Avoid reporting SA1629 inside 'seealso' elements

Closes #2679

Author: sharwell

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

@@ -336,6 +336,37 @@ public interface ITest
             await this.VerifyCSharpFixAsync(testCode, fixedTestCode).ConfigureAwait(false);
         }
 
+        [Fact]
+        [WorkItem(2679, "https://github.com/DotNetAnalyzers/StyleCopAnalyzers/issues/2679")]
+        public async Task TestElementsThatDoNotRequirePeriodsAsync()
+        {
+            var testCode = @"
+/// <summary>
+/// Test interface <see cref=""ITest"">a see element</see>
+/// </summary>
+/// <seealso href=""https://docs.microsoft.com/en-us/dotnet/framework/wpf/index"">Windows Presentation Foundation</seealso>
+public interface ITest
+{
+}
+";
+
+            var fixedTestCode = @"
+/// <summary>
+/// Test interface <see cref=""ITest"">a see element</see>.
+/// </summary>
+/// <seealso href=""https://docs.microsoft.com/en-us/dotnet/framework/wpf/index"">Windows Presentation Foundation</seealso>
+public interface ITest
+{
+}
+";
+
+            DiagnosticResult expected = this.CSharpDiagnostic().WithLocation(3, 57);
+
+            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

@@ -12,6 +12,7 @@ namespace StyleCop.Analyzers.DocumentationRules
     using Microsoft.CodeAnalysis.CSharp.Syntax;
     using Microsoft.CodeAnalysis.Diagnostics;
     using Microsoft.CodeAnalysis.Text;
+    using StyleCop.Analyzers.Helpers;
 
     /// <summary>
     /// A section of the XML header documentation for a C# element does not end with a period (also known as a full
@@ -77,6 +78,11 @@ protected override void HandleXmlElement(SyntaxNodeAnalysisContext context, bool
         {
             foreach (var xmlElement in syntaxList.OfType<XmlElementSyntax>())
             {
+                if (xmlElement.StartTag?.Name?.LocalName.ValueText == XmlCommentHelper.SeeAlsoXmlTag)
+                {
+                    continue;
+                }
+
                 var elementDone = false;
                 int? reportingLocation = null;
                 for (var i = xmlElement.Content.Count - 1; !elementDone && (i >= 0); i--)
@@ -100,11 +106,11 @@ protected override void HandleXmlElement(SyntaxNodeAnalysisContext context, bool
                             }
                         }
                     }
-                    else if (xmlElement.Content[i] is XmlEmptyElementSyntax emptyElement)
+                    else if (xmlElement.Content[i].IsInlineElement())
                     {
-                        // If a diagnostic gets reported for the element, place the diagnostic after the last empty
+                        // If a diagnostic gets reported for the element, place the diagnostic after the last inline
                         // element.
-                        reportingLocation = emptyElement.Span.End;
+                        reportingLocation = xmlElement.Content[i].Span.End;
                     }
                 }
             }

StyleCop.Analyzers/StyleCop.Analyzers/Helpers/XmlCommentHelper.cs

@@ -21,9 +21,13 @@ internal static class XmlCommentHelper
         internal const string InheritdocXmlTag = "inheritdoc";
         internal const string ReturnsXmlTag = "returns";
         internal const string ValueXmlTag = "value";
+        internal const string CXmlTag = "c";
         internal const string SeeXmlTag = "see";
+        internal const string SeeAlsoXmlTag = "seealso";
         internal const string ParamXmlTag = "param";
+        internal const string ParamRefXmlTag = "paramref";
         internal const string TypeParamXmlTag = "typeparam";
+        internal const string TypeParamRefXmlTag = "typeparamref";
         internal const string RemarksXmlTag = "remarks";
         internal const string ExampleXmlTag = "example";
         internal const string PermissionXmlTag = "permission";
@@ -264,5 +268,35 @@ internal static T GetFirstAttributeOrDefault<T>(XmlNodeSyntax nodeSyntax)
 
             return null;
         }
+
+        internal static bool IsInlineElement(this XmlNodeSyntax nodeSyntax)
+        {
+            if (nodeSyntax is XmlEmptyElementSyntax emptyElementSyntax)
+            {
+                return IsInlineElement(emptyElementSyntax.Name?.LocalName.ValueText);
+            }
+
+            if (nodeSyntax is XmlElementSyntax elementSyntax)
+            {
+                return IsInlineElement(elementSyntax.StartTag?.Name?.LocalName.ValueText);
+            }
+
+            return false;
+        }
+
+        private static bool IsInlineElement(string localName)
+        {
+            switch (localName)
+            {
+            case CXmlTag:
+            case ParamRefXmlTag:
+            case SeeXmlTag:
+            case TypeParamRefXmlTag:
+                return true;
+
+            default:
+                return false;
+            }
+        }
     }
 }

StyleCop.Analyzers/StyleCop.Analyzers/Helpers/XmlSyntaxFactory.cs

@@ -256,12 +256,12 @@ public static XmlEmptyElementSyntax SeeElement(CrefSyntax cref)
 
         public static XmlEmptyElementSyntax SeeAlsoElement(CrefSyntax cref)
         {
-            return EmptyElement("seealso").AddAttributes(CrefAttribute(cref));
+            return EmptyElement(XmlCommentHelper.SeeAlsoXmlTag).AddAttributes(CrefAttribute(cref));
         }
 
         public static XmlElementSyntax SeeAlsoElement(Uri linkAddress, SyntaxList<XmlNodeSyntax> linkText)
         {
-            XmlElementSyntax element = Element("seealso", linkText);
+            XmlElementSyntax element = Element(XmlCommentHelper.SeeAlsoXmlTag, linkText);
             return element.WithStartTag(element.StartTag.AddAttributes(TextAttribute("href", linkAddress.ToString())));
         }