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49 lines
1.4 KiB
Rust
49 lines
1.4 KiB
Rust
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// Copyright 2014 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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// This is an example where the older inference algorithm failed. The
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// specifics of why it failed are somewhat, but not entirely, tailed
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// to the algorithm. Ultimately the problem is that when computing the
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// mutual supertype of both sides of the `if` it would be faced with a
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// choice of tightening bounds or unifying variables and it took the
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// wrong path. The new algorithm avoids this problem and hence this
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// example typechecks correctly.
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enum ScopeChain<'a> {
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Link(Scope<'a>),
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End
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}
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type Scope<'a> = &'a ScopeChain<'a>;
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struct OuterContext;
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struct Context<'a> {
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foo: &'a OuterContext
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}
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impl<'a> Context<'a> {
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fn foo(&mut self, scope: Scope) {
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let link = if 1i < 2 {
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let l = Link(scope);
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self.take_scope(&l);
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l
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} else {
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Link(scope)
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};
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self.take_scope(&link);
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}
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fn take_scope(&mut self, x: Scope) {
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}
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}
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fn main() { }
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