Enable setting the TypeMap entrypoint assembly via a RuntimeHostConfigurationOption by jtschuster · Pull Request #121513 · dotnet/runtime

jtschuster · 2025-11-10T23:04:34Z

Implements the alternative to #121138 mentioned in #121138 (comment)

Enables the TypeMap to be used in Library output types. Projects can set the following RuntimeHostConfigurationOption to enable this behavior. If it exists, this option takes priority over the entrypoint assembly.

<ItemGroup>
<RuntimeHostConfigurationOption Include="System.Runtime.InteropServices.TypeMappingEntryAssembly"
Value="$(TypeMapEntryAssembly)"
Condition="$(TypeMapEntryAssembly) != ''" />
</ItemGroup>

entrypoint assembly for building the typemap.

Copilot

Pull Request Overview

This PR implements a new feature that enables the TypeMap entrypoint assembly to be configured via a RuntimeHostConfigurationOption, allowing TypeMap to be used with Library output types instead of only executable output types. The change provides a way to specify which assembly should be scanned for TypeMap attributes when the entry point assembly is not appropriate (e.g., in library scenarios).

Key changes:

Added support for System.Runtime.InteropServices.TypeMappingEntryAssembly configuration option across the CoreCLR compiler, trimmer, and runtime
Modified the --feature flag in illink to accept string values in addition to boolean values
Added new tests to validate TypeMap entry assembly configuration works correctly

Reviewed Changes

Copilot reviewed 15 out of 15 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
src/libraries/System.Private.CoreLib/src/System/Runtime/InteropServices/TypeMapLazyDictionary.cs	Modified runtime to check AppContext for TypeMappingEntryAssembly override before falling back to entry assembly
src/coreclr/tools/aot/ILCompiler/Program.cs	Added runtime knob parsing to extract TypeMappingEntryAssembly and use it for TypeMap metadata
src/tools/illink/src/linker/Linker/Driver.cs	Modified --feature flag to accept and store string values alongside boolean values
src/tools/illink/src/linker/Linker/LinkContext.cs	Added Features dictionary to store string-valued features
src/tools/illink/src/linker/Linker.Steps/MarkStep.cs	Added logic to check Features for TypeMappingEntryAssembly override
src/coreclr/tools/aot/ILCompiler.Trimming.Tests/TestCasesRunner/TrimmingDriver.cs	Added comment explaining test behavior with entry assembly
src/tests/Interop/TypeMap/*.cs	Added new runtime test files validating TypeMappingEntryAssembly configuration
src/tools/illink/test/Mono.Linker.Tests.Cases/Reflection/*.cs	Added trimmer test cases and updated existing tests for renamed method

However, it's still necessary to set the RuntimeConfigurationOption for runtime behavior on CoreCLR.

MichalStrehovsky

Looks good otherwise!

AaronRobinsonMSFT · 2026-01-05T16:19:46Z

+ RuntimeAssembly? startingAssembly;
+ if (AppContext.GetData("System.Runtime.InteropServices.TypeMappingEntryAssembly") is string entryAssemblyName)
+ {
+ startingAssembly = Assembly.Load(entryAssemblyName) as RuntimeAssembly;


This is odd. The as operator implies the returned type could be a non RuntimeAssembly. I don't believe that is true. This is a confusing cast. It should just be (RuntimeAssembly).

Ah, I forgot (RuntimeAssembly)null! returns null instead of throwing. Will update to make that clear.

…ound - Enable --typemap-entry-assembly flag in ILLink.targets for TypeMap support - Add workaround in TypeMapAttributeTypeMap for runtimes without dotnet/runtime#121513 - Use AppContext.GetData to get TypeMappingEntryAssembly and set executing assembly - Add IAndroidCallableWrapper interface for ACW types with GetFunctionPointer - Update poc-vs-spec.md with ILLink integration details - Requires locally built ILLink from dotnet/runtime with #121513 support

- Remove TrimMode='copy' to allow ILLink to trim unused proxy types - ILLink uses the 3-arg TypeMapAttribute to determine which proxies to keep - TypeMaps assembly reduced from 3.6 MB to 33 KB for HelloWorld (99.1% reduction) - Requires ILLink with --typemap-entry-assembly support (dotnet/runtime#121513)

…ound - Enable --typemap-entry-assembly flag in ILLink.targets for TypeMap support - Add workaround in TypeMapAttributeTypeMap for runtimes without dotnet/runtime#121513 - Use AppContext.GetData to get TypeMappingEntryAssembly and set executing assembly - Add IAndroidCallableWrapper interface for ACW types with GetFunctionPointer - Update poc-vs-spec.md with ILLink integration details - Requires locally built ILLink from dotnet/runtime with #121513 support

- Remove TrimMode='copy' to allow ILLink to trim unused proxy types - ILLink uses the 3-arg TypeMapAttribute to determine which proxies to keep - TypeMaps assembly reduced from 3.6 MB to 33 KB for HelloWorld (99.1% reduction) - Requires ILLink with --typemap-entry-assembly support (dotnet/runtime#121513)

Enable TypeMap apis to use an RuntimeHostConfigurationOption to find the
0edbd53
entrypoint assembly for building the typemap.

jtschuster requested review from AaronRobinsonMSFT, jkoritzinsky, sbomer and simonrozsival November 10, 2025 23:04

github-actionsBot added the area-Tools-ILLink .NET linker development as well as trimming analyzers label Nov 10, 2025

dotnet-policy-serviceBot added the linkable-framework Issues associated with delivering a linker friendly framework label Nov 10, 2025

dotnet-policy-serviceBot assigned jtschuster Nov 10, 2025

jtschuster added 2 commits November 10, 2025 16:08

Missed a place where Main was renamed to Run
cd198c0

Fix build break, generate runtimeconfig.json
fe74d8a

jtschuster added 2 commits November 11, 2025 12:52

Make test Exe
bc4753d

Need to set RequiresProcessIsolation for RuntimeConfig options?
8a2335c

jtschuster marked this pull request as ready for review November 12, 2025 17:51

jtschuster requested a review from marek-safar as a code owner November 12, 2025 17:51

CopilotAI review requested due to automatic review settings November 12, 2025 17:51

Copilotstarted reviewing on behalf of jtschuster November 12, 2025 17:52 View session

Copilotfinished reviewing on behalf of jtschuster November 12, 2025 17:53

Use runtimeknob on NativeAOT
0d42667

CopilotAI reviewed Nov 12, 2025
View reviewed changes

Pass runtimeknobs to TrimmingDriver and fix test failure.
90e9f40

build-analysisBot mentioned this pull request Nov 13, 2025
slow macOS - "##[error]The job running on agent Azure Pipelines 9 ran longer than the maximum time of 60 minutes." dotnet/dnceng#1883
Open
3 tasks

MichalStrehovsky reviewed Nov 21, 2025
View reviewed changes

Comment threadsrc/coreclr/tools/aot/ILCompiler/Program.cs Outdated

Make TypeMapEntryAssembly a first-class switch in trim tools
b6d3631
However, it's still necessary to set the RuntimeConfigurationOption for runtime behavior on CoreCLR.

Forward --typemap-entry-assembly in ilc tests
845ad5b

This was referenced Dec 11, 2025
[browser] Wasm.Build.Tests timeout - Timed out after 10s waiting for 'WASM EXIT' #116697
Open
Unable to pull image from mcr.microsoft.com #117164
Closed

MichalStrehovsky approved these changes Dec 11, 2025
View reviewed changes

Comment threadsrc/tools/illink/src/linker/Linker/LinkContext.cs Outdated
Comment threadsrc/tools/illink/src/linker/Linker/Driver.cs Outdated
Comment threadsrc/coreclr/tools/aot/ILCompiler.Trimming.Tests/TestCasesRunner/ILCompilerOptions.cs Outdated

Remove Features property, fix alignment in trimmer help message
5156a44

build-analysisBot mentioned this pull request Dec 12, 2025
"Over release of MOW - COM" assert in COM wrappers #122447
Closed

CopilotAI mentioned this pull request Dec 12, 2025
Disable UniqueMarshalling COM tests causing "Over release of MOW - COM" assertion #122473
Closed

jtschuster added 2 commits December 12, 2025 09:57

Add compat suppressions
06f4102

Don't set RuntimeHostConfigurationOption.Trim
0761be6

build-analysisBot mentioned this pull request Dec 12, 2025
[wasm/browser] Failed to connect to socket /run/dbus/system_bus_socket #120176
Closed

Create instances of source types in the proxy type map for nativeaot
cfef57a

MichalStrehovsky reviewed Dec 15, 2025
View reviewed changes

Comment threadsrc/tests/Interop/TypeMap/TypeMapEntryAssemblyApp.cs Outdated

Use new().GetType() pattern in ProxyTypeMap test
bd6d21f

jtschuster merged commit d162bba into dotnet:mainDec 15, 2025
153 of 157 checks passed

AaronRobinsonMSFT reviewed Jan 5, 2026
View reviewed changes

CopilotAI mentioned this pull request Jan 5, 2026
Change TypeMapLazyDictionary to use direct cast instead of 'as' operator for RuntimeAssembly #122885
Merged

This was referenced Jan 9, 2026
[main] Source code updates from dotnet/runtime dotnet/dotnet#4125
Closed
[main] Source code updates from dotnet/runtime dotnet/dotnet#4196
Merged

github-actionsBot locked and limited conversation to collaborators Feb 5, 2026

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Enable setting the TypeMap entrypoint assembly via a RuntimeHostConfigurationOption - #121513

Enable setting the TypeMap entrypoint assembly via a RuntimeHostConfigurationOption#121513
jtschuster merged 14 commits into
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jtschuster:TypeMapAppContext

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