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]
48 lines
1.4 KiB
Rust
48 lines
1.4 KiB
Rust
// Copyright 2013 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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use llvm;
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use llvm::{BasicBlockRef};
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use middle::trans::value::{Users, Value};
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use std::iter::{Filter, Map};
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pub struct BasicBlock(pub BasicBlockRef);
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pub type Preds<'a> = Map<'a, Value, BasicBlock, Filter<'a, Value, Users>>;
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/**
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* Wrapper for LLVM BasicBlockRef
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*/
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impl BasicBlock {
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pub fn get(&self) -> BasicBlockRef {
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let BasicBlock(v) = *self; v
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}
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pub fn as_value(self) -> Value {
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unsafe {
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Value(llvm::LLVMBasicBlockAsValue(self.get()))
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}
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}
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pub fn pred_iter(self) -> Preds<'static> {
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self.as_value().user_iter()
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.filter(|user| user.is_a_terminator_inst())
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.map(|user| user.get_parent().unwrap())
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}
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pub fn get_single_predecessor(self) -> Option<BasicBlock> {
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let mut iter = self.pred_iter();
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match (iter.next(), iter.next()) {
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(Some(first), None) => Some(first),
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_ => None
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}
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}
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}
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