Don't remove "in" from "let ... in ..." binding. (#342)

* test

* Use "let .. in .." if pattern and expr are at the same line.

* Added fix for comment after in

* Revert removed lines from fsproj

* Merge fix

* Fixed failing tests

src/Fantomas.Cmd/Fantomas.Cmd.fsproj

@@ -17,4 +17,4 @@
     <ProjectReference Include="..\Fantomas\Fantomas.fsproj" />
   </ItemGroup>
   <Import Project="..\..\.paket\Paket.Restore.targets" />
-</Project>
+</Project>

src/Fantomas.CoreGlobalTool/Fantomas.CoreGlobalTool.fsproj

@@ -18,4 +18,4 @@
     <ProjectReference Include="..\Fantomas\Fantomas.fsproj" />
   </ItemGroup>
   <Import Project="..\..\.paket\Paket.Restore.targets" />
-</Project>
+</Project>

src/Fantomas.Tests/CompilerDirectivesTests.fs

@@ -215,8 +215,6 @@ namespace Internal.Utilities.Diagnostic
 type ExtensibleDumper = A | B
 #endif
 #endif
-
-
 """
 
 [<Test>]

src/Fantomas.Tests/Fantomas.Tests.fsproj

@@ -1,4 +1,3 @@
-<?xml version="1.0" encoding="utf-8"?>
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
     <Version>2.9.1</Version>
@@ -40,10 +39,11 @@
     <Compile Include="FormattingPropertyTests.fs" />
     <Compile Include="SpecialConstructsTests.fs" />
     <Compile Include="FormatAstTests.fs" />
+    <Compile Include="LetBindingTests.fs" />
     <Compile Include="NoTrailingSpacesTests.fs" />
   </ItemGroup>
   <ItemGroup>
     <ProjectReference Include="..\Fantomas\Fantomas.fsproj" />
   </ItemGroup>
   <Import Project="..\..\.paket\Paket.Restore.targets" />
-</Project>
+</Project>

src/Fantomas.Tests/LetBindingTests.fs

@@ -0,0 +1,35 @@
+module Fantomas.Tests.LetBindingTests
+
+open NUnit.Framework
+open FsUnit
+
+open Fantomas.CodeFormatter
+open Fantomas.Tests.TestHelper
+
+[<Test>]
+let ``let in should be preserved``() =
+    formatSourceString false "let x = 1 in ()" config
+    |> should equal """let x = 1 in ()
+"""
+
+[<Test>]
+let ``let in should be preserved with PreserveEOL option``() =
+    formatSourceString false "let x = 1 in ()" { config with PreserveEndOfLine = true }
+    |> should equal """let x = 1 in ()
+"""
+
+[<Test>]
+let ``multiple let in lines, should remove in`` () =
+    let codeSnippet = """
+let f () = 
+  let x = 1 in   // the "in" keyword is available in F#
+    let y = 2 in 
+      x + y
+"""
+
+    formatSourceString false codeSnippet config
+    |> should equal """let f() =
+    let x = 1   // the "in" keyword is available in F#
+    let y = 2
+    x + y
+"""

src/Fantomas.Tests/TypeProviderTests.fs

@@ -43,14 +43,11 @@ let ``should handle lines with more than 512 characters``() =
     |> should equal """
 (new CsvFile<string * decimal * decimal>(new Func<obj, string [], string * decimal * decimal>(fun (parent : obj) (row : string []) -> CommonRuntime.GetNonOptionalValue("Name", CommonRuntime.ConvertString(TextConversions.AsOption(row.[0])), TextConversions.AsOption(row.[0])), CommonRuntime.GetNonOptionalValue("Distance", CommonRuntime.ConvertDecimal("", TextConversions.AsOption(row.[1])), TextConversions.AsOption(row.[1])), CommonRuntime.GetNonOptionalValue("Time", CommonRuntime.ConvertDecimal("", TextConversions.AsOption(row.[2])), TextConversions.AsOption(row.[2]))),
                                          new Func<string * decimal * decimal, string []>(fun (row : string * decimal * decimal) ->
-                                         [| CommonRuntime.ConvertStringBack(CommonRuntime.GetOptionalValue((let x, _, _ = row
-                                                                                                            x)))
+                                         [| CommonRuntime.ConvertStringBack(CommonRuntime.GetOptionalValue((let x, _, _ = row in x)))
                                             CommonRuntime.ConvertDecimalBack("",
-                                                                             CommonRuntime.GetOptionalValue((let _, x, _ = row
-                                                                                                             x)))
+                                                                             CommonRuntime.GetOptionalValue((let _, x, _ = row in x)))
                                             CommonRuntime.ConvertDecimalBack("",
-                                                                             CommonRuntime.GetOptionalValue((let _, _, x = row
-                                                                                                             x))) |]), (ProviderFileSystem.readTextAtRunTimeWithDesignTimeOptions @"C:\Dev\FSharp.Data-master\src\..\tests\FSharp.Data.Tests\Data" "" "SmallTest.csv"), "", '"', true, false))
+                                                                             CommonRuntime.GetOptionalValue((let _, _, x = row in x))) |]), (ProviderFileSystem.readTextAtRunTimeWithDesignTimeOptions @"C:\Dev\FSharp.Data-master\src\..\tests\FSharp.Data.Tests\Data" "" "SmallTest.csv"), "", '"', true, false))
     .Cache()
 """
 

src/Fantomas/CodePrinter.fs

@@ -619,7 +619,11 @@ and genExpr astContext = function
 
     | TypeApp(e, ts) -> genExpr astContext e -- "<" +> col sepComma ts (genType astContext false) -- ">"
     | LetOrUses(bs, e) ->
-        atCurrentColumn (genLetOrUseList astContext bs +> sepNln +> genExpr astContext e)
+        let isInSameLine =
+            match bs with
+            | [_, LetBinding(ats, px, ao, isInline, isMutable, p, _)] -> p.Range.EndLine = e.Range.StartLine
+            | _ -> false
+        atCurrentColumn (genLetOrUseList astContext bs +> ifElse isInSameLine (!- " in ") sepNln +> genExpr astContext e)
 
     // Could customize a bit if e is single line
     | TryWith(e, cs) -> 

src/Fantomas/Fantomas.fsproj

@@ -21,4 +21,4 @@
     <None Include="CodeFormatter.fsx" />
   </ItemGroup>
   <Import Project="..\..\.paket\Paket.Restore.targets" />
-</Project>
+</Project>

src/Fantomas/TokenMatcher.fs

@@ -3,11 +3,11 @@
 open System
 open System.Collections.Generic
 open System.Diagnostics
-open Fantomas
 open Microsoft.FSharp.Compiler.Range
 open Microsoft.FSharp.Compiler.PrettyNaming
 open Microsoft.FSharp.Compiler.SourceCodeServices
 open System.Text.RegularExpressions
+open Fantomas
 
 #if INTERACTIVE
 type Debug = Console
@@ -594,10 +594,17 @@ let integrateComments isPreserveEOL compilationDefines (originalText : string) (
                 addText Environment.NewLine
             for x in tokensText do addText x
             addNewLineToDirective newTokens moreOrigTokens
+
+            let isEOL (token:Token) = 
+                match token with
+                | EOL _ -> true 
+                | _ -> false
 
             let moreNewTokens =
                 if String.startsWithOrdinal "#endif" text then
                     match newTokens with
+                    | allEOL when (allEOL |> List.forall (fst >> isEOL)) ->
+                        []
                     | WhiteSpaces(ws, moreNewTokens) ->
                         let origIndent = 
                             moreOrigTokens
@@ -673,8 +680,31 @@ let integrateComments isPreserveEOL compilationDefines (originalText : string) (
             loop moreOrigTokens moreNewTokens
 
         // Emit end-of-line from new tokens
-        | _,  (NewLine newTokText :: moreNewTokens) ->
+        | (Marked(inToken,_,_)::oldTokens),  (NewLine newTokText :: moreNewTokens) ->
             Debug.WriteLine("emitting newline in new tokens '{0}'", newTokText)
+            let nextOldTokens =
+                match (inToken) with 
+                | Tok(fsInToken,_) when (fsInToken.TokenName = "IN") ->
+                    // find tokens before newline in old source
+                    let tokensBeforeNewline =
+                        oldTokens
+                        |> List.takeWhile (fun t ->
+                            match t with
+                            | Marked(EOL,_,_) -> false
+                            | _ -> true
+                        )
+                        |> List.map (fun t ->
+                            match t with
+                            | Marked(_,tokenString,_) -> tokenString
+                        )
+
+                    List.iter addText tokensBeforeNewline
+
+                    oldTokens
+                    |> List.skip (List.length tokensBeforeNewline)
+
+                | _ -> origTokens
+
             let nextNewTokens =
                 if not isPreserveEOL then 
                     addText newTokText
@@ -686,7 +716,7 @@ let integrateComments isPreserveEOL compilationDefines (originalText : string) (
                         rs
                     | _ -> moreNewTokens
 
-            loop origTokens nextNewTokens
+            loop nextOldTokens nextNewTokens
 
         | _,  ((Token newTok, newTokText) :: moreNewTokens) 
             when newTok.CharClass = FSharpTokenCharKind.WhiteSpace && newTok.ColorClass <> FSharpTokenColorKind.InactiveCode ->