Fix duplicated trivias in combination with double nested try-with statements #1969 (#1971)

* fix WIP draft

* fix test name to avoid confusion

* resolve some review comments

* cleanup

* nits

* reformat using 'dotnet fantomas src -r'

* follow test code conventions

* cover one more case

Author: KarolBajkowski

src/Fantomas.Tests/CommentTests.fs

@@ -1599,3 +1599,89 @@ type TorDirectory =
                 }
         }
 """
+
+[<Test>]
+let ``double try-with, comment before inner 'with' not duplicated, 1969`` () =
+    formatSourceString
+        false
+        """
+try
+    try
+        ()
+        // xxx
+    with
+    | _ -> ()
+with
+| _ -> ()
+"""
+        config
+    |> prepend newline
+    |> should
+        equal
+        """
+try
+    try
+        ()
+    // xxx
+    with
+    | _ -> ()
+with
+| _ -> ()
+"""
+
+[<Test>]
+let ``comment shold not be lost`` () =
+    formatSourceString
+        false
+        """
+try
+    a
+// comment
+with
+
+
+| b -> c
+"""
+        config
+    |> prepend newline
+    |> should
+        equal
+        """
+try
+    a
+// comment
+with
+
+
+| b -> c
+"""
+
+[<Test>]
+let ``nested try/with with comment on with`` () =
+    formatSourceString
+        false
+        """
+try
+    a
+with
+| b ->
+    try c
+    // inner comment
+    with
+    | d -> ()
+"""
+        config
+    |> prepend newline
+    |> should
+        equal
+        """
+try
+    a
+with
+| b ->
+    try
+        c
+    // inner comment
+    with
+    | d -> ()
+"""

src/Fantomas.Tests/CompilerDirectivesTests.fs

@@ -2659,3 +2659,36 @@ let ``indented #if directive inside another non-indented #if directive should fo
 #endif
 #endif
 """
+
+[<Test>]
+let ``double try-with, inner #if directive should not throw error, 1969`` () =
+    formatSourceString
+        false
+        """
+try
+    try
+        ()
+#if FOO
+        ()
+#endif
+    with
+    | _ -> ()
+with
+| _ -> ()
+"""
+        config
+    |> prepend newline
+    |> should
+        equal
+        """
+try
+    try
+        ()
+#if FOO
+        ()
+#endif
+    with
+    | _ -> ()
+with
+| _ -> ()
+"""

src/Fantomas/CodePrinter.fs

@@ -2023,14 +2023,20 @@ and genExpr astContext synExpr ctx =
 
                 atCurrentColumn (colWithNlnWhenItemIsMultilineUsingConfig items) ctx
         // Could customize a bit if e is single line
-        | TryWith (e, cs) ->
+        | TryWith (e, mWithToLast, cs) ->
             atCurrentColumn (
                 kw TRY !- "try "
                 +> indent
                 +> sepNln
                 +> genExpr astContext e
                 +> unindent
-                +> kw WITH !+~ "with"
+                +> (fun ctx ->
+                    let lookupRange =
+                        ctx.MkRangeWith
+                            (mWithToLast.StartLine, mWithToLast.StartColumn)
+                            (mWithToLast.StartLine, mWithToLast.StartColumn + 3)
+
+                    tokN lookupRange WITH !+~ "with" ctx)
                 +> indentOnWith
                 +> sepNln
                 +> col sepNln cs (genClause astContext true)

src/Fantomas/SourceParser.fs

@@ -1073,7 +1073,7 @@ let (|LongIdentSet|_|) =
 
 let (|TryWith|_|) =
     function
-    | SynExpr.TryWith (e, _, cs, _, _, _, _) -> Some(e, cs)
+    | SynExpr.TryWith (e, _, cs, mWithToLast, _, _, _) -> Some(e, mWithToLast, cs)
     | _ -> None
 
 let (|TryFinally|_|) =