9e6d5e152e
This patch makes error handling for region inference failures more uniform by not reporting *any* region errors until the reigon inference step. This requires threading through more information about what caused a region constraint, so that we can still give informative error messages. I have only taken partial advantage of this information: when region inference fails, we still report the same error we always did, despite the fact that we now know precisely what caused the various constriants and what the region variable represents, which we did not know before. This change is required not only to improve error messages but because the region hierarchy is not in fact fully known until regionck, because it is not clear where closure bodies fit in (our current treatment is unsound). Moreover, the relationships between free variables cannot be fully determined until type inference is otherwise complete. cc #3238.
36 lines
1.3 KiB
Rust
36 lines
1.3 KiB
Rust
// Copyright 2012 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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trait repeat<A> { fn get(&self) -> A; }
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impl<A:Copy> repeat<A> for @A {
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fn get(&self) -> A { **self }
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}
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fn repeater<A:Copy>(v: @A) -> @repeat<A> {
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// Note: owned kind is not necessary as A appears in the trait type
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@v as @repeat<A> // No
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}
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fn main() {
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// Error results because the type of is inferred to be
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// @repeat<&'blk int> where blk is the lifetime of the block below.
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let y = { //~ ERROR lifetime of variable does not enclose its declaration
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let x: &'blk int = &3;
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repeater(@x)
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};
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assert!(3 == *(y.get()));
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//~^ ERROR dereference of reference outside its lifetime
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//~^^ ERROR automatically borrowed pointer is not valid at the time of borrow
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//~^^^ ERROR lifetime of return value does not outlive the function call
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//~^^^^ ERROR cannot infer an appropriate lifetime
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}
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