Fix reporting location of SA1629 after empty elements

Fixes #2680

Author: sharwell

StyleCop.Analyzers/StyleCop.Analyzers.Test/DocumentationRules/SA1629UnitTests.cs

@@ -3,9 +3,7 @@
 
 namespace StyleCop.Analyzers.Test.DocumentationRules
 {
-    using System;
     using System.Collections.Generic;
-    using System.Linq;
     using System.Threading;
     using System.Threading.Tasks;
     using Microsoft.CodeAnalysis;
@@ -297,6 +295,43 @@ public class TestClass
             await this.VerifyCSharpDiagnosticAsync(testCode, EmptyDiagnosticResults, CancellationToken.None).ConfigureAwait(false);
         }
 
+        [Fact]
+        [WorkItem(2680, "https://github.com/DotNetAnalyzers/StyleCopAnalyzers/issues/2680")]
+        public async Task TestReportingAfterEmptyElementAsync()
+        {
+            var testCode = @"
+/// <summary>
+/// Test interface <see cref=""ITest""/>
+/// </summary>
+public interface ITest
+{
+    /// <summary>
+    /// Test method <see cref=""Method""/>
+    /// </summary>
+    void Method();
+}
+";
+
+            var fixedTestCode = @"
+/// <summary>
+/// Test interface <see cref=""ITest""/>
+/// </summary>
+public interface ITest
+{
+    /// <summary>
+    /// Test method <see cref=""Method""/>.
+    /// </summary>
+    void Method();
+}
+";
+
+            DiagnosticResult expected = this.CSharpDiagnostic().WithLocation(8, 41);
+
+            await this.VerifyCSharpDiagnosticAsync(testCode, expected, CancellationToken.None).ConfigureAwait(false);
+            await this.VerifyCSharpDiagnosticAsync(fixedTestCode, EmptyDiagnosticResults, CancellationToken.None).ConfigureAwait(false);
+            await this.VerifyCSharpFixAsync(testCode, fixedTestCode).ConfigureAwait(false);
+        }
+
         protected override Project ApplyCompilationOptions(Project project)
         {
             var resolver = new TestXmlReferenceResolver();

StyleCop.Analyzers/StyleCop.Analyzers/DocumentationRules/SA1629DocumentationTextMustEndWithAPeriod.cs

@@ -78,6 +78,7 @@ protected override void HandleXmlElement(SyntaxNodeAnalysisContext context, bool
             foreach (var xmlElement in syntaxList.OfType<XmlElementSyntax>())
             {
                 var elementDone = false;
+                int? reportingLocation = null;
                 for (var i = xmlElement.Content.Count - 1; !elementDone && (i >= 0); i--)
                 {
                     if (xmlElement.Content[i] is XmlTextSyntax contentNode)
@@ -91,14 +92,20 @@ protected override void HandleXmlElement(SyntaxNodeAnalysisContext context, bool
                             {
                                 if (!textWithoutTrailingWhitespace.EndsWith(".", StringComparison.Ordinal))
                                 {
-                                    var location = Location.Create(xmlElement.SyntaxTree, new TextSpan(textToken.SpanStart + textWithoutTrailingWhitespace.Length, 1));
+                                    var location = Location.Create(xmlElement.SyntaxTree, new TextSpan(reportingLocation ?? textToken.SpanStart + textWithoutTrailingWhitespace.Length, 1));
                                     context.ReportDiagnostic(Diagnostic.Create(Descriptor, location));
                                 }
 
                                 elementDone = true;
                             }
                         }
                     }
+                    else if (xmlElement.Content[i] is XmlEmptyElementSyntax emptyElement)
+                    {
+                        // If a diagnostic gets reported for the element, place the diagnostic after the last empty
+                        // element.
+                        reportingLocation = emptyElement.Span.End;
+                    }
                 }
             }
         }