Clarify Marshal AccessViolationException compatibility comments (#128379)

Copilot · jkotas · web-flow · commit b04ba98ab13d · 2026-05-19T23:00:23.000-07:00
Updates misleading AccessViolationException comments in Marshal interop
helpers to accurately describe compatibility behavior.

---------

Co-authored-by: copilot-swe-agent[bot] &lt;198982749+Copilot@users.noreply.github.com&gt;
Co-authored-by: jkotas &lt;6668460+jkotas@users.noreply.github.com&gt;
diff --git a/src/coreclr/System.Private.CoreLib/src/System/Runtime/InteropServices/Marshal.CoreCLR.cs b/src/coreclr/System.Private.CoreLib/src/System/Runtime/InteropServices/Marshal.CoreCLR.cs
@@ -99,7 +99,7 @@ public static long ReadInt64([MarshalAs(UnmanagedType.AsAny), In] object ptr, in
         /// </remarks>
         private static unsafe T ReadValueSlow<T>(object ptr, int ofs, Func<IntPtr, int, T> readValueHelper)
         {
-            // Consumers of this method are documented to throw AccessViolationException on any AV
+            // Compatibility: null input to these obsolete APIs throws AccessViolationException.
             if (ptr is null)
             {
                 throw new AccessViolationException();
@@ -164,7 +164,7 @@ public static void WriteInt64(object ptr, int ofs, long val)
         /// </summary>
         private static unsafe void WriteValueSlow<T>(object ptr, int ofs, T val, Action<IntPtr, int, T> writeValueHelper)
         {
-            // Consumers of this method are documented to throw AccessViolationException on any AV
+            // Compatibility: null input to these obsolete APIs throws AccessViolationException.
             if (ptr is null)
             {
                 throw new AccessViolationException();
diff --git a/src/coreclr/nativeaot/System.Private.CoreLib/src/System/Runtime/InteropServices/Marshal.NativeAot.cs b/src/coreclr/nativeaot/System.Private.CoreLib/src/System/Runtime/InteropServices/Marshal.NativeAot.cs
@@ -234,7 +234,7 @@ public static unsafe long ReadInt64(object ptr, int ofs)
         [RequiresDynamicCode("Marshalling code for the object might not be available")]
         private static unsafe T ReadValueSlow<T>(object ptr, int ofs, delegate*<IntPtr, int, T> readValueHelper)
         {
-            // Consumers of this method are documented to throw AccessViolationException on any AV
+            // Compatibility: null input to these obsolete APIs throws AccessViolationException.
             if (ptr is null)
             {
                 throw new AccessViolationException();
@@ -312,7 +312,7 @@ public static unsafe void WriteInt64(object ptr, int ofs, long val)
         [RequiresDynamicCode("Marshalling code for the object might not be available")]
         private static unsafe void WriteValueSlow<T>(object ptr, int ofs, T val, delegate*<IntPtr, int, T, void> writeValueHelper)
         {
-            // Consumers of this method are documented to throw AccessViolationException on any AV
+            // Compatibility: null input to these obsolete APIs throws AccessViolationException.
             if (ptr is null)
             {
                 throw new AccessViolationException();
diff --git a/src/libraries/System.Private.CoreLib/src/System/Runtime/InteropServices/Marshal.cs b/src/libraries/System.Private.CoreLib/src/System/Runtime/InteropServices/Marshal.cs
@@ -293,7 +293,7 @@ public static unsafe byte ReadByte(IntPtr ptr, int ofs)
             }
             catch (NullReferenceException)
             {
-                // this method is documented to throw AccessViolationException on any AV
+                // Convert NRE for null/near-null pointers to match the documented AccessViolationException.
                 throw new AccessViolationException();
             }
         }
@@ -317,7 +317,7 @@ public static unsafe short ReadInt16(IntPtr ptr, int ofs)
             }
             catch (NullReferenceException)
             {
-                // this method is documented to throw AccessViolationException on any AV
+                // Convert NRE for null/near-null pointers to match the documented AccessViolationException.
                 throw new AccessViolationException();
             }
         }
@@ -341,7 +341,7 @@ public static unsafe int ReadInt32(IntPtr ptr, int ofs)
             }
             catch (NullReferenceException)
             {
-                // this method is documented to throw AccessViolationException on any AV
+                // Convert NRE for null/near-null pointers to match the documented AccessViolationException.
                 throw new AccessViolationException();
             }
         }
@@ -388,7 +388,7 @@ public static unsafe long ReadInt64(IntPtr ptr, int ofs)
             }
             catch (NullReferenceException)
             {
-                // this method is documented to throw AccessViolationException on any AV
+                // Convert NRE for null/near-null pointers to match the documented AccessViolationException.
                 throw new AccessViolationException();
             }
         }
@@ -404,7 +404,7 @@ public static unsafe void WriteByte(IntPtr ptr, int ofs, byte val)
             }
             catch (NullReferenceException)
             {
-                // this method is documented to throw AccessViolationException on any AV
+                // Convert NRE for null/near-null pointers to match the documented AccessViolationException.
                 throw new AccessViolationException();
             }
         }
@@ -428,7 +428,7 @@ public static unsafe void WriteInt16(IntPtr ptr, int ofs, short val)
             }
             catch (NullReferenceException)
             {
-                // this method is documented to throw AccessViolationException on any AV
+                // Convert NRE for null/near-null pointers to match the documented AccessViolationException.
                 throw new AccessViolationException();
             }
         }
@@ -461,7 +461,7 @@ public static unsafe void WriteInt32(IntPtr ptr, int ofs, int val)
             }
             catch (NullReferenceException)
             {
-                // this method is documented to throw AccessViolationException on any AV
+                // Convert NRE for null/near-null pointers to match the documented AccessViolationException.
                 throw new AccessViolationException();
             }
         }
@@ -508,7 +508,7 @@ public static unsafe void WriteInt64(IntPtr ptr, int ofs, long val)
             }
             catch (NullReferenceException)
             {
-                // this method is documented to throw AccessViolationException on any AV
+                // Convert NRE for null/near-null pointers to match the documented AccessViolationException.
                 throw new AccessViolationException();
             }
         }

Original file line number	Diff line number	Diff line change
`@@ -99,7 +99,7 @@ public static long ReadInt64([MarshalAs(UnmanagedType.AsAny), In] object ptr, in`
`99`	`99`	`/// </remarks>`
`100`	`100`	`private static unsafe T ReadValueSlow<T>(object ptr, int ofs, Func<IntPtr, int, T> readValueHelper)`
`101`	`101`	`{`
`102`		`- // Consumers of this method are documented to throw AccessViolationException on any AV`
	`102`	`+ // Compatibility: null input to these obsolete APIs throws AccessViolationException.`
`103`	`103`	`if (ptr is null)`
`104`	`104`	`{`
`105`	`105`	`throw new AccessViolationException();`
`@@ -164,7 +164,7 @@ public static void WriteInt64(object ptr, int ofs, long val)`
`164`	`164`	`/// </summary>`
`165`	`165`	`private static unsafe void WriteValueSlow<T>(object ptr, int ofs, T val, Action<IntPtr, int, T> writeValueHelper)`
`166`	`166`	`{`
`167`		`- // Consumers of this method are documented to throw AccessViolationException on any AV`
	`167`	`+ // Compatibility: null input to these obsolete APIs throws AccessViolationException.`
`168`	`168`	`if (ptr is null)`
`169`	`169`	`{`
`170`	`170`	`throw new AccessViolationException();`
Original file line number	Diff line number	Diff line change
`@@ -234,7 +234,7 @@ public static unsafe long ReadInt64(object ptr, int ofs)`
`234`	`234`	`[RequiresDynamicCode("Marshalling code for the object might not be available")]`
`235`	`235`	`private static unsafe T ReadValueSlow<T>(object ptr, int ofs, delegate*<IntPtr, int, T> readValueHelper)`
`236`	`236`	`{`
`237`		`- // Consumers of this method are documented to throw AccessViolationException on any AV`
	`237`	`+ // Compatibility: null input to these obsolete APIs throws AccessViolationException.`
`238`	`238`	`if (ptr is null)`
`239`	`239`	`{`
`240`	`240`	`throw new AccessViolationException();`
`@@ -312,7 +312,7 @@ public static unsafe void WriteInt64(object ptr, int ofs, long val)`
`312`	`312`	`[RequiresDynamicCode("Marshalling code for the object might not be available")]`
`313`	`313`	`private static unsafe void WriteValueSlow<T>(object ptr, int ofs, T val, delegate*<IntPtr, int, T, void> writeValueHelper)`
`314`	`314`	`{`
`315`		`- // Consumers of this method are documented to throw AccessViolationException on any AV`
	`315`	`+ // Compatibility: null input to these obsolete APIs throws AccessViolationException.`
`316`	`316`	`if (ptr is null)`
`317`	`317`	`{`
`318`	`318`	`throw new AccessViolationException();`
Original file line number	Diff line number	Diff line change
`@@ -293,7 +293,7 @@ public static unsafe byte ReadByte(IntPtr ptr, int ofs)`
`293`	`293`	`}`
`294`	`294`	`catch (NullReferenceException)`
`295`	`295`	`{`
`296`		`- // this method is documented to throw AccessViolationException on any AV`
	`296`	`+ // Convert NRE for null/near-null pointers to match the documented AccessViolationException.`
`297`	`297`	`throw new AccessViolationException();`
`298`	`298`	`}`
`299`	`299`	`}`
`@@ -317,7 +317,7 @@ public static unsafe short ReadInt16(IntPtr ptr, int ofs)`
`317`	`317`	`}`
`318`	`318`	`catch (NullReferenceException)`
`319`	`319`	`{`
`320`		`- // this method is documented to throw AccessViolationException on any AV`
	`320`	`+ // Convert NRE for null/near-null pointers to match the documented AccessViolationException.`
`321`	`321`	`throw new AccessViolationException();`
`322`	`322`	`}`
`323`	`323`	`}`
`@@ -341,7 +341,7 @@ public static unsafe int ReadInt32(IntPtr ptr, int ofs)`
`341`	`341`	`}`
`342`	`342`	`catch (NullReferenceException)`
`343`	`343`	`{`
`344`		`- // this method is documented to throw AccessViolationException on any AV`
	`344`	`+ // Convert NRE for null/near-null pointers to match the documented AccessViolationException.`
`345`	`345`	`throw new AccessViolationException();`
`346`	`346`	`}`
`347`	`347`	`}`
`@@ -388,7 +388,7 @@ public static unsafe long ReadInt64(IntPtr ptr, int ofs)`
`388`	`388`	`}`
`389`	`389`	`catch (NullReferenceException)`
`390`	`390`	`{`
`391`		`- // this method is documented to throw AccessViolationException on any AV`
	`391`	`+ // Convert NRE for null/near-null pointers to match the documented AccessViolationException.`
`392`	`392`	`throw new AccessViolationException();`
`393`	`393`	`}`
`394`	`394`	`}`
`@@ -404,7 +404,7 @@ public static unsafe void WriteByte(IntPtr ptr, int ofs, byte val)`
`404`	`404`	`}`
`405`	`405`	`catch (NullReferenceException)`
`406`	`406`	`{`
`407`		`- // this method is documented to throw AccessViolationException on any AV`
	`407`	`+ // Convert NRE for null/near-null pointers to match the documented AccessViolationException.`
`408`	`408`	`throw new AccessViolationException();`
`409`	`409`	`}`
`410`	`410`	`}`
`@@ -428,7 +428,7 @@ public static unsafe void WriteInt16(IntPtr ptr, int ofs, short val)`
`428`	`428`	`}`
`429`	`429`	`catch (NullReferenceException)`
`430`	`430`	`{`
`431`		`- // this method is documented to throw AccessViolationException on any AV`
	`431`	`+ // Convert NRE for null/near-null pointers to match the documented AccessViolationException.`
`432`	`432`	`throw new AccessViolationException();`
`433`	`433`	`}`
`434`	`434`	`}`
`@@ -461,7 +461,7 @@ public static unsafe void WriteInt32(IntPtr ptr, int ofs, int val)`
`461`	`461`	`}`
`462`	`462`	`catch (NullReferenceException)`
`463`	`463`	`{`
`464`		`- // this method is documented to throw AccessViolationException on any AV`
	`464`	`+ // Convert NRE for null/near-null pointers to match the documented AccessViolationException.`
`465`	`465`	`throw new AccessViolationException();`
`466`	`466`	`}`
`467`	`467`	`}`
`@@ -508,7 +508,7 @@ public static unsafe void WriteInt64(IntPtr ptr, int ofs, long val)`
`508`	`508`	`}`
`509`	`509`	`catch (NullReferenceException)`
`510`	`510`	`{`
`511`		`- // this method is documented to throw AccessViolationException on any AV`
	`511`	`+ // Convert NRE for null/near-null pointers to match the documented AccessViolationException.`
`512`	`512`	`throw new AccessViolationException();`
`513`	`513`	`}`
`514`	`514`	`}`