Correct prefix of synbinding in collected computation expression. Fixes

fsprojects#1628.

src/Fantomas.Tests/LetBindingTests.fs

@@ -1831,3 +1831,42 @@ type Viewport =
       longitude: float
       zoom: int }
 """
+
+[<Test>]
+let ``recursive let bindings in sequential expression, 1628`` () =
+    formatSourceString
+        false
+        """
+let foobar () =
+    Console.WriteLine("Hello")
+
+    let rec foo () = bar "Hello"
+    and bar str = printf "%s" str |> ignore
+
+    foo ()
+
+let foobar () =
+    let rec foo () = bar "Hello"
+    and bar str = printf "%s" str |> ignore
+
+    foo ()
+"""
+        config
+    |> prepend newline
+    |> should
+        equal
+        """
+let foobar () =
+    Console.WriteLine("Hello")
+
+    let rec foo () = bar "Hello"
+    and bar str = printf "%s" str |> ignore
+
+    foo ()
+
+let foobar () =
+    let rec foo () = bar "Hello"
+    and bar str = printf "%s" str |> ignore
+
+    foo ()
+"""

src/Fantomas/CodePrinter.fs

@@ -1426,10 +1426,7 @@ and genExpr astContext synExpr ctx =
         | CompExprBody statements ->
             let genCompExprStatement astContext ces =
                 match ces with
-                | LetOrUseStatement (isRecursive, isUse, binding) ->
-                    let prefix =
-                        sprintf "%s%s" (if isUse then "use " else "let ") (if isRecursive then "rec " else "")
-
+                | LetOrUseStatement (prefix, binding) ->
                     enterNodeFor (synBindingToFsAstType binding) binding.RangeOfBindingAndRhs
                     +> genLetBinding astContext prefix binding
                 | LetOrUseBangStatement (isUse, pat, expr, r) ->
@@ -1448,14 +1445,14 @@ and genExpr astContext synExpr ctx =
 
             let getRangeOfCompExprStatement ces =
                 match ces with
-                | LetOrUseStatement (_, _, binding) -> binding.RangeOfBindingAndRhs
+                | LetOrUseStatement (_, binding) -> binding.RangeOfBindingAndRhs
                 | LetOrUseBangStatement (_, _, _, r) -> r
                 | AndBangStatement (_, _, r) -> r
                 | OtherStatement expr -> expr.Range
 
             let getSepNln ces r =
                 match ces with
-                | LetOrUseStatement (_, _, b) ->
+                | LetOrUseStatement (_, b) ->
                     sepNlnConsideringTriviaContentBeforeForMainNode (synBindingToFsAstType b) r
                 | LetOrUseBangStatement _ -> sepNlnConsideringTriviaContentBeforeForMainNode SynExpr_LetOrUseBang r
                 | AndBangStatement _ -> sepNlnConsideringTriviaContentBeforeForToken AND_BANG r

src/Fantomas/SourceParser.fs

@@ -906,22 +906,20 @@ let rec (|LetOrUses|_|) =
     | _ -> None
 
 type ComputationExpressionStatement =
-    | LetOrUseStatement of recursive: bool * isUse: bool * SynBinding
+    | LetOrUseStatement of prefix: string * binding: SynBinding
     | LetOrUseBangStatement of isUse: bool * SynPat * SynExpr * range
     | AndBangStatement of SynPat * SynExpr * range
     | OtherStatement of SynExpr
 
 let rec collectComputationExpressionStatements e : ComputationExpressionStatement list =
     match e with
-    | SynExpr.LetOrUse (isRecursive, isUse, bindings, body, _) ->
-        let bindings =
-            bindings
-            |> List.map (fun b -> LetOrUseStatement(isRecursive, isUse, b))
+    | LetOrUses (bindings, body) ->
+        let letBindings = bindings |> List.map LetOrUseStatement
 
         let returnExpr =
             collectComputationExpressionStatements body
 
-        [ yield! bindings; yield! returnExpr ]
+        letBindings @ returnExpr
     | SynExpr.LetOrUseBang (_, isUse, _, pat, expr, andBangs, body, r) ->
         let letOrUseBang =
             LetOrUseBangStatement(isUse, pat, expr, r)