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[NativeAOT] Array marshalling differences exposed by pointer-array tests #134628
Description
The pointer-array tests enabled for NativeAOT in #134284 expose three existing marshalling differences. This issue tracks the runtime fixes and re-enabling the narrowly excluded cases; the pointer-array PR will not change NativeAOT implementation code.
Observed failures
Build 1611133, commit 0c9d8ed20049c5544988c9ad301c3aa106292a96 (CI merge 6c596a6378674dddf2886805ba2a1810275d400c), Windows x64 NativeAOT Checked. The test-run display name says coreclr windows x64 Checked, but the Interop console uses nativeaottest.cmd. The uploaded result XML contains 27 failing cases in these four test methods:
| Cases | Actual behavior | Expected behavior |
|---|---|---|
PointerArrayFieldTests.CopyFixedArrays(true) (1 case) |
A null ByValArray field leaves prefilled native memory unchanged (0x123456789ABCDEF0). |
Clear the field's native array storage. |
PointerArrayTests.CopyArrayByRef(kind, -1) and CopyOutArray(kind, -1) (14 + 4 cases) |
A null native array with length zero becomes an empty managed array. | Preserve null. |
PointerArrayTests.CopyArrayInReversePInvoke(functionPointers, length) for lengths 1, 4, 5, and 21 (8 cases) |
The native verification returns 0 after the managed callback reverses the array. | Copy the callback's pointer values back to the original native buffer. |
The corresponding non-null forward-copy, pinning, and fixed-field cases pass. These tests also pass on CoreCLR. The failures were identified from CI results and source inspection; they have not been independently reproduced with a local NativeAOT execution.
Source inspection
ByValArrayMarshaller.EmitMarshalFieldManagedToNativebranches to the end when the managed field is null, without clearing its native storage.ArrayMarshaller.TransformNativeToManagedallocates an array for byref parameters based on the element count without checking whether the native pointer is null.- Reverse array copy-out selects an element marshaler with
In = falseinGetElementMarshaller.EmitMarshalElementManagedToNativethen callsAllocAndTransformManagedToNative, which skips the value transfer whenInis false. For blittable pointer elements, this emits default native values rather than the managed values.
Re-enable condition
After correcting these paths, re-enable the NativeAOT exclusions associated with this issue and run the exact null-array, null-fixed-field, and nonempty reverse-copy cases, while retaining the currently passing array coverage.
Note
This issue was prepared with GitHub Copilot assistance from CI evidence and source inspection.
Activity
dotnet-policy-service commentedon Sep 24, 2026
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Fix pointer array copying and various array pinning regressions in Co…