Update return values for GC.GetGeneration (#8993)

Author: gewarren

xml/System/GC.xml

@@ -1083,22 +1083,24 @@ This method is most useful in monitoring scenarios for measuring the difference
       <Docs>
         <param name="obj">The object that generation information is retrieved for.</param>
         <summary>Returns the current generation number of the specified object.</summary>
-        <returns>The current generation number of <paramref name="obj" />.</returns>
+        <returns>The current generation number of <paramref name="obj" />, or <see cref="F:System.Int32.MaxValue">Int32.MaxValue</see>.</returns>
         <remarks>
           <format type="text/markdown"><![CDATA[
 
 ## Remarks
- Use this method to determine the age of an object, and then use that information with the <xref:System.GC.Collect%2A> method to force the garbage collector to collect objects in the same generation. For example, use this method when you have a set of objects that are created as a group and that become inaccessible at the same time.
 
+Use this method to determine the age of an object, and then use that information with the <xref:System.GC.Collect%2A> method to force the garbage collector to collect objects in the same generation. For example, use this method when you have a set of objects that are created as a group and that become inaccessible at the same time.
 
+Starting in .NET 8, this method might return <xref:System.Int32.MaxValue> for objects allocated on non-GC heaps. For more information, see [GC.GetGeneration might return Int32.MaxValue](/dotnet/core/compatibility/core-libraries/8.0/getgeneration-return-value).
 
 ## Examples
- The following example demonstrates how to use the <xref:System.GC.GetGeneration%2A> method to determine the age of an object. The example then performs garbage collections to clean up memory and compare the pre and post collection memory totals in the console.
 
- :::code language="cpp" source="~/snippets/cpp/VS_Snippets_CLR_System/system.gc.collect int example/CPP/class1.cpp" id="Snippet1":::
- :::code language="csharp" source="~/snippets/csharp/System/GC/Overview/class1.cs" id="Snippet1":::
- :::code language="fsharp" source="~/snippets/fsharp/System/GC/Overview/class1.fs" id="Snippet1":::
- :::code language="vb" source="~/snippets/visualbasic/VS_Snippets_CLR_System/system.gc.collect int example/VB/class1.vb" id="Snippet1":::
+The following example demonstrates how to use the <xref:System.GC.GetGeneration%2A> method to determine the age of an object. The example then performs garbage collections to clean up memory and compare the pre and post collection memory totals in the console.
+
+:::code language="cpp" source="~/snippets/cpp/VS_Snippets_CLR_System/system.gc.collect int example/CPP/class1.cpp" id="Snippet1":::
+:::code language="csharp" source="~/snippets/csharp/System/GC/Overview/class1.cs" id="Snippet1":::
+:::code language="fsharp" source="~/snippets/fsharp/System/GC/Overview/class1.fs" id="Snippet1":::
+:::code language="vb" source="~/snippets/visualbasic/VS_Snippets_CLR_System/system.gc.collect int example/VB/class1.vb" id="Snippet1":::
 
  ]]></format>
         </remarks>
@@ -1150,17 +1152,22 @@ This method is most useful in monitoring scenarios for measuring the difference
       <Docs>
         <param name="wo">A <see cref="T:System.WeakReference" /> that refers to the target object whose generation number is to be determined.</param>
         <summary>Returns the current generation number of the target of a specified weak reference.</summary>
-        <returns>The current generation number of the target of <paramref name="wo" />.</returns>
+        <returns>The current generation number of the target of <paramref name="wo" />, or <see cref="P:System.Int32.MaxValue" />.</returns>
         <remarks>
           <format type="text/markdown"><![CDATA[
 
+## Remarks
+
+Starting in .NET 8, this method might return <xref:System.Int32.MaxValue> for objects allocated on non-GC heaps. For more information, see [GC.GetGeneration might return Int32.MaxValue](/dotnet/core/compatibility/core-libraries/8.0/getgeneration-return-value).
+
 ## Examples
- The following example demonstrates the use of the <xref:System.GC.GetGeneration%2A> method to determine the age of a weak reference object.
 
- :::code language="cpp" source="~/snippets/cpp/VS_Snippets_CLR_System/system.GC.GetGenerationWeak Example/CPP/systemgcgetgenerationweak.cpp" id="Snippet1":::
- :::code language="csharp" source="~/snippets/csharp/System/GC/GetGeneration/systemgcgetgenerationweak.cs" id="Snippet1":::
- :::code language="fsharp" source="~/snippets/fsharp/System/GC/GetGeneration/systemgcgetgenerationweak.fs" id="Snippet1":::
- :::code language="vb" source="~/snippets/visualbasic/VS_Snippets_CLR_System/system.GC.GetGenerationWeak Example/VB/systemgcgetgenerationweak.vb" id="Snippet1":::
+The following example demonstrates the use of the <xref:System.GC.GetGeneration%2A> method to determine the age of a weak reference object.
+
+:::code language="cpp" source="~/snippets/cpp/VS_Snippets_CLR_System/system.GC.GetGenerationWeak Example/CPP/systemgcgetgenerationweak.cpp" id="Snippet1":::
+:::code language="csharp" source="~/snippets/csharp/System/GC/GetGeneration/systemgcgetgenerationweak.cs" id="Snippet1":::
+:::code language="fsharp" source="~/snippets/fsharp/System/GC/GetGeneration/systemgcgetgenerationweak.fs" id="Snippet1":::
+:::code language="vb" source="~/snippets/visualbasic/VS_Snippets_CLR_System/system.GC.GetGenerationWeak Example/VB/systemgcgetgenerationweak.vb" id="Snippet1":::
 
  ]]></format>
         </remarks>