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Update AV1554: Do not use optional parameters in interface methods or their concrete implementations #367

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dennisdoomen merged 1 commit into from
May 9, 2026
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Update AV1554: Do not use optional parameters in interface methods or their concrete implementations #367

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6 changes: 3 additions & 3 deletions _rules/1554.md
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Original file line number Diff line number Diff line change
@@ -1,11 +1,11 @@
---
rule_id: 1554
rule_category: maintainability
title: Do not use optional parameters in interface methods or their concrete implementations
title: Do not use optional parameters with defaults in interface methods or their concrete implementations
severity: 1
---
When an interface method defines an optional parameter, its default value is discarded during overload resolution unless you call the concrete class through the interface reference.
When an interface method defines an optional parameter with a default value, its default value is discarded during overload resolution unless you call the concrete class through the interface reference.

When a concrete implementation of an interface method sets a default argument for a parameter, the default value is discarded during overload resolution if you call the concrete class through the interface reference.

See the series on optional argument corner cases by Eric Lippert (part [one](https://docs.microsoft.com/en-us/archive/blogs/ericlippert/optional-argument-corner-cases-part-one), [two](https://docs.microsoft.com/en-us/archive/blogs/ericlippert/optional-argument-corner-cases-part-two), [three](https://docs.microsoft.com/en-us/archive/blogs/ericlippert/optional-argument-corner-cases-part-three), [four](https://docs.microsoft.com/en-us/archive/blogs/ericlippert/optional-argument-corner-cases-part-four)) for more details.
See the series on optional argument corner cases by Eric Lippert (part [one](https://learn.microsoft.com/en-us/archive/blogs/ericlippert/optional-argument-corner-cases-part-one), [two](https://learn.microsoft.com/en-us/archive/blogs/ericlippert/optional-argument-corner-cases-part-two), [three](https://learn.microsoft.com/en-us/archive/blogs/ericlippert/optional-argument-corner-cases-part-three), [four](https://learn.microsoft.com/en-us/archive/blogs/ericlippert/optional-argument-corner-cases-part-four)) for more details.