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add ellided lifetime
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dpc committed Feb 1, 2018
1 parent fe7e1a4 commit accd997
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Showing 4 changed files with 55 additions and 4 deletions.
10 changes: 9 additions & 1 deletion src/librustc/lint/builtin.rs
Original file line number Diff line number Diff line change
Expand Up @@ -246,6 +246,12 @@ declare_lint! {
"raw pointer to an inference variable"
}

declare_lint! {
pub ELIDED_LIFETIME_IN_PATH,
Allow,
"hidden lifetime parameters are deprecated, try `Foo<'_>`"
}

/// Does nothing as a lint pass, but registers some `Lint`s
/// which are used by other parts of the compiler.
#[derive(Copy, Clone)]
Expand Down Expand Up @@ -291,7 +297,9 @@ impl LintPass for HardwiredLints {
UNUSED_MUT,
COERCE_NEVER,
SINGLE_USE_LIFETIME,
TYVAR_BEHIND_RAW_POINTER
TYVAR_BEHIND_RAW_POINTER,
ELIDED_LIFETIME_IN_PATH

)
}
}
Expand Down
16 changes: 13 additions & 3 deletions src/librustc/middle/resolve_lifetime.rs
Original file line number Diff line number Diff line change
Expand Up @@ -737,7 +737,7 @@ impl<'a, 'tcx> Visitor<'tcx> for LifetimeContext<'a, 'tcx> {

fn visit_lifetime(&mut self, lifetime_ref: &'tcx hir::Lifetime) {
if lifetime_ref.is_elided() {
self.resolve_elided_lifetimes(slice::from_ref(lifetime_ref));
self.resolve_elided_lifetimes(slice::from_ref(lifetime_ref), false);
return;
}
if lifetime_ref.is_static() {
Expand Down Expand Up @@ -1444,7 +1444,7 @@ impl<'a, 'tcx> LifetimeContext<'a, 'tcx> {
}

if params.lifetimes.iter().all(|l| l.is_elided()) {
self.resolve_elided_lifetimes(&params.lifetimes);
self.resolve_elided_lifetimes(&params.lifetimes, true);
} else {
for l in &params.lifetimes {
self.visit_lifetime(l);
Expand Down Expand Up @@ -1803,14 +1803,24 @@ impl<'a, 'tcx> LifetimeContext<'a, 'tcx> {
}
}

fn resolve_elided_lifetimes(&mut self, lifetime_refs: &'tcx [hir::Lifetime]) {
fn resolve_elided_lifetimes(&mut self, lifetime_refs: &'tcx [hir::Lifetime], deprecated: bool) {
if lifetime_refs.is_empty() {
return;
}

let span = lifetime_refs[0].span;
let id = lifetime_refs[0].id;
let mut late_depth = 0;
let mut scope = self.scope;
if deprecated {
self.tcx
.struct_span_lint_node(
lint::builtin::ELIDED_LIFETIME_IN_PATH,
id,
span,
&format!("hidden lifetime parameters are deprecated, try `Foo<'_>`"))
.emit();
}
let error = loop {
match *scope {
// Do not assign any resolution, it will be inferred.
Expand Down
19 changes: 19 additions & 0 deletions src/test/ui/in-band-lifetimes/ellided-lifetimes.rs
Original file line number Diff line number Diff line change
@@ -0,0 +1,19 @@
// Copyright 2018 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
#![allow(warnings)]
#![allow(unused_variables, dead_code, unused, bad_style)]
#![deny(elided_lifetime_in_path)]

struct Foo<'a> { x: &'a u32 }
fn foo(x: &Foo) {
//~^ ERROR: hidden lifetime parameters are deprecated, try `Foo<'_>`
}

fn main() {}
14 changes: 14 additions & 0 deletions src/test/ui/in-band-lifetimes/ellided-lifetimes.stderr
Original file line number Diff line number Diff line change
@@ -0,0 +1,14 @@
error: hidden lifetime parameters are deprecated, try `Foo<'_>`
--> $DIR/ellided-lifetimes.rs:15:12
|
15 | fn foo(x: &Foo) {
| ^^^
|
note: lint level defined here
--> $DIR/ellided-lifetimes.rs:12:9
|
12 | #![deny(elided_lifetime_in_path)]
| ^^^^^^^^^^^^^^^^^^^^^^^

error: aborting due to previous error

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