__ComObject doesn't support dynamic interface map (redux)
#123725
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This was originally fixed naively which resulted in an incomplete fix. The activation path issues remained and this current fix addresses the underlying issue - adding IDIC to __ComObject.
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Tagging subscribers to this area: @dotnet/interop-contrib |
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Pull request overview
Revisits the fix for COM interop casting involving System.__ComObject and the dynamic interface map, adding broader validation and updating test infrastructure to cover the previously missed scenario.
Changes:
- Updates COM test contracts and native/managed test clients to use a revised interface shape for validating COM interface casting behavior.
- Extends COM interop tests to validate the expected interfaces are present on activated COM classes.
- Refines
MethodTable::HasDynamicInterfaceMap()logic and adds explanatory comments about the dynamic interface map’s intent and usage.
Reviewed changes
Copilot reviewed 6 out of 6 changed files in this pull request and generated 2 comments.
Show a summary per file
| File | Description |
|---|---|
| src/tests/Interop/COM/ServerContracts/Server.Contracts.h | Removes IInterface2 and updates Marshal_Interface to return IInterface1. |
| src/tests/Interop/COM/ServerContracts/Server.Contracts.cs | Adjusts managed contract interfaces to align with updated COM interop validation scenarios. |
| src/tests/Interop/COM/NativeServer/MiscTypesTesting.h | Updates native COM server to implement/return IInterface1 for interface marshalling tests. |
| src/tests/Interop/COM/NativeClients/MiscTypes/MiscTypes.cpp | Updates native COM client test to use IInterface1 in interface marshalling validation. |
| src/tests/Interop/COM/NETClients/MiscTypes/Program.cs | Adds/updates managed COM client validation for interface identity/casting behavior. |
| src/coreclr/vm/methodtable.h | Updates HasDynamicInterfaceMap() logic and documents the rationale/usage in COM interop. |
jkoritzinsky
approved these changes
Jan 28, 2026
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In #112375 a fix was checked in with insufficient validation. An issue was reported offline that uncovered a deficiency in that fix and the validation. This PR revisits that issue, adds the needed comprehensive testing, and adds comments on the utility of the dynamic interface map.
Re fixes #112371