print Trivia before entire LetBang expression. Fixes fsprojects#879

nojaf · Jun 1, 2020 · c9f3dc5 · c9f3dc5
1 parent 8824f4a
commit c9f3dc5
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Showing 2 changed files with 60 additions and 2 deletions.
diff --git a/src/Fantomas.Tests/ComputationExpressionTests.fs b/src/Fantomas.Tests/ComputationExpressionTests.fs
@@ -1315,4 +1315,61 @@ let a =
         let! bar = async { return foo a }
         return bar
     }
+"""
+
+[<Test>]
+let ``new line between let and let bang, 879`` () =
+    formatSourceString false """let rec loop () =
+        async {
+          let! msg = inbox.Receive()
+
+          match msg with
+          | Handle (eventSource,command,reply) ->
+              let! stream = eventSource |> eventStore.GetStream
+
+              let newEvents =
+                stream |> Result.map (asEvents >> behaviour command >> enveloped eventSource)
+
+              let! result =
+                newEvents
+                |> function
+                    | Ok events -> eventStore.Append events
+                    | Error err -> async { return Error err }
+
+              do reply.Reply result
+
+              return! loop ()
+        }
+"""  ({ config with
+            SpaceBeforeUppercaseInvocation = true
+            IndentSpaceNum = 2
+            SpaceAroundDelimiter = false
+            MultilineBlockBracketsOnSameColumn = true })
+    |> prepend newline
+    |> should equal """
+let rec loop () =
+  async {
+    let! msg = inbox.Receive ()
+
+    match msg with
+    | Handle (eventSource, command, reply) ->
+        let! stream = eventSource |> eventStore.GetStream
+
+        let newEvents =
+          stream
+          |> Result.map
+               (asEvents
+                >> behaviour command
+                >> enveloped eventSource)
+
+        let! result =
+          newEvents
+          |> function
+          | Ok events -> eventStore.Append events
+          | Error err -> async { return Error err}
+
+        do reply.Reply result
+
+        return! loop ()
+  }
 """
diff --git a/src/Fantomas/CodePrinter.fs b/src/Fantomas/CodePrinter.fs
@@ -968,8 +968,9 @@ and genExpr astContext synExpr =
                     sprintf "%s%s" (if isUse then "use " else "let ") (if isRecursive then "rec " else "")
 
                 genLetBinding astContext prefix binding
-            | LetOrUseBangStatement(isUse, pat, expr, _) ->
-                ifElse isUse (!- "use! ") (!- "let! ")
+            | LetOrUseBangStatement(isUse, pat, expr, r) ->
+                enterNode r // print Trivia before entire LetBang expression
+                +> ifElse isUse (!- "use! ") (!- "let! ")
                 +> genPat astContext pat -- " = "
                 +> autoIndentAndNlnIfExpressionExceedsPageWidth (genExpr astContext expr)
             | AndBangStatement(pat, expr) ->