From 3e3de67baec027ae3cebe4e5e2f86e565eb9bda6 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B6rn=20Hellander?= <bjorn.hellander@gmail.com>
Date: Sat, 8 Apr 2023 08:16:41 +0200
Subject: [PATCH] Correct SA1515 to not fire on the second line of a file
 header #3630

---
 .../LayoutRules/SA1515UnitTests.cs            | 26 +++++++++++++++++++
 ...gleLineCommentMustBePrecededByBlankLine.cs |  2 +-
 2 files changed, 27 insertions(+), 1 deletion(-)

diff --git a/StyleCop.Analyzers/StyleCop.Analyzers.Test/LayoutRules/SA1515UnitTests.cs b/StyleCop.Analyzers/StyleCop.Analyzers.Test/LayoutRules/SA1515UnitTests.cs
index 778af1e74..96c55e982 100644
--- a/StyleCop.Analyzers/StyleCop.Analyzers.Test/LayoutRules/SA1515UnitTests.cs
+++ b/StyleCop.Analyzers/StyleCop.Analyzers.Test/LayoutRules/SA1515UnitTests.cs
@@ -5,6 +5,7 @@
 
 namespace StyleCop.Analyzers.Test.LayoutRules
 {
+    using System;
     using System.Threading;
     using System.Threading.Tasks;
     using Microsoft.CodeAnalysis.Testing;
@@ -269,5 +270,30 @@ public Class1()
 
             await VerifyCSharpDiagnosticAsync(testCode, DiagnosticResult.EmptyDiagnosticResults, CancellationToken.None).ConfigureAwait(false);
         }
+
+        /// <summary>
+        /// Verifies that the analyzer does not fire in file headers (i.e. one line comments at the start of the file).
+        /// </summary>
+        /// <param name="numberOfHeaderLines">The number of lines in the header.</param>
+        /// <returns>A <see cref="Task"/> representing the asynchronous unit test.</returns>
+        [Theory]
+        [InlineData(1)]
+        [InlineData(2)]
+        [InlineData(3)]
+        [WorkItem(3630, "https://github.com/DotNetAnalyzers/StyleCopAnalyzers/issues/3630")]
+        public async Task TestFileHeaderAsync(int numberOfHeaderLines)
+        {
+            var testCode = @"
+class TestClass
+{
+}";
+
+            for (var i = 0; i < numberOfHeaderLines; i++)
+            {
+                testCode = "// A comment line." + Environment.NewLine + testCode;
+            }
+
+            await VerifyCSharpDiagnosticAsync(testCode, DiagnosticResult.EmptyDiagnosticResults, CancellationToken.None).ConfigureAwait(false);
+        }
     }
 }
diff --git a/StyleCop.Analyzers/StyleCop.Analyzers/LayoutRules/SA1515SingleLineCommentMustBePrecededByBlankLine.cs b/StyleCop.Analyzers/StyleCop.Analyzers/LayoutRules/SA1515SingleLineCommentMustBePrecededByBlankLine.cs
index 6e9faf64c..e19dfb582 100644
--- a/StyleCop.Analyzers/StyleCop.Analyzers/LayoutRules/SA1515SingleLineCommentMustBePrecededByBlankLine.cs
+++ b/StyleCop.Analyzers/StyleCop.Analyzers/LayoutRules/SA1515SingleLineCommentMustBePrecededByBlankLine.cs
@@ -198,7 +198,7 @@ private static bool IsPrecededBySingleLineCommentOnOwnLineOrDocumentation<T>(T t
                     break;
 
                 case SyntaxKind.SingleLineCommentTrivia:
-                    return IsOnOwnLine(triviaList, triviaIndex);
+                    return IsOnOwnLine(triviaList, triviaIndex) || currentTrivia.Span.Start == 0;
 
                 case SyntaxKind.SingleLineDocumentationCommentTrivia:
                     return true;