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Weak type aliases for Edition 2024
https://github.com/rust-lang/rust/issues/112792
Implied vs explicit where clauses
Currently
type Alias<'a, T> = &'a T;
errors withfeature(lazy_type_alias)
.Analogy
type Foo<..> = Bar
struct Foo<..> { b: Bar }
Question Niko can't remember
If we require
T: Clone
…T: Clone
Otherwise
If we wanted
type Alias<T> = NeedsClone<T>
to work, how would we implement it?predicates_of(def_id)
query, we populate it with the WF requirements from the right-hand side of the type aliasfun side-effect: adding additional trait bounds to the environment can break stuff, might want to be more clever :)
https://play.rust-lang.org/?version=nightly&mode=debug&edition=2021&gist=a82011eb51dee31831068b14bd279916
variance
fmease is working on computing the variance of a weak type alias by computing it from the rhs.