Deduplicate implicitly implemented interface methods in member resolution#2711
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…tion When resolving a member against a concrete type, candidate methods are collected both from the type itself and from every implemented interface. An implicitly implemented interface method was therefore added twice, showing up as a duplicated candidate signature in detailed resolution error messages (e.g. "candidate signatures: MyMethod(String a), MyMethod(String a)") and doing redundant work during overload resolution. Skip interface-sourced (and object-sourced) methods whose signature is already covered by an earlier candidate. The signature comparison is structural so generic methods match across their distinct generic parameter instances, while genuinely different methods - such as an interface method hiding an object method with a different return type - are kept. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
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enabled auto-merge (squash)
July 20, 2026 17:55
This was referenced Jul 22, 2026
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Fixes the duplicated candidate signatures reported in #2523 (comment).
Problem
When a member is resolved against a concrete type,
TypeResolver.TryFindMemberAccessorcollects candidate methods both from the type itself and from every implemented interface. An implicitly implemented interface method is present in both sets, so it was added twice. WithExposeDetailedResolutionErrorsenabled a failed call then reported the same signature twice:The duplicate also meant redundant work during overload resolution since both entries bind to the same implementation.
Fix
Interface-sourced (and, for interface targets,
object-sourced) methods are now skipped when an earlier candidate already has the same signature. Because class methods are collected first, the class implementation wins, matching C# semantics for a call on the concrete type. The signature comparison is structural:Tof the class method vsTof the interface method), including through constructed generics, by-ref and array typesObject.GetHashCode()with a different return type, orEquals()overloadingEquals(object)- the existingInteropExplicitTypeTestscovering those scenarios still passThe same dedupe is applied to the explicit interface implementation path, where identical redeclared signatures from multiple interfaces could previously also be reported twice.
Testing
Added a regression test mirroring the discussion repro (interface implementation exposed through an
object-typed property). FullJint.TestsandJint.Tests.PublicInterfacesuites pass on net10.0 and net472.🤖 Generated with Claude Code