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Fix NullReferenceException in DestroyStructure for blittable types - #126795

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Fix NullReferenceException in DestroyStructure for blittable types#126795
jkoritzinsky merged 4 commits into
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copilot/fix-destroystructure-blittable-test

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Description

BoxedLayoutTypeMarshaler<T> (introduced in #126621) routes DestroyStructure for blittable value types through StructureMarshaler<T>.Free, which unconditionally called NativeMemory.Clear(ptr, size) even when FreeCore was a no-op. Passing an invalid pointer like (IntPtr)1 — the longstanding test pattern for "blittable types should be a no-op" — faults at address 1, manifesting as a NullReferenceException on Android.

Changes

  • StructureMarshaler<T>: Added a s_isBlittable static field (initialized once via Marshal.HasLayout). Free() now skips both FreeCore and NativeMemory.Clear for blittable types. For non-blittable types (array marshaling path via NonBlittableStructureArrayFree), the JIT generates a FreeCore IL stub that frees native sub-structures; NativeMemory.Clear still follows to prevent double-free.

  • LayoutClassMarshaler<T>.Methods: Added IsBlittable property using the existing s_nativeSizeForBlittableTypes field (non-zero ⟺ blittable). Access to IsBlittable is wrapped in a GetIsBlittable() method that follows the same [MethodImpl(MethodImplOptions.NoInlining)] + try/catch (TypeInitializationException) pattern used by all other Methods accessors, ensuring TypeLoadException is surfaced instead of TypeInitializationException on recursive native layout failures. Free() is now a no-op for blittable reference types — same fix, same reasoning.

Testing

Existing DestroyStructure_Blittable_Success test covers the regression. Full System.Runtime.InteropServices.Tests suite: 2549 passed, 0 failed.

CopilotAI review requested due to automatic review settings April 11, 2026 19:51
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CopilotAI linked an issue Apr 11, 2026 that may be closed by this pull request
System.Runtime.InteropServices.Tests.DestroyStructureTests.DestroyStructure_Blittable_Success failing in CI #126788
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@jkoritzinsky
Fix DestroyStructure_Blittable_Success: skip NativeMemory.Clear for b…
2fec7f8
…littable types in StructureMarshaler and LayoutClassMarshaler
For blittable types, FreeCore is a no-op (uses the C# body since TryGenerateStructMarshallingMethod
returns false for blittable types). Calling NativeMemory.Clear on a potentially invalid pointer
(like (IntPtr)1 used in tests) causes a NullReferenceException/fault.
Fix by:
1. Adding s_isBlittable static field to StructureMarshaler<T> (initialized via Marshal.HasLayout)
2. Adding IsBlittable property to LayoutClassMarshaler<T>.Methods (using existing s_nativeSizeForBlittableTypes)
3. Skipping FreeCore and NativeMemory.Clear in both Free() methods for blittable types
This restores the original behavior where DestroyStructure is a no-op for blittable types.
Agent-Logs-Url: https://github.com/dotnet/runtime/sessions/f610b358-8378-4bba-b4dd-98615601bdeb
Co-authored-by: jkoritzinsky <1571408+jkoritzinsky@users.noreply.github.com>
CopilotAI requested review from Copilot and removed request for CopilotApril 11, 2026 20:28
@jkoritzinsky
Rename ComputeIsBlittable to InitIsBlittable and add comment to Metho…
a830c1b
…ds.IsBlittable
Agent-Logs-Url: https://github.com/dotnet/runtime/sessions/f610b358-8378-4bba-b4dd-98615601bdeb
Co-authored-by: jkoritzinsky <1571408+jkoritzinsky@users.noreply.github.com>
CopilotAI requested review from Copilot and removed request for CopilotApril 11, 2026 20:29
CopilotAI changed the title [WIP] Fix null reference exception in DestroyStructure_Blittable_Success testFix NullReferenceException in DestroyStructure for blittable typesApr 11, 2026
CopilotAI requested a review from jkoritzinskyApril 11, 2026 20:34
@am11

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Failure seems related https://helix.dot.net/api/2019-06-17/jobs/ac25ae7c-952e-4650-900f-5f3fcb70ec27/workitems/Interop/consol

Test FAIL: Xunit.Sdk.ThrowsException: Assert.Throws() Failure: Exception type was not an exact match
Expected: typeof(System.TypeLoadException)
Actual: typeof(System.TypeInitializationException)
at Xunit.Assert.ThrowsImpl(Type exceptionType, Exception exception, Func`2 inspector) in /_/src/arcade/src/Microsoft.DotNet.XUnitAssert/src/ExceptionAsserts.cs:line 509
at MarshalArrayAsField.LPArray.Test.RunTest2(String report)
at MarshalArrayAsField.LPArray.Test.TestEntryPoint()
Xunit.Sdk.EqualException: Assert.Equal() Failure: Values differ
Expected: 100
Actual: 101
at Xunit.Assert.Equal[T](T expected, T actual, IEqualityComparer`1 comparer) in /_/src/arcade/src/Microsoft.DotNet.XUnitAssert/src/EqualityAsserts.cs:line 102
at Program.<<Main>$>g__TestExecutor41|0_42(StreamWriter tempLogSw, StreamWriter statsCsvSw, <>c__DisplayClass0_0&)
21:55:07.441 Failed test: global::MarshalArrayAsField.LPArray.Test.TestEntryPoint()
21:55:07.446 Running test: global::MarshalArrayAsParam.Default.ArrayMarshal.TestMarshalByVal_NoAttributes()
ByVal marshaling CLR array as c-style-array no attributes

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Comment threadsrc/coreclr/System.Private.CoreLib/src/System/StubHelpers.cs Outdated
@jkoritzinsky
Wrap IsBlittable access in no-inline method with TypeInitializationEx…
844dcd8
…ception try-catch pattern
Agent-Logs-Url: https://github.com/dotnet/runtime/sessions/f3d7123a-231f-4ec5-9460-294f83aeb412
Co-authored-by: jkoritzinsky <1571408+jkoritzinsky@users.noreply.github.com>
CopilotAI requested review from Copilot and removed request for CopilotApril 12, 2026 02:43
CopilotAI requested a review from jkoritzinskyApril 12, 2026 02:44
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jkoritzinsky marked this pull request as ready for review April 12, 2026 03:14
CopilotAI review requested due to automatic review settings April 12, 2026 03:14
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Comment threadsrc/coreclr/System.Private.CoreLib/src/System/StubHelpers.cs
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Pull request overview

Fixes a crash in Marshal.DestroyStructure for blittable layout types by avoiding NativeMemory.Clear on potentially invalid pointers (e.g., (IntPtr)1), and preserves the existing “unwrap TypeInitializationException” behavior for blittable detection in the layout-class marshaler.

Changes:

  • Skip FreeCore/NativeMemory.Clear in StructureMarshaler<T>.Free when T is blittable (computed once via Marshal.HasLayout).
  • Add Methods.IsBlittable + GetIsBlittable() wrapper in LayoutClassMarshaler<T> and make Free a no-op for blittable layout classes.
  • Keep NativeMemory.Clear for non-blittable types to prevent double-free after nested cleanup.

Comment threadsrc/coreclr/System.Private.CoreLib/src/System/StubHelpers.cs
Comment threadsrc/coreclr/System.Private.CoreLib/src/System/StubHelpers.cs
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jkoritzinsky enabled auto-merge (squash) April 12, 2026 04:41
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is there a build analysis pattern for this? would be good for various pr's hitting it

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Not sure why automerge failed here; BA is green?

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Not sure why automerge failed here; BA is green?

Conversations need to be resolved i think

@jkoritzinsky
jkoritzinsky merged commit 6df558c into mainApr 12, 2026
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jkoritzinsky deleted the copilot/fix-destroystructure-blittable-test branch April 12, 2026 14:38
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is there a build analysis pattern for this? would be good for various pr's hitting it

Yes the closed issue had the BA template.

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System.Runtime.InteropServices.Tests.DestroyStructureTests.DestroyStructure_Blittable_Success failing in CI

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Fix NullReferenceException in DestroyStructure for blittable types by Copilot · Pull Request #126795 · dotnet/runtime · GitHub
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Fix NullReferenceException in DestroyStructure for blittable types - #126795
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jkoritzinsky merged 4 commits into
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copilot/fix-destroystructure-blittable-test
Apr 12, 2026
Merged
Fix NullReferenceException in DestroyStructure for blittable types#126795
jkoritzinsky merged 4 commits into
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copilot/fix-destroystructure-blittable-test
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Description
BoxedLayoutTypeMarshaler<T> (introduced in #126621) routes DestroyStructure for blittable value types through StructureMarshaler<T>.Free, which unconditionally called NativeMemory.Clear(ptr, size) even when FreeCore was a no-op. Passing an invalid pointer like (IntPtr)1 — the longstanding test pattern for "blittable types should be a no-op" — faults at address 1, manifesting as a NullReferenceException on Android.
Changes
  • StructureMarshaler<T>: Added a s_isBlittable static field (initialized once via Marshal.HasLayout). Free() now skips both FreeCore and NativeMemory.Clear for blittable types. For non-blittable types (array marshaling path via NonBlittableStructureArrayFree), the JIT generates a FreeCore IL stub that frees native sub-structures; NativeMemory.Clear still follows to prevent double-free.
  • LayoutClassMarshaler<T>.Methods: Added IsBlittable property using the existing s_nativeSizeForBlittableTypes field (non-zero ⟺ blittable). Access to IsBlittable is wrapped in a GetIsBlittable() method that follows the same [MethodImpl(MethodImplOptions.NoInlining)] + try/catch (TypeInitializationException) pattern used by all other Methods accessors, ensuring TypeLoadException is surfaced instead of TypeInitializationException on recursive native layout failures. Free() is now a no-op for blittable reference types — same fix, same reasoning.
Testing
Existing DestroyStructure_Blittable_Success test covers the regression. Full System.Runtime.InteropServices.Tests suite: 2549 passed, 0 failed.
CopilotAI
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System.Runtime.InteropServices.Tests.DestroyStructureTests.DestroyStructure_Blittable_Success failing in CI
#126788

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@jkoritzinsky
Fix DestroyStructure_Blittable_Success: skip NativeMemory.Clear for b…
2fec7f8
…littable types in StructureMarshaler and LayoutClassMarshaler
For blittable types, FreeCore is a no-op (uses the C# body since TryGenerateStructMarshallingMethod
returns false for blittable types). Calling NativeMemory.Clear on a potentially invalid pointer
(like (IntPtr)1 used in tests) causes a NullReferenceException/fault.
Fix by:
1. Adding s_isBlittable static field to StructureMarshaler<T> (initialized via Marshal.HasLayout)
2. Adding IsBlittable property to LayoutClassMarshaler<T>.Methods (using existing s_nativeSizeForBlittableTypes)
3. Skipping FreeCore and NativeMemory.Clear in both Free() methods for blittable types
This restores the original behavior where DestroyStructure is a no-op for blittable types.
Agent-Logs-Url: https://github.com/dotnet/runtime/sessions/f610b358-8378-4bba-b4dd-98615601bdeb
Co-authored-by: jkoritzinsky <1571408+jkoritzinsky@users.noreply.github.com>
CopilotAI
requested review from
Copilot
and removed request for
CopilotApril 11, 2026 20:28
@jkoritzinsky
Rename ComputeIsBlittable to InitIsBlittable and add comment to Metho…
a830c1b
…ds.IsBlittable
Agent-Logs-Url: https://github.com/dotnet/runtime/sessions/f610b358-8378-4bba-b4dd-98615601bdeb
Co-authored-by: jkoritzinsky <1571408+jkoritzinsky@users.noreply.github.com>
CopilotAI
requested review from
Copilot
and removed request for
CopilotApril 11, 2026 20:29
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changed the title
[WIP] Fix null reference exception in DestroyStructure_Blittable_Success testFix NullReferenceException in DestroyStructure for blittable typesApr 11, 2026
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Failure seems related https://helix.dot.net/api/2019-06-17/jobs/ac25ae7c-952e-4650-900f-5f3fcb70ec27/workitems/Interop/consol
Test FAIL: Xunit.Sdk.ThrowsException: Assert.Throws() Failure: Exception type was not an exact match
Expected: typeof(System.TypeLoadException)
Actual: typeof(System.TypeInitializationException)
at Xunit.Assert.ThrowsImpl(Type exceptionType, Exception exception, Func`2 inspector) in /_/src/arcade/src/Microsoft.DotNet.XUnitAssert/src/ExceptionAsserts.cs:line 509
at MarshalArrayAsField.LPArray.Test.RunTest2(String report)
at MarshalArrayAsField.LPArray.Test.TestEntryPoint()
Xunit.Sdk.EqualException: Assert.Equal() Failure: Values differ
Expected: 100
Actual: 101
at Xunit.Assert.Equal[T](T expected, T actual, IEqualityComparer`1 comparer) in /_/src/arcade/src/Microsoft.DotNet.XUnitAssert/src/EqualityAsserts.cs:line 102
at Program.<<Main>$>g__TestExecutor41|0_42(StreamWriter tempLogSw, StreamWriter statsCsvSw, <>c__DisplayClass0_0&)
21:55:07.441 Failed test: global::MarshalArrayAsField.LPArray.Test.TestEntryPoint()
21:55:07.446 Running test: global::MarshalArrayAsParam.Default.ArrayMarshal.TestMarshalByVal_NoAttributes()
ByVal marshaling CLR array as c-style-array no attributes

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Comment threadsrc/coreclr/System.Private.CoreLib/src/System/StubHelpers.cs
Outdated

@jkoritzinsky
Wrap IsBlittable access in no-inline method with TypeInitializationEx…
844dcd8
…ception try-catch pattern
Agent-Logs-Url: https://github.com/dotnet/runtime/sessions/f3d7123a-231f-4ec5-9460-294f83aeb412
Co-authored-by: jkoritzinsky <1571408+jkoritzinsky@users.noreply.github.com>
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Pull request overview
Fixes a crash in Marshal.DestroyStructure for blittable layout types by avoiding NativeMemory.Clear on potentially invalid pointers (e.g., (IntPtr)1), and preserves the existing “unwrap TypeInitializationException” behavior for blittable detection in the layout-class marshaler.
Changes:
  • Skip FreeCore/NativeMemory.Clear in StructureMarshaler<T>.Free when T is blittable (computed once via Marshal.HasLayout).
  • Add Methods.IsBlittable + GetIsBlittable() wrapper in LayoutClassMarshaler<T> and make Free a no-op for blittable layout classes.
  • Keep NativeMemory.Clear for non-blittable types to prevent double-free after nested cleanup.
Comment threadsrc/coreclr/System.Private.CoreLib/src/System/StubHelpers.cs
Comment threadsrc/coreclr/System.Private.CoreLib/src/System/StubHelpers.cs
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is there a build analysis pattern for this? would be good for various pr's hitting it
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Not sure why automerge failed here; BA is green?
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Not sure why automerge failed here; BA is green?
Conversations need to be resolved i think
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is there a build analysis pattern for this? would be good for various pr's hitting it
Yes the closed issue had the BA template.
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System.Runtime.InteropServices.Tests.DestroyStructureTests.DestroyStructure_Blittable_Success failing in CI


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Fix NullReferenceException in DestroyStructure for blittable types by Copilot · Pull Request #126795 · dotnet/runtime · GitHub
Skip to content
Fix NullReferenceException in DestroyStructure for blittable types - #126795
Merged
jkoritzinsky merged 4 commits into
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copilot/fix-destroystructure-blittable-test
Apr 12, 2026
Merged
Fix NullReferenceException in DestroyStructure for blittable types#126795
jkoritzinsky merged 4 commits into
mainfrom 
copilot/fix-destroystructure-blittable-test
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Description
BoxedLayoutTypeMarshaler<T> (introduced in #126621) routes DestroyStructure for blittable value types through StructureMarshaler<T>.Free, which unconditionally called NativeMemory.Clear(ptr, size) even when FreeCore was a no-op. Passing an invalid pointer like (IntPtr)1 — the longstanding test pattern for "blittable types should be a no-op" — faults at address 1, manifesting as a NullReferenceException on Android.
Changes
  • StructureMarshaler<T>: Added a s_isBlittable static field (initialized once via Marshal.HasLayout). Free() now skips both FreeCore and NativeMemory.Clear for blittable types. For non-blittable types (array marshaling path via NonBlittableStructureArrayFree), the JIT generates a FreeCore IL stub that frees native sub-structures; NativeMemory.Clear still follows to prevent double-free.
  • LayoutClassMarshaler<T>.Methods: Added IsBlittable property using the existing s_nativeSizeForBlittableTypes field (non-zero ⟺ blittable). Access to IsBlittable is wrapped in a GetIsBlittable() method that follows the same [MethodImpl(MethodImplOptions.NoInlining)] + try/catch (TypeInitializationException) pattern used by all other Methods accessors, ensuring TypeLoadException is surfaced instead of TypeInitializationException on recursive native layout failures. Free() is now a no-op for blittable reference types — same fix, same reasoning.
Testing
Existing DestroyStructure_Blittable_Success test covers the regression. Full System.Runtime.InteropServices.Tests suite: 2549 passed, 0 failed.
CopilotAI
review requested due to automatic review settings
April 11, 2026 19:51
CopilotAI
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System.Runtime.InteropServices.Tests.DestroyStructureTests.DestroyStructure_Blittable_Success failing in CI
#126788

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@jkoritzinsky
Fix DestroyStructure_Blittable_Success: skip NativeMemory.Clear for b…
2fec7f8
…littable types in StructureMarshaler and LayoutClassMarshaler
For blittable types, FreeCore is a no-op (uses the C# body since TryGenerateStructMarshallingMethod
returns false for blittable types). Calling NativeMemory.Clear on a potentially invalid pointer
(like (IntPtr)1 used in tests) causes a NullReferenceException/fault.
Fix by:
1. Adding s_isBlittable static field to StructureMarshaler<T> (initialized via Marshal.HasLayout)
2. Adding IsBlittable property to LayoutClassMarshaler<T>.Methods (using existing s_nativeSizeForBlittableTypes)
3. Skipping FreeCore and NativeMemory.Clear in both Free() methods for blittable types
This restores the original behavior where DestroyStructure is a no-op for blittable types.
Agent-Logs-Url: https://github.com/dotnet/runtime/sessions/f610b358-8378-4bba-b4dd-98615601bdeb
Co-authored-by: jkoritzinsky <1571408+jkoritzinsky@users.noreply.github.com>
CopilotAI
requested review from
Copilot
and removed request for
CopilotApril 11, 2026 20:28
@jkoritzinsky
Rename ComputeIsBlittable to InitIsBlittable and add comment to Metho…
a830c1b
…ds.IsBlittable
Agent-Logs-Url: https://github.com/dotnet/runtime/sessions/f610b358-8378-4bba-b4dd-98615601bdeb
Co-authored-by: jkoritzinsky <1571408+jkoritzinsky@users.noreply.github.com>
CopilotAI
requested review from
Copilot
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CopilotApril 11, 2026 20:29
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[WIP] Fix null reference exception in DestroyStructure_Blittable_Success testFix NullReferenceException in DestroyStructure for blittable typesApr 11, 2026
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Failure seems related https://helix.dot.net/api/2019-06-17/jobs/ac25ae7c-952e-4650-900f-5f3fcb70ec27/workitems/Interop/consol
Test FAIL: Xunit.Sdk.ThrowsException: Assert.Throws() Failure: Exception type was not an exact match
Expected: typeof(System.TypeLoadException)
Actual: typeof(System.TypeInitializationException)
at Xunit.Assert.ThrowsImpl(Type exceptionType, Exception exception, Func`2 inspector) in /_/src/arcade/src/Microsoft.DotNet.XUnitAssert/src/ExceptionAsserts.cs:line 509
at MarshalArrayAsField.LPArray.Test.RunTest2(String report)
at MarshalArrayAsField.LPArray.Test.TestEntryPoint()
Xunit.Sdk.EqualException: Assert.Equal() Failure: Values differ
Expected: 100
Actual: 101
at Xunit.Assert.Equal[T](T expected, T actual, IEqualityComparer`1 comparer) in /_/src/arcade/src/Microsoft.DotNet.XUnitAssert/src/EqualityAsserts.cs:line 102
at Program.<<Main>$>g__TestExecutor41|0_42(StreamWriter tempLogSw, StreamWriter statsCsvSw, <>c__DisplayClass0_0&)
21:55:07.441 Failed test: global::MarshalArrayAsField.LPArray.Test.TestEntryPoint()
21:55:07.446 Running test: global::MarshalArrayAsParam.Default.ArrayMarshal.TestMarshalByVal_NoAttributes()
ByVal marshaling CLR array as c-style-array no attributes

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Comment threadsrc/coreclr/System.Private.CoreLib/src/System/StubHelpers.cs
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Wrap IsBlittable access in no-inline method with TypeInitializationEx…
844dcd8
…ception try-catch pattern
Agent-Logs-Url: https://github.com/dotnet/runtime/sessions/f3d7123a-231f-4ec5-9460-294f83aeb412
Co-authored-by: jkoritzinsky <1571408+jkoritzinsky@users.noreply.github.com>
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Pull request overview
Fixes a crash in Marshal.DestroyStructure for blittable layout types by avoiding NativeMemory.Clear on potentially invalid pointers (e.g., (IntPtr)1), and preserves the existing “unwrap TypeInitializationException” behavior for blittable detection in the layout-class marshaler.
Changes:
  • Skip FreeCore/NativeMemory.Clear in StructureMarshaler<T>.Free when T is blittable (computed once via Marshal.HasLayout).
  • Add Methods.IsBlittable + GetIsBlittable() wrapper in LayoutClassMarshaler<T> and make Free a no-op for blittable layout classes.
  • Keep NativeMemory.Clear for non-blittable types to prevent double-free after nested cleanup.
Comment threadsrc/coreclr/System.Private.CoreLib/src/System/StubHelpers.cs
Comment threadsrc/coreclr/System.Private.CoreLib/src/System/StubHelpers.cs
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is there a build analysis pattern for this? would be good for various pr's hitting it
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Not sure why automerge failed here; BA is green?
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Not sure why automerge failed here; BA is green?
Conversations need to be resolved i think
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is there a build analysis pattern for this? would be good for various pr's hitting it
Yes the closed issue had the BA template.
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System.Runtime.InteropServices.Tests.DestroyStructureTests.DestroyStructure_Blittable_Success failing in CI


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Fix NullReferenceException in DestroyStructure for blittable types by Copilot · Pull Request #126795 · dotnet/runtime · GitHub
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Fix NullReferenceException in DestroyStructure for blittable types - #126795
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copilot/fix-destroystructure-blittable-test
Apr 12, 2026
Merged
Fix NullReferenceException in DestroyStructure for blittable types#126795
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copilot/fix-destroystructure-blittable-test
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Description
BoxedLayoutTypeMarshaler<T> (introduced in #126621) routes DestroyStructure for blittable value types through StructureMarshaler<T>.Free, which unconditionally called NativeMemory.Clear(ptr, size) even when FreeCore was a no-op. Passing an invalid pointer like (IntPtr)1 — the longstanding test pattern for "blittable types should be a no-op" — faults at address 1, manifesting as a NullReferenceException on Android.
Changes
  • StructureMarshaler<T>: Added a s_isBlittable static field (initialized once via Marshal.HasLayout). Free() now skips both FreeCore and NativeMemory.Clear for blittable types. For non-blittable types (array marshaling path via NonBlittableStructureArrayFree), the JIT generates a FreeCore IL stub that frees native sub-structures; NativeMemory.Clear still follows to prevent double-free.
  • LayoutClassMarshaler<T>.Methods: Added IsBlittable property using the existing s_nativeSizeForBlittableTypes field (non-zero ⟺ blittable). Access to IsBlittable is wrapped in a GetIsBlittable() method that follows the same [MethodImpl(MethodImplOptions.NoInlining)] + try/catch (TypeInitializationException) pattern used by all other Methods accessors, ensuring TypeLoadException is surfaced instead of TypeInitializationException on recursive native layout failures. Free() is now a no-op for blittable reference types — same fix, same reasoning.
Testing
Existing DestroyStructure_Blittable_Success test covers the regression. Full System.Runtime.InteropServices.Tests suite: 2549 passed, 0 failed.
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System.Runtime.InteropServices.Tests.DestroyStructureTests.DestroyStructure_Blittable_Success failing in CI
#126788

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@jkoritzinsky
Fix DestroyStructure_Blittable_Success: skip NativeMemory.Clear for b…
2fec7f8
…littable types in StructureMarshaler and LayoutClassMarshaler
For blittable types, FreeCore is a no-op (uses the C# body since TryGenerateStructMarshallingMethod
returns false for blittable types). Calling NativeMemory.Clear on a potentially invalid pointer
(like (IntPtr)1 used in tests) causes a NullReferenceException/fault.
Fix by:
1. Adding s_isBlittable static field to StructureMarshaler<T> (initialized via Marshal.HasLayout)
2. Adding IsBlittable property to LayoutClassMarshaler<T>.Methods (using existing s_nativeSizeForBlittableTypes)
3. Skipping FreeCore and NativeMemory.Clear in both Free() methods for blittable types
This restores the original behavior where DestroyStructure is a no-op for blittable types.
Agent-Logs-Url: https://github.com/dotnet/runtime/sessions/f610b358-8378-4bba-b4dd-98615601bdeb
Co-authored-by: jkoritzinsky <1571408+jkoritzinsky@users.noreply.github.com>
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@jkoritzinsky
Rename ComputeIsBlittable to InitIsBlittable and add comment to Metho…
a830c1b
…ds.IsBlittable
Agent-Logs-Url: https://github.com/dotnet/runtime/sessions/f610b358-8378-4bba-b4dd-98615601bdeb
Co-authored-by: jkoritzinsky <1571408+jkoritzinsky@users.noreply.github.com>
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[WIP] Fix null reference exception in DestroyStructure_Blittable_Success testFix NullReferenceException in DestroyStructure for blittable typesApr 11, 2026
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Failure seems related https://helix.dot.net/api/2019-06-17/jobs/ac25ae7c-952e-4650-900f-5f3fcb70ec27/workitems/Interop/consol
Test FAIL: Xunit.Sdk.ThrowsException: Assert.Throws() Failure: Exception type was not an exact match
Expected: typeof(System.TypeLoadException)
Actual: typeof(System.TypeInitializationException)
at Xunit.Assert.ThrowsImpl(Type exceptionType, Exception exception, Func`2 inspector) in /_/src/arcade/src/Microsoft.DotNet.XUnitAssert/src/ExceptionAsserts.cs:line 509
at MarshalArrayAsField.LPArray.Test.RunTest2(String report)
at MarshalArrayAsField.LPArray.Test.TestEntryPoint()
Xunit.Sdk.EqualException: Assert.Equal() Failure: Values differ
Expected: 100
Actual: 101
at Xunit.Assert.Equal[T](T expected, T actual, IEqualityComparer`1 comparer) in /_/src/arcade/src/Microsoft.DotNet.XUnitAssert/src/EqualityAsserts.cs:line 102
at Program.<<Main>$>g__TestExecutor41|0_42(StreamWriter tempLogSw, StreamWriter statsCsvSw, <>c__DisplayClass0_0&)
21:55:07.441 Failed test: global::MarshalArrayAsField.LPArray.Test.TestEntryPoint()
21:55:07.446 Running test: global::MarshalArrayAsParam.Default.ArrayMarshal.TestMarshalByVal_NoAttributes()
ByVal marshaling CLR array as c-style-array no attributes

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Comment threadsrc/coreclr/System.Private.CoreLib/src/System/StubHelpers.cs
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@jkoritzinsky
Wrap IsBlittable access in no-inline method with TypeInitializationEx…
844dcd8
…ception try-catch pattern
Agent-Logs-Url: https://github.com/dotnet/runtime/sessions/f3d7123a-231f-4ec5-9460-294f83aeb412
Co-authored-by: jkoritzinsky <1571408+jkoritzinsky@users.noreply.github.com>
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Pull request overview
Fixes a crash in Marshal.DestroyStructure for blittable layout types by avoiding NativeMemory.Clear on potentially invalid pointers (e.g., (IntPtr)1), and preserves the existing “unwrap TypeInitializationException” behavior for blittable detection in the layout-class marshaler.
Changes:
  • Skip FreeCore/NativeMemory.Clear in StructureMarshaler<T>.Free when T is blittable (computed once via Marshal.HasLayout).
  • Add Methods.IsBlittable + GetIsBlittable() wrapper in LayoutClassMarshaler<T> and make Free a no-op for blittable layout classes.
  • Keep NativeMemory.Clear for non-blittable types to prevent double-free after nested cleanup.
Comment threadsrc/coreclr/System.Private.CoreLib/src/System/StubHelpers.cs
Comment threadsrc/coreclr/System.Private.CoreLib/src/System/StubHelpers.cs
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is there a build analysis pattern for this? would be good for various pr's hitting it
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Not sure why automerge failed here; BA is green?
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Not sure why automerge failed here; BA is green?
Conversations need to be resolved i think
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is there a build analysis pattern for this? would be good for various pr's hitting it
Yes the closed issue had the BA template.
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System.Runtime.InteropServices.Tests.DestroyStructureTests.DestroyStructure_Blittable_Success failing in CI


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, 'i');
if (__m === '*' || __re.test(location.href)) {
// Strip utm_, fbclid, gclid, etc. from all links on page
(function() {
var trackingParams = ['utm_source', 'utm_medium', 'utm_campaign', 'utm_term', 'utm_content',
'fbclid', 'gclid', 'dclid', 'msclkid', 'yclid',
'ref', 'ref_src', 'source', 'medium', 'campaign'];
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try {
var u = new URL(url, window.location.origin);
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try {
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var __re = new RegExp('^' + "youtube\\.com" + '
Fix NullReferenceException in DestroyStructure for blittable types by Copilot · Pull Request #126795 · dotnet/runtime · GitHub
Skip to content
Fix NullReferenceException in DestroyStructure for blittable types - #126795
Merged
jkoritzinsky merged 4 commits into
mainfrom 
copilot/fix-destroystructure-blittable-test
Apr 12, 2026
Merged
Fix NullReferenceException in DestroyStructure for blittable types#126795
jkoritzinsky merged 4 commits into
mainfrom 
copilot/fix-destroystructure-blittable-test
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Description
BoxedLayoutTypeMarshaler<T> (introduced in #126621) routes DestroyStructure for blittable value types through StructureMarshaler<T>.Free, which unconditionally called NativeMemory.Clear(ptr, size) even when FreeCore was a no-op. Passing an invalid pointer like (IntPtr)1 — the longstanding test pattern for "blittable types should be a no-op" — faults at address 1, manifesting as a NullReferenceException on Android.
Changes
  • StructureMarshaler<T>: Added a s_isBlittable static field (initialized once via Marshal.HasLayout). Free() now skips both FreeCore and NativeMemory.Clear for blittable types. For non-blittable types (array marshaling path via NonBlittableStructureArrayFree), the JIT generates a FreeCore IL stub that frees native sub-structures; NativeMemory.Clear still follows to prevent double-free.
  • LayoutClassMarshaler<T>.Methods: Added IsBlittable property using the existing s_nativeSizeForBlittableTypes field (non-zero ⟺ blittable). Access to IsBlittable is wrapped in a GetIsBlittable() method that follows the same [MethodImpl(MethodImplOptions.NoInlining)] + try/catch (TypeInitializationException) pattern used by all other Methods accessors, ensuring TypeLoadException is surfaced instead of TypeInitializationException on recursive native layout failures. Free() is now a no-op for blittable reference types — same fix, same reasoning.
Testing
Existing DestroyStructure_Blittable_Success test covers the regression. Full System.Runtime.InteropServices.Tests suite: 2549 passed, 0 failed.
CopilotAI
review requested due to automatic review settings
April 11, 2026 19:51
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from CopilotApril 11, 2026 19:51
CopilotAI
linked an issue
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that may be
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System.Runtime.InteropServices.Tests.DestroyStructureTests.DestroyStructure_Blittable_Success failing in CI
#126788

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@jkoritzinsky
Fix DestroyStructure_Blittable_Success: skip NativeMemory.Clear for b…
2fec7f8
…littable types in StructureMarshaler and LayoutClassMarshaler
For blittable types, FreeCore is a no-op (uses the C# body since TryGenerateStructMarshallingMethod
returns false for blittable types). Calling NativeMemory.Clear on a potentially invalid pointer
(like (IntPtr)1 used in tests) causes a NullReferenceException/fault.
Fix by:
1. Adding s_isBlittable static field to StructureMarshaler<T> (initialized via Marshal.HasLayout)
2. Adding IsBlittable property to LayoutClassMarshaler<T>.Methods (using existing s_nativeSizeForBlittableTypes)
3. Skipping FreeCore and NativeMemory.Clear in both Free() methods for blittable types
This restores the original behavior where DestroyStructure is a no-op for blittable types.
Agent-Logs-Url: https://github.com/dotnet/runtime/sessions/f610b358-8378-4bba-b4dd-98615601bdeb
Co-authored-by: jkoritzinsky <1571408+jkoritzinsky@users.noreply.github.com>
CopilotAI
requested review from
Copilot
and removed request for
CopilotApril 11, 2026 20:28
@jkoritzinsky
Rename ComputeIsBlittable to InitIsBlittable and add comment to Metho…
a830c1b
…ds.IsBlittable
Agent-Logs-Url: https://github.com/dotnet/runtime/sessions/f610b358-8378-4bba-b4dd-98615601bdeb
Co-authored-by: jkoritzinsky <1571408+jkoritzinsky@users.noreply.github.com>
CopilotAI
requested review from
Copilot
and removed request for
CopilotApril 11, 2026 20:29
CopilotAI
changed the title
[WIP] Fix null reference exception in DestroyStructure_Blittable_Success testFix NullReferenceException in DestroyStructure for blittable typesApr 11, 2026
CopilotAI
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from jkoritzinskyApril 11, 2026 20:34
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Failure seems related https://helix.dot.net/api/2019-06-17/jobs/ac25ae7c-952e-4650-900f-5f3fcb70ec27/workitems/Interop/consol
Test FAIL: Xunit.Sdk.ThrowsException: Assert.Throws() Failure: Exception type was not an exact match
Expected: typeof(System.TypeLoadException)
Actual: typeof(System.TypeInitializationException)
at Xunit.Assert.ThrowsImpl(Type exceptionType, Exception exception, Func`2 inspector) in /_/src/arcade/src/Microsoft.DotNet.XUnitAssert/src/ExceptionAsserts.cs:line 509
at MarshalArrayAsField.LPArray.Test.RunTest2(String report)
at MarshalArrayAsField.LPArray.Test.TestEntryPoint()
Xunit.Sdk.EqualException: Assert.Equal() Failure: Values differ
Expected: 100
Actual: 101
at Xunit.Assert.Equal[T](T expected, T actual, IEqualityComparer`1 comparer) in /_/src/arcade/src/Microsoft.DotNet.XUnitAssert/src/EqualityAsserts.cs:line 102
at Program.<<Main>$>g__TestExecutor41|0_42(StreamWriter tempLogSw, StreamWriter statsCsvSw, <>c__DisplayClass0_0&)
21:55:07.441 Failed test: global::MarshalArrayAsField.LPArray.Test.TestEntryPoint()
21:55:07.446 Running test: global::MarshalArrayAsParam.Default.ArrayMarshal.TestMarshalByVal_NoAttributes()
ByVal marshaling CLR array as c-style-array no attributes

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Wrap IsBlittable access in no-inline method with TypeInitializationEx…
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…ception try-catch pattern
Agent-Logs-Url: https://github.com/dotnet/runtime/sessions/f3d7123a-231f-4ec5-9460-294f83aeb412
Co-authored-by: jkoritzinsky <1571408+jkoritzinsky@users.noreply.github.com>
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Pull request overview
Fixes a crash in Marshal.DestroyStructure for blittable layout types by avoiding NativeMemory.Clear on potentially invalid pointers (e.g., (IntPtr)1), and preserves the existing “unwrap TypeInitializationException” behavior for blittable detection in the layout-class marshaler.
Changes:
  • Skip FreeCore/NativeMemory.Clear in StructureMarshaler<T>.Free when T is blittable (computed once via Marshal.HasLayout).
  • Add Methods.IsBlittable + GetIsBlittable() wrapper in LayoutClassMarshaler<T> and make Free a no-op for blittable layout classes.
  • Keep NativeMemory.Clear for non-blittable types to prevent double-free after nested cleanup.
Comment threadsrc/coreclr/System.Private.CoreLib/src/System/StubHelpers.cs
Comment threadsrc/coreclr/System.Private.CoreLib/src/System/StubHelpers.cs
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is there a build analysis pattern for this? would be good for various pr's hitting it
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Not sure why automerge failed here; BA is green?
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Not sure why automerge failed here; BA is green?
Conversations need to be resolved i think
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is there a build analysis pattern for this? would be good for various pr's hitting it
Yes the closed issue had the BA template.
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System.Runtime.InteropServices.Tests.DestroyStructureTests.DestroyStructure_Blittable_Success failing in CI


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, 'i');
if (__m === '*' || __re.test(location.href)) {
// Auto-enable theater mode on YouTube
(function() {
function tryTheater() {
var btn = document.querySelector('button[aria-label="Theater mode"], ytd-player #player button[title="Theater mode"]');
if (btn && !btn.classList.contains('activated')) {
btn.click();
}
}
// Try immediately
tryTheater();
// Try after navigation (SPA)
var lastUrl = location.href;
setInterval(function() {
if (location.href !== lastUrl) {
lastUrl = location.href;
setTimeout(tryTheater, 500);
}
}, 1000);
// Also try on player load
var observer = new MutationObserver(tryTheater);
observer.observe(document.body, { childList: true, subtree: true });
})();
}
} catch(__e) { console.warn('[Userscript:YouTube Theater Mode Default]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '
Fix NullReferenceException in DestroyStructure for blittable types by Copilot · Pull Request #126795 · dotnet/runtime · GitHub
Skip to content
Fix NullReferenceException in DestroyStructure for blittable types - #126795
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Fix NullReferenceException in DestroyStructure for blittable types#126795
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Description
BoxedLayoutTypeMarshaler<T> (introduced in #126621) routes DestroyStructure for blittable value types through StructureMarshaler<T>.Free, which unconditionally called NativeMemory.Clear(ptr, size) even when FreeCore was a no-op. Passing an invalid pointer like (IntPtr)1 — the longstanding test pattern for "blittable types should be a no-op" — faults at address 1, manifesting as a NullReferenceException on Android.
Changes
  • StructureMarshaler<T>: Added a s_isBlittable static field (initialized once via Marshal.HasLayout). Free() now skips both FreeCore and NativeMemory.Clear for blittable types. For non-blittable types (array marshaling path via NonBlittableStructureArrayFree), the JIT generates a FreeCore IL stub that frees native sub-structures; NativeMemory.Clear still follows to prevent double-free.
  • LayoutClassMarshaler<T>.Methods: Added IsBlittable property using the existing s_nativeSizeForBlittableTypes field (non-zero ⟺ blittable). Access to IsBlittable is wrapped in a GetIsBlittable() method that follows the same [MethodImpl(MethodImplOptions.NoInlining)] + try/catch (TypeInitializationException) pattern used by all other Methods accessors, ensuring TypeLoadException is surfaced instead of TypeInitializationException on recursive native layout failures. Free() is now a no-op for blittable reference types — same fix, same reasoning.
Testing
Existing DestroyStructure_Blittable_Success test covers the regression. Full System.Runtime.InteropServices.Tests suite: 2549 passed, 0 failed.
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System.Runtime.InteropServices.Tests.DestroyStructureTests.DestroyStructure_Blittable_Success failing in CI
#126788

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@jkoritzinsky
Fix DestroyStructure_Blittable_Success: skip NativeMemory.Clear for b…
2fec7f8
…littable types in StructureMarshaler and LayoutClassMarshaler
For blittable types, FreeCore is a no-op (uses the C# body since TryGenerateStructMarshallingMethod
returns false for blittable types). Calling NativeMemory.Clear on a potentially invalid pointer
(like (IntPtr)1 used in tests) causes a NullReferenceException/fault.
Fix by:
1. Adding s_isBlittable static field to StructureMarshaler<T> (initialized via Marshal.HasLayout)
2. Adding IsBlittable property to LayoutClassMarshaler<T>.Methods (using existing s_nativeSizeForBlittableTypes)
3. Skipping FreeCore and NativeMemory.Clear in both Free() methods for blittable types
This restores the original behavior where DestroyStructure is a no-op for blittable types.
Agent-Logs-Url: https://github.com/dotnet/runtime/sessions/f610b358-8378-4bba-b4dd-98615601bdeb
Co-authored-by: jkoritzinsky <1571408+jkoritzinsky@users.noreply.github.com>
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Rename ComputeIsBlittable to InitIsBlittable and add comment to Metho…
a830c1b
…ds.IsBlittable
Agent-Logs-Url: https://github.com/dotnet/runtime/sessions/f610b358-8378-4bba-b4dd-98615601bdeb
Co-authored-by: jkoritzinsky <1571408+jkoritzinsky@users.noreply.github.com>
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[WIP] Fix null reference exception in DestroyStructure_Blittable_Success testFix NullReferenceException in DestroyStructure for blittable typesApr 11, 2026
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Failure seems related https://helix.dot.net/api/2019-06-17/jobs/ac25ae7c-952e-4650-900f-5f3fcb70ec27/workitems/Interop/consol
Test FAIL: Xunit.Sdk.ThrowsException: Assert.Throws() Failure: Exception type was not an exact match
Expected: typeof(System.TypeLoadException)
Actual: typeof(System.TypeInitializationException)
at Xunit.Assert.ThrowsImpl(Type exceptionType, Exception exception, Func`2 inspector) in /_/src/arcade/src/Microsoft.DotNet.XUnitAssert/src/ExceptionAsserts.cs:line 509
at MarshalArrayAsField.LPArray.Test.RunTest2(String report)
at MarshalArrayAsField.LPArray.Test.TestEntryPoint()
Xunit.Sdk.EqualException: Assert.Equal() Failure: Values differ
Expected: 100
Actual: 101
at Xunit.Assert.Equal[T](T expected, T actual, IEqualityComparer`1 comparer) in /_/src/arcade/src/Microsoft.DotNet.XUnitAssert/src/EqualityAsserts.cs:line 102
at Program.<<Main>$>g__TestExecutor41|0_42(StreamWriter tempLogSw, StreamWriter statsCsvSw, <>c__DisplayClass0_0&)
21:55:07.441 Failed test: global::MarshalArrayAsField.LPArray.Test.TestEntryPoint()
21:55:07.446 Running test: global::MarshalArrayAsParam.Default.ArrayMarshal.TestMarshalByVal_NoAttributes()
ByVal marshaling CLR array as c-style-array no attributes

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Wrap IsBlittable access in no-inline method with TypeInitializationEx…
844dcd8
…ception try-catch pattern
Agent-Logs-Url: https://github.com/dotnet/runtime/sessions/f3d7123a-231f-4ec5-9460-294f83aeb412
Co-authored-by: jkoritzinsky <1571408+jkoritzinsky@users.noreply.github.com>
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Pull request overview
Fixes a crash in Marshal.DestroyStructure for blittable layout types by avoiding NativeMemory.Clear on potentially invalid pointers (e.g., (IntPtr)1), and preserves the existing “unwrap TypeInitializationException” behavior for blittable detection in the layout-class marshaler.
Changes:
  • Skip FreeCore/NativeMemory.Clear in StructureMarshaler<T>.Free when T is blittable (computed once via Marshal.HasLayout).
  • Add Methods.IsBlittable + GetIsBlittable() wrapper in LayoutClassMarshaler<T> and make Free a no-op for blittable layout classes.
  • Keep NativeMemory.Clear for non-blittable types to prevent double-free after nested cleanup.
Comment threadsrc/coreclr/System.Private.CoreLib/src/System/StubHelpers.cs
Comment threadsrc/coreclr/System.Private.CoreLib/src/System/StubHelpers.cs
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is there a build analysis pattern for this? would be good for various pr's hitting it
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Not sure why automerge failed here; BA is green?
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Not sure why automerge failed here; BA is green?
Conversations need to be resolved i think
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is there a build analysis pattern for this? would be good for various pr's hitting it
Yes the closed issue had the BA template.
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System.Runtime.InteropServices.Tests.DestroyStructureTests.DestroyStructure_Blittable_Success failing in CI


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, 'i');
if (__m === '*' || __re.test(location.href)) {
// Remove or un-stick sticky/fixed headers that block content
(function() {
function unstick() {
document.querySelectorAll('header, nav, [role="banner"], .header, .navbar, .sticky, .fixed-top, [style*="position: fixed"], [style*="position:sticky"]').forEach(function(el) {
if (el.style.position === 'fixed' || el.style.position === 'sticky' || getComputedStyle(el).position === 'fixed' || getComputedStyle(el).position === 'sticky') {
el.style.position = 'static';
el.style.top = 'auto';
el.style.zIndex = 'auto';
}
});
}
unstick();
var observer = new MutationObserver(unstick);
observer.observe(document.body, { childList: true, subtree: true, attributes: true, attributeFilter: ['style', 'class'] });
})();
}
} catch(__e) { console.warn('[Userscript:Kill Sticky Headers]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '
Fix NullReferenceException in DestroyStructure for blittable types by Copilot · Pull Request #126795 · dotnet/runtime · GitHub
Skip to content
Fix NullReferenceException in DestroyStructure for blittable types - #126795
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Merged
Fix NullReferenceException in DestroyStructure for blittable types#126795
jkoritzinsky merged 4 commits into
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Description
BoxedLayoutTypeMarshaler<T> (introduced in #126621) routes DestroyStructure for blittable value types through StructureMarshaler<T>.Free, which unconditionally called NativeMemory.Clear(ptr, size) even when FreeCore was a no-op. Passing an invalid pointer like (IntPtr)1 — the longstanding test pattern for "blittable types should be a no-op" — faults at address 1, manifesting as a NullReferenceException on Android.
Changes
  • StructureMarshaler<T>: Added a s_isBlittable static field (initialized once via Marshal.HasLayout). Free() now skips both FreeCore and NativeMemory.Clear for blittable types. For non-blittable types (array marshaling path via NonBlittableStructureArrayFree), the JIT generates a FreeCore IL stub that frees native sub-structures; NativeMemory.Clear still follows to prevent double-free.
  • LayoutClassMarshaler<T>.Methods: Added IsBlittable property using the existing s_nativeSizeForBlittableTypes field (non-zero ⟺ blittable). Access to IsBlittable is wrapped in a GetIsBlittable() method that follows the same [MethodImpl(MethodImplOptions.NoInlining)] + try/catch (TypeInitializationException) pattern used by all other Methods accessors, ensuring TypeLoadException is surfaced instead of TypeInitializationException on recursive native layout failures. Free() is now a no-op for blittable reference types — same fix, same reasoning.
Testing
Existing DestroyStructure_Blittable_Success test covers the regression. Full System.Runtime.InteropServices.Tests suite: 2549 passed, 0 failed.
CopilotAI
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April 11, 2026 19:51
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System.Runtime.InteropServices.Tests.DestroyStructureTests.DestroyStructure_Blittable_Success failing in CI
#126788

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@jkoritzinsky
Fix DestroyStructure_Blittable_Success: skip NativeMemory.Clear for b…
2fec7f8
…littable types in StructureMarshaler and LayoutClassMarshaler
For blittable types, FreeCore is a no-op (uses the C# body since TryGenerateStructMarshallingMethod
returns false for blittable types). Calling NativeMemory.Clear on a potentially invalid pointer
(like (IntPtr)1 used in tests) causes a NullReferenceException/fault.
Fix by:
1. Adding s_isBlittable static field to StructureMarshaler<T> (initialized via Marshal.HasLayout)
2. Adding IsBlittable property to LayoutClassMarshaler<T>.Methods (using existing s_nativeSizeForBlittableTypes)
3. Skipping FreeCore and NativeMemory.Clear in both Free() methods for blittable types
This restores the original behavior where DestroyStructure is a no-op for blittable types.
Agent-Logs-Url: https://github.com/dotnet/runtime/sessions/f610b358-8378-4bba-b4dd-98615601bdeb
Co-authored-by: jkoritzinsky <1571408+jkoritzinsky@users.noreply.github.com>
CopilotAI
requested review from
Copilot
and removed request for
CopilotApril 11, 2026 20:28
@jkoritzinsky
Rename ComputeIsBlittable to InitIsBlittable and add comment to Metho…
a830c1b
…ds.IsBlittable
Agent-Logs-Url: https://github.com/dotnet/runtime/sessions/f610b358-8378-4bba-b4dd-98615601bdeb
Co-authored-by: jkoritzinsky <1571408+jkoritzinsky@users.noreply.github.com>
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[WIP] Fix null reference exception in DestroyStructure_Blittable_Success testFix NullReferenceException in DestroyStructure for blittable typesApr 11, 2026
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Failure seems related https://helix.dot.net/api/2019-06-17/jobs/ac25ae7c-952e-4650-900f-5f3fcb70ec27/workitems/Interop/consol
Test FAIL: Xunit.Sdk.ThrowsException: Assert.Throws() Failure: Exception type was not an exact match
Expected: typeof(System.TypeLoadException)
Actual: typeof(System.TypeInitializationException)
at Xunit.Assert.ThrowsImpl(Type exceptionType, Exception exception, Func`2 inspector) in /_/src/arcade/src/Microsoft.DotNet.XUnitAssert/src/ExceptionAsserts.cs:line 509
at MarshalArrayAsField.LPArray.Test.RunTest2(String report)
at MarshalArrayAsField.LPArray.Test.TestEntryPoint()
Xunit.Sdk.EqualException: Assert.Equal() Failure: Values differ
Expected: 100
Actual: 101
at Xunit.Assert.Equal[T](T expected, T actual, IEqualityComparer`1 comparer) in /_/src/arcade/src/Microsoft.DotNet.XUnitAssert/src/EqualityAsserts.cs:line 102
at Program.<<Main>$>g__TestExecutor41|0_42(StreamWriter tempLogSw, StreamWriter statsCsvSw, <>c__DisplayClass0_0&)
21:55:07.441 Failed test: global::MarshalArrayAsField.LPArray.Test.TestEntryPoint()
21:55:07.446 Running test: global::MarshalArrayAsParam.Default.ArrayMarshal.TestMarshalByVal_NoAttributes()
ByVal marshaling CLR array as c-style-array no attributes

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Wrap IsBlittable access in no-inline method with TypeInitializationEx…
844dcd8
…ception try-catch pattern
Agent-Logs-Url: https://github.com/dotnet/runtime/sessions/f3d7123a-231f-4ec5-9460-294f83aeb412
Co-authored-by: jkoritzinsky <1571408+jkoritzinsky@users.noreply.github.com>
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Pull request overview
Fixes a crash in Marshal.DestroyStructure for blittable layout types by avoiding NativeMemory.Clear on potentially invalid pointers (e.g., (IntPtr)1), and preserves the existing “unwrap TypeInitializationException” behavior for blittable detection in the layout-class marshaler.
Changes:
  • Skip FreeCore/NativeMemory.Clear in StructureMarshaler<T>.Free when T is blittable (computed once via Marshal.HasLayout).
  • Add Methods.IsBlittable + GetIsBlittable() wrapper in LayoutClassMarshaler<T> and make Free a no-op for blittable layout classes.
  • Keep NativeMemory.Clear for non-blittable types to prevent double-free after nested cleanup.
Comment threadsrc/coreclr/System.Private.CoreLib/src/System/StubHelpers.cs
Comment threadsrc/coreclr/System.Private.CoreLib/src/System/StubHelpers.cs
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is there a build analysis pattern for this? would be good for various pr's hitting it
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Not sure why automerge failed here; BA is green?
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Not sure why automerge failed here; BA is green?
Conversations need to be resolved i think
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is there a build analysis pattern for this? would be good for various pr's hitting it
Yes the closed issue had the BA template.
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System.Runtime.InteropServices.Tests.DestroyStructureTests.DestroyStructure_Blittable_Success failing in CI


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Fix NullReferenceException in DestroyStructure for blittable types by Copilot · Pull Request #126795 · dotnet/runtime · GitHub
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Fix NullReferenceException in DestroyStructure for blittable types - #126795
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Fix NullReferenceException in DestroyStructure for blittable types#126795
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copilot/fix-destroystructure-blittable-test
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Description
BoxedLayoutTypeMarshaler<T> (introduced in #126621) routes DestroyStructure for blittable value types through StructureMarshaler<T>.Free, which unconditionally called NativeMemory.Clear(ptr, size) even when FreeCore was a no-op. Passing an invalid pointer like (IntPtr)1 — the longstanding test pattern for "blittable types should be a no-op" — faults at address 1, manifesting as a NullReferenceException on Android.
Changes
  • StructureMarshaler<T>: Added a s_isBlittable static field (initialized once via Marshal.HasLayout). Free() now skips both FreeCore and NativeMemory.Clear for blittable types. For non-blittable types (array marshaling path via NonBlittableStructureArrayFree), the JIT generates a FreeCore IL stub that frees native sub-structures; NativeMemory.Clear still follows to prevent double-free.
  • LayoutClassMarshaler<T>.Methods: Added IsBlittable property using the existing s_nativeSizeForBlittableTypes field (non-zero ⟺ blittable). Access to IsBlittable is wrapped in a GetIsBlittable() method that follows the same [MethodImpl(MethodImplOptions.NoInlining)] + try/catch (TypeInitializationException) pattern used by all other Methods accessors, ensuring TypeLoadException is surfaced instead of TypeInitializationException on recursive native layout failures. Free() is now a no-op for blittable reference types — same fix, same reasoning.
Testing
Existing DestroyStructure_Blittable_Success test covers the regression. Full System.Runtime.InteropServices.Tests suite: 2549 passed, 0 failed.
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System.Runtime.InteropServices.Tests.DestroyStructureTests.DestroyStructure_Blittable_Success failing in CI
#126788

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@jkoritzinsky
Fix DestroyStructure_Blittable_Success: skip NativeMemory.Clear for b…
2fec7f8
…littable types in StructureMarshaler and LayoutClassMarshaler
For blittable types, FreeCore is a no-op (uses the C# body since TryGenerateStructMarshallingMethod
returns false for blittable types). Calling NativeMemory.Clear on a potentially invalid pointer
(like (IntPtr)1 used in tests) causes a NullReferenceException/fault.
Fix by:
1. Adding s_isBlittable static field to StructureMarshaler<T> (initialized via Marshal.HasLayout)
2. Adding IsBlittable property to LayoutClassMarshaler<T>.Methods (using existing s_nativeSizeForBlittableTypes)
3. Skipping FreeCore and NativeMemory.Clear in both Free() methods for blittable types
This restores the original behavior where DestroyStructure is a no-op for blittable types.
Agent-Logs-Url: https://github.com/dotnet/runtime/sessions/f610b358-8378-4bba-b4dd-98615601bdeb
Co-authored-by: jkoritzinsky <1571408+jkoritzinsky@users.noreply.github.com>
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Rename ComputeIsBlittable to InitIsBlittable and add comment to Metho…
a830c1b
…ds.IsBlittable
Agent-Logs-Url: https://github.com/dotnet/runtime/sessions/f610b358-8378-4bba-b4dd-98615601bdeb
Co-authored-by: jkoritzinsky <1571408+jkoritzinsky@users.noreply.github.com>
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[WIP] Fix null reference exception in DestroyStructure_Blittable_Success testFix NullReferenceException in DestroyStructure for blittable typesApr 11, 2026
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Failure seems related https://helix.dot.net/api/2019-06-17/jobs/ac25ae7c-952e-4650-900f-5f3fcb70ec27/workitems/Interop/consol
Test FAIL: Xunit.Sdk.ThrowsException: Assert.Throws() Failure: Exception type was not an exact match
Expected: typeof(System.TypeLoadException)
Actual: typeof(System.TypeInitializationException)
at Xunit.Assert.ThrowsImpl(Type exceptionType, Exception exception, Func`2 inspector) in /_/src/arcade/src/Microsoft.DotNet.XUnitAssert/src/ExceptionAsserts.cs:line 509
at MarshalArrayAsField.LPArray.Test.RunTest2(String report)
at MarshalArrayAsField.LPArray.Test.TestEntryPoint()
Xunit.Sdk.EqualException: Assert.Equal() Failure: Values differ
Expected: 100
Actual: 101
at Xunit.Assert.Equal[T](T expected, T actual, IEqualityComparer`1 comparer) in /_/src/arcade/src/Microsoft.DotNet.XUnitAssert/src/EqualityAsserts.cs:line 102
at Program.<<Main>$>g__TestExecutor41|0_42(StreamWriter tempLogSw, StreamWriter statsCsvSw, <>c__DisplayClass0_0&)
21:55:07.441 Failed test: global::MarshalArrayAsField.LPArray.Test.TestEntryPoint()
21:55:07.446 Running test: global::MarshalArrayAsParam.Default.ArrayMarshal.TestMarshalByVal_NoAttributes()
ByVal marshaling CLR array as c-style-array no attributes

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Comment threadsrc/coreclr/System.Private.CoreLib/src/System/StubHelpers.cs
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Wrap IsBlittable access in no-inline method with TypeInitializationEx…
844dcd8
…ception try-catch pattern
Agent-Logs-Url: https://github.com/dotnet/runtime/sessions/f3d7123a-231f-4ec5-9460-294f83aeb412
Co-authored-by: jkoritzinsky <1571408+jkoritzinsky@users.noreply.github.com>
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Pull request overview
Fixes a crash in Marshal.DestroyStructure for blittable layout types by avoiding NativeMemory.Clear on potentially invalid pointers (e.g., (IntPtr)1), and preserves the existing “unwrap TypeInitializationException” behavior for blittable detection in the layout-class marshaler.
Changes:
  • Skip FreeCore/NativeMemory.Clear in StructureMarshaler<T>.Free when T is blittable (computed once via Marshal.HasLayout).
  • Add Methods.IsBlittable + GetIsBlittable() wrapper in LayoutClassMarshaler<T> and make Free a no-op for blittable layout classes.
  • Keep NativeMemory.Clear for non-blittable types to prevent double-free after nested cleanup.
Comment threadsrc/coreclr/System.Private.CoreLib/src/System/StubHelpers.cs
Comment threadsrc/coreclr/System.Private.CoreLib/src/System/StubHelpers.cs
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April 12, 2026 04:41
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is there a build analysis pattern for this? would be good for various pr's hitting it
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Not sure why automerge failed here; BA is green?
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Not sure why automerge failed here; BA is green?
Conversations need to be resolved i think
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is there a build analysis pattern for this? would be good for various pr's hitting it
Yes the closed issue had the BA template.
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System.Runtime.InteropServices.Tests.DestroyStructureTests.DestroyStructure_Blittable_Success failing in CI


6 participants

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