mirror of https://github.com/rust-lang/rust
44 lines
1.1 KiB
Rust
44 lines
1.1 KiB
Rust
// A simpler variant of `outlives-from-argument` where cells are
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// passed by value.
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//
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// This is simpler because there are no "extraneous" region
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// relationships. In the 'main' variant, there are a number of
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// anonymous regions as well.
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//@ compile-flags:-Zverbose-internals
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#![feature(rustc_attrs)]
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use std::cell::Cell;
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// Callee knows that:
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//
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// 'x: 'a
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// 'b: 'y
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//
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// so if we are going to ensure that `'x: 'y`, then `'a: 'b` must
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// hold.
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fn establish_relationships<'a, 'b, F>(_cell_a: Cell<&'a u32>, _cell_b: Cell<&'b u32>, _closure: F)
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where
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F: for<'x, 'y> FnMut(
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Cell<&'a &'x u32>, // shows that 'x: 'a
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Cell<&'y &'b u32>, // shows that 'b: 'y
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Cell<&'x u32>,
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Cell<&'y u32>,
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),
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{
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}
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fn demand_y<'x, 'y>(_outlives1: Cell<&&'x u32>, _outlives2: Cell<&'y &u32>, _y: &'y u32) {}
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#[rustc_regions]
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fn test<'a, 'b>(cell_a: Cell<&'a u32>, cell_b: Cell<&'b u32>) {
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establish_relationships(cell_a, cell_b, |outlives1, outlives2, x, y| {
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// Only works if 'x: 'y:
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demand_y(outlives1, outlives2, x.get())
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//~^ ERROR lifetime may not live long enough
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});
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}
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fn main() {}
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