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Use adjusted parent layout size to handle a non-zero-sized class inheriting from a zero-sized class that inherits from another zero-sized class. #50861

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Merged
merged 4 commits into from
Apr 20, 2021
Merged

Use adjusted parent layout size to handle a non-zero-sized class inheriting from a zero-sized class that inherits from another zero-sized class. #50861

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06380af
Use adjusted parent layout size to handle a non-zero-sized class inhe…
jkoritzinsky Apr 7, 2021
fb6615b
Add test in LayoutClassTests for this case.
jkoritzinsky Apr 7, 2021
f4c7d5e
Merge branch 'main' into fixes/50764
jkoritzinsky Apr 9, 2021
3ed19ed
Merge branch 'main' into fixes/50764
jkoritzinsky Apr 12, 2021
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11 changes: 5 additions & 6 deletions src/coreclr/vm/classlayoutinfo.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -612,7 +612,7 @@ VOID EEClassLayoutInfo::CollectLayoutFieldMetadataThrowing(
pEEClassLayoutInfoOut->m_cbPackingSize = packingSize;

BOOL fParentHasLayout = pParentMT && pParentMT->HasLayout();
UINT32 cbAdjustedParentLayoutNativeSize = 0;
UINT32 cbAdjustedParentLayoutSize = 0;
EEClassLayoutInfo *pParentLayoutInfo = NULL;
if (fParentHasLayout)
{
Expand All @@ -622,11 +622,11 @@ VOID EEClassLayoutInfo::CollectLayoutFieldMetadataThrowing(
// got bumped up to a size of 1 for compatibility reasons, then
// we need to remove the padding, but ONLY for inheritance situations.
if (pParentLayoutInfo->IsZeroSized()) {
cbAdjustedParentLayoutNativeSize = 0;
cbAdjustedParentLayoutSize = 0;
}
else
{
cbAdjustedParentLayoutNativeSize = pParentMT->GetNumInstanceFieldBytes();
cbAdjustedParentLayoutSize = pParentMT->GetNumInstanceFieldBytes();
}
}

Expand Down Expand Up @@ -668,7 +668,7 @@ VOID EEClassLayoutInfo::CollectLayoutFieldMetadataThrowing(
}
CQuickArray<LayoutRawFieldInfo*> pSortArray;
pSortArray.ReSizeThrows(cbSortArraySize.Value());
SetOffsetsAndSortFields(pInternalImport, cl, pInfoArrayOut, cInstanceFields, fExplicitOffsets, cbAdjustedParentLayoutNativeSize, pModule, pSortArray.Ptr());
SetOffsetsAndSortFields(pInternalImport, cl, pInfoArrayOut, cInstanceFields, fExplicitOffsets, cbAdjustedParentLayoutSize, pModule, pSortArray.Ptr());

ULONG classSizeInMetadata = 0;
if (FAILED(pInternalImport->GetClassTotalSize(cl, &classSizeInMetadata)))
Expand All @@ -690,14 +690,13 @@ VOID EEClassLayoutInfo::CollectLayoutFieldMetadataThrowing(
}

BYTE parentManagedAlignmentRequirement = 0;
UINT32 parentSize = pParentMT->GetNumInstanceFieldBytes();
if (pParentMT && (pParentMT->IsManagedSequential() || (pParentMT->GetClass()->HasExplicitFieldOffsetLayout() && pParentMT->IsBlittable())))
{
parentManagedAlignmentRequirement = pParentLayoutInfo->m_ManagedLargestAlignmentRequirementOfAllMembers;
}

CalculateSizeAndFieldOffsets(
parentSize,
cbAdjustedParentLayoutSize,
cInstanceFields,
fExplicitOffsets,
pSortArray.Ptr(),
Expand Down
20 changes: 18 additions & 2 deletions src/tests/Interop/LayoutClass/LayoutClassTest.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -12,6 +12,11 @@ public class EmptyBase
{
}

[StructLayout(LayoutKind.Sequential)]
public class EmptyBase2 : EmptyBase
{
}

[StructLayout(LayoutKind.Sequential)]
public class SeqDerivedClass : EmptyBase
{
Expand All @@ -23,6 +28,17 @@ public SeqDerivedClass(int _a)
}
}

[StructLayout(LayoutKind.Sequential)]
public class SeqDerivedClass2 : EmptyBase2
{
public int a;

public SeqDerivedClass2(int _a)
{
a = _a;
}
}

[StructLayout(LayoutKind.Sequential)]
public sealed class SeqClass
{
Expand Down Expand Up @@ -185,8 +201,8 @@ public static void DerivedClassWithEmptyBase()
Console.WriteLine($"Running {nameof(DerivedClassWithEmptyBase)}...");

string s = "before";
var p = new SeqDerivedClass(42);
Assert.IsTrue(DerivedSeqLayoutClassByRef(p, 42));
Assert.IsTrue(DerivedSeqLayoutClassByRef(new SeqDerivedClass(42), 42));
Assert.IsTrue(DerivedSeqLayoutClassByRef(new SeqDerivedClass2(42), 42));
}

public static void ExplicitClass()
Expand Down