31 lines
801 B
Rust
31 lines
801 B
Rust
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//@ revisions: current next
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//@[next] compile-flags: -Znext-solver
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//@ ignore-compare-mode-next-solver (explicit revisions)
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//@ check-pass
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#![allow(unconditional_recursion)]
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// Regression test for trait-system-refactor-initiative#182.
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trait Id {
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type This;
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}
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impl<T> Id for T {
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type This = T;
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}
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fn to_assoc<T>(x: T) -> <T as Id>::This {
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x
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}
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fn mirror<T>(x: Vec<T>) -> impl Id<This = Vec<T>> {
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let x = to_assoc(mirror(x));
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// `?x` equals `<opaque::<T> as Id>::This`. We need to eagerly infer the
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// type of `?x` to prevent this method call from resulting in an error.
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//
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// We could use both the item bound to normalize to `Vec<T>`, or the
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// blanket impl to normalize to `opaque::<T>`. We have to go with the
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// item bound.
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x.len();
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x
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}
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fn main() {}
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