Allow null langword fixer at the end of an XML tag (#76552)

Author: CyrusNajmabadi

src/Features/CSharpTest/ReplaceDocCommentTextWithTag/ReplaceDocCommentTextWithTagTests.cs

@@ -75,6 +75,44 @@ class C<TKey>
             """);
     }
 
+    [Fact, WorkItem("https://github.com/dotnet/roslyn/issues/76548")]
+    public async Task TestEndOfKeyword_XmlCloseTagFollowing()
+    {
+        await TestInRegularAndScriptAsync(
+            """
+            /// <summary>Testing keyword null[||]</summary>
+            class C<TKey>
+            {
+            }
+            """,
+
+            """
+            /// <summary>Testing keyword <see langword="null"/></summary>
+            class C<TKey>
+            {
+            }
+            """);
+    }
+
+    [Fact, WorkItem("https://github.com/dotnet/roslyn/issues/76548")]
+    public async Task TestEndOfKeyword_XmlOpenTagPreceding()
+    {
+        await TestInRegularAndScriptAsync(
+            """
+            /// <summary>[||]null is an option.</summary>
+            class C<TKey>
+            {
+            }
+            """,
+
+            """
+            /// <summary><see langword="null"/> is an option.</summary>
+            class C<TKey>
+            {
+            }
+            """);
+    }
+
     [Fact]
     public async Task TestSelectedKeyword()
     {

src/Features/Core/Portable/ReplaceDocCommentTextWithTag/AbstractReplaceDocCommentTextWithTagCodeRefactoringProvider.cs

@@ -28,7 +28,13 @@ public override async Task ComputeRefactoringsAsync(CodeRefactoringContext conte
         var token = root.FindToken(span.Start, findInsideTrivia: true);
 
         if (!IsXmlTextToken(token))
-            return;
+        {
+            token = root.FindTokenFromEnd(span.Start, findInsideTrivia: true);
+            if (!IsXmlTextToken(token))
+            {
+                return;
+            }
+        }
 
         if (!token.FullSpan.Contains(span))
             return;

src/Features/VisualBasicTest/ReplaceDocCommentTextWithTag/ReplaceDocCommentTextWithTagTests.vb

@@ -68,6 +68,32 @@ class C(Of TKey)
 end class")
         End Function
 
+        <Fact, WorkItem("https://github.com/dotnet/roslyn/issues/76548")>
+        Public Async Function TestEndOfKeyword_XmlCloseTagFollowing() As Task
+            Await TestInRegularAndScriptAsync(
+"
+''' <summary>Testing keyword MustInherit[||]</summary>
+class C(Of TKey)
+end class",
+"
+''' <summary>Testing keyword <see langword=""MustInherit""/></summary>
+class C(Of TKey)
+end class")
+        End Function
+
+        <Fact, WorkItem("https://github.com/dotnet/roslyn/issues/76548")>
+        Public Async Function TestEndOfKeyword_XmlOpenTagPreceding() As Task
+            Await TestInRegularAndScriptAsync(
+"
+''' <summary>[||]MustInherit is a thing</summary>
+class C(Of TKey)
+end class",
+"
+''' <summary>[||]<see langword=""MustInherit""/> is a thing</summary>
+class C(Of TKey)
+end class")
+        End Function
+
         <Fact>
         Public Async Function TestSelectedKeyword() As Task
             Await TestInRegularAndScriptAsync(