# Invalid redeclaration compile error when extending generic type in more than one way

**URL:** <https://forums.swift.org/t/invalid-redeclaration-compile-error-when-extending-generic-type-in-more-than-one-way/42516>\
**Category:** Using Swift\
**Created:** [December 4, 2020, 4:31pm UTC](https://forums.swift.org/t/invalid-redeclaration-compile-error-when-extending-generic-type-in-more-than-one-way/42516 "2020-12-04T16:31:51Z")\
**Posts on this page:** 1\
**Showing post:** 6

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**Author:** ![Nevin](https://sea2.discourse-cdn.com/swift/user_avatar/forums.swift.org/nevin/32/617_2.png) [@Nevin](https://forums.swift.org/u/Nevin)\
**Post date:** [December 4, 2020, 5:53pm UTC](https://forums.swift.org/t/invalid-redeclaration-compile-error-when-extending-generic-type-in-more-than-one-way/42516/6 "2020-12-04T17:53:30Z")

</div>

You might find some or all of these threads relevant:

[Matching behavior with expectations for associated types and typealiases in constrained protocol extensions](https://forums.swift.org/t/matching-behavior-with-expectations-for-associated-types-and-typealiases-in-constrained-protocol-extensions/37099)

[How does `associatedtype` inference work](https://forums.swift.org/t/how-does-associatedtype-inference-work/37017)

[Typealias in constrained extension, should this compile?](https://forums.swift.org/t/typealias-in-constrained-extension-should-this-compile/34863)

[Should this program really compile (is the where clause ignored)?](https://forums.swift.org/t/should-this-program-really-compile-is-the-where-clause-ignored/22995)

[What kind of magic behavior is this?](https://forums.swift.org/t/what-kind-of-magic-behavior-is-this/22014)

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