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adding lint for single use lifetime names

This commit is contained in:
Niko Matsakis 2017-11-23 08:05:58 -05:00 committed by gaurikholkar
parent 75a02a919c
commit e741dad629
12 changed files with 258 additions and 15 deletions
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9
src/librustc/lint/builtin.rs
View File

@ -234,6 +234,12 @@ declare_lint! {
"detect coercion to !"
}
declare_lint! {
pub SINGLE_USE_LIFETIME,
Allow,
"detects single use lifetimes"
}
/// Does nothing as a lint pass, but registers some `Lint`s
/// which are used by other parts of the compiler.
#[derive(Copy, Clone)]
@ -277,7 +283,8 @@ impl LintPass for HardwiredLints {
DEPRECATED,
UNUSED_UNSAFE,
UNUSED_MUT,
COERCE_NEVER
COERCE_NEVER,
SINGLE_USE_LIFETIME
)
}
}

94
src/librustc/middle/resolve_lifetime.rs
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@ -31,6 +31,7 @@ use syntax_pos::Span;
use errors::DiagnosticBuilder;
use util::nodemap::{DefIdMap, FxHashMap, FxHashSet, NodeMap, NodeSet};
use std::slice;
use rustc::lint;
use hir;
use hir::intravisit::{self, NestedVisitorMap, Visitor};
@ -56,6 +57,13 @@ impl LifetimeDefOrigin {
}
}
// This counts the no of times a lifetime is used
#[derive(Clone, Copy, Debug)]
pub enum LifetimeUseSet<'tcx> {
One(&'tcx hir::Lifetime),
Many,
}
#[derive(Clone, Copy, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable, Debug)]
pub enum Region {
Static,
@ -245,6 +253,8 @@ struct LifetimeContext<'a, 'tcx: 'a> {
// Cache for cross-crate per-definition object lifetime defaults.
xcrate_object_lifetime_defaults: DefIdMap<Vec<ObjectLifetimeDefault>>,
lifetime_uses: DefIdMap<LifetimeUseSet<'tcx>>,
}
#[derive(Debug)]
@ -407,6 +417,7 @@ fn krate<'tcx>(tcx: TyCtxt<'_, 'tcx, 'tcx>) -> NamedRegionMap {
is_in_fn_syntax: false,
labels_in_fn: vec![],
xcrate_object_lifetime_defaults: DefIdMap(),
lifetime_uses: DefIdMap(),
};
for (_, item) in &krate.items {
visitor.visit_item(item);
@ -443,8 +454,11 @@ impl<'a, 'tcx> Visitor<'tcx> for LifetimeContext<'a, 'tcx> {
fn visit_item(&mut self, item: &'tcx hir::Item) {
match item.node {
hir::ItemFn(ref decl, _, _, _, ref generics, _) => {
self.visit_early_late(None, decl, generics, |this| {
intravisit::walk_item(this, item);
self.visit_early_late(None,
decl,
generics,
|this| {
intravisit::walk_item(this, item);
});
}
hir::ItemExternCrate(_)
@ -498,9 +512,12 @@ impl<'a, 'tcx> Visitor<'tcx> for LifetimeContext<'a, 'tcx> {
fn visit_foreign_item(&mut self, item: &'tcx hir::ForeignItem) {
match item.node {
hir::ForeignItemFn(ref decl, _, ref generics) => {
self.visit_early_late(None, decl, generics, |this| {
intravisit::walk_foreign_item(this, item);
})
self.visit_early_late(None,
decl,
generics,
|this| {
intravisit::walk_foreign_item(this, item);
})
}
hir::ForeignItemStatic(..) => {
intravisit::walk_foreign_item(self, item);
@ -1142,12 +1159,41 @@ impl<'a, 'tcx> LifetimeContext<'a, 'tcx> {
is_in_fn_syntax: self.is_in_fn_syntax,
labels_in_fn,
xcrate_object_lifetime_defaults,
lifetime_uses: DefIdMap(),
};
debug!("entering scope {:?}", this.scope);
f(self.scope, &mut this);
debug!("exiting scope {:?}", this.scope);
self.labels_in_fn = this.labels_in_fn;
self.xcrate_object_lifetime_defaults = this.xcrate_object_lifetime_defaults;
for (def_id, lifetimeuseset) in &this.lifetime_uses {
match lifetimeuseset {
&LifetimeUseSet::One(_) => {
let node_id = this.tcx.hir.as_local_node_id(*def_id).unwrap();
debug!("node id first={:?}", node_id);
if let hir::map::NodeLifetime(hir_lifetime) = this.tcx.hir.get(node_id) {
let span = hir_lifetime.span;
let id = hir_lifetime.id;
debug!("id ={:?} span = {:?} hir_lifetime = {:?}",
node_id,
span,
hir_lifetime);
this.tcx
.struct_span_lint_node(lint::builtin::SINGLE_USE_LIFETIME,
id,
span,
&format!("lifetime name `{}` only used once",
hir_lifetime.name.name()))
.emit();
}
}
_ => {
debug!("Not one use lifetime");
}
}
}
}
/// Visits self by adding a scope and handling recursive walk over the contents with `walk`.
@ -1239,9 +1285,8 @@ impl<'a, 'tcx> LifetimeContext<'a, 'tcx> {
}
}
fn resolve_lifetime_ref(&mut self, lifetime_ref: &hir::Lifetime) {
fn resolve_lifetime_ref(&mut self, lifetime_ref: &'tcx hir::Lifetime) {
debug!("resolve_lifetime_ref(lifetime_ref={:?})", lifetime_ref);
// Walk up the scope chain, tracking the number of fn scopes
// that we pass through, until we find a lifetime with the
// given name or we run out of scopes.
@ -1533,8 +1578,8 @@ impl<'a, 'tcx> LifetimeContext<'a, 'tcx> {
}
// Foreign functions, `fn(...) -> R` and `Trait(...) -> R` (both types and bounds).
hir::map::NodeForeignItem(_) | hir::map::NodeTy(_) | hir::map::NodeTraitRef(_) => None,
hir::map::NodeForeignItem(_) | hir::map::NodeTy(_) | hir::map::NodeTraitRef(_) =>
None,
// Everything else (only closures?) doesn't
// actually enjoy elision in return types.
_ => {
@ -1710,7 +1755,7 @@ impl<'a, 'tcx> LifetimeContext<'a, 'tcx> {
}
}
fn resolve_elided_lifetimes(&mut self, lifetime_refs: &[hir::Lifetime]) {
fn resolve_elided_lifetimes(&mut self, lifetime_refs: &'tcx [hir::Lifetime]) {
if lifetime_refs.is_empty() {
return;
}
@ -1865,7 +1910,7 @@ impl<'a, 'tcx> LifetimeContext<'a, 'tcx> {
}
}
fn resolve_object_lifetime_default(&mut self, lifetime_ref: &hir::Lifetime) {
fn resolve_object_lifetime_default(&mut self, lifetime_ref: &'tcx hir::Lifetime) {
let mut late_depth = 0;
let mut scope = self.scope;
let lifetime = loop {
@ -1887,7 +1932,7 @@ impl<'a, 'tcx> LifetimeContext<'a, 'tcx> {
self.insert_lifetime(lifetime_ref, lifetime.shifted(late_depth));
}
fn check_lifetime_defs(&mut self, old_scope: ScopeRef, lifetimes: &[hir::LifetimeDef]) {
fn check_lifetime_defs(&mut self, old_scope: ScopeRef, lifetimes: &'tcx [hir::LifetimeDef]) {
for i in 0..lifetimes.len() {
let lifetime_i = &lifetimes[i];
@ -1971,7 +2016,9 @@ impl<'a, 'tcx> LifetimeContext<'a, 'tcx> {
}
}
fn check_lifetime_def_for_shadowing(&self, mut old_scope: ScopeRef, lifetime: &hir::Lifetime) {
fn check_lifetime_def_for_shadowing(&self,
mut old_scope: ScopeRef,
lifetime: &'tcx hir::Lifetime) {
for &(label, label_span) in &self.labels_in_fn {
// FIXME (#24278): non-hygienic comparison
if lifetime.name.name() == label {
@ -2020,7 +2067,7 @@ impl<'a, 'tcx> LifetimeContext<'a, 'tcx> {
}
}
fn insert_lifetime(&mut self, lifetime_ref: &hir::Lifetime, def: Region) {
fn insert_lifetime(&mut self, lifetime_ref: &'tcx hir::Lifetime, def: Region) {
if lifetime_ref.id == ast::DUMMY_NODE_ID {
span_bug!(
lifetime_ref.span,
@ -2036,6 +2083,25 @@ impl<'a, 'tcx> LifetimeContext<'a, 'tcx> {
self.tcx.sess.codemap().span_to_string(lifetime_ref.span)
);
self.map.defs.insert(lifetime_ref.id, def);
match def {
Region::LateBoundAnon(..) |
Region::Static => {
// These are anonymous lifetimes or lifetimes that are not declared.
}
Region::Free(_, def_id) |
Region::LateBound(_, def_id, _) |
Region::EarlyBound(_, def_id, _) => {
// A lifetime declared by the user.
if !self.lifetime_uses.contains_key(&def_id) {
self.lifetime_uses
.insert(def_id, LifetimeUseSet::One(lifetime_ref));
} else {
self.lifetime_uses.insert(def_id, LifetimeUseSet::Many);
}
}
}
}
}

16
src/test/ui/in-band-lifetimes/single_use_lifetimes-2.rs Normal file
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@ -0,0 +1,16 @@
// Copyright 2017 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.
#![deny(single_use_lifetime)]
// FIXME(#44752) -- this scenario should not be warned
fn deref<'x>() -> &'x u32 { //~ ERROR lifetime name `'x` only used once
22
}
fn main() { }

14
src/test/ui/in-band-lifetimes/single_use_lifetimes-2.stderr Normal file
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@ -0,0 +1,14 @@
error: lifetime name `'x` only used once
--> $DIR/single_use_lifetimes-2.rs:12:10
|
12 | fn deref<'x>() -> &'x u32 { //~ ERROR lifetime name `'x` only used once
| ^^
|
note: lint level defined here
--> $DIR/single_use_lifetimes-2.rs:10:9
|
10 | #![deny(single_use_lifetime)]
| ^^^^^^^^^^^^^^^^^^^
error: aborting due to previous error

20
src/test/ui/in-band-lifetimes/single_use_lifetimes-3.rs Normal file
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@ -0,0 +1,20 @@
// Copyright 2017 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.
#![deny(single_use_lifetime)]
struct Foo<'x> { //~ ERROR lifetime name `'x` only used once
x: &'x u32 // no warning!
}
// Once #44524 is fixed, this should issue a warning.
impl<'y> Foo<'y> { //~ ERROR lifetime name `'y` only used once
fn method() { }
}
fn main() { }

20
src/test/ui/in-band-lifetimes/single_use_lifetimes-3.stderr Normal file
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@ -0,0 +1,20 @@
error: lifetime name `'x` only used once
--> $DIR/single_use_lifetimes-3.rs:11:12
|
11 | struct Foo<'x> { //~ ERROR lifetime name `'x` only used once
| ^^
|
note: lint level defined here
--> $DIR/single_use_lifetimes-3.rs:10:9
|
10 | #![deny(single_use_lifetime)]
| ^^^^^^^^^^^^^^^^^^^
error: lifetime name `'y` only used once
--> $DIR/single_use_lifetimes-3.rs:16:6
|
16 | impl<'y> Foo<'y> { //~ ERROR lifetime name `'y` only used once
| ^^
error: aborting due to 2 previous errors

20
src/test/ui/in-band-lifetimes/single_use_lifetimes-4.rs Normal file
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@ -0,0 +1,20 @@
// Copyright 2017 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.
#![deny(single_use_lifetime)]
// Neither should issue a warning, as explicit lifetimes are mandatory in this case
struct Foo<'x> { //~ ERROR lifetime name `'x` only used once
x: &'x u32
}
enum Bar<'x> { //~ ERROR lifetime name `'x` only used once
Variant(&'x u32)
}
fn main() { }

20
src/test/ui/in-band-lifetimes/single_use_lifetimes-4.stderr Normal file
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@ -0,0 +1,20 @@
error: lifetime name `'x` only used once
--> $DIR/single_use_lifetimes-4.rs:12:12
|
12 | struct Foo<'x> { //~ ERROR lifetime name `'x` only used once
| ^^
|
note: lint level defined here
--> $DIR/single_use_lifetimes-4.rs:10:9
|
10 | #![deny(single_use_lifetime)]
| ^^^^^^^^^^^^^^^^^^^
error: lifetime name `'x` only used once
--> $DIR/single_use_lifetimes-4.rs:16:10
|
16 | enum Bar<'x> { //~ ERROR lifetime name `'x` only used once
| ^^
error: aborting due to 2 previous errors

16
src/test/ui/in-band-lifetimes/single_use_lifetimes-5.rs Normal file
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@ -0,0 +1,16 @@
// Copyright 2017 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.
#![deny(single_use_lifetime)]
// Should not issue a warning, as explicit lifetimes are mandatory in this case:
trait Foo<'x> { //~ ERROR lifetime name `'x` only used once
fn foo(&self, arg: &'x u32);
}
fn main() { }

14
src/test/ui/in-band-lifetimes/single_use_lifetimes-5.stderr Normal file
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@ -0,0 +1,14 @@
error: lifetime name `'x` only used once
--> $DIR/single_use_lifetimes-5.rs:12:11
|
12 | trait Foo<'x> { //~ ERROR lifetime name `'x` only used once
| ^^
|
note: lint level defined here
--> $DIR/single_use_lifetimes-5.rs:10:9
|
10 | #![deny(single_use_lifetime)]
| ^^^^^^^^^^^^^^^^^^^
error: aborting due to previous error

16
src/test/ui/in-band-lifetimes/single_use_lifetimes.rs Normal file
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@ -0,0 +1,16 @@
// Copyright 2017 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.
#![deny(single_use_lifetime)]
fn deref<'x>(v: &'x u32) -> u32 { //~ ERROR lifetime name `'x` only used once
*v
}
fn main() {}

14
src/test/ui/in-band-lifetimes/single_use_lifetimes.stderr Normal file
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@ -0,0 +1,14 @@
error: lifetime name `'x` only used once
--> $DIR/single_use_lifetimes.rs:12:10
|
12 | fn deref<'x>(v: &'x u32) -> u32 { //~ ERROR lifetime name `'x` only used once
| ^^
|
note: lint level defined here
--> $DIR/single_use_lifetimes.rs:10:9
|
10 | #![deny(single_use_lifetime)]
| ^^^^^^^^^^^^^^^^^^^
error: aborting due to previous error