[cDAC] Add typed field extension methods for Data classes by max-charlamb · Pull Request #126713 · dotnet/runtime

max-charlamb · 2026-04-09T15:30:53Z

Summary

Add typed field extension methods for the cDAC managed reader and convert all IData<T> classes to use them. This builds on the native data descriptor type system (#126163) to add managed-side type validation.

Changes

TargetFieldExtensions.cs — New extension methods on Target:

ReadField<T> — reads a primitive field with Debug.Assert type validation
ReadPointerField / ReadPointerFieldOrNull — reads pointer fields (required/optional)
ReadNUIntField — reads native unsigned integer fields
ReadCodePointerField — reads code pointer fields
ReadDataField<T> / ReadDataFieldPointer<T> — reads inline/pointer-to Data struct fields
ReadFieldOrDefault<T> — reads optional primitive fields with default value

When the data descriptor includes type information (debug/checked builds), these methods assert that the declared field type is compatible with the C# read type.

All ~130 IData<T> classes converted to use the new extension methods, replacing direct target.Read<T>(address + (ulong)type.Fields[...].Offset) calls.

Bugs found and fixed

The type system caught several pre-existing issues:

DynamicStaticsInfo.GCStatics/NonGCStatics — descriptor said uint32, native type is TADDR (pointer)
EEClass.FieldDescList — used Read<ulong> for a pointer field (broken on 32-bit)
ExceptionClause.ClassToken — read TypeHandle (nuint) as uint
SimpleComCallWrapper.RefCount — property was ulong, native is LONGLONG (signed)
NativeCodeVersionNode.NativeCode — descriptor was T_POINTER, actually CodePointer
MethodTable.EEClassOrCanonMT — descriptor was T_NUINT, managed reads as pointer

Note

This content was generated with the assistance of GitHub Copilot.

Add TargetFieldExtensions with ReadField<T>, ReadPointerField, ReadNUIntField, ReadCodePointerField, ReadDataField<T>, and ReadDataFieldPointer<T> extension methods. Each method validates the field type name from the data descriptor (when present) against the C# read type via Debug.Assert. Convert all ~110 IData<T> classes to use the new extension methods. Fix pre-existing bugs found by the type system: - DynamicStaticsInfo.GCStatics/NonGCStatics: was uint32, is TADDR (pointer) - EEClass.FieldDescList: was Read<ulong>, should be ReadPointer - ExceptionClause.ClassToken: was reading TypeHandle (nuint) as uint - SimpleComCallWrapper.RefCount: was ulong, native is LONGLONG (signed) - NativeCodeVersionNode.NativeCode: was T_POINTER, is PCODE (CodePointer) - MethodTable.EEClassOrCanonMT: was T_NUINT, managed reads as pointer Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot

Pull request overview

Adds managed-side typed field read helpers for cDAC Target and migrates cDAC IData<T> data readers to use them, enabling debug/checked build validation against native data descriptor field types.

Changes:

Introduces TargetFieldExtensions with typed field reads and Debug.Assert type compatibility checks.
Converts cDAC IData<T> data classes to use the new typed read helpers (replacing manual Read<T>(address + offset) patterns).
Adds descriptor/type verification infrastructure (test + generator + runtime helper) and updates select native descriptor field annotations.

Reviewed changes

Copilot reviewed 115 out of 115 changed files in this pull request and generated 8 comments.

Show a summary per file

File	Description
src/native/managed/cdac/tests/ContractDescriptor/TypeVerificationTests.cs	Adds a test intended to validate managed reads against a checked descriptor’s declared field types.
src/native/managed/cdac/tests/ContractDescriptor/checked-descriptor.json	Adds a checked-build contract descriptor fixture containing field offsets + type names.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader/DataDescriptorTypeVerification.cs	Adds a DEBUG-only verification entrypoint and a noop `Target` wrapper for type-check instantiation.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Generators/Microsoft.Diagnostics.DataContractReader.Generators.csproj	Adds a new Roslyn generator project intended to generate verification code.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Generators/DataTypeVerificationGenerator.cs	Implements a generator to discover `IData<T>` implementations and emit `VerifyAllDataTypes`.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Microsoft.Diagnostics.DataContractReader.Contracts.csproj	Adds `InternalsVisibleTo` for `Microsoft.Diagnostics.DataContractReader`.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/VirtualCallStubManager.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/UnwindInfo.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/TypeDesc.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/TLSIndex.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/ThreadStressLog.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/ThreadStore.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/ThreadLocalData.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/Thread.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/ThisPtrRetBufPrecodeData.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/TableSegment.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/SystemDomain.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/SyncTableEntry.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/SyncBlockCache.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/SyncBlock.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/StubPrecodeData.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/String.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/StressLogModuleDesc.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/StressLogChunk.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/StressLog.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/SimpleComCallWrapper.cs	Switches field reads to typed helper methods; adjusts RefCount type.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/RuntimeFunction.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/RealCodeHeader.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/ReadyToRunSection.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/ReadyToRunInfo.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/ReadyToRunHeader.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/ReadyToRunCoreInfo.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/ReadyToRunCoreHeader.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/RCWCleanupList.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/RCW.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/RangeSectionFragment.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/RangeSection.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/ProfControlBlock.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/ProbeExtensionResult.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/PrecodeMachineDescriptor.cs	Switches field reads to typed helper methods (and modifies precode parsing logic).
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/PortableEntryPoint.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/PlatformMetadata.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/PEImageLayout.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/PEImage.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/PEAssembly.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/PatchpointInfo.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/ObjectHeader.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/Object.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/NativeObjectWrapperObject.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/NativeCodeVersionNode.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/ModuleLookupMap.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/Module.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/MethodTableAuxiliaryData.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/MethodTable.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/MethodDescVersioningState.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/MethodDescCodeData.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/MethodDescChunk.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/MethodDesc.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/ManagedObjectWrapperLayout.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/ManagedObjectWrapperHolderObject.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/LoaderAllocator.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/InterfaceEntry.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/InflightTLSData.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/ImageDataDirectory.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/ILCodeVersionNode.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/ILCodeVersioningState.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/IdDispenser.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/HashMap.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/HandleTableMap.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/HandleTableBucket.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/HandleTable.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/GenericsDictInfo.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/GCAllocContext.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/GC/OOMHistory.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/GC/HeapSegment.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/GC/Generation.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/GC/GCHeapSVR.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/Frames/TransitionBlock.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/Frames/TailCallFrame.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/Frames/StubDispatchFrame.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/Frames/SoftwareExceptionFrame.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/Frames/ResumableFrame.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/Frames/InlinedCallFrame.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/Frames/HijackFrame.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/Frames/HijackArgsAMD64.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/Frames/FuncEvalFrame.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/Frames/FramedMethodFrame.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/Frames/Frame.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/Frames/DebuggerEval.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/FixupPrecodeData.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/FieldDesc.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/ExceptionLookupTableEntry.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/ExceptionInfo.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/ExceptionClause.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/Exception.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/EEJitManager.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/EEClass.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/DynamicStaticsInfo.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/DynamicMetadata.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/DynamicILBlobEntry.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/DacEnumerableHash.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/CtxEntry.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/CoreLibBinder.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/ComMethodTable.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/ComCallWrapper.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/CodeHeapListNode.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/CGrowableSymbolStream.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/AssemblyBinder.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/Assembly.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/ArrayListBase.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/Array.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/AppDomain.cs	Switches field reads to typed helper methods.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/BuiltInCOM_1.cs	Adjusts SCCW refcount masking after `RefCount` signedness change.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Abstractions/TargetFieldExtensions.cs	Adds the new typed field read extensions + type compatibility asserts.
src/coreclr/vm/datadescriptor/datadescriptor.inc	Updates select native descriptor field type annotations to match actual semantics.

Comments suppressed due to low confidence (1)

src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/PrecodeMachineDescriptor.cs:57

StubPrecodeSize is read using nameof(FixupStubPrecodeSize) (line 46), so it will fetch the wrong field offset and size when both fields exist. This will corrupt StubBytes/StubIgnoredBytes reads. Read StubPrecodeSize from its own field name and ensure the else branch resets the Stub* members (currently it resets Fixup* instead).

src/native/managed/cdac/tests/ContractDescriptor/TypeVerificationTests.cs

Copilot · 2026-04-09T15:41:17Z

src/native/managed/cdac/tests/ContractDescriptor/TypeVerificationTests.cs

+    private static void CreateData<T>(Target target) where T : IData<T>
+    {
+        T.Create(target, default);
+    }


CreateData<T> is unused (the test uses TryCreate<T> everywhere). With warnings-as-errors enabled in this repo, unused members can break builds; remove it or use it.

src/native/managed/cdac/tests/ContractDescriptor/TypeVerificationTests.cs

.../managed/cdac/Microsoft.Diagnostics.DataContractReader.Abstractions/TargetFieldExtensions.cs

...ics.DataContractReader.Generators/Microsoft.Diagnostics.DataContractReader.Generators.csproj

...ed/cdac/Microsoft.Diagnostics.DataContractReader.Generators/DataTypeVerificationGenerator.cs

...tive/managed/cdac/Microsoft.Diagnostics.DataContractReader/DataDescriptorTypeVerification.cs

…sions Convert Data classes in Frames/, GC/, and root Data/ that were missed by the initial conversion (subdirectory files, string literal field keys, underscore-prefixed variable names). Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

dotnet-policy-service · 2026-04-09T17:08:09Z

Tagging subscribers to this area: @steveisok, @tommcdon, @dotnet/dotnet-diag
See info in area-owners.md if you want to be subscribed.

Copilot

Pull request overview

Copilot reviewed 115 out of 115 changed files in this pull request and generated 2 comments.

Copilot · 2026-04-09T17:10:30Z

...ged/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/PrecodeMachineDescriptor.cs


        if (type.Fields.ContainsKey(nameof(StubPrecodeSize)))
        {
-            StubPrecodeSize = target.Read<byte>(address + (ulong)type.Fields[nameof(FixupStubPrecodeSize)].Offset);
+            StubPrecodeSize = target.ReadField<byte>(address, type, nameof(FixupStubPrecodeSize));
            StubBytes = new byte[StubPrecodeSize.Value];
            target.ReadBuffer(address + (ulong)type.Fields[nameof(StubBytes)].Offset, StubBytes);
            StubIgnoredBytes = new byte[StubPrecodeSize.Value];


In the StubPrecodeSize branch, StubPrecodeSize is read using nameof(FixupStubPrecodeSize) rather than nameof(StubPrecodeSize), so it will use the wrong field offset/value (and may throw if the fixup field isn't present). Also, the else branch for StubPrecodeSize currently nulls out FixupBytes/FixupIgnoredBytes instead of StubBytes/StubIgnoredBytes, which can leave the stub byte arrays in an incorrect state.

Copilot · 2026-04-09T17:10:30Z

...anaged/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/NativeCodeVersionNode.cs

        {
-            GCCoverageInfo = target.ReadPointer(address + (ulong)type.Fields[nameof(GCCoverageInfo)].Offset);
+            GCCoverageInfo = target.ReadPointerField(address, type, nameof(GCCoverageInfo));
        }
-        OptimizationTier = target.Read<uint>(address + (ulong)type.Fields[nameof(OptimizationTier)].Offset);
+        OptimizationTier = target.ReadField<uint>(address, type, nameof(OptimizationTier));


OptimizationTier is still read via target.Read<uint>(address + ...) instead of the new ReadField<uint>(...) helper. Using ReadField here would keep this type’s field reads consistent and allow the descriptor type validation to apply to OptimizationTier as well.

github-actions · 2026-04-09T17:17:56Z

🤖 Copilot Code Review — PR #126713

Note

This review was generated by Copilot.

Holistic Assessment

Motivation: Well-justified. Introduces typed field extension methods that reduce boilerplate across ~110 Data classes and add debug-time type validation via Debug.Assert. The type validation already surfaced 6 real type mismatches in the existing code (e.g., reading a pointer as uint32, reading a signed LONGLONG as ulong). This is a meaningful improvement to maintainability and correctness.

Approach: Good. Extension methods on Target are idiomatic and discoverable. The [Conditional("DEBUG")] assertions have zero overhead in release builds. The conversion is mechanical and straightforward, keeping the behavioral change surface small.

Summary: ⚠️ Needs Human Review. The change is well-motivated and the mechanical conversion looks correct throughout. However, there is one pre-existing bug that is now more visible and should ideally be fixed in this PR, plus a few items for the author/reviewer to confirm.

Detailed Findings

✅ Type Bug Fixes — Correct based on native type declarations

All 6 type corrections mentioned in the commit message are verified against native C++ types:

Field	Old (incorrect)	New (correct)	Verified against
`DynamicStaticsInfo.GCStatics/NonGCStatics`	`T_UINT32` / `Read<uint>`	`T_POINTER` / `ReadPointerField`	`TADDR` in `methodtable.h:612-613`
`EEClass.FieldDescList`	`Read<ulong>` (always 8 bytes)	`ReadPointerField` (pointer-size)	`T_POINTER` in `datadescriptor.inc`
`SimpleComCallWrapper.RefCount`	`ulong`	`long`	`T_INT64` in `datadescriptor.inc:1219`
`NativeCodeVersionNode.NativeCode`	`T_POINTER`	`TYPE(CodePointer)`	`PCODE` type semantics
`MethodTable.EEClassOrCanonMT`	`T_NUINT`	`T_POINTER`	Union of `DPTR(EEClass)` / `TADDR` in `methodtable.h:3980-3981`
`ExceptionClause.ClassToken`	Double-read of `TypeHandle` as `uint`	Derives from `NUInt` value	Avoids wrong-size read on 64-bit

The SimpleComCallWrapper.RefCount consumer in BuiltInCOM_1.cs was correctly updated: the ComRefCount enum was already long-based, and the & RefCountMask (0x7FFFFFFF) result is safely cast to (uint) before widening to the ulong property on SimpleComCallWrapperData.

✅ TargetFieldExtensions Design — Well structured

The API covers the key field read patterns (primitive, pointer, NUInt, CodePointer, inline data, data pointer) with optional/required variants. [Conditional("DEBUG")] on the assertion helpers is the right pattern.

✅ datadescriptor.inc Changes — Correct

The 3 changes to the native data descriptor match the actual C++ field types.

⚠️ Pre-existing Bug in PrecodeMachineDescriptor — Now more visible, should fix

PrecodeMachineDescriptor.cs line 46:

StubPrecodeSize = target.ReadField<byte>(address, type, nameof(FixupStubPrecodeSize));

This reads FixupStubPrecodeSize but assigns to StubPrecodeSize. This was a pre-existing bug (the old code had the same nameof(FixupStubPrecodeSize) mismatch), but the mechanical conversion preserved it. Since this PR touches exactly this line and the extension methods are specifically designed to make field names explicit, this would be a good opportunity to fix it to nameof(StubPrecodeSize).

This is flagged as a warning rather than an error because it's pre-existing and the fix could go into a follow-up if preferred.

💡 Incomplete Conversion of Inline Data Reads — Follow-up opportunity

Seven+ ProcessedData.GetOrAdd<T>(address + (ulong)type.Fields[...].Offset) patterns (in EEAllocContext, InflightTLSData, PEImage, ReadyToRunSection, RuntimeThreadLocals, GCHeapSVR, Generation) could use ReadDataField<T>. Only Thread.cs uses the new ReadDataFieldPointer<T>. The MaybeGetPrecodeType local function in PrecodeMachineDescriptor also still uses the old pattern.

This is fine as a follow-up since the methods were introduced to also benefit code outside Data classes, but worth noting for completeness.

💡 Some ContainsKey Patterns Could Use OrNull/OrDefault

Several if (type.Fields.ContainsKey(...)) ReadPointerField(...) patterns (in LoaderAllocator, GCHeapSVR, MethodDesc.GCCoverageInfo, InlinedCallFrame.SPAfterProlog) could use ReadPointerFieldOrNull. However, some of these have additional logic beyond a simple read, so the existing explicit patterns may be clearer. Author's judgment call.

Generated by Code Review for issue #126713 · ◷

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max-charlamb force-pushed the dev/max-charlamb-/runtime-cdac-managed-typing branch from ee38f27 to a291681 Compare April 9, 2026 17:00

Copilot AI review requested due to automatic review settings April 9, 2026 17:04

max-charlamb force-pushed the dev/max-charlamb-/runtime-cdac-managed-typing branch from a291681 to c3a2982 Compare April 9, 2026 17:04

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max-charlamb added area-Diagnostics-cdac and removed area-Diagnostics-coreclr labels Apr 9, 2026

max-charlamb force-pushed the dev/max-charlamb-/runtime-cdac-managed-typing branch from c3a2982 to 8ad41e4 Compare April 9, 2026 17:07

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[cDAC] Add typed field extension methods for Data classes#126713

[cDAC] Add typed field extension methods for Data classes#126713
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max-charlamb commented Apr 9, 2026

Summary

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Bugs found and fixed

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Pull request overview

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github-actions bot commented Apr 9, 2026

🤖 Copilot Code Review — PR #126713

Holistic Assessment

Detailed Findings

✅ Type Bug Fixes — Correct based on native type declarations

✅ TargetFieldExtensions Design — Well structured

✅ datadescriptor.inc Changes — Correct

⚠️ Pre-existing Bug in PrecodeMachineDescriptor — Now more visible, should fix

💡 Incomplete Conversion of Inline Data Reads — Follow-up opportunity

💡 Some ContainsKey Patterns Could Use OrNull/OrDefault

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