Preserve in keyword. Fixes fsprojects#340.

src/Fantomas.Tests/LetBindingTests.fs

@@ -11,7 +11,7 @@ let ``let in should be preserved`` () =
 """
 
 [<Test>]
-let ``multiple let in lines, should remove in`` () =
+let ``multiple let in lines, should keep in`` () =
     let codeSnippet = """
 let f () =
   let x = 1 in   // the "in" keyword is available in F#
@@ -21,13 +21,13 @@ let f () =
 
     formatSourceString false codeSnippet config
     |> should equal """let f () =
-    let x = 1 // the "in" keyword is available in F#
-    let y = 2
+    let x = 1 in // the "in" keyword is available in F#
+    let y = 2 in
     x + y
 """
 
 [<Test>]
-let ``multiple let in lines, should remove in, block comment`` () =
+let ``multiple let in lines, should keep in, block comment`` () =
     let codeSnippet = """
 let f () =
   let x = 1 in   (* the "in" keyword is available in F# *)
@@ -41,13 +41,13 @@ let f () =
         ({ config with
                MaxValueBindingWidth = 50 })
     |> should equal """let f () =
-    let x = 1 (* the "in" keyword is available in F# *)
-    let y = 2
+    let x = 1 in (* the "in" keyword is available in F# *)
+    let y = 2 in
     x + y
 """
 
 [<Test>]
-let ``multiline let in, should remove in`` () =
+let ``multiline let in, should keep in`` () =
     let codeSnippet = """
 let f () =
   let x = 1 in if longIdentifierThatWillForceThisConstructToBeMultiline
@@ -59,7 +59,7 @@ let f () =
     |> prepend newline
     |> should equal """
 let f () =
-    let x = 1
+    let x = 1 in
 
     if longIdentifierThatWillForceThisConstructToBeMultiline
     then x
@@ -78,7 +78,7 @@ let f () =
     |> prepend newline
     |> should equal """
 let f () =
-    let x = 1
+    let x = 1 in
 
     (while true do
         ()
@@ -552,7 +552,9 @@ let ``handle hash directives before equals, 728`` () =
         ()
 
     """ config
-    |> should equal """let Baz (firstParam: string)
+    |> prepend newline
+    |> should equal """
+let Baz (firstParam: string)
 #if DEBUG
         (_: int)
 #else
@@ -972,7 +974,7 @@ let x =
 let ``preserve in keyword via trivia, 340`` () =
     formatSourceString false """
 let x = List.singleton <|
-        let item = "text"
+        let item = "text" in
         item
 """  config
     |> prepend newline

src/Fantomas.Tests/TypeProviderTests.fs

@@ -30,8 +30,6 @@ let ``should throw FormatException on unparsed input`` () =
         |> ignore)
     |> ignore
 
-
-
 [<Test>]
 let ``should handle lines with more than 512 characters`` () =
     formatSourceString false """

src/Fantomas.Tests/VerboseSyntaxConversionTests.fs

@@ -23,6 +23,6 @@ let ``verbose syntax`` () =
 let div2 = 2
 
 let f x =
-    let r = x % div2
+    let r = x % div2 in
     if r = 1 then ("Odd") else ("Even")
 """

src/Fantomas/AstTransformer.fs

@@ -985,8 +985,14 @@ module private Ast =
     and visitSynBinding (binding: SynBinding): Node =
         match binding with
         | Binding (access, kind, mustInline, isMutable, attrs, _, valData, headPat, returnInfo, expr, range, _) ->
-            { Type = Binding_
-              Range = r range
+            let t =
+                match kind with
+                | SynBindingKind.StandaloneExpression -> StandaloneExpression_
+                | SynBindingKind.NormalBinding -> NormalBinding_
+                | SynBindingKind.DoBinding -> DoBinding_
+
+            { Type = t
+              Range = r binding.RangeOfBindingAndRhs
               Properties =
                   p [ yield "mustInline" ==> mustInline
                       yield "isMutable" ==> isMutable

src/Fantomas/CodePrinter.fs

@@ -404,20 +404,20 @@ and genModuleDecl astContext (node: SynModuleDecl) =
         let sepBAndBs =
             match List.tryHead bs with
             | Some b' ->
-                let r = b'.RangeOfBindingSansRhs
+                let r = b'.RangeOfBindingAndRhs
 
                 sepNln
-                +> sepNlnConsideringTriviaContentBeforeForMainNode Binding_ r
+                +> sepNlnConsideringTriviaContentBeforeForMainNode (synBindingToFsAstType b) r
             | None -> id
 
         genLetBinding { astContext with IsFirstChild = true } "let rec " b
         +> sepBAndBs
         +> colEx (fun (b': SynBinding) ->
-            let r = b'.RangeOfBindingSansRhs
+            let r = b'.RangeOfBindingAndRhs
 
             sepNln
-            +> sepNlnConsideringTriviaContentBeforeForMainNode Binding_ r) bs (fun andBinding ->
-               enterNodeFor Binding_ andBinding.RangeOfBindingSansRhs
+            +> sepNlnConsideringTriviaContentBeforeForMainNode (synBindingToFsAstType b) r) bs (fun andBinding ->
+               enterNodeFor (synBindingToFsAstType b) andBinding.RangeOfBindingAndRhs
                +> genLetBinding { astContext with IsFirstChild = false } "and " andBinding)
 
     | ModuleAbbrev (s1, s2) -> !- "module " -- s1 +> sepEq +> sepSpace -- s2
@@ -715,7 +715,6 @@ and genLetBinding astContext pref b =
         +> leadingExpressionIsMultiline
             (afterLetKeyword
              +> genPat
-             +> dumpAndContinue
              +> enterNodeTokenByName rangeBetweenBindingPatternAndExpression EQUALS)
                (genExprSepEqPrependType astContext p e (Some(valInfo)))
 
@@ -729,7 +728,7 @@ and genLetBinding astContext pref b =
         +> autoIndentAndNlnIfExpressionExceedsPageWidth (genExpr astContext e)
 
     | b -> failwithf "%O isn't a let binding" b
-    +> leaveNodeFor Binding_ b.RangeOfBindingSansRhs
+    +> leaveNodeFor (synBindingToFsAstType b) b.RangeOfBindingAndRhs
 
 and genShortGetProperty astContext (pat: SynPat) e =
     genExprSepEqPrependType astContext pat e None false
@@ -803,10 +802,10 @@ and genMemberBindingList astContext node =
         | [] -> []
         | mb :: rest ->
             let expr = genMemberBinding astContext mb
-            let r = mb.RangeOfBindingSansRhs
+            let r = mb.RangeOfBindingAndRhs
 
             let sepNln =
-                sepNlnConsideringTriviaContentBeforeForMainNode Binding_ r
+                sepNlnConsideringTriviaContentBeforeForMainNode (synBindingToFsAstType mb) r
 
             (expr, sepNln, r) :: (collectItems rest)
 
@@ -1051,7 +1050,7 @@ and genMemberBinding astContext b =
             +> sepSpaceOrIndentAndNlnIfExpressionExceedsPageWidth (genExpr astContext e)
 
     | b -> failwithf "%O isn't a member binding" b
-    |> genTriviaFor Binding_ b.RangeOfBindingSansRhs
+    |> genTriviaFor (synBindingToFsAstType b) b.RangeOfBindingAndRhs
 
 and genMemberFlags astContext (mf: MemberFlags) =
     match mf with
@@ -1523,7 +1522,7 @@ and genExpr astContext synExpr =
                 let prefix =
                     sprintf "%s%s" (if isUse then "use " else "let ") (if isRecursive then "rec " else "")
 
-                enterNodeFor Binding_ binding.RangeOfBindingSansRhs
+                enterNodeFor (synBindingToFsAstType binding) binding.RangeOfBindingAndRhs
                 +> genLetBinding astContext prefix binding
             | LetOrUseBangStatement (isUse, pat, expr, r) ->
                 enterNodeFor SynExpr_LetOrUseBang r // print Trivia before entire LetBang expression
@@ -1541,14 +1540,14 @@ and genExpr astContext synExpr =
 
         let getRangeOfCompExprStatement ces =
             match ces with
-            | LetOrUseStatement (_, _, binding) -> binding.RangeOfBindingSansRhs
+            | LetOrUseStatement (_, _, binding) -> binding.RangeOfBindingAndRhs
             | LetOrUseBangStatement (_, _, _, r) -> r
             | AndBangStatement (_, _, r) -> r
             | OtherStatement expr -> expr.Range
 
         let getSepNln ces r =
             match ces with
-            | LetOrUseStatement _ -> sepNlnConsideringTriviaContentBeforeForMainNode Binding_ r
+            | LetOrUseStatement (_, _, b) -> sepNlnConsideringTriviaContentBeforeForMainNode (synBindingToFsAstType b) r
             | LetOrUseBangStatement _ -> sepNlnConsideringTriviaContentBeforeForMainNode SynExpr_LetOrUseBang r
             | AndBangStatement _ -> sepNlnConsideringTriviaContentBeforeForToken AND_BANG r
             | OtherStatement e -> sepNlnConsideringTriviaContentBeforeForMainNode (synExprToFsAstType e) r
@@ -2005,45 +2004,61 @@ and genExpr astContext synExpr =
         genExpr astContext e
         +> genGenericTypeParameters astContext ts
     | LetOrUses (bs, e) ->
-        let isFromAst (ctx: Context) = ctx.Content = String.Empty
+        let inKeyWordTrivia (binding: SynBinding) ctx =
+            let inRange =
+                mkRange "IN" binding.RangeOfBindingAndRhs.End e.Range.Start
+
+            Map.tryFindOrEmptyList IN ctx.TriviaTokenNodes
+            |> TriviaHelpers.``keyword token inside range`` inRange
+            |> List.tryHead
 
         let isInSameLine ctx =
             match bs with
-            | [ _, LetBinding (_, _, _, _, _, p, _, _) ] ->
-                // the `` keyword should be a trivia thing
-                not (isFromAst ctx)
+            | [ _, (LetBinding (_, _, _, _, _, p, _, _) as binding) ] ->
+                Option.isSome (inKeyWordTrivia binding ctx)
                 && p.Range.EndLine = e.Range.StartLine
                 && not (futureNlnCheck (genExpr astContext e) ctx)
             | _ -> false
 
+        let genInKeyword (binding: SynBinding) (ctx: Context) =
+            match inKeyWordTrivia binding ctx with
+            | Some (_, tn) ->
+                (printContentBefore tn
+                 +> !- " in "
+                 +> printContentAfter tn) ctx
+            | None -> sepNone ctx
+
         fun ctx ->
             if isInSameLine ctx then
+                // short expression with in keyword
+                // f.ex. let a in ()
                 atCurrentColumn
-                    (col sepNone bs (fun (p, x) ->
-                         genLetBinding
-                             { astContext with
-                                   IsFirstChild = p <> "and" }
-                             p
-                             x)
-                     -- " in "
+                    (optSingle (fun (p, x) ->
+                        genLetBinding
+                            { astContext with
+                                  IsFirstChild = p <> "and" }
+                            p
+                            x
+                        +> genInKeyword x) (List.tryHead bs)
                      +> genExpr astContext e)
                     ctx
             else
                 let letBindings (bs: (string * SynBinding) list) =
                     bs
                     |> List.map (fun (p, x) ->
                         let expr =
-                            enterNodeFor Binding_ x.RangeOfBindingSansRhs
+                            enterNodeFor (synBindingToFsAstType x) x.RangeOfBindingAndRhs
                             +> genLetBinding
                                 { astContext with
                                       IsFirstChild = p <> "and" }
                                    p
                                    x
+                            +> genInKeyword x
 
-                        let range = x.RangeOfBindingSansRhs
+                        let range = x.RangeOfBindingAndRhs
 
                         let sepNln =
-                            sepNlnConsideringTriviaContentBeforeForMainNode Binding_ range
+                            sepNlnConsideringTriviaContentBeforeForMainNode (synBindingToFsAstType x) range
 
                         expr, sepNln, range)
 
@@ -2110,7 +2125,7 @@ and genExpr astContext synExpr =
 
                 let fsAstType, r =
                     match e with
-                    | LetOrUses ((_, fb) :: _, _) -> Binding_, fb.RangeOfBindingSansRhs
+                    | LetOrUses ((_, fb) :: _, _) -> (synBindingToFsAstType fb), fb.RangeOfBindingAndRhs
                     | _ -> synExprToFsAstType e, e.Range
 
                 let sepNln =
@@ -4560,11 +4575,7 @@ and infixOperatorFromTrivia range fallback (ctx: Context) =
 
     let isValidIdent x = Regex.Match(x, validIdentRegex).Success
 
-    TriviaHelpers.getNodesForTypes
-        [ SynPat_LongIdent
-          SynPat_Named
-          Binding_ ]
-        ctx.TriviaMainNodes
+    TriviaHelpers.getNodesForTypes [ SynPat_LongIdent; SynPat_Named ] ctx.TriviaMainNodes
     |> List.choose (fun t ->
         match t.Range = range with
         | true ->

src/Fantomas/SourceTransformer.fs

@@ -306,3 +306,9 @@ let synModuleSigDeclToFsAstType =
     | SynModuleSigDecl.HashDirective _ -> SynModuleSigDecl_HashDirective
     | SynModuleSigDecl.NamespaceFragment _ -> SynModuleSigDecl_NamespaceFragment
     | SynModuleSigDecl.ModuleAbbrev _ -> SynModuleSigDecl_ModuleAbbrev
+
+let synBindingToFsAstType (Binding (_, kind, _, _, _, _, _, _, _, _, _, _)) =
+    match kind with
+    | SynBindingKind.StandaloneExpression -> StandaloneExpression_
+    | SynBindingKind.NormalBinding -> NormalBinding_
+    | SynBindingKind.DoBinding -> DoBinding_

src/Fantomas/TokenParser.fs

@@ -666,7 +666,8 @@ let private tokenNames =
       "WITH"
       "MEMBER"
       "AND_BANG"
-      "FUNCTION" ]
+      "FUNCTION"
+      "IN" ]
 
 let private tokenKinds = [ FSharpTokenCharKind.Operator ]
 
@@ -718,6 +719,7 @@ let internal getFsToken tokenName =
     | "INFIX_STAR_STAR_OP" -> INFIX_STAR_STAR_OP
     | "FUNCTION" -> FUNCTION
     | "LPAREN_STAR_RPAREN" -> LPAREN_STAR_RPAREN
+    | "IN" -> IN
     | _ -> failwithf "was not expecting token %s" tokenName
 
 let getTriviaNodesFromTokens (tokens: Token list) =

src/Fantomas/Trivia.fs

@@ -239,14 +239,14 @@ let private updateTriviaNode (lens: TriviaNodeAssigner -> unit) (triviaNodes: Tr
     //        |> List.mapi (fun idx tn -> if idx = index then lens tn else tn)
     | None -> triviaNodes
 
-let private findBindingThatStartsWith (triviaNodes: TriviaNodeAssigner list) column line =
+let private findNamedPatThatStartsWith (triviaNodes: TriviaNodeAssigner list) column line =
     triviaNodes
     |> List.tryFind (fun t ->
         match t.Type with
-        | MainNode (Binding_) when (t.Range.StartColumn = column
-                                    && t.Range.StartLine = line) -> true
         | MainNode (SynPat_Named) when (t.Range.StartColumn = column
                                         && t.Range.StartLine = line) -> true
+        | MainNode (SynPat_LongIdent) when (t.Range.StartColumn = column
+                                            && t.Range.StartLine = line) -> true
         | _ -> false)
 
 let private findParsedHashOnLineAndEndswith (triviaNodes: TriviaNodeAssigner list) startLine endColumn =
@@ -388,9 +388,13 @@ let private addTriviaToTriviaNode triviaBetweenAttributeAndParentBinding
         |> updateTriviaNode (fun tn -> tn.ContentBefore.Add(Keyword(kw))) triviaNodes
 
     | { Item = Keyword ({ Content = keyword }); Range = range } when (keyword = "in") ->
-        // find largest SynExpr right before in range
-        findNodeBeforeLineAndColumn triviaNodes range.StartLine range.StartColumn
-        |> updateTriviaNode (fun tn -> tn.ContentAfter.Add trivia.Item) triviaNodes
+        // find In keyword TriviaNode
+        triviaNodes
+        |> List.tryFind (fun tn ->
+            match tn.Type with
+            | Token (IN, _) -> RangeHelpers.rangeEq range tn.Range
+            | _ -> false)
+        |> updateTriviaNode (fun tn -> tn.ContentItself <- Some trivia.Item) triviaNodes
 
     | { Item = Keyword ({ Content = keyword }); Range = range } when (keyword = "if"
                                                                       || keyword = "then"
@@ -439,7 +443,7 @@ let private addTriviaToTriviaNode triviaBetweenAttributeAndParentBinding
         |> updateTriviaNode (fun tn -> tn.ContentItself <- Some chNode) triviaNodes
 
     | { Item = IdentOperatorAsWord (_) as ifw; Range = range } ->
-        findBindingThatStartsWith triviaNodes range.StartColumn range.StartLine
+        findNamedPatThatStartsWith triviaNodes range.StartColumn range.StartLine
         |> updateTriviaNode (fun tn -> tn.ContentItself <- Some ifw) triviaNodes
 
     | { Item = IdentBetweenTicks (_) as iNode; Range = range } ->

src/Fantomas/TriviaTypes.fs

@@ -50,6 +50,7 @@ type FsTokenType =
     | INFIX_STAR_STAR_OP
     | FUNCTION
     | LPAREN_STAR_RPAREN
+    | IN
 
 type Token =
     { TokenInfo: FSharpTokenInfo
@@ -207,7 +208,9 @@ type FsAstType =
     | SynSimplePat_Attrib
     | SynSimplePats_SimplePats
     | SynSimplePats_Typed
-    | Binding_
+    | StandaloneExpression_
+    | NormalBinding_
+    | DoBinding_
     | SynBindingReturnInfo_
     | SynValTyparDecls_
     | TyparDecl_