52 lines
1.2 KiB
Rust
52 lines
1.2 KiB
Rust
// Test where we fail to approximate due to demanding a postdom
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// relationship between our upper bounds.
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// compile-flags:-Zverbose
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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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// 'x: 'b
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// 'c: 'y
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//
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// we have to prove that `'x: 'y`. We currently can only approximate
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// via a postdominator -- hence we fail to choose between `'a` and
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// `'b` here and report the error in the closure.
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fn establish_relationships<'a, 'b, 'c, F>(
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_cell_a: Cell<&'a u32>,
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_cell_b: Cell<&'b u32>,
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_cell_c: Cell<&'c u32>,
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_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<&'b &'x u32>, // shows that 'x: 'b
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Cell<&'y &'c u32>, // shows that 'c: '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>(_cell_x: Cell<&'x u32>, _cell_y: Cell<&'y u32>, _y: &'y u32) {}
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#[rustc_regions]
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fn supply<'a, 'b, 'c>(cell_a: Cell<&'a u32>, cell_b: Cell<&'b u32>, cell_c: Cell<&'c u32>) {
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establish_relationships(
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cell_a,
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cell_b,
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cell_c,
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|_outlives1, _outlives2, _outlives3, x, y| {
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// Only works if 'x: 'y:
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let p = x.get();
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demand_y(x, y, p) //~ ERROR
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},
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);
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}
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fn main() {}
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