+        server
+        "
+let a b =
+    9$0
+    null"
+        Diagnostics.acceptAll
+        selectCodeFix
+        "
+let a b =
+    (9) |> ignore
+    null"
+
+      testCaseAsync "ignore infix application"
+      <| CodeFix.check
+        server
+        "
+let a b =
+    0 / 9$0
+    null"
+        Diagnostics.acceptAll
+        selectCodeFix
+        "
+let a b =
+    (0 / 9) |> ignore
+    null"
+
+      testCaseAsync "ignore member invocation"
+      <| CodeFix.check
+        server
+        "
+open System.Collections.Generic
+
+let foo () =
+    let dict = dict []
+    di$0ct.TryAdd(\"foo\", \"bar\")
+    ()"
+        Diagnostics.acceptAll
+        selectCodeFix
+        "
+open System.Collections.Generic
+
+let foo () =
+    let dict = dict []
+    (dict.TryAdd(\"foo\", \"bar\")) |> ignore
+    ()"
+
+      ])

test/FsAutoComplete.Tests.Lsp/CodeFixTests/Tests.fs

@@ -3436,4 +3436,5 @@ let tests textFactory state =
       AddTypeAliasToSignatureFileTests.tests state
       UpdateTypeAbbreviationInSignatureFileTests.tests state
       AddBindingToSignatureFileTests.tests state
-      ReplaceLambdaWithDotLambdaTests.tests state ]
+      ReplaceLambdaWithDotLambdaTests.tests state
+      IgnoreExpressionTests.tests state ]