Do not warn if a comma follows a preprocessor directive

Author: MattFromRVA

StyleCop.Analyzers/StyleCop.Analyzers.Test/SpacingRules/SA1001UnitTests.cs

@@ -349,6 +349,27 @@ public void TestMethod()
             await VerifyCSharpFixAsync(testCode, expected, fixedCode, CancellationToken.None).ConfigureAwait(false);
         }
 
+        [Fact]
+        [WorkItem(3816, "https://github.com/DotNetAnalyzers/StyleCopAnalyzers/issues/3816")]
+        public async Task TestCommaFollowingPreprocessorDirectiveAsync()
+        {
+            var testCode = @"
+interface IFormattable {}
+interface ISpanFormattable {}
+
+partial struct Money : IFormattable
+#if !NETSTANDARD
+    , ISpanFormattable
+#endif
+{
+}
+";
+
+            var expected = DiagnosticResult.EmptyDiagnosticResults;
+
+            await VerifyCSharpDiagnosticAsync(testCode, expected, CancellationToken.None).ConfigureAwait(false);
+        }
+
         private Task TestCommaInStatementOrDeclAsync(string originalStatement, DiagnosticResult expected, string fixedStatement)
         {
             return this.TestCommaInStatementOrDeclAsync(originalStatement, new[] { expected }, fixedStatement);

StyleCop.Analyzers/StyleCop.Analyzers/SpacingRules/SA1001CommasMustBeSpacedCorrectly.cs

@@ -7,6 +7,7 @@ namespace StyleCop.Analyzers.SpacingRules
 {
     using System;
     using System.Collections.Immutable;
+    using System.Linq;
     using Microsoft.CodeAnalysis;
     using Microsoft.CodeAnalysis.CSharp;
     using Microsoft.CodeAnalysis.Diagnostics;
@@ -76,6 +77,14 @@ private static void HandleCommaToken(SyntaxTreeAnalysisContext context, SyntaxTo
                 return;
             }
 
+            // Check if the comma follows a preprocessor directive
+            if (token.HasLeadingTrivia && token.LeadingTrivia.Any(trivia =>
+                trivia.IsDirective))
+            {
+                // Ignore this comma as it follows a preprocessor directive
+                return;
+            }
+
             // check for a following space
             bool missingFollowingSpace = true;
 

documentation/SA1001.md

@@ -28,6 +28,12 @@ A comma should be followed by a single space, except in the following cases.
 * A comma may appear at the end of a line
 * A comma should not be followed by a space when used in an open generic type in a `typeof` expression
 * A comma is part of a string interpolation alignment component. For example:`$"{x,3}"`
+* A comma follows a preprocessor directive. For example:
+  ```csharp
+  partial struct Money : IFormattable
+  #if !NETSTANDARD
+      , ISpanFormattable
+  #endif
 
 A comma should never be preceded by a space or appear as the first token on a line.