feat: support reordering modifers with a leading comment (#1786)

Resolves #1784

It might be possible reorder all modiferes with comments and keep this
logic. Perhaps this breaks something 🤷

Co-authored-by: Bela VanderVoort <twobitbela@gmail.com>

Author: TimothyMakkison

Src/CSharpier.Core/CSharp/SyntaxPrinter/Modifiers.cs

@@ -101,9 +101,11 @@ Func<IReadOnlyList<SyntaxToken>, Doc> print
         // reordering modifiers inside of #ifs can lead to code that doesn't compile
         var willReorderModifiers =
             modifiers.Count > 1
-            && !modifiers.Any(o => o.LeadingTrivia.Any(p => p.IsDirective || p.IsComment()));
+            && !modifiers.Skip(1).Any(o => o.LeadingTrivia.Any(p => p.IsDirective || p.IsComment()))
+            && !modifiers[0].LeadingTrivia.Any(p => p.IsDirective);
 
         var sortedModifiers = modifiers.ToArray();
+        var leadingToken = sortedModifiers.FirstOrDefault();
         if (willReorderModifiers)
         {
             Array.Sort(sortedModifiers, Comparer);
@@ -112,6 +114,15 @@ Func<IReadOnlyList<SyntaxToken>, Doc> print
         if (willReorderModifiers && !sortedModifiers.SequenceEqual(modifiers))
         {
             context.State.ReorderedModifiers = true;
+
+            var leadingTrivia = leadingToken.LeadingTrivia;
+            var leadingTokenIndex = Array.FindIndex(
+                sortedModifiers,
+                token => token == leadingToken
+            );
+            sortedModifiers[leadingTokenIndex] = sortedModifiers[leadingTokenIndex]
+                .WithLeadingTrivia(new SyntaxTriviaList());
+            sortedModifiers[0] = sortedModifiers[0].WithLeadingTrivia(leadingTrivia);
         }
 
         return print(sortedModifiers);

Src/CSharpier.Tests/FormattingTests/TestFiles/cs/Modifiers_Sort_Preprocessors.expected.test

@@ -0,0 +1,31 @@
+public class DontReorderThis
+{
+#if !SILVERLIGHT
+    [Attribute]
+#endif
+    internal
+#if !SILVERLIGHT
+    unsafe
+#endif
+    static String Method() { }
+
+#if MONO
+    public void NewSymbolSet() { }
+#endif
+
+#if !SILVERLIGHT
+    [Attribute]
+#endif
+    private
+#if !SILVERLIGHT
+    static
+#endif
+    string Field;
+
+    // leading comment should reorder modifiers
+    public static void Method() { }
+
+    static
+    // midway comment should not reorder modifiers
+    public void Method1() { }
+}

Src/CSharpier.Tests/FormattingTests/TestFiles/cs/Modifiers_Sort_Preprocessors.test

@@ -22,6 +22,10 @@ public class DontReorderThis
 #endif
     string Field;
 
-    // comment should not reorder modifiers
+    // leading comment should reorder modifiers
     static public void Method() { }
+
+    static 
+    // midway comment should not reorder modifiers
+    public void Method1() { }
 }