For context, I'm working on a pet project that includes a Span type that annotates a value with a start and end in some input: struct Span<T> { start: usize, end: usize, value: T } This Span is used to wrap errors (e.g. Result<_, Span<E>>), which I would like to be compatible with ? co…

I recommend you to implement .map() method instead of From trait (as Option<T> and Result<T, E> do). Then v.map(Into::into) allows you to convert v: Span<T> into Span<U>. EDIT: Sorry I overlooked Result<_, Span<E>> use case... I don't think it's possible to use ? to convert Span<T> into Span<U>. …

Is it possible to impl `From<Wrapper<T>>` for `Wrapper<U>`?

help

alice March 26, 2020, 7:14pm 2

No, sorry, it's not possible to make an exception for U = T.

Incompatible lifetimes - mutable references in an async loop

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Is it possible to impl `From<Wrapper<T>>` for `Wrapper<U>`?

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