Print trivia for SynExpr explicitly. (fsprojects#1688)

* Print trivia for inferred casts. Fixes fsprojects#1685.

* Print trivia for SynExpr explicitly.

src/Fantomas.Tests/CastTests.fs

@@ -136,3 +136,77 @@ let waitAndUpcast (x: Task<'t>) =
 
     x.Result :?> AmazonWebServiceResponse
 """
+
+[<Test>]
+let ``trivia newline before inferred upcast, 1685`` () =
+    formatSourceString
+        false
+        """
+namespace Blah
+
+module Foo =
+
+    let foo =
+        { new IDisposable with
+            member __.Dispose () =
+            do ()
+
+            upcast ()
+        }
+"""
+        { config with
+              SpaceBeforeColon = true
+              SpaceBeforeSemicolon = true
+              IndentOnTryWith = true }
+    |> prepend newline
+    |> should
+        equal
+        """
+namespace Blah
+
+module Foo =
+
+    let foo =
+        { new IDisposable with
+            member __.Dispose() =
+                do ()
+
+                upcast () }
+"""
+
+[<Test>]
+let ``trivia newline before inferred downcast`` () =
+    formatSourceString
+        false
+        """
+namespace Blah
+
+module Foo =
+
+    let foo =
+        { new IDisposable with
+            member __.Dispose () =
+            do ()
+
+            downcast ()
+        }
+"""
+        { config with
+              SpaceBeforeColon = true
+              SpaceBeforeSemicolon = true
+              IndentOnTryWith = true }
+    |> prepend newline
+    |> should
+        equal
+        """
+namespace Blah
+
+module Foo =
+
+    let foo =
+        { new IDisposable with
+            member __.Dispose() =
+                do ()
+
+                downcast () }
+"""

src/Fantomas.Tests/CommentTests.fs

@@ -1483,3 +1483,43 @@ let ``line comment after embedded il`` () =
         """
 (# "" x : 'U #) // bar
 """
+
+[<Test>]
+let ``line comment before SynExpr.AddressOf`` () =
+    formatSourceString
+        false
+        """
+open FSharp.NativeInterop
+
+let Main() =
+  let mutable x = 3.1415
+  // meh?
+  &&x
+"""
+        config
+    |> prepend newline
+    |> should
+        equal
+        """
+open FSharp.NativeInterop
+
+let Main () =
+    let mutable x = 3.1415
+    // meh?
+    &&x
+"""
+
+[<Test>]
+let ``line comment after SynExpr.Null, 1676`` () =
+    formatSourceString
+        false
+        """
+let v = f null // comment
+"""
+        config
+    |> prepend newline
+    |> should
+        equal
+        """
+let v = f null // comment
+"""

src/Fantomas.Tests/ComputationExpressionTests.fs

@@ -2403,3 +2403,28 @@ aggregateResult {
           More = more }
 }
 """
+
+[<Test>]
+let ``line comment above SynExpr.LetOrUseBang`` () =
+    formatSourceString
+        false
+        """
+let x =
+    async {
+        // bar
+        let! f =   foo()
+        ()
+    }
+"""
+        config
+    |> prepend newline
+    |> should
+        equal
+        """
+let x =
+    async {
+        // bar
+        let! f = foo ()
+        ()
+    }
+"""

src/Fantomas/CodePrinter.fs

@@ -2600,7 +2600,43 @@ and genExpr astContext synExpr ctx =
             | SynExpr.Do _ -> genTriviaFor SynExpr_Do synExpr.Range
             | SynExpr.TypeApp _ -> genTriviaFor SynExpr_TypeApp synExpr.Range
             | SynExpr.Lazy _ -> genTriviaFor SynExpr_Lazy synExpr.Range
-            | _ -> id)
+            | SynExpr.InferredUpcast _ -> genTriviaFor SynExpr_InferredUpcast synExpr.Range
+            | SynExpr.InferredDowncast _ -> genTriviaFor SynExpr_InferredDowncast synExpr.Range
+            | SynExpr.AddressOf _ -> genTriviaFor SynExpr_AddressOf synExpr.Range
+            | SynExpr.Null _ -> genTriviaFor SynExpr_Null synExpr.Range
+            | SynExpr.TraitCall _ -> genTriviaFor SynExpr_TraitCall synExpr.Range
+            | SynExpr.DotNamedIndexedPropertySet _ -> genTriviaFor SynExpr_DotNamedIndexedPropertySet synExpr.Range
+            | SynExpr.NamedIndexedPropertySet _ -> genTriviaFor SynExpr_NamedIndexedPropertySet synExpr.Range
+            | SynExpr.Set _ -> genTriviaFor SynExpr_Set synExpr.Range
+            | SynExpr.Quote _ -> genTriviaFor SynExpr_Quote synExpr.Range
+            | SynExpr.ArbitraryAfterError _ -> genTriviaFor SynExpr_ArbitraryAfterError synExpr.Range
+            | SynExpr.DiscardAfterMissingQualificationAfterDot _ ->
+                genTriviaFor SynExpr_DiscardAfterMissingQualificationAfterDot synExpr.Range
+            | SynExpr.DotSet _ -> genTriviaFor SynExpr_DotSet synExpr.Range
+            | SynExpr.Fixed _ -> genTriviaFor SynExpr_Fixed synExpr.Range
+            | SynExpr.FromParseError _ -> genTriviaFor SynExpr_FromParseError synExpr.Range
+            | SynExpr.ImplicitZero _ -> genTriviaFor SynExpr_ImplicitZero synExpr.Range
+            | SynExpr.LibraryOnlyStaticOptimization _ ->
+                genTriviaFor SynExpr_LibraryOnlyStaticOptimization synExpr.Range
+            | SynExpr.LibraryOnlyILAssembly _ -> genTriviaFor SynExpr_LibraryOnlyILAssembly synExpr.Range
+            | SynExpr.LibraryOnlyUnionCaseFieldGet _ -> genTriviaFor SynExpr_LibraryOnlyUnionCaseFieldGet synExpr.Range
+            | SynExpr.LibraryOnlyUnionCaseFieldSet _ -> genTriviaFor SynExpr_LibraryOnlyUnionCaseFieldSet synExpr.Range
+            | SynExpr.SequentialOrImplicitYield _ -> genTriviaFor SynExpr_SequentialOrImplicitYield synExpr.Range
+            | SynExpr.TypeTest _ -> genTriviaFor SynExpr_TypeTest synExpr.Range
+            | SynExpr.Const _ ->
+                // SynConst has trivia attached to it
+                id
+            | SynExpr.LetOrUse _
+            | SynExpr.Sequential _
+            | SynExpr.CompExpr _ ->
+                // first and last nested node has trivia attached to it
+                id
+            | SynExpr.LetOrUseBang _ ->
+                // printed as part of CompBody
+                id
+            | SynExpr.Typed _ ->
+                // child nodes contain trivia
+                id)
 
     expr ctx