Fix ERP042 false positive on properties#327
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EventSource implicit event-method detection treated property setters as event methods because they are non-static, non-virtual and void-returning. Restrict detection to ordinary methods so properties no longer trigger ERP042. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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Pull request overview
Fixes a false positive in ERP042 (EventSource implementation correctness) where property setters in EventSource-derived types were mistakenly treated as implicit ETW event methods.
Changes:
- Restricts implicit event-method detection to
MethodKind.Ordinaryto ignore accessors/operators. - Applies the same filtering when computing ordinal-based implicit event IDs.
- Adds a unit test ensuring properties do not trigger ERP042, and updates the sample
DemoEventSourceaccordingly.
Reviewed changes
Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.
| File | Description |
|---|---|
| src/ErrorProne.NET.CoreAnalyzers/EventSourceAnalysis/EventSourceAnalyzer.cs | Narrows implicit event-method detection and ordinal inference to ordinary methods. |
| src/ErrorProne.NET.CoreAnalyzers.Tests/CoreAnalyzers/EventSourceAnalyzerTests.cs | Adds a regression test ensuring properties don’t trigger ERP042. |
| samples/ErrorProne.Samples/CoreAnalyzers/DemoEventSource.cs | Adds properties to reproduce/validate the original false positive scenario manually. |
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| // Only ordinary methods can be event methods. Property/event accessors, operators, etc. must be ignored even | ||
| // though some of them (like property setters) are non-static, non-virtual and void-returning. | ||
| if (method.MethodKind == MethodKind.Ordinary && !method.IsStatic && !method.IsVirtual && method.ReturnsVoid && !method.IsConstructor() && method.MethodKind != MethodKind.Destructor) |
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Good catch - removed the redundant !IsConstructor() and MethodKind != Destructor checks; MethodKind.Ordinary already covers those.
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| // "Implicitly: by the ordinal number of the method in the class (thus the first method in the class is 1, second 2 …)" | ||
| var methods = method.ContainingType.GetMembers().OfType<IMethodSymbol>().Where(m => !m.IsStatic && !m.IsVirtual && m.ReturnsVoid).ToList(); | ||
| var methods = method.ContainingType.GetMembers().OfType<IMethodSymbol>().Where(m => m.MethodKind == MethodKind.Ordinary && !m.IsStatic && !m.IsVirtual && m.ReturnsVoid).ToList(); | ||
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Fixed. Extracted IsImplicitEventMethodCandidate and the ordinal list now uses the same eligibility rules, so [NonEvent] methods no longer shift the inferred id. Added a regression test.
…al shift - Extract IsImplicitEventMethodCandidate; MethodKind.Ordinary already excludes constructors/destructors so drop the redundant checks. - Exclude [NonEvent] methods from the ordinal list so they no longer shift the inferred implicit event ID. - Add regression test for the NonEvent ordinal shift. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Add a dedicated No_Warn_On_Non_Void_Method unit test and a non-void method in the DemoEventSource sample to document that only void-returning methods are implicit event methods. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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Problem
ERP042 (EventSource implementation correctness) emitted a warning that a private method "does not call WriteEvent" for properties declared in an
EventSource-derived class.Root cause
In
EventSourceAnalyzer.TryGetEventMethod, implicit event-method detection treated any non-static, non-virtual, void-returning method as an ETW event method. A property setter matches all of those criteria (it returnsvoid), so properties were incorrectly flagged.Fix
Restrict implicit event-method detection to
MethodKind.Ordinary, excluding property/event accessors, operators, etc. Applied to both the event-method check and the ordinal index computation used to infer event IDs.Testing
No_Warn_On_Propertiesunit test covering auto-properties, expression-bodied properties, and full get/set properties alongside a valid event method.DemoEventSourcesample with properties to manually reproduce the original false positive.Co-authored-by: Copilot 223556219+Copilot@users.noreply.github.com