[browser][trimmed] DI generic constraint tests conflict with trimmability validation #134266

Description

Aggressively trimmed browser library tests enable Microsoft.Extensions.DependencyInjection.VerifyOpenGenericServiceTrimmability. Seven existing CallSiteFactoryTest cases then fail during container construction because their deliberately varied open-generic constraint shapes do not satisfy that validation contract.

Affected methods:

CreateCallSite_Throws_IfClosedTypeDoesNotSatisfyStructGenericConstraint
CreateCallSite_ReturnsService_IfClosedTypeSatisfiesStructGenericConstraint
CreateCallSite_Throws_IfClosedTypeDoesNotSatisfyNewGenericConstraint
CreateCallSite_ReturnsService_IfClosedTypeSatisfiesNewGenericConstraint
CreateCallSite_ReturnsMatchingTypesThatMatchCorrectConstraints (three data rows)

Reproduction Steps

Build and run Microsoft.Extensions.DependencyInjection.Tests for browser-Wasm with:

EnableAggressiveTrimming=true
TestTrimming=true
Configuration=Release

The failures reproduce on CoreCLR and Mono browser trimming.

Expected behavior

Tests not specifically validating trimming annotations should continue exercising their intended generic-constraint behavior, or be adapted to a service registration shape valid under the trimming feature switch.

Actual behavior

Representative exception:

System.ArgumentException: Generic implementation type 'ClassWithStructConstraint`1' has a DefaultConstructorConstraint ('new()' constraint), but the generic service type 'IFakeOpenGenericService`1' doesn't.
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteFactory.ValidateTrimmingAnnotations(...)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteFactory.Populate()

Regression?

Unknown. Broad aggressive-trimming browser coverage is newly enabled.

Known Workarounds

Temporarily exclude only the affected methods/data rows under aggressively trimmed browser builds. All non-trimmed coverage remains enabled, and dedicated open-generic trimmability validation tests remain active.

Configuration

Browser-Wasm Release with aggressive trimming, CoreCLR and Mono.

Other information

A linker descriptor is not the appropriate fix because the exception is intentional validation behavior, not missing generic metadata.