add a newline after the operator in SameInfix applications to let comment be printed (#2892)

* in the multilineExpr of SameInfix Apps, add a newline after the operator if there's ContentAfter

* Slightly stricter check.

* Add release notes.

---------

Co-authored-by: Florian Verdonck <[email protected]>

Author: dawedawe

CHANGELOG.md

@@ -1,13 +1,14 @@
 # Changelog
 
-## [Unreleased]
+## [6.0.4] - 2023-06-02
 
 ### Changed
 * Update FCS to 'Prototype signature files for lex files', commit 5b74995780a0e9d24a5db025e68b31e6d910f71f
 
 ### Fixed
 * Missing space before arrow. [#2888](https://github.com/fsprojects/fantomas/issues/2888)
 * Cons pattern in let bindings is converted to invalid code. [#1996](https://github.com/fsprojects/fantomas/issues/1996)
+* Trivia after infix operator is not restored correctly. [#2887](https://github.com/fsprojects/fantomas/issues/2887)
 
 ## [6.0.3] - 2023-05-14
 

src/Fantomas.Core.Tests/CommentTests.fs

@@ -2612,3 +2612,45 @@ let (* this comment disappears after formatting *) a = []
         """
 let (* this comment disappears after formatting *) a = []
 """
+
+[<Test>]
+let ``trivia after infix operator is not restored correctly, 2887`` () =
+    formatSourceString
+        false
+        """
+let EnableHeapTerminationOnCorruption() =
+        if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows) &&  Environment.OSVersion.Version.Major >= 6 && // If OS is Vista or higher
+            Environment.Version.Major < 3) then // and CLR not 3.0 or higher
+            let HeapEnableTerminationOnCorruption = 1u : uint32
+            if not (HeapSetInformation(GetProcessHeap(), HeapEnableTerminationOnCorruption, UIntPtr.Zero, UIntPtr.Zero)) then
+                  raise (System.Security.SecurityException(
+                            "Unable to enable unmanaged process execution option TerminationOnCorruption. " +
+                            "HeapSetInformation() returned FALSE; LastError = 0x" +
+                            GetLastError().ToString("X").PadLeft(8, '0') + "."))
+"""
+        config
+    |> prepend newline
+    |> should
+        equal
+        """
+let EnableHeapTerminationOnCorruption () =
+    if
+        (RuntimeInformation.IsOSPlatform(OSPlatform.Windows)
+         && Environment.OSVersion.Version.Major >= 6
+         && // If OS is Vista or higher
+         Environment.Version.Major < 3)
+    then // and CLR not 3.0 or higher
+        let HeapEnableTerminationOnCorruption = 1u: uint32
+
+        if
+            not (HeapSetInformation(GetProcessHeap(), HeapEnableTerminationOnCorruption, UIntPtr.Zero, UIntPtr.Zero))
+        then
+            raise (
+                System.Security.SecurityException(
+                    "Unable to enable unmanaged process execution option TerminationOnCorruption. "
+                    + "HeapSetInformation() returned FALSE; LastError = 0x"
+                    + GetLastError().ToString("X").PadLeft(8, '0')
+                    + "."
+                )
+            )
+"""

src/Fantomas.Core/CodePrinter.fs

@@ -772,7 +772,7 @@ let genExpr (e: Expr) =
                 +> sepNln
                 +> col sepNln es (fun (operator, e) ->
                     genSingleTextNode operator
-                    +> sepSpace
+                    +> sepNlnWhenWriteBeforeNewlineNotEmptyOr sepSpace
                     +> (fun ctx ->
                         match e with
                         | Expr.Lambda _ when