# F-pattern\_types : Subsets enums using as

**URL:** https://internals.rust-lang.org/t/f-pattern-types-subsets-enums-using-as/24048
**Category:** language design
**Created:** [March 3, 2026, 3:47am UTC](https://internals.rust-lang.org/t/f-pattern-types-subsets-enums-using-as/24048 "2026-03-03T03:47:17Z")
**Posts on this page:** 1
**Showing post:** 18

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### Author: ![DidingasLushis](https://sea2.discourse-cdn.com/flex002/user_avatar/internals.rust-lang.org/didingaslushis/32/14152_2.png) [@DidingasLushis](https://internals.rust-lang.org/u/DidingasLushis)
#### Post date: [March 3, 2026, 11:10pm UTC](https://internals.rust-lang.org/t/f-pattern-types-subsets-enums-using-as/24048/18 "2026-03-03T23:10:45Z")

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My thought exactly and the reason I brought this up.

Prior discussion: [Memory-layout-compatible enum/struct subsets](https://internals.rust-lang.org/t/memory-layout-compatible-enum-struct-subsets/20331)

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