57 lines
1.8 KiB
Rust
57 lines
1.8 KiB
Rust
// Copyright 2016 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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// Test a case where we are trying to prove `'x: 'y` and are forced to
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// approximate the shorter end-point (`'y`) to with `'static`. This is
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// because `'y` is higher-ranked but we know of only irrelevant
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// relations to other regions. Note that `'static` shows up in the
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// stderr output as `'0`.
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//
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// FIXME(#45827) Because of shortcomings in the MIR type checker,
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// these errors are not (yet) reported.
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// compile-flags:-Zborrowck=mir -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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// 'y: 'b
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//
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// so the only way we can ensure that `'x: 'y` is to show that
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// `'a: 'static`.
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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<&'b &'y u32>, // shows that 'y: 'b
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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>(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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//~^ ERROR borrowed data escapes outside of function
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//~| ERROR unsatisfied lifetime constraints
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// Only works if 'x: 'y:
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demand_y(x, y, x.get())
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});
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}
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fn main() {}
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