1 #![warn(clippy::needless_lifetimes)]
5 clippy::needless_pass_by_value,
6 clippy::unnecessary_wraps,
10 fn distinct_lifetimes<'a, 'b>(_x: &'a u8, _y: &'b u8, _z: u8) {}
12 fn distinct_and_static<'a, 'b>(_x: &'a u8, _y: &'b u8, _z: &'static u8) {}
14 // No error; same lifetime on two params.
15 fn same_lifetime_on_input<'a>(_x: &'a u8, _y: &'a u8) {}
17 // No error; static involved.
18 fn only_static_on_input(_x: &u8, _y: &u8, _z: &'static u8) {}
20 fn mut_and_static_input(_x: &mut u8, _y: &'static str) {}
22 fn in_and_out<'a>(x: &'a u8, _y: u8) -> &'a u8 {
26 // No error; multiple input refs.
27 fn multiple_in_and_out_1<'a>(x: &'a u8, _y: &'a u8) -> &'a u8 {
31 // No error; multiple input refs.
32 fn multiple_in_and_out_2<'a, 'b>(x: &'a u8, _y: &'b u8) -> &'a u8 {
36 // No error; multiple input refs
37 async fn func<'a>(args: &[&'a str]) -> Option<&'a str> {
41 // No error; static involved.
42 fn in_static_and_out<'a>(x: &'a u8, _y: &'static u8) -> &'a u8 {
47 fn deep_reference_1<'a, 'b>(x: &'a u8, _y: &'b u8) -> Result<&'a u8, ()> {
51 // No error; two input refs.
52 fn deep_reference_2<'a>(x: Result<&'a u8, &'a u8>) -> &'a u8 {
56 fn deep_reference_3<'a>(x: &'a u8, _y: u8) -> Result<&'a u8, ()> {
60 // Where-clause, but without lifetimes.
61 fn where_clause_without_lt<'a, T>(x: &'a u8, _y: u8) -> Result<&'a u8, ()>
68 type Ref<'r> = &'r u8;
70 // No error; same lifetime on two params.
71 fn lifetime_param_1<'a>(_x: Ref<'a>, _y: &'a u8) {}
73 fn lifetime_param_2<'a, 'b>(_x: Ref<'a>, _y: &'b u8) {}
75 // No error; bounded lifetime.
76 fn lifetime_param_3<'a, 'b: 'a>(_x: Ref<'a>, _y: &'b u8) {}
78 // No error; bounded lifetime.
79 fn lifetime_param_4<'a, 'b>(_x: Ref<'a>, _y: &'b u8)
85 struct Lt<'a, I: 'static> {
89 // No error; fn bound references `'a`.
90 fn fn_bound<'a, F, I>(_m: Lt<'a, I>, _f: F) -> Lt<'a, I>
92 F: Fn(Lt<'a, I>) -> Lt<'a, I>,
97 fn fn_bound_2<'a, F, I>(_m: Lt<'a, I>, _f: F) -> Lt<'a, I>
99 for<'x> F: Fn(Lt<'x, I>) -> Lt<'x, I>,
104 // No error; see below.
105 fn fn_bound_3<'a, F: FnOnce(&'a i32)>(x: &'a i32, f: F) {
109 fn fn_bound_3_cannot_elide() {
113 // This will fail if we elide lifetimes of `fn_bound_3`.
114 fn_bound_3(p, |y| q = y);
117 // No error; multiple input refs.
118 fn fn_bound_4<'a, F: FnOnce() -> &'a ()>(cond: bool, x: &'a (), f: F) -> &'a () {
119 if cond { x } else { f() }
127 fn self_and_out<'s>(&'s self) -> &'s u8 {
131 // No error; multiple input refs.
132 fn self_and_in_out<'s, 't>(&'s self, _x: &'t u8) -> &'s u8 {
136 fn distinct_self_and_in<'s, 't>(&'s self, _x: &'t u8) {}
138 // No error; same lifetimes on two params.
139 fn self_and_same_in<'s>(&'s self, _x: &'s u8) {}
142 struct Foo<'a>(&'a u8);
145 // No error; lifetime `'a` not defined in method.
146 fn self_shared_lifetime(&self, _: &'a u8) {}
147 // No error; bounds exist.
148 fn self_bound_lifetime<'b: 'a>(&self, _: &'b u8) {}
151 fn already_elided<'a>(_: &u8, _: &'a u8) -> &'a u8 {
155 fn struct_with_lt<'a>(_foo: Foo<'a>) -> &'a str {
159 // No warning; two input lifetimes (named on the reference, anonymous on `Foo`).
160 fn struct_with_lt2<'a>(_foo: &'a Foo) -> &'a str {
164 // No warning; two input lifetimes (anonymous on the reference, named on `Foo`).
165 fn struct_with_lt3<'a>(_foo: &Foo<'a>) -> &'a str {
169 // No warning; two input lifetimes.
170 fn struct_with_lt4<'a, 'b>(_foo: &'a Foo<'b>) -> &'a str {
174 trait WithLifetime<'a> {}
176 type WithLifetimeAlias<'a> = dyn WithLifetime<'a>;
178 // Should not warn because it won't build without the lifetime.
179 fn trait_obj_elided<'a>(_arg: &'a dyn WithLifetime) -> &'a str {
183 // Should warn because there is no lifetime on `Drop`, so this would be
184 // unambiguous if we elided the lifetime.
185 fn trait_obj_elided2<'a>(_arg: &'a dyn Drop) -> &'a str {
189 type FooAlias<'a> = Foo<'a>;
191 fn alias_with_lt<'a>(_foo: FooAlias<'a>) -> &'a str {
195 // No warning; two input lifetimes (named on the reference, anonymous on `FooAlias`).
196 fn alias_with_lt2<'a>(_foo: &'a FooAlias) -> &'a str {
200 // No warning; two input lifetimes (anonymous on the reference, named on `FooAlias`).
201 fn alias_with_lt3<'a>(_foo: &FooAlias<'a>) -> &'a str {
205 // No warning; two input lifetimes.
206 fn alias_with_lt4<'a, 'b>(_foo: &'a FooAlias<'b>) -> &'a str {
210 fn named_input_elided_output<'a>(_arg: &'a str) -> &str {
214 fn elided_input_named_output<'a>(_arg: &str) -> &'a str {
218 fn trait_bound_ok<'a, T: WithLifetime<'static>>(_: &'a u8, _: T) {
221 fn trait_bound<'a, T: WithLifetime<'a>>(_: &'a u8, _: T) {
225 // Don't warn on these; see issue #292.
226 fn trait_bound_bug<'a, T: WithLifetime<'a>>() {
236 fn iter<'a>(&'a self) -> Box<dyn Iterator<Item = usize> + 'a> {
241 trait LintContext<'a> {}
243 fn f<'a, T: LintContext<'a>>(_: &T) {}
245 fn test<'a>(x: &'a [u8]) -> u8 {
246 let y: &'a u8 = &x[5];
250 // Issue #3284: give hint regarding lifetime in return type.
254 fn out_return_type_lts<'a>(e: &'a str) -> Cow<'a> {
258 // Make sure we still warn on implementations
261 fn needless_lt<'a>(x: &'a u8) {}
264 impl BadTrait for () {
265 fn needless_lt<'a>(_x: &'a u8) {}
276 impl<'a> Foo for Baz<'a> {}
278 fn baz<'a>(&'a self) -> impl Foo + 'a {
284 mod nested_elision_sites {
287 // closure trait bounds subject to nested elision
288 // don't lint because they refer to outer lifetimes
289 fn trait_fn<'a>(i: &'a i32) -> impl Fn() -> &'a i32 {
292 fn trait_fn_mut<'a>(i: &'a i32) -> impl FnMut() -> &'a i32 {
295 fn trait_fn_once<'a>(i: &'a i32) -> impl FnOnce() -> &'a i32 {
300 fn impl_trait_in_input_position<'a>(f: impl Fn() -> &'a i32) -> &'a i32 {
303 fn impl_trait_in_output_position<'a>(i: &'a i32) -> impl Fn() -> &'a i32 {
307 fn impl_trait_elidable_nested_named_lifetimes<'a>(i: &'a i32, f: impl for<'b> Fn(&'b i32) -> &'b i32) -> &'a i32 {
310 fn impl_trait_elidable_nested_anonymous_lifetimes<'a>(i: &'a i32, f: impl Fn(&i32) -> &i32) -> &'a i32 {
315 fn generics_not_elidable<'a, T: Fn() -> &'a i32>(f: T) -> &'a i32 {
319 fn generics_elidable<'a, T: Fn(&i32) -> &i32>(i: &'a i32, f: T) -> &'a i32 {
324 fn where_clause_not_elidable<'a, T>(f: T) -> &'a i32
331 fn where_clause_elidadable<'a, T>(i: &'a i32, f: T) -> &'a i32
339 fn pointer_fn_in_input_position<'a>(f: fn(&'a i32) -> &'a i32, i: &'a i32) -> &'a i32 {
342 fn pointer_fn_in_output_position<'a>(_: &'a i32) -> fn(&'a i32) -> &'a i32 {
346 fn pointer_fn_elidable<'a>(i: &'a i32, f: fn(&i32) -> &i32) -> &'a i32 {
351 fn nested_fn_pointer_1<'a>(_: &'a i32) -> fn(fn(&'a i32) -> &'a i32) -> i32 {
354 fn nested_fn_pointer_2<'a>(_: &'a i32) -> impl Fn(fn(&'a i32)) {
359 fn nested_fn_pointer_3<'a>(_: &'a i32) -> fn(fn(&i32) -> &i32) -> i32 {
362 fn nested_fn_pointer_4<'a>(_: &'a i32) -> impl Fn(fn(&i32)) {
369 pub fn apply_deref<'a, T, F, R>(x: &'a T, f: F) -> R
372 F: FnOnce(&'a T::Target) -> R,
384 fn implicit<'a>(&'a self) -> &'a () {
387 fn implicit_mut<'a>(&'a mut self) -> &'a () {
391 fn explicit<'a>(self: &'a Arc<Self>) -> &'a () {
394 fn explicit_mut<'a>(self: &'a mut Rc<Self>) -> &'a () {
398 fn lifetime_elsewhere<'a>(self: Box<Self>, here: &'a ()) -> &'a () {
404 fn implicit<'a>(&'a self) -> &'a ();
405 fn implicit_provided<'a>(&'a self) -> &'a () {
409 fn explicit<'a>(self: &'a Arc<Self>) -> &'a ();
410 fn explicit_provided<'a>(self: &'a Arc<Self>) -> &'a () {
414 fn lifetime_elsewhere<'a>(self: Box<Self>, here: &'a ()) -> &'a ();
415 fn lifetime_elsewhere_provided<'a>(self: Box<Self>, here: &'a ()) -> &'a () {