From 410e2baccc9943140881ffcedfe4aaa6239de6bf Mon Sep 17 00:00:00 2001
From: nojaf <florian.verdonck@outlook.com>
Date: Sat, 28 Mar 2020 11:20:21 +0100
Subject: [PATCH] Add extra space between prefix operator and string. Fixes
 #736

---
 src/Fantomas.Tests/OperatorTests.fs | 9 +++++++++
 src/Fantomas/CodePrinter.fs         | 8 +++++++-
 src/Fantomas/SourceParser.fs        | 7 ++++++-
 3 files changed, 22 insertions(+), 2 deletions(-)

diff --git a/src/Fantomas.Tests/OperatorTests.fs b/src/Fantomas.Tests/OperatorTests.fs
index 5a33ec6a3d..cd549a01d7 100644
--- a/src/Fantomas.Tests/OperatorTests.fs
+++ b/src/Fantomas.Tests/OperatorTests.fs
@@ -341,4 +341,13 @@ let ``equal sign operator should not move to next line`` () =
     |> should equal """
 let result =
     (typ.GetInterface(typeof<System.Collections.IEnumerable>.FullName) = null)
+"""
+
+[<Test>]
+let ``operator before verbatim string add extra space, 736`` () =
+    formatSourceString false """Target M.Tools (fun _ -> !! @"Tools\Tools.sln" |> rebuild)
+"""  config
+    |> prepend newline
+    |> should equal """
+Target M.Tools (fun _ -> !! @"Tools\Tools.sln" |> rebuild)
 """
\ No newline at end of file
diff --git a/src/Fantomas/CodePrinter.fs b/src/Fantomas/CodePrinter.fs
index 0d46fe85b2..bdb31a987f 100644
--- a/src/Fantomas/CodePrinter.fs
+++ b/src/Fantomas/CodePrinter.fs
@@ -988,7 +988,13 @@ and genExpr astContext synExpr =
         ifElse astContext.IsNakedRange expr (sepOpenS +> expr +> sepCloseS)
     // Separate two prefix ops by spaces
     | PrefixApp(s1, PrefixApp(s2, e)) -> !- (sprintf "%s %s" s1 s2) +> genExpr astContext e
-    | PrefixApp(s, e) -> !- s +> genExpr astContext e
+    | PrefixApp(s, e) ->
+        let extraSpaceBeforeString =
+            match e with
+            | String(_) -> sepSpace
+            | _ -> sepNone
+
+        !- s +> extraSpaceBeforeString +> genExpr astContext e
     // Handle spaces of infix application based on which category it belongs to
     | InfixApps(e, es) ->
         let sepAfterExpr f =
diff --git a/src/Fantomas/SourceParser.fs b/src/Fantomas/SourceParser.fs
index da7b80a529..751fe01d1d 100644
--- a/src/Fantomas/SourceParser.fs
+++ b/src/Fantomas/SourceParser.fs
@@ -184,9 +184,14 @@ let rec (|Const|) c =
     // Auto print may cut off the array
     | SynConst.UInt16s us -> sprintf "%A" us
 
+let (|String|_|) e =
+    match e with
+    | SynExpr.Const(SynConst.String(s,_),_) -> Some s
+    | _ -> None
+
 let (|MultilineString|_|) e =
     match e with
-    | SynExpr.Const(SynConst.String(s,_),_) when (String.isMultiline s) -> Some e
+    | String(s) when (String.isMultiline s) -> Some e
     | _ -> None
 
 let (|Unresolved|) (Const s as c, r) = (c, r, s)