6f99a27886
This implements RFC 39. Omitted lifetimes in return values will now be
inferred to more useful defaults, and an error is reported if a lifetime
in a return type is omitted and one of the two lifetime elision rules
does not specify what it should be.
This primarily breaks two uncommon code patterns. The first is this:
unsafe fn get_foo_out_of_thin_air() -> &Foo {
...
}
This should be changed to:
unsafe fn get_foo_out_of_thin_air() -> &'static Foo {
...
}
The second pattern that needs to be changed is this:
enum MaybeBorrowed<'a> {
Borrowed(&'a str),
Owned(String),
}
fn foo() -> MaybeBorrowed {
Owned(format!("hello world"))
}
Change code like this to:
enum MaybeBorrowed<'a> {
Borrowed(&'a str),
Owned(String),
}
fn foo() -> MaybeBorrowed<'static> {
Owned(format!("hello world"))
}
Closes #15552.
[breaking-change]
120 lines
2.5 KiB
Rust
120 lines
2.5 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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// Test lifetimes are linked properly when we create dependent region pointers.
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// Issue #3148.
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struct A {
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value: B
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}
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struct B {
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v1: int,
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v2: [int, ..3],
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v3: Vec<int> ,
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v4: C,
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v5: Box<C>,
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v6: Option<C>
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}
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struct C {
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f: int
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}
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fn get_v1(a: &A) -> &int {
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// Region inferencer must deduce that &v < L2 < L1
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let foo = &a.value; // L1
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&foo.v1 // L2
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}
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fn get_v2(a: &A, i: uint) -> &int {
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let foo = &a.value;
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&foo.v2[i]
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}
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fn get_v3(a: &A, i: uint) -> &int {
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let foo = &a.value;
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foo.v3.get(i)
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}
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fn get_v4(a: &A, _i: uint) -> &int {
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let foo = &a.value;
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&foo.v4.f
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}
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fn get_v5(a: &A, _i: uint) -> &int {
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let foo = &a.value;
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&foo.v5.f
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}
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fn get_v6_a(a: &A, _i: uint) -> &int {
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match a.value.v6 {
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Some(ref v) => &v.f,
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None => fail!()
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}
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}
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fn get_v6_b(a: &A, _i: uint) -> &int {
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match *a {
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A { value: B { v6: Some(ref v), .. } } => &v.f,
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_ => fail!()
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}
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}
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fn get_v6_c(a: &A, _i: uint) -> &int {
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match a {
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&A { value: B { v6: Some(ref v), .. } } => &v.f,
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_ => fail!()
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}
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}
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fn get_v5_ref(a: &A, _i: uint) -> &int {
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match &a.value {
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&B {v5: box C {f: ref v}, ..} => v
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}
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}
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pub fn main() {
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let a = A {value: B {v1: 22,
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v2: [23, 24, 25],
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v3: vec!(26, 27, 28),
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v4: C { f: 29 },
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v5: box C { f: 30 },
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v6: Some(C { f: 31 })}};
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let p = get_v1(&a);
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assert_eq!(*p, a.value.v1);
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let p = get_v2(&a, 1);
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assert_eq!(*p, a.value.v2[1]);
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let p = get_v3(&a, 1);
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assert_eq!(*p, *a.value.v3.get(1));
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let p = get_v4(&a, 1);
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assert_eq!(*p, a.value.v4.f);
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let p = get_v5(&a, 1);
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assert_eq!(*p, a.value.v5.f);
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let p = get_v6_a(&a, 1);
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assert_eq!(*p, a.value.v6.unwrap().f);
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let p = get_v6_b(&a, 1);
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assert_eq!(*p, a.value.v6.unwrap().f);
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let p = get_v6_c(&a, 1);
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assert_eq!(*p, a.value.v6.unwrap().f);
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let p = get_v5_ref(&a, 1);
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assert_eq!(*p, a.value.v5.f);
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}
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