Fix ConstructorInfo.GetGenericArguments to return empty array#128059
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steveisok merged 6 commits intoMay 13, 2026
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Constructors are never generic methods in the CLR (there is no IL or language support for generic constructors). Previously, calling GetGenericArguments() on a ConstructorInfo threw NotSupportedException because the call fell through to the base MethodBase implementation, which throws by design when not overridden. RuntimeMethodInfo returns an empty array for non-generic methods, but RuntimeConstructorInfo did not override the method and so threw. Add a single override on the abstract ConstructorInfo base so the fix applies uniformly to all subclasses (CoreCLR, Mono, NativeAOT, MetadataLoadContext, custom ConstructorInfo subclasses, etc.). Fixes dotnet#128041 Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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Pull request overview
This PR changes ConstructorInfo.GetGenericArguments() to return an empty Type[] instead of falling back to MethodBase.GetGenericArguments() (which throws). This makes constructors behave like other non-generic methods when queried for generic arguments.
Changes:
- Override
ConstructorInfo.GetGenericArguments()inSystem.Private.CoreLibto always return an empty array. - Add a regression test asserting
ConstructorInfo.GetGenericArguments()is empty for constructors on both non-generic and generic types.
Reviewed changes
Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.
| File | Description |
|---|---|
| src/libraries/System.Private.CoreLib/src/System/Reflection/ConstructorInfo.cs | Adds ConstructorInfo.GetGenericArguments() override returning an empty array for all constructors. |
| src/libraries/System.Runtime/tests/System.Reflection.Tests/ConstructorInfoTests.cs | Adds xUnit coverage ensuring constructors’ GetGenericArguments() returns an empty array across representative types. |
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NativeAOT previously overrode ConstructorInfo.GetGenericArguments() to throw NotSupportedException for desktop compat. Remove that override so the new ConstructorInfo base implementation (returns empty array) is used uniformly. Update two tests that asserted the prior throw behavior to assert the new empty-array contract: - System.Reflection.Context CustomConstructorInfo test - System.Reflection.MetadataLoadContext invariant test (TestConstructorInfoCommonInvariants is the upstream of several failing tests in TypeTests and ConstructorTests) Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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This is a breaking change that would need settled before merging. |
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The System.Reflection.MetadataLoadContext tests target both NetCoreAppCurrent and NetFrameworkCurrent. On .NET Framework, ConstructorInfo.GetGenericArguments() still throws NotSupportedException (this fix only ships in .NET Core). Guard the invariant check with #if NET so the test asserts the appropriate behavior on each runtime. This addresses the remaining failures in the Libraries_NET481 leg: TestConstructors1, TestInvariantCode, TestMakeArray, TestInvariants, TestMakeGenericType, and TestMakeMdArray (all upstream-rooted in TestConstructorInfoCommonInvariants). Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Per @max-charlamb's suggestion, add coverage for an open generic type (GenericClassWithConstructor<>) in addition to the closed one. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
max-charlamb
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May 12, 2026
jkotas
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May 12, 2026
jkotas
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May 12, 2026
Per @jkotas's review, the public override on a public type needs to be declared in the reference assembly so it appears in the public API surface area. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Per @jkotas's review, the ConstructorInfo base class already defines MemberType => MemberTypes.Constructor (and exposes it in the reference assembly), so the override on RuntimeConstructorInfo.CoreCLR is unnecessary. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
jkotas
approved these changes
May 12, 2026
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Constructors are never generic methods in the CLR (there is no IL or language support for generic constructors). Previously, calling GetGenericArguments() on a ConstructorInfo threw NotSupportedException because the call fell through to the base MethodBase implementation, which throws by design when not overridden.
RuntimeMethodInfo returns an empty array for non-generic methods, but RuntimeConstructorInfo did not override the method and so threw. Add a single override on the abstract ConstructorInfo base so the fix applies uniformly to all subclasses (CoreCLR, Mono, NativeAOT, MetadataLoadContext, custom ConstructorInfo subclasses, etc.).
Fixes #128041