mirror of https://github.com/rust-lang/rust
85 lines
1.9 KiB
Rust
85 lines
1.9 KiB
Rust
// Test cases where we constrain `<T as Anything<'b>>::AssocType` to
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// outlive `'a` and there is a unique bound in the trait definition of
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// `Anything` -- i.e., we know that `AssocType` outlives `'b`. In this
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// case, the best way to satisfy the trait bound is to show that `'b:
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// 'a`, which can be done in various ways.
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//@ compile-flags:-Zverbose-internals
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#![allow(warnings)]
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#![feature(rustc_attrs)]
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use std::cell::Cell;
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trait Anything<'a> {
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type AssocType: 'a;
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}
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fn with_signature<'a, T, F>(cell: Cell<&'a ()>, t: T, op: F)
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where
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F: FnOnce(Cell<&'a ()>, T),
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{
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op(cell, t)
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}
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fn require<'a, 'b, T>(_cell: Cell<&'a ()>, _t: T)
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where
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T: Anything<'b>,
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T::AssocType: 'a,
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{
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}
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#[rustc_regions]
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fn no_relationships_late<'a, 'b, T>(cell: Cell<&'a ()>, t: T)
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where
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T: Anything<'b>,
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{
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with_signature(cell, t, |cell, t| require(cell, t));
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//~^ ERROR
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}
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#[rustc_regions]
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fn no_relationships_early<'a, 'b, T>(cell: Cell<&'a ()>, t: T)
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where
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T: Anything<'b>,
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'a: 'a,
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{
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with_signature(cell, t, |cell, t| require(cell, t));
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//~^ ERROR
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}
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#[rustc_regions]
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fn projection_outlives<'a, 'b, T>(cell: Cell<&'a ()>, t: T)
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where
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T: Anything<'b>,
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T::AssocType: 'a,
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{
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// We are projecting `<T as Anything<'b>>::AssocType`, and we know
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// that this outlives `'a` because of the where-clause.
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with_signature(cell, t, |cell, t| require(cell, t));
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}
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#[rustc_regions]
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fn elements_outlive<'a, 'b, T>(cell: Cell<&'a ()>, t: T)
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where
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T: Anything<'b>,
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'b: 'a,
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{
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with_signature(cell, t, |cell, t| require(cell, t));
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}
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#[rustc_regions]
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fn one_region<'a, T>(cell: Cell<&'a ()>, t: T)
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where
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T: Anything<'a>,
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{
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// Note that in this case the closure still propagates an external
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// requirement between two variables in its signature, but the
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// creator maps both those two region variables to `'a` on its
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// side.
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with_signature(cell, t, |cell, t| require(cell, t));
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}
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fn main() {}
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