mirror of
https://github.com/rust-lang/rust-clippy
synced 2024-12-05 02:50:32 +00:00
262 lines
5.7 KiB
Rust
262 lines
5.7 KiB
Rust
#![warn(clippy::needless_lifetimes)]
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#![allow(dead_code, clippy::needless_pass_by_value)]
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fn distinct_lifetimes<'a, 'b>(_x: &'a u8, _y: &'b u8, _z: u8) {}
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fn distinct_and_static<'a, 'b>(_x: &'a u8, _y: &'b u8, _z: &'static u8) {}
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// No error; same lifetime on two params.
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fn same_lifetime_on_input<'a>(_x: &'a u8, _y: &'a u8) {}
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// No error; static involved.
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fn only_static_on_input(_x: &u8, _y: &u8, _z: &'static u8) {}
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fn mut_and_static_input(_x: &mut u8, _y: &'static str) {}
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fn in_and_out<'a>(x: &'a u8, _y: u8) -> &'a u8 {
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x
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}
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// No error; multiple input refs.
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fn multiple_in_and_out_1<'a>(x: &'a u8, _y: &'a u8) -> &'a u8 {
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x
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}
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// No error; multiple input refs.
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fn multiple_in_and_out_2<'a, 'b>(x: &'a u8, _y: &'b u8) -> &'a u8 {
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x
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}
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// No error; static involved.
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fn in_static_and_out<'a>(x: &'a u8, _y: &'static u8) -> &'a u8 {
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x
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}
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// No error.
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fn deep_reference_1<'a, 'b>(x: &'a u8, _y: &'b u8) -> Result<&'a u8, ()> {
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Ok(x)
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}
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// No error; two input refs.
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fn deep_reference_2<'a>(x: Result<&'a u8, &'a u8>) -> &'a u8 {
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x.unwrap()
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}
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fn deep_reference_3<'a>(x: &'a u8, _y: u8) -> Result<&'a u8, ()> {
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Ok(x)
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}
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// Where-clause, but without lifetimes.
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fn where_clause_without_lt<'a, T>(x: &'a u8, _y: u8) -> Result<&'a u8, ()>
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where
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T: Copy,
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{
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Ok(x)
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}
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type Ref<'r> = &'r u8;
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// No error; same lifetime on two params.
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fn lifetime_param_1<'a>(_x: Ref<'a>, _y: &'a u8) {}
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fn lifetime_param_2<'a, 'b>(_x: Ref<'a>, _y: &'b u8) {}
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// No error; bounded lifetime.
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fn lifetime_param_3<'a, 'b: 'a>(_x: Ref<'a>, _y: &'b u8) {}
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// No error; bounded lifetime.
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fn lifetime_param_4<'a, 'b>(_x: Ref<'a>, _y: &'b u8)
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where
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'b: 'a,
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{
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}
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struct Lt<'a, I: 'static> {
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x: &'a I,
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}
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// No error; fn bound references `'a`.
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fn fn_bound<'a, F, I>(_m: Lt<'a, I>, _f: F) -> Lt<'a, I>
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where
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F: Fn(Lt<'a, I>) -> Lt<'a, I>,
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{
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unreachable!()
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}
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fn fn_bound_2<'a, F, I>(_m: Lt<'a, I>, _f: F) -> Lt<'a, I>
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where
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for<'x> F: Fn(Lt<'x, I>) -> Lt<'x, I>,
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{
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unreachable!()
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}
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// No error; see below.
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fn fn_bound_3<'a, F: FnOnce(&'a i32)>(x: &'a i32, f: F) {
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f(x);
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}
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fn fn_bound_3_cannot_elide() {
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let x = 42;
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let p = &x;
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let mut q = &x;
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// This will fail if we elide lifetimes of `fn_bound_3`.
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fn_bound_3(p, |y| q = y);
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}
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// No error; multiple input refs.
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fn fn_bound_4<'a, F: FnOnce() -> &'a ()>(cond: bool, x: &'a (), f: F) -> &'a () {
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if cond {
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x
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} else {
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f()
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}
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}
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struct X {
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x: u8,
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}
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impl X {
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fn self_and_out<'s>(&'s self) -> &'s u8 {
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&self.x
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}
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// No error; multiple input refs.
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fn self_and_in_out<'s, 't>(&'s self, _x: &'t u8) -> &'s u8 {
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&self.x
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}
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fn distinct_self_and_in<'s, 't>(&'s self, _x: &'t u8) {}
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// No error; same lifetimes on two params.
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fn self_and_same_in<'s>(&'s self, _x: &'s u8) {}
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}
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struct Foo<'a>(&'a u8);
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impl<'a> Foo<'a> {
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// No error; lifetime `'a` not defined in method.
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fn self_shared_lifetime(&self, _: &'a u8) {}
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// No error; bounds exist.
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fn self_bound_lifetime<'b: 'a>(&self, _: &'b u8) {}
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}
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fn already_elided<'a>(_: &u8, _: &'a u8) -> &'a u8 {
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unimplemented!()
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}
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fn struct_with_lt<'a>(_foo: Foo<'a>) -> &'a str {
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unimplemented!()
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}
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// No warning; two input lifetimes (named on the reference, anonymous on `Foo`).
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fn struct_with_lt2<'a>(_foo: &'a Foo) -> &'a str {
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unimplemented!()
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}
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// No warning; two input lifetimes (anonymous on the reference, named on `Foo`).
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fn struct_with_lt3<'a>(_foo: &Foo<'a>) -> &'a str {
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unimplemented!()
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}
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// No warning; two input lifetimes.
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fn struct_with_lt4<'a, 'b>(_foo: &'a Foo<'b>) -> &'a str {
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unimplemented!()
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}
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trait WithLifetime<'a> {}
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type WithLifetimeAlias<'a> = dyn WithLifetime<'a>;
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// Should not warn because it won't build without the lifetime.
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fn trait_obj_elided<'a>(_arg: &'a dyn WithLifetime) -> &'a str {
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unimplemented!()
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}
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// Should warn because there is no lifetime on `Drop`, so this would be
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// unambiguous if we elided the lifetime.
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fn trait_obj_elided2<'a>(_arg: &'a dyn Drop) -> &'a str {
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unimplemented!()
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}
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type FooAlias<'a> = Foo<'a>;
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fn alias_with_lt<'a>(_foo: FooAlias<'a>) -> &'a str {
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unimplemented!()
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}
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// No warning; two input lifetimes (named on the reference, anonymous on `FooAlias`).
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fn alias_with_lt2<'a>(_foo: &'a FooAlias) -> &'a str {
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unimplemented!()
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}
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// No warning; two input lifetimes (anonymous on the reference, named on `FooAlias`).
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fn alias_with_lt3<'a>(_foo: &FooAlias<'a>) -> &'a str {
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unimplemented!()
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}
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// No warning; two input lifetimes.
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fn alias_with_lt4<'a, 'b>(_foo: &'a FooAlias<'b>) -> &'a str {
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unimplemented!()
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}
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fn named_input_elided_output<'a>(_arg: &'a str) -> &str {
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unimplemented!()
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}
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fn elided_input_named_output<'a>(_arg: &str) -> &'a str {
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unimplemented!()
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}
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fn trait_bound_ok<'a, T: WithLifetime<'static>>(_: &'a u8, _: T) {
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unimplemented!()
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}
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fn trait_bound<'a, T: WithLifetime<'a>>(_: &'a u8, _: T) {
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unimplemented!()
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}
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// Don't warn on these; see issue #292.
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fn trait_bound_bug<'a, T: WithLifetime<'a>>() {
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unimplemented!()
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}
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// See issue #740.
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struct Test {
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vec: Vec<usize>,
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}
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impl Test {
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fn iter<'a>(&'a self) -> Box<dyn Iterator<Item = usize> + 'a> {
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unimplemented!()
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}
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}
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trait LintContext<'a> {}
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fn f<'a, T: LintContext<'a>>(_: &T) {}
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fn test<'a>(x: &'a [u8]) -> u8 {
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let y: &'a u8 = &x[5];
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*y
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}
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// Issue #3284: give hint regarding lifetime in return type.
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struct Cow<'a> {
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x: &'a str,
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}
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fn out_return_type_lts<'a>(e: &'a str) -> Cow<'a> {
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unimplemented!()
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}
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// Make sure we still warn on implementations
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mod issue4291 {
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trait BadTrait {
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fn needless_lt<'a>(x: &'a u8) {}
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}
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impl BadTrait for () {
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fn needless_lt<'a>(_x: &'a u8) {}
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}
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}
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fn main() {}
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