CsWin32 follow-up: CLR metadata + TypeLib interop migration#13853
Open
JeremyKuhne wants to merge 2 commits into
Open
CsWin32 follow-up: CLR metadata + TypeLib interop migration#13853JeremyKuhne wants to merge 2 commits into
JeremyKuhne wants to merge 2 commits into
Conversation
Continues the CsWin32 struct-based COM migration from dotnet#13705 and dotnet#13746, this time covering the CLR metadata APIs (IMetaDataDispenser / IMetaDataImport2 / IMetaDataAssemblyImport) consumed by AssemblyInformation and ManifestUtil.MetadataReader, plus the ICreateTypeLib path used by RegisterAssembly. New files - src/Tasks/AssemblyDependency/Metadata/ - Metadata.cs folder header / namespace docs - IMetaDataDispenser.cs OpenScope with typed CorOpenFlags - IMetaDataImport2.cs GetCustomAttributeByName + GetPEKind with canonical inherited 3-72 slot map - IMetaDataAssemblyImport.cs GetAssemblyProps / GetAssemblyRefProps / GetFileProps / EnumAssemblyRefs / EnumFiles / GetAssemblyFromScope / CloseEnum - ASSEMBLYMETADATA.cs blittable struct from cor.h - OSINFO.cs blittable struct from cor.h - CorOpenFlags.cs typed [Flags] enum - CorAssemblyFlags.cs typed [Flags] enum - CorTokenType.cs 26 mdt* table-type tags - Tokens.cs MdToken / MdAssembly / MdAssemblyRef / MdFile readonly structs with validating constructors - src/Tasks/TypeLib/ICreateTypeLib.cs struct-based wrapper for RegisterAssembly - src/Tasks.UnitTests/MetadataReader_Tests.cs 12 tests / 24 cross-TFM (PEReader on net10, COM on net472), verifies identity parity for Accessibility.dll Modifications - AssemblyInformation.cs uses MdAssembly / BufferScope<char> / typed CorAssemblyFlags; OpenScope asks for IMetaDataImport2 directly (skips one QI); AllocAsmMeta / FreeAsmMeta eliminated - MetadataReader.cs net472 path migrated from [ComImport] to struct-based COM via AgileComPointer; failure to OpenScope returns null (per-file contract) - RegisterAssembly.cs uses the new ICreateTypeLib struct - Microsoft.Build.Tasks.csproj wildcard <Compile Include> for the Fusion / Metadata / TypeLib folders (FeatureWindowsInterop-gated) - NativeMethods.cs legacy [ComImport] declarations removed; only oleaut32 typelib P/Invokes remain; System.Runtime.Versioning using gated on FEATURE_WINDOWSINTEROP for source-build Skills - .github/skills/cswin32-com/SKILL.md adds 'Strongly-typed handle / token wrappers' with CLR validation table; pair-pointer to cswin32-interop; error- handling-parity guidance; IComIID polyfill heading rename - .github/skills/cswin32-interop/SKILL.md reorganized: Rules / Blittable signatures / Infrastructure / BufferScope<T> / Gotchas; source-build verification note Verified - Normal build: 0 warnings, 0 errors (net472 + net10.0) - Source build: 0 warnings, 0 errors (DotNetBuildSourceOnly=true DotNetBuild=true) - Tests: 24/24 pass on both TFMs
Contributor
🔍 Skill Validator Results
Summary
Full validator output```text Found 2 skill(s) [cswin32-interop] 📊 cswin32-interop: 3,402 BPE tokens [chars/4: 3,195] (standard ~), 14 sections, 3 code blocks [cswin32-interop] ⚠ Skill is 3,402 BPE tokens (chars/4 estimate: 3,195) — approaching "comprehensive" range where gains diminish. [cswin32-com] 📊 cswin32-com: 4,200 BPE tokens [chars/4: 4,075] (standard ~), 13 sections, 6 code blocks [cswin32-com] ⚠ Skill is 4,200 BPE tokens (chars/4 estimate: 4,075) — approaching "comprehensive" range where gains diminish. ✅ All checks passed (2 skill(s)) ``` |
Contributor
There was a problem hiding this comment.
Pull request overview
Migrates CLR metadata (IMetaData*) and typelib authoring (ICreateTypeLib) interop from [ComImport]/RCW-based calls to CsWin32-style struct-based COM, improving blittability and aligning Tasks/ManifestUtil with the newer ComScope<T> / AgileComPointer<T> infrastructure.
Changes:
- Adds new struct-based COM definitions for CLR metadata APIs and strongly-typed metadata token wrappers (
MdAssembly,MdAssemblyRef, etc.). - Updates
AssemblyInformationandManifestUtil.MetadataReaderto useCoCreateInstance,ComScope<T>, andAgileComPointer<T>instead of[ComImport]interfaces and manual marshalling. - Migrates
RegisterAssembly’sICreateTypeLib.SaveAllChangesusage to a struct-based COM call and removes legacy declarations fromNativeMethods.cs; adds unit tests for MetadataReader parity.
Reviewed changes
Copilot reviewed 19 out of 19 changed files in this pull request and generated 1 comment.
Show a summary per file
| File | Description |
|---|---|
| src/Tasks/TypeLib/ICreateTypeLib.cs | New struct-based COM wrapper for ICreateTypeLib (typelib persistence). |
| src/Tasks/RegisterAssembly.cs | Uses QI + struct-based ICreateTypeLib to call SaveAllChanges(). |
| src/Tasks/NativeMethods.cs | Removes legacy [ComImport] declarations for metadata + typelib interop. |
| src/Tasks/Microsoft.Build.Tasks.csproj | Switches to wildcard Compile includes for Fusion/Metadata/TypeLib interop folders under FeatureWindowsInterop. |
| src/Tasks/ManifestUtil/MetadataReader.cs | Replaces net472 COM RCW usage with CoCreateInstance + ComScope<T> + AgileComPointer<T>. |
| src/Tasks/AssemblyDependency/Metadata/Tokens.cs | Adds strongly-typed CLR metadata token wrappers and conversions. |
| src/Tasks/AssemblyDependency/Metadata/OSINFO.cs | Adds blittable OSINFO struct for CLR metadata APIs. |
| src/Tasks/AssemblyDependency/Metadata/Metadata.cs | Adds CorMetadata helper (CLSID constants) for activation. |
| src/Tasks/AssemblyDependency/Metadata/IMetaDataImport2.cs | Adds struct-based COM for IMetaDataImport2 with vtable slot mapping. |
| src/Tasks/AssemblyDependency/Metadata/IMetaDataDispenser.cs | Adds struct-based COM for IMetaDataDispenser::OpenScope. |
| src/Tasks/AssemblyDependency/Metadata/IMetaDataAssemblyImport.cs | Adds struct-based COM for IMetaDataAssemblyImport methods used by RAR/ManifestUtil. |
| src/Tasks/AssemblyDependency/Metadata/CorTokenType.cs | Adds typed CorTokenType table-tag enum for token decoding/validation. |
| src/Tasks/AssemblyDependency/Metadata/CorOpenFlags.cs | Adds typed CorOpenFlags for OpenScope options. |
| src/Tasks/AssemblyDependency/Metadata/CorAssemblyFlags.cs | Adds typed CorAssemblyFlags for assembly/ref flags. |
| src/Tasks/AssemblyDependency/Metadata/ASSEMBLYMETADATA.cs | Adds blittable ASSEMBLYMETADATA struct and allocation contract docs. |
| src/Tasks/AssemblyDependency/AssemblyInformation.cs | Uses new metadata COM structs + AgileComPointer<T>; removes AllocAsmMeta/FreeAsmMeta. |
| src/Tasks.UnitTests/MetadataReader_Tests.cs | New parity/regression tests for MetadataReader across TFMs. |
| .github/skills/cswin32-interop/SKILL.md | Documentation updates for interop rules and parity guidance. |
| .github/skills/cswin32-com/SKILL.md | Documentation updates for COM patterns, token wrappers, and error-handling parity. |
![github-actions[bot]](https://avatars.githubusercontent.com/in/15368?s=60&v=4){kind=small}
Contributor
There was a problem hiding this comment.
Review Summary: COM Interop Migration to CsWin32 Struct-Based Patterns
This is a well-executed migration from legacy [ComImport] / Marshal.GetComInterfaceForObject() patterns to CsWin32 struct-based COM vtable patterns. The change is mechanically sound and follows the same patterns established in the WMI and Fusion interop code in this repo.
✅ Verified Correct
- Vtable indices: All slot numbers verified against the removed
[ComImport]declarations (IMetaDataAssemblyImportslots 3-15,IMetaDataImport2slots 60/70,ICreateTypeLibslot 12). - ComScope / AgileComPointer lifecycle: The
takeOwnership: falsesemantics are correctly used — GIT AddRefs, ComScope'susingreleases the transient ref, leaving GIT as the sole owner. - DisposeManagedResources vs DisposeUnmanagedResources: Correct switch since
AgileComPointer<T>is a managed class with its own finalizer. - Memory safety in RegisterAssembly: The bridge between RCW (
ITypeLib) and struct-based COM (ICreateTypeLib) is properly structured with nested try/finally. - HRESULT checking: Every COM call checks the return via
.ThrowOnFailure()— an improvement over the old pattern where some calls silently swallowed errors. - Test coverage: The new
MetadataReader_Tests.csprovides good coverage including threading, idempotent disposal, negative paths, and cross-assembly validation. - Token types: The strongly-typed
MdAssembly/MdAssemblyRef/MdFilewrappers with documented bypass semantics for native out-params are well-designed.
⚠️ One Performance Suggestion (Non-Blocking)
GetStringCustomAttribute acquires its own ComScope<IMetaDataImport2> via a GIT round-trip on every call, even when the caller (GetAssemblyMetadata) already holds one. This introduces ~4 unnecessary GIT lookups per GetAssemblyMetadata() invocation. The old code passed IMetaDataImport2 as a parameter. Consider accepting a pointer parameter in a follow-up to eliminate this overhead for the RAR hot path.
Assessment
No blocking issues. The vtable layouts, memory management, disposal patterns, and behavioral contracts are all correct. The one actionable suggestion (GIT round-trip reduction) is a minor performance optimization, not a correctness concern. This PR is ready to merge from a technical review perspective.
Note
🔒 Integrity filter blocked 1 item
The following item were blocked because they don't meet the GitHub integrity level.
- #13853
pull_request_read: has lower integrity than agent requires. The agent cannot read data with integrity below "approved".
To allow these resources, lower min-integrity in your GitHub frontmatter:
tools:
github:
min-integrity: approved # merged | approved | unapproved | noneGenerated by Expert Code Review (on open) for issue #13853 · ● 14M
HasAssemblyAttribute (MetadataReader.cs) - Initialize valuePtr/valueLen and treat hr != S_OK as 'not present'. The old [ComImport] signature gave us out params that the marshaller zeroed on failure; with raw pointers an error HRESULT that does not write pcbData could leave valueLen indeterminate. Now S_FALSE and error HRESULTs both deterministically return false. - Drop the CA1806 suppression / now-unused System.Diagnostics.CodeAnalysis using since the HRESULT is checked. GetStringCustomAttribute (AssemblyInformation.cs) - Accept a borrowed IMetaDataImport2* parameter instead of opening a new ComScope (which round-trips through the GIT) per call. GetAssemblyMetadata reuses its existing import2 scope across 4-5 attribute lookups; GetFrameworkName opens one scope of its own. Both addressed Copilot reviewer / expert-reviewer feedback on PR dotnet#13853.
Member
There was a problem hiding this comment.
It seems like a lifetime ago now, but I hand-rolled my own version of this COM interface back in 2005. This is so much better than what I wrote at the time. 😄
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
CsWin32 follow-up: CLR metadata + TypeLib interop migration
Continues the CsWin32 struct-based COM migration from #13705 and #13746,
this time covering the CLR metadata APIs (IMetaDataDispenser /
IMetaDataImport2 / IMetaDataAssemblyImport) consumed by AssemblyInformation
and ManifestUtil.MetadataReader, plus the ICreateTypeLib path used by
RegisterAssembly.
New files
with canonical inherited 3-72 slot map
GetFileProps / EnumAssemblyRefs / EnumFiles /
GetAssemblyFromScope / CloseEnum
readonly structs with validating constructors
RegisterAssembly
(PEReader on net10, COM on
net472), verifies identity
parity for Accessibility.dll
Modifications
CorAssemblyFlags; OpenScope asks for
IMetaDataImport2 directly (skips one QI);
AllocAsmMeta / FreeAsmMeta eliminated
struct-based COM via AgileComPointer; failure
to OpenScope returns null (per-file contract)
Fusion / Metadata / TypeLib folders
(FeatureWindowsInterop-gated)
only oleaut32 typelib P/Invokes remain;
System.Runtime.Versioning using gated on
FEATURE_WINDOWSINTEROP for source-build
Skills
token wrappers' with CLR
validation table; pair-pointer
to cswin32-interop; error-
handling-parity guidance;
IComIID polyfill heading rename
signatures / Infrastructure /
BufferScope / Gotchas;
source-build verification note
Verified
(DotNetBuildSourceOnly=true DotNetBuild=true)