fix(source-gen): stop parameter resolver keeping every non-public test-class method (IL2111)

[thomhurst]

Problem

TUnit 1.72.0 breaks Native AOT / trimmed publishes that passed on 1.71.0:

TestSource.g.cs(167): Trim analysis error IL2111: ..TestSource..cctor(): Method 'X.ReconnectKnownBrokerAsync(Object,Type,CancellationToken)'
with parameters or return value with `DynamicallyAccessedMembersAttribute` is accessed via reflection.

#6923 passes typeof(TestClass) to ParameterMetadataFactory.ForMethod/ForGenericMethod/ForConstructor, whose declaringType was annotated with NonPublicMethods. The trimmer therefore keeps every private method of every test class, and reports IL2111 for any private helper that has a [DynamicallyAccessedMembers] parameter. Before #6923 the generated per-parameter lambdas used intrinsic GetMethod(name, flags, types) calls, which kept only the test method itself.

Reproduced with a minimal project (PublishTrimmed): 1.71.0 clean, 1.72.0 reports IL2111 for a private helper with a [DynamicallyAccessedMembers] Type parameter.

Fix

• DeclaringTypeMembers is now PublicConstructors | PublicMethods. ClassMetadata.Type already requests these on the same type, so this adds no trimming roots compared with 1.71.0.
• The resolver looks up public methods only.
• Non-public (internal) test methods use the new ParameterMetadataFactory.ForNonPublicMethod(...). The generator passes a no-op delegate carrying [DynamicDependency("<exact signature>", typeof(T))], so the trimmer keeps exactly that method and no same-name overloads (every GetMethod intrinsic narrows only by name). The resolver matches overloads by static-ness, generic arity and parameter shape.

Tests

• ParameterReflectionInfoTests: new Internal_Method test (non-public path), and a private helper with a [DynamicallyAccessedMembers] parameter as a trim regression guard. The factory helper methods moved into a public nested class because the factory now looks up public members only.
• Trimmed publish of TUnit.TestProject: the guard helper produces no IL2111 (remaining IL2111 warnings exist before this change, e.g. ClassHookContext.ClassType.set in hook registration, also present in 1.71.0).
• Source generator snapshot tests pass unchanged; PublicAPI snapshots updated for the new method and narrowed annotation.
• ParameterReflectionInfoTests, ParameterReflectionInfoTests+Nested, InternalMethodWithArgumentsTests pass in source-gen and reflection modes.

Summary by CodeRabbit

• New Features
  • Parameter metadata can now be resolved for non-public methods, including generic methods and overloaded methods with matching parameter types.
• Bug Fixes
  • Improved selection of overloaded methods using parameter types, static status, and generic parameter count.
  • Improved parameter and declaring-method metadata resolution in trimmed applications, including for non-public and generic methods, helping preserve accurate reflection metadata.

CI coverage gap

This got through CI because the only AOT publish that fails on trim warnings is TUnit.NugetTester (warnings as errors). None of its test classes had a private helper with a [DynamicallyAccessedMembers] parameter. The TUnit.TestProject AOT publish doesn't treat warnings as errors, and it already has about 105 IL2111 warnings, so a new one wouldn't stand out.

This PR adds TrimmedMemberRootingTests to the NuGet tester. It has a private annotated helper and an internal test method with parameters. I checked it with a trimmed publish (ILLink stand-in, since there is no MSVC linker locally):

• TUnit 1.72.0: error IL2111: ...TrimmedMemberRootingTests.CountInstanceFields(Object, Type)
• This branch (packed locally): no IL2111 for the helper; both tests pass

Class hooks are left out on purpose: hook registration already reports IL2111 for ClassHookContext.ClassType.set, and 1.71.0 does too. Adding a hook here would fail the gate until that's fixed.

[chatgpt-codex-connector]

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📝 Code Review	✅ Completed 2026-09-29T20:35:03.034275Z	4a32d8c	New commits

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📝 Walkthrough

Walkthrough

The source generator now emits rooted lookup paths for non-public methods. ParameterMetadataFactory resolves methods using parameter shape and, when supplied, static status and generic arity. Reflection and trimming tests cover the lookup behavior and generated metadata.

Changes

Non-public method lookup

Layer / File(s)	Summary
Lookup contract and resolution src/TUnit.Core/ParameterMetadataFactory.cs, tests/TUnit.PublicAPI/*.verified.txt	ParameterMetadataFactory adds ForNonPublicMethod and a generic-method overload. Resolution uses parameter shape and can also use static status and generic arity. Declaring-type member annotations no longer request preservation of non-public methods.
Generated lookup and metadata src/TUnit.Core.SourceGenerator/Utilities/MetadataGenerationHelper.cs, tests/TUnit.Core.SourceGenerator.Tests/*.verified.txt	The source generator emits a rooted lookup path for non-public methods and passes generic arity to generic-method metadata calls. Generated snapshots include the updated arguments and non-public method registrations.
Reflection and trimming coverage tests/TUnit.TestProject/ParameterReflectionInfoTests.cs, tests/TUnit.TestProject/NonPublicTestMethodRootingTests.cs, tools/tunit-nuget-tester/TUnit.NugetTester/TUnit.NugetTester/TrimmedMemberRootingTests.cs, tests/TUnit.Core.SourceGenerator.Tests/NonPublicTestMethodRootingTests.cs	Tests cover internal and private method metadata, generic overload selection, exact-signature rooting, and annotated private helpers. The NuGet tester tests cover parameter metadata and annotated helpers in trimmed test cases.

Priority: ➖ Normal

Estimated code review effort: 3 (Moderate) | ~25 minutes

Change: Bug fix

Merge Risk: ⚪ Minimal · up to be2a6

No concrete regression in non-public method resolution or trimming roots was established. The change appears mergeable after normal checks.

Security Architecture Review

Security architecture risk: 🔵 Low · up to be2a6

The change affects how test-method metadata is retained and resolved in trimmed applications. The reviewed paths do not establish a new security boundary bypass or attacker-facing entrypoint, but the public contract and its downstream behavior warrant attention.

Retained concerns
No architecture-level concerns identified.

Security review details

Security Blast Radius

• inferred — The reviewed effect is method retention and metadata lookup in consuming test assemblies. No credential, privileged sink, or cross-service path is identified in the reviewed change.

Trust Boundaries and Controls

• observed — The public factory takes a caller-supplied type and method name and performs reflection lookup; its non-public root delegate is not executed. This metadata API is not shown serving as an authorization control.

Resilience and Maintainability Implications

• observed — The resolver still has a count-based fallback after stricter signature matching. That behavior matters to metadata-selection predictability, but the reviewed evidence does not connect it to a security-control failure.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 20.83% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 48 functions across 6 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely identifies the main source-generator fix: stopping the parameter resolver from retaining every non-public test-class method to address IL2111.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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_{A rabbit checks each method's name,
Then matches shape and arity the same.
A rooted path keeps methods near,
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[chatgpt-codex-connector]

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[github-actions]

Review

The fix is sound. Narrowing DeclaringTypeMembers to public members matches what ClassMetadata.Type already roots. Routing non-public methods through a per-method intrinsic GetMethod lookup restores the pre-#6923 trimming footprint. The private-helper regression test is a useful guard. I did not build or run anything, so this comes from reading the diff.

Concerns

1. The generic/type-parameter non-public path probably reintroduces the problem. GenerateNonPublicMethodLookup uses typeof(T).GetMethods(Public | NonPublic | Instance | Static) plus a FirstOrDefault predicate for generic methods. The trimmer only treats GetMethod(name, flags, ...) with a constant name as precise. GetMethods(flags) roots every non-public method of the class. A non-public generic test method would therefore keep all private helpers and produce IL2111 again. Nothing in the PR tests this case; the new test is a non-generic internal method. Consider resolving generic methods with GetMethod("Name", flags) (name only, constant flags), which is intrinsic, and disambiguating by parameter count at runtime. Alternatively, document the limitation and add a trimmed-publish check for an internal generic test method.

2. Non-public constructors regress. ForConstructor now uses public-only GetConstructor, and the annotation keeps only PublicConstructors. If a test class can have a non-public constructor, ReflectionInfo resolves to an empty array. Please confirm whether that case is supported, or route it through a lookup like methods.

3. Silent miss. Resolve() returns an empty array when the member is null. Confirm that the Lookup kind still produces the descriptive message that Unresolvable_Member_Reports_Lookup_In_Exception covers for the other kinds.

Minor

• Private_Helper_With_Annotated_Parameter always passes as a plain unit test. It only guards against IL2111 when the trimmed publish is checked in CI. A comment saying so would keep it from being mistaken for runtime coverage.

Overall this is a good targeted fix. I'd resolve or explicitly test item 1 before merging.

[greptile-apps]

Confidence Score: 5/5

[Medium risk] Refactors how the test framework roots non-public test methods.

The PR appears safe to merge; no new actionable issue or outstanding previous finding was identified.

Summary

The PR narrows trimming roots for test-class methods while preserving reflection metadata for non-public tests.

• Generated code roots each parameterized non-public test method by signature.
• A cross-target attribute polyfill and regression tests support the new path.

Diagram

%%{init: {'theme': 'neutral'}}%%
flowchart LR
  A[Non-public test method] --> B[Generated metadata]
  B --> C[Exact-signature DynamicDependency]
  C --> D[Trimmed method retained]
  B --> E[ForNonPublicMethod]
  E --> F[Parameter reflection metadata]

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Inline comments:
Review comments at
@src/TUnit.Core.SourceGenerator/Utilities/MetadataGenerationHelper.cs:
- Around line 256-271: Update the generic-method predicate in
GenerateNonPublicMethodLookup to match the intended method’s static/instance
status, generic arity, and parameter type shape, not just its name and parameter
count. Preserve the existing non-generic lookup path.

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• tests/TUnit.PublicAPI/Tests.Core_Library_Has_No_API_Changes.DotNet8_0.verified.txt
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[github-actions]

Review

Good, well-scoped fix. Narrowing DeclaringTypeMembers to what ClassMetadata.Type already roots removes the IL2111 regression. Moving non-public methods to a per-method intrinsic lookup (ForMethodLookup) restores the 1.71.0 rooting. The tests, PublicAPI snapshots and Describe() cleanup look right.

Concern: the generic non-public branch probably reintroduces the same problem

GenerateNonPublicMethodLookup uses typeof(T).GetMethods(Public | NonPublic | Instance | Static) plus FirstOrDefault for generic methods, or methods whose parameters use type parameters. The trimmer recognises GetMethods(flags) on a constant typeof as an intrinsic that roots every matching method. So an internal or private generic test method would again keep all non-public methods of the class, and a private helper with a DynamicallyAccessedMembers parameter would get IL2111 again. The new tests only cover a non-generic internal method, so they wouldn't catch it.

Options:

• Use GetMethod(name, flags) without a types array for generic methods. It is intrinsic and roots only methods with that name. It is ambiguous for overloads, so match afterwards by parameter count, as you already do.
• Or emit a GetMethod-by-name lookup, catch AmbiguousMatchException, and fall back to GetMethods at runtime only in that rare case (with a justified suppression).

Please also add an internal generic test method to TrimmedMemberRootingTests so the trimmed-publish guard covers this branch.

Smaller points

• DeclaredAccessibility != Public only looks at the method. Please confirm the public-only resolver lookup can't be reached for a public method on a non-public containing type, and that source-gen and reflection modes agree.
• Private_Helper_With_Annotated_Parameter in ParameterReflectionInfoTests duplicates the nuget-tester test and is a runtime no-op unless that project is trim-published. Consider dropping it.
• The PR description says CI didn't catch this. Wiring the nuget-tester trimmed publish with warnings-as-errors into CI would prevent a repeat. I couldn't see whether that is included here.

Overall: a solid fix for the reported case, but I'd address the generic-method branch before merging.

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[github-actions]

Review of #6937

The fix looks sound. Dropping NonPublicMethods from DeclaringTypeMembers removes the IL2111 trigger. Routing non-public methods through a generated intrinsic GetMethod(name, flags) restores the pre-#6923 rooting, which kept only the test method itself. Each test method gets one lambda instead of one per parameter. Two things I'd look at:

1. Overloaded non-public methods keep every same-named overload. If GetMethod(name, flags) throws AmbiguousMatchException, FindAmongOverloads calls GetMethods under an UnconditionalSuppressMessage(IL2080). The justification is reasonable, because the intrinsic keeps all methods with that name. But the suppression is only correct as long as the generator always emits that lookup. A small snapshot or unit test that hits the ambiguous-overload path with an internal method would guard against the two drifting apart. I couldn't see one in the diff.

2. FindNonPublicMethod is a suppressed dead path in trimmed apps. Generated code no longer reaches it, and only direct callers of the public factories can. Suppressing IL2080 there hides a real trimming gap for them, and they only get a runtime lookup failure. Since these factories are EditorBrowsable(Never), I'd consider removing the fallback. Alternatively, keep it but say plainly in the code that it doesn't work under trimming.

Minor: ParameterInfoResolver now has two constructors and two nullable declaring-type fields (_declaringType and _lookupType), with ! used throughout Describe and Resolve. Splitting it into a lookup-based resolver and an annotated-type resolver behind a common abstraction would remove the null-forgiving operators and make the trimming contract explicit per type.

Overall this looks good to merge. The generated code is unchanged apart from the extra arguments, and the trim regression guard test is a useful addition.

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[github-actions]

Review of #6937

The fix targets the right cause. Narrowing DeclaringTypeMembers to PublicConstructors | PublicMethods stops the trimmer from rooting every private helper. That is what produced the IL2111 errors. Using [DynamicDependency] with the exact doc-ID signature for non-public test methods is a sound way to keep one method without keeping its same-name overloads. Adding static-ness and generic-arity matching to the resolver is a good hardening too. I found no blocking issues. I did not build or run anything, and I could not load the code-review skill, so this is a manual read of the diff.

Points worth checking:

1. Inherited non-public test methods. [DynamicDependency(sig, typeof(containingType))] roots members on containingType. If the generator can emit containingType as a derived class for a test method declared as internal on a base class, the root may not cover the base member. FindDeclaredNonPublicMethod also does not use DeclaredOnly, so it would find an inherited method that the trimmer never kept. Please confirm containingType is the declaring type, or add a test with an internal test method inherited from a base class in the trimmed publish.

2. Silent fallback in GetDynamicDependencySignature. When the doc ID is unavailable or doesn't match, it returns method.Name. That roots all same-name overloads, which brings back the IL2111 risk for that case. It is unlikely to be hit, but an inline comment saying so would help. A generator diagnostic would be better if this path is ever reachable.

3. Lambda attributes and LangVersion. The emitted [DynamicDependency] static () => { } needs C# 10 or later. The #if NET5_0_OR_GREATER guard covers the attribute's existence but not the language version. This is probably fine, since TUnit already requires modern C#. Please confirm the generator's other outputs make the same assumption.

4. Overload fallback. FindBestMatch still falls back to the first name-and-count match when no shape matches. That keeps the old behaviour, but it can attach the wrong ParameterInfo silently. Consider logging or returning null when several count-only candidates exist. Not a blocker.

5. Public API surface. The new ForGenericMethod and ForNonPublicMethod overloads and the ParameterInfoResolver constructor are public. Please make sure the TUnit.PublicAPI snapshots are updated if they cover these types.

Overall this is a good, well-documented fix, and the regression tests (Internal_Method, the private helper with a [DynamicallyAccessedMembers] parameter, and the trimmed publish) cover the reported failure. The only thing I'd want confirmed before merge is the inherited-method case in point 1.