Reconcile ReleaseHolder, ComHolderPreemp, and ComHolderAnyMode by AaronRobinsonMSFT · Pull Request #130373 · dotnet/runtime

AaronRobinsonMSFT · 2026-07-08T19:25:13Z

Converge the three COM-interface RAII holders (ReleaseHolder, ComHolderPreemp, ComHolderAnyMode) onto the LifetimeHolder<Traits> pattern.

Changes

ReleaseHolder is retargeted to LifetimeHolder<ReleaseHolderTraits<T>>, adopting ComHolderPreemp's preemptive-mode release semantics (the VM default). Free() uses a MODE_PREEMPTIVE contract gated on ENABLE_CONTRACTS_IMPL, so non-VM consumers (utilcode, md, DAC, createdump) fall back to a static-contract annotation.
ComHolderPreemp is removed; ReleaseHolder replaces all uses.
ComHolderAnyMode is renamed to ReleaseHolderAnyMode.
Both holders' static_assert is relaxed from is_base_of<IUnknown, T> to a duck-typed "T has a Release() member" check (holder_detail::HasReleaseMethod), so ReleaseHolder can hold non-IUnknown types that expose Release().

Converge the three COM-interface RAII holders onto the LifetimeHolder<Traits> pattern: - Retarget ReleaseHolder to LifetimeHolder<ReleaseHolderTraits<T>>, adopting ComHolderPreemp's preemptive-mode release semantics (the VM default). The Free() contract is MODE_PREEMPTIVE, gated on ENABLE_CONTRACTS_IMPL so non-VM consumers (utilcode, md, DAC, createdump) use a static-contract annotation. - Remove ComHolderPreemp entirely; ReleaseHolder replaces all uses. - Rename ComHolderAnyMode to ReleaseHolderAnyMode. - Relax both holders' static_assert from is_base_of<IUnknown, T> to a duck-typed "T has a Release() member" check (holder_detail::HasReleaseMethod), so ReleaseHolder can hold non-IUnknown types that expose Release(). Migrate all call sites off the legacy SpecializedWrapper API onto the LifetimeHolder API (Extract->Detach, Clear->Free, GetValue/IsNull/Assign/SuppressRelease removed). Read-after-suppress sites are restructured to detach into a raw pointer to preserve exception-safety and refcount behavior. BindAssemblySpec is refactored so the CoreLib singleton borrow no longer relies on SuppressRelease. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

dotnet-policy-service · 2026-07-08T19:27:09Z

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Copilot

Pull request overview

This PR refactors CoreCLR’s COM / ref-counted RAII “holder” usage to converge on the LifetimeHolder<Traits> pattern: replacing legacy SpecializedWrapper APIs (Extract, Clear, GetValue, etc.), removing ComHolderPreemp, and renaming ComHolderAnyMode to ReleaseHolderAnyMode.

Changes:

Retargets ReleaseHolder to a LifetimeHolder<ReleaseHolderTraits<T>> implementation and introduces HolderDetail::HasReleaseMethod for duck-typed Release() detection.
Renames / consolidates COM holders (ComHolderAnyMode → ReleaseHolderAnyMode; removes ComHolderPreemp) and migrates call sites to Detach() / Free() patterns.
Refactors a few lifetime/ownership patterns (notably AppDomain::BindAssemblySpec) to avoid relying on legacy holder APIs.

Show a summary per file

File	Description
src/coreclr/vm/wrappers.h	Renames `ComHolderAnyModeTraits`/alias to `ReleaseHolderAnyMode*` and removes `ComHolderPreemp` traits.
src/coreclr/vm/weakreferencenative.cpp	Migrates `ComHolderPreemp<>` usages to `ReleaseHolder<>`.
src/coreclr/vm/stubmgr.cpp	Migrates `ComHolderAnyMode<>` usages to `ReleaseHolderAnyMode<>`.
src/coreclr/vm/stubhelpers.cpp	Migrates `ComHolderAnyMode<>` usages to `ReleaseHolderAnyMode<>`.
src/coreclr/vm/stdinterfaces.cpp	Migrates COM holders to `ReleaseHolder<>` / `ReleaseHolderAnyMode<>`.
src/coreclr/vm/runtimecallablewrapper.cpp	Migrates COM holders and adjusts a `CCWHolder` lifetime flow to use `Detach()`.
src/coreclr/vm/rejit.cpp	Removes legacy `= NULL` initialization pattern for `ReleaseHolder`.
src/coreclr/vm/peimagelayout.cpp	Replaces `Extract()` with `Detach()` when returning owned layouts.
src/coreclr/vm/peimage.cpp	Migrates metadata COM holder to `ReleaseHolderAnyMode<>`.
src/coreclr/vm/peassembly.cpp	Migrates `ComHolderPreemp<>` to `ReleaseHolder<>`.
src/coreclr/vm/olevariant.cpp	Migrates COM holders to `ReleaseHolder<>` / `ReleaseHolderAnyMode<>`.
src/coreclr/vm/olecontexthelpers.cpp	Migrates `ComHolderPreemp<>` to `ReleaseHolder<>`.
src/coreclr/vm/nativeimage.cpp	Replaces legacy holder APIs (`IsNull`/`Extract`) with `== NULL` and `Detach()`.
src/coreclr/vm/marshalnative.cpp	Updates `CCWHolder` initialization to brace-init and adjusts holder usage.
src/coreclr/vm/interoputil.cpp	Call sites migrated to new holder type names.
src/coreclr/vm/interopconverter.cpp	Migrates COM holders and replaces legacy holder APIs in a few places.
src/coreclr/vm/encee.cpp	Renames holder types in EnC path comments and variables.
src/coreclr/vm/eetoprofinterfaceimpl.cpp	Replaces `Extract()+NULL` patterns with `Detach()` for ownership transfer.
src/coreclr/vm/dllimport.cpp	Updates holder assignment to use `operator=` instead of `Assign`.
src/coreclr/vm/dispparammarshaler.cpp	Migrates COM holders to `ReleaseHolderAnyMode<>`.
src/coreclr/vm/crossloaderallocatorhash.inl	Updates holder initialization style and uses `Detach()` for returns.
src/coreclr/vm/coreassemblyspec.cpp	Uses `Detach()` when returning owned binder assembly.
src/coreclr/vm/commodule.cpp	Migrates COM holders to `ReleaseHolder<>` / `ReleaseHolderAnyMode<>`.
src/coreclr/vm/comconnectionpoints.cpp	Migrates `ComHolderAnyMode<>` to `ReleaseHolderAnyMode<>`.
src/coreclr/vm/comcallablewrapper.cpp	Migrates holders and refactors template-return ownership to use `Detach()`.
src/coreclr/vm/comcache.cpp	Migrates COM holders and replaces `Extract()` with `Detach()`.
src/coreclr/vm/clrex.cpp	Migrates error-info holder to `ReleaseHolderAnyMode<>`.
src/coreclr/vm/ceeload.cpp	Migrates symbol reader holders to `ReleaseHolder<>` and modernizes initialization.
src/coreclr/vm/assemblynative.cpp	Passes holder directly to tracing (via implicit pointer conversion).
src/coreclr/vm/assembly.cpp	Uses `Detach()` for ownership transfer and brace-init for holders.
src/coreclr/vm/appdomain.hpp	Adjusts `FindCachedFile` signature (removes unused `fThrow`).
src/coreclr/vm/appdomain.cpp	Refactors `BindAssemblySpec` lifetime management; simplifies `FindCachedFile`.
src/coreclr/md/enc/mdinternalrw.cpp	Fixes `QueryInterface` call to pass `void**`.
src/coreclr/inc/holder.h	Removes legacy `ReleaseHolder` wrapper, adds `LifetimeHolder`-based `ReleaseHolder` + `HasReleaseMethod`.
src/coreclr/dlls/mscoree/exports.cpp	Uses `Detach()` to transfer host handle ownership.
src/coreclr/debug/ee/debugger.cpp	Migrates `ComHolderPreemp<>` to `ReleaseHolder<>`.
src/coreclr/debug/daccess/enummem.cpp	Replaces legacy holder APIs (`Clear`/`GetValue`) with `Free()` and direct holder conversions.
src/coreclr/debug/daccess/dacdbiimpl.cpp	Removes `= nullptr` initialization for `ReleaseHolder`.
src/coreclr/debug/daccess/daccess.cpp	Removes `= nullptr` initialization for `ReleaseHolder`.
src/coreclr/debug/daccess/cdac.h	Replaces `Extract()` with `Detach()` in move operations.
src/coreclr/debug/createdump/threadinfo.cpp	Replaces `Extract()` with `Detach()` when transferring method ownership into a frame.
src/coreclr/debug/createdump/createdumpunix.cpp	Updates holder initialization to brace-init.
src/coreclr/debug/createdump/crashinfo.cpp	Removes `= nullptr` initialization for `ReleaseHolder`.
src/coreclr/binder/defaultassemblybinder.cpp	Replaces `Extract()` with `Detach()` for binder assembly ownership transfer.
src/coreclr/binder/customassemblybinder.cpp	Replaces `Extract()` with `Detach()` for binder assembly ownership transfer.
src/coreclr/binder/assemblybindercommon.cpp	Replaces `Extract()` with `Detach()` for binder assembly ownership transfer.
src/coreclr/binder/assembly.cpp	Replaces `Extract()` with `Detach()` for assembly-name ownership transfer.

Copilot's findings

Files reviewed: 47/47 changed files
Comments generated: 4

holder.h now includes contract.h (for the MODE_PREEMPTIVE CONTRACTL in ReleaseHolderTraits::Free), which pulled check.inl -> clrhost.h -> holder.h back into itself before Holder/LifetimeHolder were defined. Remove the clrhost.h include from check.inl to break the cycle, and make the two headers that were relying on that transitive path self-sufficient: - inc/sigbuilder.h: include corhdr.h for CorElementType/mdToken. - jit/jitstd/algorithm.h: include <utility> for std::swap used by jitstd::sort. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot

Copilot's findings

Files reviewed: 50/50 changed files
Comments generated: 2

- Added DBI_COMPILE definition for conditional compilation in clrdefinitions.cmake. - Updated Debugger::GetAndSendTransitionStubInfo to use g_pEEInterface for IP validation. - Refined contract enabling conditions in contract.h to include DBI builds. - Modified ReleaseHolderTraits to use ENABLE_EE_CONTRACTS for contract checks. - Removed unused IsIPInModule function from utilcode.h and implemented it in ExecutionManager. - Updated various files to consistently use ExecutionManager::IsIPInModule for IP validation.

Copilot

Copilot's findings

Files reviewed: 62/62 changed files
Comments generated: 2

ReleaseHolder's Detach() clears the holder's value (unlike the old Extract(), which retained it via SuppressRelease). BindAssemblyByProbingPaths detached pAssembly into *ppAssembly and then dereferenced pAssembly for the ref-def check, hitting the operator-> null assert (holder.h:974) on the TPA bind path at startup, crashing every coreclr test process. Use a local for the detached pointer and read from it. Also sequence the image reads before Detach() in nativeimage.cpp OpenR2RFromPE, where the member accesses and Detach() were unsequenced call arguments. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Copilot-Session: 6457cb5c-e732-41ad-8cc0-af22e64c1f49

Copilot

Copilot's findings

Files reviewed: 62/62 changed files
Comments generated: 2

Copilot

Copilot's findings

Files reviewed: 62/62 changed files
Comments generated: 1

Copilot

Copilot's findings

Files reviewed: 62/62 changed files
Comments generated: 1

Co-authored-by: Aaron R Robinson <arobins@microsoft.com>

Copilot

Copilot's findings

Files reviewed: 62/62 changed files
Comments generated: 3

Copilot

Copilot's findings

Files reviewed: 62/62 changed files
Comments generated: 2

jkotas · 2026-07-14T19:06:16Z

-// Also, we won't enable contracts if this is a DAC build.
-#if defined(ENABLE_CONTRACTS_DATA) && !defined(DACCESS_COMPILE) && !defined(CROSS_COMPILE)
+// Also, we won't enable contracts if a DAC or DBI build, or a cross build.
+#if defined(ENABLE_CONTRACTS_DATA) && !defined(DACCESS_COMPILE) && !defined(DBI_COMPILE) && !defined(CROSS_COMPILE)


DAC and DBI are the only cross-compiled components. CROSS_COMPILE condition is redundant.

jkotas · 2026-07-14T19:06:49Z



-// We only enable contracts in _DEBUG builds
+// We only enable contract data in _DEBUG builds and non-JIT builds.


This comment is 100% useless since it just rephrases the simple condition in plain English.

A good comment would explain "why" we are doing this.

jkotas · 2026-07-14T19:08:45Z

@@ -2092,6 +2090,5 @@ extern Volatile<LONG> g_DbgSuppressAllocationAsserts;
    STATIC_CONTRACT_MODE_PREEMPTIVE;

 #define AFTER_CONTRACTS


Suggested change

#define AFTER_CONTRACTS

Dead code?

jkotas · 2026-07-14T19:11:05Z

+struct ReleaseHolderTraits final
+{
+    static_assert(
+        HolderDetail::HasReleaseMethod<TYPE>::value,


Is the error message from the C++ compiler too inscrutable otherwise? (I am fine with this diagnostic, I am just wondering how much of an improvement it is.)

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elinor-fung mentioned this pull request Jul 11, 2026

[browser] Use the new version of V8 with exnref #129849

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[android] Android.Device_Emulator.JIT.Test failing on emulators with CoreCLR #112633

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Flaky timeout in CreateFileChangeToken_RootDeletedAndRecreated_TokenFiresWhenFileCreated #129691

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Merge branch 'main' into reconcile-releaseholder

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Co-authored-by: Aaron R Robinson <arobins@microsoft.com>

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		// We only enable contracts in _DEBUG builds
		// We only enable contract data in _DEBUG builds and non-JIT builds.

		@@ -2092,6 +2090,5 @@ extern Volatile<LONG> g_DbgSuppressAllocationAsserts;
		STATIC_CONTRACT_MODE_PREEMPTIVE;

		#define AFTER_CONTRACTS

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