Skip PhantomData in Unsize checks by dingxiangfei2009 · Pull Request #149968

Skip PhantomData in Unsize checks by dingxiangfei2009 · Pull Request #149968 · rust-lang/rust

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Dec 14, 2025

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Dec 14, 2025

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Dec 15, 2025

This patch proposes relaxation on the type unsizing
condition.
`PhantomData` has been in the current type system
exempted from being treated as carrying any data,
including dropck, virtual call dispatch by
`DispatchFromDyn` and unsizing container by
`CoerceUnsize`.
`PhantomData` is a special 1-ZST that really
carries no "data" of the types it captures.

I propose that we should also extend this
interpretation to `Unsize`.

Signed-off-by: Xiangfei Ding <dingxiangfei2009@protonmail.ch>

ojeda mentioned this pull request

Jan 19, 2026

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