Merge pull request #2177 from vweijsters/fix-2176

SA1515 now properly ignores end of line comments when determining consecutive comment lines

Author: sharwell

StyleCop.Analyzers/StyleCop.Analyzers.Test/LayoutRules/SA1515UnitTests.cs

@@ -210,6 +210,43 @@ public void TestMethod() { }
             await this.VerifyCSharpDiagnosticAsync(testCode, EmptyDiagnosticResults, CancellationToken.None).ConfigureAwait(false);
         }
 
+        /// <summary>
+        /// Verifies that a comment between two statements with an end of line comment is handled properly.
+        /// This is a regression test for #2176
+        /// </summary>
+        /// <returns>A <see cref="Task"/> representing the asynchronous unit test.</returns>
+        [Fact]
+        public async Task TestCommentBetweenStatementsWithEndOfLineCommentAsync()
+        {
+            var testCode = @"
+public class TestConstants
+{
+  public const string Constant1 = ""1""; // my end of line comment
+  // my comment
+  public const string Constant2 = ""2""; // my second end of line comment
+}
+";
+
+            var fixedTestCode = @"
+public class TestConstants
+{
+  public const string Constant1 = ""1""; // my end of line comment
+
+  // my comment
+  public const string Constant2 = ""2""; // my second end of line comment
+}
+";
+
+            DiagnosticResult[] expectedDiagnostic =
+            {
+                this.CSharpDiagnostic().WithLocation(5, 3),
+            };
+
+            await this.VerifyCSharpDiagnosticAsync(testCode, expectedDiagnostic, CancellationToken.None).ConfigureAwait(false);
+            await this.VerifyCSharpDiagnosticAsync(fixedTestCode, EmptyDiagnosticResults, CancellationToken.None).ConfigureAwait(false);
+            await this.VerifyCSharpFixAsync(testCode, fixedTestCode).ConfigureAwait(false);
+        }
+
         /// <inheritdoc/>
         protected override IEnumerable<DiagnosticAnalyzer> GetCSharpDiagnosticAnalyzers()
         {

StyleCop.Analyzers/StyleCop.Analyzers/LayoutRules/SA1515SingleLineCommentMustBePrecededByBlankLine.cs

@@ -105,44 +105,50 @@ public override void Initialize(AnalysisContext context)
         private static void HandleSyntaxTree(SyntaxTreeAnalysisContext context)
         {
             var syntaxRoot = context.Tree.GetRoot(context.CancellationToken);
+            var previousCommentNotOnOwnLine = false;
 
             foreach (var trivia in syntaxRoot.DescendantTrivia().Where(trivia => trivia.IsKind(SyntaxKind.SingleLineCommentTrivia)))
             {
                 if (trivia.FullSpan.Start == 0)
                 {
                     // skip the trivia if it is at the start of the file
+                    previousCommentNotOnOwnLine = false;
                     continue;
                 }
 
                 if (trivia.ToString().StartsWith("////", StringComparison.Ordinal))
                 {
                     // ignore commented out code
+                    previousCommentNotOnOwnLine = false;
                     continue;
                 }
 
                 int triviaIndex;
-
-                // PERF: Explicitly cast to IReadOnlyList so we only box once.
                 var triviaList = TriviaHelper.GetContainingTriviaList(trivia, out triviaIndex);
 
                 if (!IsOnOwnLine(triviaList, triviaIndex))
                 {
                     // ignore comments after other code elements.
+                    previousCommentNotOnOwnLine = true;
                     continue;
                 }
 
                 if (IsPrecededByBlankLine(triviaList, triviaIndex))
                 {
                     // allow properly formatted blank line comments.
+                    previousCommentNotOnOwnLine = false;
                     continue;
                 }
 
-                if (IsPrecededBySingleLineCommentOrDocumentation(triviaList, triviaIndex))
+                if (!previousCommentNotOnOwnLine && IsPrecededBySingleLineCommentOrDocumentation(triviaList, triviaIndex))
                 {
                     // allow consecutive single line comments.
+                    previousCommentNotOnOwnLine = false;
                     continue;
                 }
 
+                previousCommentNotOnOwnLine = false;
+
                 if (IsAtStartOfScope(trivia))
                 {
                     // allow single line comment at scope start.
@@ -184,7 +190,8 @@ private static bool IsPrecededBySingleLineCommentOrDocumentation<T>(T triviaList
             triviaIndex--;
             while ((eolCount < 2) && (triviaIndex >= 0))
             {
-                switch (triviaList[triviaIndex].Kind())
+                var currentTrivia = triviaList[triviaIndex];
+                switch (currentTrivia.Kind())
                 {
                 case SyntaxKind.WhitespaceTrivia:
                     triviaIndex--;