Print trivia for MatchLambda in multiline infix expression. (#2456)

CHANGELOG.md

@@ -9,6 +9,7 @@
 * Idempotency problem when using a list with interpolated strings. [#2242](https://github.com/fsprojects/fantomas/issues/2242)
 * Idempotency problem when using set and spread syntax. [#2392](https://github.com/fsprojects/fantomas/issues/2392)
 * Formatting (*) returns ( * ). [#2452](https://github.com/fsprojects/fantomas/issues/2452)
+* Comment after last case of function with operator is removed.[#2454](https://github.com/fsprojects/fantomas/issues/2454)
 
 ## [5.0.0-beta-007] - 2022-08-19
 

src/Fantomas.Core.Tests/OperatorTests.fs

@@ -1430,3 +1430,26 @@ let (*) x y = x + y
         """
 let (*) x y = x + y
 """
+
+[<Test>]
+let ``trivia after match lambda in infix operation, 2454`` () =
+    formatSourceString
+        false
+        """
+id
+>> function
+    | -1 -> -1 // first comment
+    | 0 -> 0 // second comment
+    | _ -> 1 // third comment
+"""
+        config
+    |> prepend newline
+    |> should
+        equal
+        """
+id
+>> function
+    | -1 -> -1 // first comment
+    | 0 -> 0 // second comment
+    | _ -> 1 // third comment
+"""

src/Fantomas.Core/CodePrinter.fs

@@ -2326,6 +2326,7 @@ and genExprInMultilineInfixExpr astContext e =
     | MatchLambda (keywordRange, cs) ->
         (!- "function " |> genTriviaFor SynExpr_MatchLambda_Function keywordRange)
         +> indentSepNlnUnindent (genClauses astContext cs)
+        |> genTriviaFor SynExpr_MatchLambda e.Range
     | Record _ -> atCurrentColumnIndent (genExpr astContext e)
     | _ -> genExpr astContext e