Fix CrossGen2 TypeMap blob-only type references by jkoritzinsky · Pull Request #131610 · dotnet/runtime

jkoritzinsky · 2026-07-30T19:44:19Z

Add support for resolving types referenced only by custom attribute arguments (no TypeRef rows, no AssemblyRef rows for the type's containing assembly).

Fixes #131527

Note

This PR description was generated with assistance from AI/Copilot.

… in assembly attributes

azure-pipelines · 2026-07-30T19:45:11Z

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Copilot

Pull request overview

This PR fixes ReadyToRun/CrossGen2 compilation of TypeMap payloads when mapped System.Type values appear only in custom-attribute blobs (no TypeRef rows), by ensuring required tokens can still be generated and by adding a regression test that exercises this metadata shape.

Changes:

Add a new TypeMap regression input assembly authored in IL that encodes mapped types only in custom-attribute blobs.
Update TypeMap emission/import paths to pass the “triggering module” context so CrossGen2 can create/resolve the needed tokens for blob-only type references.
Add a fallback in MutableModule when an AssemblyRef name can’t be inferred via TypeRef-table scanning (blob-only scenarios).

Reviewed changes

Copilot reviewed 13 out of 13 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
src/tests/Interop/TypeMap/TypeMapBlobOnlyLib.ilproj	New IL test project producing the blob-only typemap assembly.
src/tests/Interop/TypeMap/TypeMapBlobOnlyLib.il	IL that encodes TypeMap types in CA blobs without `TypeRef` rows for mapped types.
src/tests/Interop/TypeMap/TypeMapApp.csproj	Wires the new IL project into the TypeMap test app build.
src/tests/Interop/TypeMap/TypeMapApp.cs	Adds an xUnit test validating external/proxy maps for the blob-only assembly.
src/tests/Interop/TypeMap/GroupTypes.cs	Introduces the new group marker type used by the test.
src/coreclr/tools/Common/Compiler/INativeFormatTypeReferenceProvider.cs	Extends type-reference encoding to accept an optional module context.
src/coreclr/tools/aot/ILCompiler.ReadyToRun/TypeSystem/Mutable/MutableModule.cs	Adds blob-only fallback for resolving an assembly name when no `TypeRef` mapping exists.
src/coreclr/tools/aot/ILCompiler.ReadyToRun/Compiler/TypeMapAssemblyTargetsNode.cs	Passes module context when importing/encoding group type references.
src/coreclr/tools/aot/ILCompiler.ReadyToRun/Compiler/ReadyToRunProxyTypeMapNode.cs	Passes triggering module context for typemap key/value type imports and encoding.
src/coreclr/tools/aot/ILCompiler.ReadyToRun/Compiler/ReadyToRunExternalTypeMapNode.cs	Passes triggering module context for typemap value type imports and encoding.
src/coreclr/tools/aot/ILCompiler.ReadyToRun/Compiler/ReadyToRunCodegenCompilation.cs	Initializes token manager earlier and provides it to the import reference provider.
src/coreclr/tools/aot/ILCompiler.ReadyToRun/Compiler/DependencyAnalysis/ImportReferenceProvider.cs	Ensures def tokens are available when a module context is provided.
src/coreclr/tools/aot/ILCompiler.Compiler/Compiler/DependencyAnalysis/NodeFactory.cs	Updates the external references provider implementation signature to match the interface change.

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

Copilot

Pull request overview

Copilot reviewed 13 out of 13 changed files in this pull request and generated 1 comment.

Comments suppressed due to low confidence (1)

src/coreclr/tools/aot/ILCompiler.ReadyToRun/Compiler/DependencyAnalysis/ImportReferenceProvider.cs:53

EncodeReferenceToType takes an optional module = null (and the interface also allows callers to omit it), but the method asserts module is not null. This is inconsistent and would cause Debug builds to fail if a future call site uses the optional parameter. Either make module required everywhere or allow null here (and just skip token pre-creation when it’s null, as GetImportToType already does).

        internal Vertex EncodeReferenceToType(NativeWriter writer, TypeDesc type, ModuleDesc module = null)
        {
            Debug.Assert(module is not null);
            Import typeImport = GetImportToType(type, module);
            return writer.GetTuple(writer.GetUnsignedConstant((uint)typeImport.Table.IndexFromBeginningOfArray), writer.GetUnsignedConstant((uint)typeImport.IndexFromBeginningOfArray));

Copilot

Pull request overview

Copilot reviewed 19 out of 19 changed files in this pull request and generated no new comments.

jtschuster

Looks good to me assuming you confirmed the TypeMapBlobOnlyLib.il does put the ref in the custom attribute blob.

Co-authored-by: Jackson Schuster <36744439+jtschuster@users.noreply.github.com>

Copilot

Pull request overview

Copilot reviewed 19 out of 19 changed files in this pull request and generated no new comments.

Comments suppressed due to low confidence (2)

src/coreclr/tools/aot/ILCompiler.ReadyToRun/Compiler/DependencyAnalysis/ImportReferenceProvider.cs:53

INativeFormatTypeReferenceProvider.EncodeReferenceToType is now called with module == null by non-R2R providers (e.g., ExternalReferencesTableIndex), so asserting module is not null here makes the contract inconsistent and risks debug-only failures if this provider is ever used in a context that doesn't have/need a requiring-module. GetImportToType already supports moduleRequiringImport == null; consider allowing that here as well.

        internal Vertex EncodeReferenceToType(NativeWriter writer, TypeDesc type, ModuleDesc module)
        {
            Debug.Assert(module is not null);
            Import typeImport = GetImportToType(type, module);
            return writer.GetTuple(writer.GetUnsignedConstant((uint)typeImport.Table.IndexFromBeginningOfArray), writer.GetUnsignedConstant((uint)typeImport.IndexFromBeginningOfArray));

src/coreclr/tools/aot/ILCompiler.ReadyToRun/Compiler/DependencyAnalysis/ImportReferenceProvider.cs:26

GetImportToType now dereferences _externalReferenceTokenManager when moduleRequiringImport is non-null, but there is no assertion/guard that Initialize(...) has been called. If GetImportToType is ever used before initialization (or in a code path where initialization is skipped), this will throw a NullReferenceException and be hard to diagnose.

            if (moduleRequiringImport is not null)
            {
                _externalReferenceTokenManager.EnsureDefTokensAreAvailable(type, moduleRequiringImport, referencesAreForAsyncMethod: false);
            }

jkoritzinsky · 2026-08-03T03:37:49Z

/ba-g libraries test failure unrelated

Copilot

Pull request overview

Copilot reviewed 19 out of 19 changed files in this pull request and generated no new comments.

Suppressed comments (1)

src/tests/Interop/TypeMap/TypeMapApp.cs:330

The proxy type map assertions appear to use the wrong key direction for the Lib5 entry, and they also use typeof(...) lookups even though this file already documents that proxy-map lookups should use new ...().GetType() to satisfy trimming rules. TypeMapping.GetOrCreateProxyTypeMapping<T> maps source type → proxy type (see existing TypeMapEntryAssemblyApp.cs usage), so the Lib5 assertion should index by Lib5Type1 and expect Lib5Proxy1.

        IReadOnlyDictionary<Type, Type> proxyMap = TypeMapping.GetOrCreateProxyTypeMapping<BlobOnlyAttributeTypeNames>();
        Assert.Equal(typeof(S1), proxyMap[typeof(C1)]);
        Assert.Equal(typeof(C1), proxyMap[typeof(S1)]);
        Assert.Equal(typeof(Lib5Type1), proxyMap[typeof(Lib5Proxy1)]);

jtschuster

Do we want to backport this to rc1?

jkoritzinsky · 2026-08-19T21:13:25Z

I thought this got merged in already. Yeah we need to backport this.

jkoritzinsky · 2026-08-19T21:13:33Z

/ba-g build monitor infra failure

jkoritzinsky · 2026-08-19T21:14:08Z

/backport to release/11.0-rc1

github-actions · 2026-08-19T21:14:17Z

Started backporting to release/11.0-rc1 (link to workflow run)

@jkoritzinsky

…132537) Backport of #131610 to release/11.0-rc1 /cc @jkoritzinsky ## Customer Impact - [ ] Customer reported - [X] Found internally Crossgen2 crashes during build for .NET-for-iOS scenarios without workaround. The iOS team currently has a workaround in place in their code. ## Regression - [ ] Yes - [X] No ## Testing Comprehensive unit tests were added for the scenario. ## Risk Low, extensive testing for the fix and the affected API is very self-contained. **IMPORTANT**: If this backport is for a servicing release, please verify that: - For .NET 8 and .NET 9: The PR target branch is `release/X.0-staging`, not `release/X.0`. - For .NET 10+: The PR target branch is `release/X.0` (no `-staging` suffix). ## Package authoring no longer needed in .NET 9 **IMPORTANT**: Starting with .NET 9, you no longer need to edit a NuGet package's csproj to enable building and bump the version. Keep in mind that we still need package authoring in .NET 8 and older versions. --------- Co-authored-by: Jeremy Koritzinsky <jekoritz@microsoft.com>

…nable to encode a type in crossgen2's precomputed TypeMap (#132984) PR #131610 enabled Crossgen2 to precompute TypeMap entries for types referenced only by type name strings in custom-attribute blobs. These references in attributes do not inherently require corresponding `TypeRef` or `AssemblyRef` metadata rows. Roslyn generally emits full assembly identities for external types and may also introduce metadata references, but other valid producers may emit only the serialized name. Crossgen2 successfully resolves that string to a `TypeDesc`. It therefore knows the target module and full assembly identity. The problem occurs when translating that result into a ReadyToRun type fixup. The mutable manifest currently represents an out-of-bubble reference using: ``` #<assembly-simple-name>:<source-module-index> ``` At runtime this means: 1. Resolve the source module by index. 2. Find an `AssemblyRef` with that simple name in the source module. 3. Bind that `AssemblyRef`. 4. Resolve the synthetic `TypeRef`. PR #131610 supplied the target assembly’s simple name even but step 2 was impossible because the source module had no corresponding `AssemblyRef`. The resulting fixup is well-formed, but cannot be resolved. See #132811 for additional info. To workaround the issue, we emit the (TypeMapGroup, ProxyOrExternalMap) entry with a `0` state, which tells the runtime to build the map from attributes instead of using the precomputed map. This was done previously for maps that are expected to throw a type system exception. This allows some parts of the type map to still be encoded if a single entry is unencodable. The fix going into main is #133038, which is more involved, modifies the R2R format, and bumps the R2R version. Since there are workarounds for the mobile team, we can do this less risky change for the backport. ## Customer Impact Found internally. Crossgenned apps with a valid precomputed type map can throw at runtime. ## Regression Yes. The original TypeMap implementation would create the map only at runtime. The TypeMap precomputation PR introduced issue #131527. The fix for that introduced issue #132811, the one this fixes. ## Testing The existing test suite caught the issue but wasn't run in the PRs because crossgen tests aren't a part the default 'runtime' pipeline. The crossgen2 pipelines catch this issue and will be green if the issue is fixed. ## Risk Low. The fix doesn't introduce new features or a change to the TypeMap section format. It utilizes existing functionality to force runtime computation of the map. There is a risk that we haven't caught all possible edge cases.

jkoritzinsky added 3 commits July 29, 2026 15:13

Ensure the correct tokens are available for typerefs that may only be…

47de42f

… in assembly attributes

Add TypeMap blob-only IL regression test

6775747

Handle blob-only typemap types without AssemblyRef rows

020d683

Copilot AI lite review requested due to automatic review settings July 30, 2026 19:44

jkoritzinsky requested a review from MichalStrehovsky as a code owner July 30, 2026 19:44

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jkoritzinsky added area-ReadyToRun and removed area-crossgen2-coreclr only use for closed issues labels Jul 30, 2026

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Comment thread ...reclr/tools/aot/ILCompiler.ReadyToRun/Compiler/DependencyAnalysis/ImportReferenceProvider.cs Outdated

Comment thread src/coreclr/tools/aot/ILCompiler.ReadyToRun/TypeSystem/Mutable/MutableModule.cs

Avoid extra work when looking for assembly references

bd78634

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

Copilot AI review requested due to automatic review settings July 30, 2026 20:35

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Comment thread src/coreclr/tools/aot/ILCompiler.ReadyToRun/TypeSystem/Mutable/MutableModule.cs

Make module argument to EncodeReferenceToType explicit at all call sites

fab9519

Copilot AI review requested due to automatic review settings July 30, 2026 20:55

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jtschuster approved these changes Jul 30, 2026

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Comment thread ...reclr/tools/aot/ILCompiler.ReadyToRun/Compiler/DependencyAnalysis/ImportReferenceProvider.cs Outdated

Update ImportReferenceProvider.cs

c240451

Co-authored-by: Jackson Schuster <36744439+jtschuster@users.noreply.github.com>

Copilot AI review requested due to automatic review settings July 31, 2026 00:56

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jkoritzinsky enabled auto-merge (squash) July 31, 2026 02:41

jkoritzinsky mentioned this pull request Aug 1, 2026

[wasm][R2R] Create manifest token when type reference wasn't pre-registered #131651

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jkoritzinsky requested a review from elinor-fung August 3, 2026 03:38

elinor-fung approved these changes Aug 4, 2026

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Comment thread src/coreclr/tools/aot/ILCompiler.ReadyToRun/TypeSystem/Mutable/MutableModule.cs Outdated

Comment thread src/tests/Interop/TypeMap/TypeMapBlobOnlyLib.il

Cleanup and add additional test case

5b174e5

Copilot AI review requested due to automatic review settings August 10, 2026 23:46

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jtschuster approved these changes Aug 19, 2026

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jkoritzinsky merged commit 00ecce5 into dotnet:main Aug 19, 2026
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[release/11.0-rc1] Fix CrossGen2 TypeMap blob-only type references #132537

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