Fix xml attribute name classification

src/EditorFeatures/CSharpTest/Classification/SyntacticClassifierTests.cs

@@ -5518,5 +5518,60 @@ class C
                 Punctuation.Semicolon,
                 Punctuation.CloseCurly);
         }
+
+        [Fact, WorkItem(48094, "https://github.com/dotnet/roslyn/issues/48094")]
+        public async Task TestXmlAttributeNameSpan1()
+        {
+            var source = @"/// <param name=""value""></param>";
+            using var workspace = CreateWorkspace(source, options: null, TestHost.InProcess);
+            var document = workspace.CurrentSolution.Projects.First().Documents.First();
+
+            var classifications = await GetSyntacticClassificationsAsync(document, new TextSpan(0, source.Length));
+            Assert.Equal(new[]
+            {
+                new ClassifiedSpan(ClassificationTypeNames.XmlDocCommentDelimiter, new TextSpan(0, 3)),
+                new ClassifiedSpan(ClassificationTypeNames.XmlDocCommentText, new TextSpan(3, 1)),
+                new ClassifiedSpan(ClassificationTypeNames.XmlDocCommentDelimiter, new TextSpan(4, 1)),
+                new ClassifiedSpan(ClassificationTypeNames.XmlDocCommentName, new TextSpan(5, 5)),
+                new ClassifiedSpan(ClassificationTypeNames.XmlDocCommentAttributeName, new TextSpan(11, 4)),
+                new ClassifiedSpan(ClassificationTypeNames.XmlDocCommentDelimiter, new TextSpan(15, 1)),
+                new ClassifiedSpan(ClassificationTypeNames.XmlDocCommentAttributeQuotes, new TextSpan(16, 1)),
+                new ClassifiedSpan(ClassificationTypeNames.Identifier, new TextSpan(17, 5)),
+                new ClassifiedSpan(ClassificationTypeNames.XmlDocCommentAttributeQuotes, new TextSpan(22, 1)),
+                new ClassifiedSpan(ClassificationTypeNames.XmlDocCommentDelimiter, new TextSpan(23, 1)),
+                new ClassifiedSpan(ClassificationTypeNames.XmlDocCommentDelimiter, new TextSpan(24, 2)),
+                new ClassifiedSpan(ClassificationTypeNames.XmlDocCommentName, new TextSpan(26, 5)),
+                new ClassifiedSpan(ClassificationTypeNames.XmlDocCommentDelimiter, new TextSpan(31, 1))
+            }, classifications);
+        }
+
+        [Fact, WorkItem(48094, "https://github.com/dotnet/roslyn/issues/48094")]
+        public async Task TestXmlAttributeNameSpan2()
+        {
+            var source = @"
+/// <param
+/// name=""value""></param>";
+            using var workspace = CreateWorkspace(source, options: null, TestHost.InProcess);
+            var document = workspace.CurrentSolution.Projects.First().Documents.First();
+
+            var classifications = await GetSyntacticClassificationsAsync(document, new TextSpan(0, source.Length));
+            Assert.Equal(new[]
+            {
+                new ClassifiedSpan(ClassificationTypeNames.XmlDocCommentDelimiter, new TextSpan(2, 3)),
+                new ClassifiedSpan(ClassificationTypeNames.XmlDocCommentText, new TextSpan(5, 1)),
+                new ClassifiedSpan(ClassificationTypeNames.XmlDocCommentDelimiter, new TextSpan(6, 1)),
+                new ClassifiedSpan(ClassificationTypeNames.XmlDocCommentName, new TextSpan(7, 5)),
+                new ClassifiedSpan(ClassificationTypeNames.XmlDocCommentDelimiter, new TextSpan(14, 3)),
+                new ClassifiedSpan(ClassificationTypeNames.XmlDocCommentAttributeName, new TextSpan(18, 4)),
+                new ClassifiedSpan(ClassificationTypeNames.XmlDocCommentDelimiter, new TextSpan(22, 1)),
+                new ClassifiedSpan(ClassificationTypeNames.XmlDocCommentAttributeQuotes, new TextSpan(23, 1)),
+                new ClassifiedSpan(ClassificationTypeNames.Identifier, new TextSpan(24, 5)),
+                new ClassifiedSpan(ClassificationTypeNames.XmlDocCommentAttributeQuotes, new TextSpan(29, 1)),
+                new ClassifiedSpan(ClassificationTypeNames.XmlDocCommentDelimiter, new TextSpan(30, 1)),
+                new ClassifiedSpan(ClassificationTypeNames.XmlDocCommentDelimiter, new TextSpan(31, 2)),
+                new ClassifiedSpan(ClassificationTypeNames.XmlDocCommentName, new TextSpan(33, 5)),
+                new ClassifiedSpan(ClassificationTypeNames.XmlDocCommentDelimiter, new TextSpan(38, 1))
+            }, classifications);
+        }
     }
 }

src/Workspaces/CSharp/Portable/Classification/Worker_DocumentationComments.cs

@@ -200,28 +200,32 @@ private void ClassifyXmlTextToken(SyntaxToken token)
 
         private void ClassifyXmlName(XmlNameSyntax node)
         {
-            string classificationType;
-            if (node.Parent is XmlAttributeSyntax)
+            var classificationType = node.Parent switch
             {
-                classificationType = ClassificationTypeNames.XmlDocCommentAttributeName;
-            }
-            else if (node.Parent is XmlProcessingInstructionSyntax)
-            {
-                classificationType = ClassificationTypeNames.XmlDocCommentProcessingInstruction;
-            }
-            else
-            {
-                classificationType = ClassificationTypeNames.XmlDocCommentName;
-            }
+                XmlAttributeSyntax => ClassificationTypeNames.XmlDocCommentAttributeName,
+                XmlProcessingInstructionSyntax => ClassificationTypeNames.XmlDocCommentProcessingInstruction,
+                _ => ClassificationTypeNames.XmlDocCommentName,
+            };
 
             var prefix = node.Prefix;
             if (prefix != null)
             {
-                AddXmlClassification(prefix.Prefix, classificationType);
-                AddXmlClassification(prefix.ColonToken, classificationType);
+                AddXmlNameTokenClassification(prefix.Prefix, classificationType);
+                AddXmlNameTokenClassification(prefix.ColonToken, classificationType);
             }
 
-            AddXmlClassification(node.LocalName, classificationType);
+            AddXmlNameTokenClassification(node.LocalName, classificationType);
+        }
+
+        private void AddXmlNameTokenClassification(SyntaxToken token, string classificationType)
+        {
+            if (token.HasLeadingTrivia)
+                ClassifyXmlTrivia(token.LeadingTrivia, whitespaceClassificationType: null);
+
+            AddClassification(token, classificationType);
+
+            if (token.HasTrailingTrivia)
+                ClassifyXmlTrivia(token.TrailingTrivia, whitespaceClassificationType: null);
         }
 
         private void ClassifyXmlElement(XmlElementSyntax node)