1 #![warn(clippy::needless_lifetimes)]
5 clippy::needless_pass_by_value,
6 clippy::unnecessary_wraps,
11 fn distinct_lifetimes<'a, 'b>(_x: &'a u8, _y: &'b u8, _z: u8) {}
13 fn distinct_and_static<'a, 'b>(_x: &'a u8, _y: &'b u8, _z: &'static u8) {}
15 // No error; same lifetime on two params.
16 fn same_lifetime_on_input<'a>(_x: &'a u8, _y: &'a u8) {}
18 // No error; static involved.
19 fn only_static_on_input(_x: &u8, _y: &u8, _z: &'static u8) {}
21 fn mut_and_static_input(_x: &mut u8, _y: &'static str) {}
23 fn in_and_out<'a>(x: &'a u8, _y: u8) -> &'a u8 {
27 // No error; multiple input refs.
28 fn multiple_in_and_out_1<'a>(x: &'a u8, _y: &'a u8) -> &'a u8 {
32 // No error; multiple input refs.
33 fn multiple_in_and_out_2<'a, 'b>(x: &'a u8, _y: &'b u8) -> &'a u8 {
37 // No error; multiple input refs
38 async fn func<'a>(args: &[&'a str]) -> Option<&'a str> {
42 // No error; static involved.
43 fn in_static_and_out<'a>(x: &'a u8, _y: &'static u8) -> &'a u8 {
48 fn deep_reference_1<'a, 'b>(x: &'a u8, _y: &'b u8) -> Result<&'a u8, ()> {
52 // No error; two input refs.
53 fn deep_reference_2<'a>(x: Result<&'a u8, &'a u8>) -> &'a u8 {
57 fn deep_reference_3<'a>(x: &'a u8, _y: u8) -> Result<&'a u8, ()> {
61 // Where-clause, but without lifetimes.
62 fn where_clause_without_lt<'a, T>(x: &'a u8, _y: u8) -> Result<&'a u8, ()>
69 type Ref<'r> = &'r u8;
71 // No error; same lifetime on two params.
72 fn lifetime_param_1<'a>(_x: Ref<'a>, _y: &'a u8) {}
74 fn lifetime_param_2<'a, 'b>(_x: Ref<'a>, _y: &'b u8) {}
76 // No error; bounded lifetime.
77 fn lifetime_param_3<'a, 'b: 'a>(_x: Ref<'a>, _y: &'b u8) {}
79 // No error; bounded lifetime.
80 fn lifetime_param_4<'a, 'b>(_x: Ref<'a>, _y: &'b u8)
86 struct Lt<'a, I: 'static> {
90 // No error; fn bound references `'a`.
91 fn fn_bound<'a, F, I>(_m: Lt<'a, I>, _f: F) -> Lt<'a, I>
93 F: Fn(Lt<'a, I>) -> Lt<'a, I>,
98 fn fn_bound_2<'a, F, I>(_m: Lt<'a, I>, _f: F) -> Lt<'a, I>
100 for<'x> F: Fn(Lt<'x, I>) -> Lt<'x, I>,
105 // No error; see below.
106 fn fn_bound_3<'a, F: FnOnce(&'a i32)>(x: &'a i32, f: F) {
110 fn fn_bound_3_cannot_elide() {
114 // This will fail if we elide lifetimes of `fn_bound_3`.
115 fn_bound_3(p, |y| q = y);
118 // No error; multiple input refs.
119 fn fn_bound_4<'a, F: FnOnce() -> &'a ()>(cond: bool, x: &'a (), f: F) -> &'a () {
120 if cond { x } else { f() }
128 fn self_and_out<'s>(&'s self) -> &'s u8 {
132 // No error; multiple input refs.
133 fn self_and_in_out<'s, 't>(&'s self, _x: &'t u8) -> &'s u8 {
137 fn distinct_self_and_in<'s, 't>(&'s self, _x: &'t u8) {}
139 // No error; same lifetimes on two params.
140 fn self_and_same_in<'s>(&'s self, _x: &'s u8) {}
143 struct Foo<'a>(&'a u8);
146 // No error; lifetime `'a` not defined in method.
147 fn self_shared_lifetime(&self, _: &'a u8) {}
148 // No error; bounds exist.
149 fn self_bound_lifetime<'b: 'a>(&self, _: &'b u8) {}
152 fn already_elided<'a>(_: &u8, _: &'a u8) -> &'a u8 {
156 fn struct_with_lt<'a>(_foo: Foo<'a>) -> &'a str {
160 // No warning; two input lifetimes (named on the reference, anonymous on `Foo`).
161 fn struct_with_lt2<'a>(_foo: &'a Foo) -> &'a str {
165 // No warning; two input lifetimes (anonymous on the reference, named on `Foo`).
166 fn struct_with_lt3<'a>(_foo: &Foo<'a>) -> &'a str {
170 // No warning; two input lifetimes.
171 fn struct_with_lt4<'a, 'b>(_foo: &'a Foo<'b>) -> &'a str {
175 trait WithLifetime<'a> {}
177 type WithLifetimeAlias<'a> = dyn WithLifetime<'a>;
179 // Should not warn because it won't build without the lifetime.
180 fn trait_obj_elided<'a>(_arg: &'a dyn WithLifetime) -> &'a str {
184 // Should warn because there is no lifetime on `Drop`, so this would be
185 // unambiguous if we elided the lifetime.
186 fn trait_obj_elided2<'a>(_arg: &'a dyn Drop) -> &'a str {
190 type FooAlias<'a> = Foo<'a>;
192 fn alias_with_lt<'a>(_foo: FooAlias<'a>) -> &'a str {
196 // No warning; two input lifetimes (named on the reference, anonymous on `FooAlias`).
197 fn alias_with_lt2<'a>(_foo: &'a FooAlias) -> &'a str {
201 // No warning; two input lifetimes (anonymous on the reference, named on `FooAlias`).
202 fn alias_with_lt3<'a>(_foo: &FooAlias<'a>) -> &'a str {
206 // No warning; two input lifetimes.
207 fn alias_with_lt4<'a, 'b>(_foo: &'a FooAlias<'b>) -> &'a str {
211 fn named_input_elided_output<'a>(_arg: &'a str) -> &str {
215 fn elided_input_named_output<'a>(_arg: &str) -> &'a str {
219 fn trait_bound_ok<'a, T: WithLifetime<'static>>(_: &'a u8, _: T) {
222 fn trait_bound<'a, T: WithLifetime<'a>>(_: &'a u8, _: T) {
226 // Don't warn on these; see issue #292.
227 fn trait_bound_bug<'a, T: WithLifetime<'a>>() {
237 fn iter<'a>(&'a self) -> Box<dyn Iterator<Item = usize> + 'a> {
242 trait LintContext<'a> {}
244 fn f<'a, T: LintContext<'a>>(_: &T) {}
246 fn test<'a>(x: &'a [u8]) -> u8 {
247 let y: &'a u8 = &x[5];
251 // Issue #3284: give hint regarding lifetime in return type.
255 fn out_return_type_lts<'a>(e: &'a str) -> Cow<'a> {
259 // Make sure we still warn on implementations
262 fn needless_lt<'a>(x: &'a u8) {}
265 impl BadTrait for () {
266 fn needless_lt<'a>(_x: &'a u8) {}
277 impl<'a> Foo for Baz<'a> {}
279 fn baz<'a>(&'a self) -> impl Foo + 'a {
285 mod nested_elision_sites {
288 // closure trait bounds subject to nested elision
289 // don't lint because they refer to outer lifetimes
290 fn trait_fn<'a>(i: &'a i32) -> impl Fn() -> &'a i32 {
293 fn trait_fn_mut<'a>(i: &'a i32) -> impl FnMut() -> &'a i32 {
296 fn trait_fn_once<'a>(i: &'a i32) -> impl FnOnce() -> &'a i32 {
301 fn impl_trait_in_input_position<'a>(f: impl Fn() -> &'a i32) -> &'a i32 {
304 fn impl_trait_in_output_position<'a>(i: &'a i32) -> impl Fn() -> &'a i32 {
308 fn impl_trait_elidable_nested_named_lifetimes<'a>(i: &'a i32, f: impl for<'b> Fn(&'b i32) -> &'b i32) -> &'a i32 {
311 fn impl_trait_elidable_nested_anonymous_lifetimes<'a>(i: &'a i32, f: impl Fn(&i32) -> &i32) -> &'a i32 {
316 fn generics_not_elidable<'a, T: Fn() -> &'a i32>(f: T) -> &'a i32 {
320 fn generics_elidable<'a, T: Fn(&i32) -> &i32>(i: &'a i32, f: T) -> &'a i32 {
325 fn where_clause_not_elidable<'a, T>(f: T) -> &'a i32
332 fn where_clause_elidadable<'a, T>(i: &'a i32, f: T) -> &'a i32
340 fn pointer_fn_in_input_position<'a>(f: fn(&'a i32) -> &'a i32, i: &'a i32) -> &'a i32 {
343 fn pointer_fn_in_output_position<'a>(_: &'a i32) -> fn(&'a i32) -> &'a i32 {
347 fn pointer_fn_elidable<'a>(i: &'a i32, f: fn(&i32) -> &i32) -> &'a i32 {
352 fn nested_fn_pointer_1<'a>(_: &'a i32) -> fn(fn(&'a i32) -> &'a i32) -> i32 {
355 fn nested_fn_pointer_2<'a>(_: &'a i32) -> impl Fn(fn(&'a i32)) {
360 fn nested_fn_pointer_3<'a>(_: &'a i32) -> fn(fn(&i32) -> &i32) -> i32 {
363 fn nested_fn_pointer_4<'a>(_: &'a i32) -> impl Fn(fn(&i32)) {
370 pub fn apply_deref<'a, T, F, R>(x: &'a T, f: F) -> R
373 F: FnOnce(&'a T::Target) -> R,
385 fn implicit<'a>(&'a self) -> &'a () {
388 fn implicit_mut<'a>(&'a mut self) -> &'a () {
392 fn explicit<'a>(self: &'a Arc<Self>) -> &'a () {
395 fn explicit_mut<'a>(self: &'a mut Rc<Self>) -> &'a () {
399 fn lifetime_elsewhere<'a>(self: Box<Self>, here: &'a ()) -> &'a () {
405 fn implicit<'a>(&'a self) -> &'a ();
406 fn implicit_provided<'a>(&'a self) -> &'a () {
410 fn explicit<'a>(self: &'a Arc<Self>) -> &'a ();
411 fn explicit_provided<'a>(self: &'a Arc<Self>) -> &'a () {
415 fn lifetime_elsewhere<'a>(self: Box<Self>, here: &'a ()) -> &'a ();
416 fn lifetime_elsewhere_provided<'a>(self: Box<Self>, here: &'a ()) -> &'a () {