diff options
Diffstat (limited to 'src/tools/clippy/tests/ui/needless_lifetimes.rs')
-rw-r--r-- | src/tools/clippy/tests/ui/needless_lifetimes.rs | 422 |
1 files changed, 422 insertions, 0 deletions
diff --git a/src/tools/clippy/tests/ui/needless_lifetimes.rs b/src/tools/clippy/tests/ui/needless_lifetimes.rs new file mode 100644 index 000000000..fc686b1da --- /dev/null +++ b/src/tools/clippy/tests/ui/needless_lifetimes.rs @@ -0,0 +1,422 @@ +#![warn(clippy::needless_lifetimes)] +#![allow( + dead_code, + clippy::boxed_local, + clippy::needless_pass_by_value, + clippy::unnecessary_wraps, + dyn_drop, + clippy::get_first +)] + +fn distinct_lifetimes<'a, 'b>(_x: &'a u8, _y: &'b u8, _z: u8) {} + +fn distinct_and_static<'a, 'b>(_x: &'a u8, _y: &'b u8, _z: &'static u8) {} + +// No error; same lifetime on two params. +fn same_lifetime_on_input<'a>(_x: &'a u8, _y: &'a u8) {} + +// No error; static involved. +fn only_static_on_input(_x: &u8, _y: &u8, _z: &'static u8) {} + +fn mut_and_static_input(_x: &mut u8, _y: &'static str) {} + +fn in_and_out<'a>(x: &'a u8, _y: u8) -> &'a u8 { + x +} + +// No error; multiple input refs. +fn multiple_in_and_out_1<'a>(x: &'a u8, _y: &'a u8) -> &'a u8 { + x +} + +// No error; multiple input refs. +fn multiple_in_and_out_2<'a, 'b>(x: &'a u8, _y: &'b u8) -> &'a u8 { + x +} + +// No error; multiple input refs +async fn func<'a>(args: &[&'a str]) -> Option<&'a str> { + args.get(0).cloned() +} + +// No error; static involved. +fn in_static_and_out<'a>(x: &'a u8, _y: &'static u8) -> &'a u8 { + x +} + +// No error. +fn deep_reference_1<'a, 'b>(x: &'a u8, _y: &'b u8) -> Result<&'a u8, ()> { + Ok(x) +} + +// No error; two input refs. +fn deep_reference_2<'a>(x: Result<&'a u8, &'a u8>) -> &'a u8 { + x.unwrap() +} + +fn deep_reference_3<'a>(x: &'a u8, _y: u8) -> Result<&'a u8, ()> { + Ok(x) +} + +// Where-clause, but without lifetimes. +fn where_clause_without_lt<'a, T>(x: &'a u8, _y: u8) -> Result<&'a u8, ()> +where + T: Copy, +{ + Ok(x) +} + +type Ref<'r> = &'r u8; + +// No error; same lifetime on two params. +fn lifetime_param_1<'a>(_x: Ref<'a>, _y: &'a u8) {} + +fn lifetime_param_2<'a, 'b>(_x: Ref<'a>, _y: &'b u8) {} + +// No error; bounded lifetime. +fn lifetime_param_3<'a, 'b: 'a>(_x: Ref<'a>, _y: &'b u8) {} + +// No error; bounded lifetime. +fn lifetime_param_4<'a, 'b>(_x: Ref<'a>, _y: &'b u8) +where + 'b: 'a, +{ +} + +struct Lt<'a, I: 'static> { + x: &'a I, +} + +// No error; fn bound references `'a`. +fn fn_bound<'a, F, I>(_m: Lt<'a, I>, _f: F) -> Lt<'a, I> +where + F: Fn(Lt<'a, I>) -> Lt<'a, I>, +{ + unreachable!() +} + +fn fn_bound_2<'a, F, I>(_m: Lt<'a, I>, _f: F) -> Lt<'a, I> +where + for<'x> F: Fn(Lt<'x, I>) -> Lt<'x, I>, +{ + unreachable!() +} + +// No error; see below. +fn fn_bound_3<'a, F: FnOnce(&'a i32)>(x: &'a i32, f: F) { + f(x); +} + +fn fn_bound_3_cannot_elide() { + let x = 42; + let p = &x; + let mut q = &x; + // This will fail if we elide lifetimes of `fn_bound_3`. + fn_bound_3(p, |y| q = y); +} + +// No error; multiple input refs. +fn fn_bound_4<'a, F: FnOnce() -> &'a ()>(cond: bool, x: &'a (), f: F) -> &'a () { + if cond { x } else { f() } +} + +struct X { + x: u8, +} + +impl X { + fn self_and_out<'s>(&'s self) -> &'s u8 { + &self.x + } + + // No error; multiple input refs. + fn self_and_in_out<'s, 't>(&'s self, _x: &'t u8) -> &'s u8 { + &self.x + } + + fn distinct_self_and_in<'s, 't>(&'s self, _x: &'t u8) {} + + // No error; same lifetimes on two params. + fn self_and_same_in<'s>(&'s self, _x: &'s u8) {} +} + +struct Foo<'a>(&'a u8); + +impl<'a> Foo<'a> { + // No error; lifetime `'a` not defined in method. + fn self_shared_lifetime(&self, _: &'a u8) {} + // No error; bounds exist. + fn self_bound_lifetime<'b: 'a>(&self, _: &'b u8) {} +} + +fn already_elided<'a>(_: &u8, _: &'a u8) -> &'a u8 { + unimplemented!() +} + +fn struct_with_lt<'a>(_foo: Foo<'a>) -> &'a str { + unimplemented!() +} + +// No warning; two input lifetimes (named on the reference, anonymous on `Foo`). +fn struct_with_lt2<'a>(_foo: &'a Foo) -> &'a str { + unimplemented!() +} + +// No warning; two input lifetimes (anonymous on the reference, named on `Foo`). +fn struct_with_lt3<'a>(_foo: &Foo<'a>) -> &'a str { + unimplemented!() +} + +// No warning; two input lifetimes. +fn struct_with_lt4<'a, 'b>(_foo: &'a Foo<'b>) -> &'a str { + unimplemented!() +} + +trait WithLifetime<'a> {} + +type WithLifetimeAlias<'a> = dyn WithLifetime<'a>; + +// Should not warn because it won't build without the lifetime. +fn trait_obj_elided<'a>(_arg: &'a dyn WithLifetime) -> &'a str { + unimplemented!() +} + +// Should warn because there is no lifetime on `Drop`, so this would be +// unambiguous if we elided the lifetime. +fn trait_obj_elided2<'a>(_arg: &'a dyn Drop) -> &'a str { + unimplemented!() +} + +type FooAlias<'a> = Foo<'a>; + +fn alias_with_lt<'a>(_foo: FooAlias<'a>) -> &'a str { + unimplemented!() +} + +// No warning; two input lifetimes (named on the reference, anonymous on `FooAlias`). +fn alias_with_lt2<'a>(_foo: &'a FooAlias) -> &'a str { + unimplemented!() +} + +// No warning; two input lifetimes (anonymous on the reference, named on `FooAlias`). +fn alias_with_lt3<'a>(_foo: &FooAlias<'a>) -> &'a str { + unimplemented!() +} + +// No warning; two input lifetimes. +fn alias_with_lt4<'a, 'b>(_foo: &'a FooAlias<'b>) -> &'a str { + unimplemented!() +} + +fn named_input_elided_output<'a>(_arg: &'a str) -> &str { + unimplemented!() +} + +fn elided_input_named_output<'a>(_arg: &str) -> &'a str { + unimplemented!() +} + +fn trait_bound_ok<'a, T: WithLifetime<'static>>(_: &'a u8, _: T) { + unimplemented!() +} +fn trait_bound<'a, T: WithLifetime<'a>>(_: &'a u8, _: T) { + unimplemented!() +} + +// Don't warn on these; see issue #292. +fn trait_bound_bug<'a, T: WithLifetime<'a>>() { + unimplemented!() +} + +// See issue #740. +struct Test { + vec: Vec<usize>, +} + +impl Test { + fn iter<'a>(&'a self) -> Box<dyn Iterator<Item = usize> + 'a> { + unimplemented!() + } +} + +trait LintContext<'a> {} + +fn f<'a, T: LintContext<'a>>(_: &T) {} + +fn test<'a>(x: &'a [u8]) -> u8 { + let y: &'a u8 = &x[5]; + *y +} + +// Issue #3284: give hint regarding lifetime in return type. +struct Cow<'a> { + x: &'a str, +} +fn out_return_type_lts<'a>(e: &'a str) -> Cow<'a> { + unimplemented!() +} + +// Make sure we still warn on implementations +mod issue4291 { + trait BadTrait { + fn needless_lt<'a>(x: &'a u8) {} + } + + impl BadTrait for () { + fn needless_lt<'a>(_x: &'a u8) {} + } +} + +mod issue2944 { + trait Foo {} + struct Bar; + struct Baz<'a> { + bar: &'a Bar, + } + + impl<'a> Foo for Baz<'a> {} + impl Bar { + fn baz<'a>(&'a self) -> impl Foo + 'a { + Baz { bar: self } + } + } +} + +mod nested_elision_sites { + // issue #issue2944 + + // closure trait bounds subject to nested elision + // don't lint because they refer to outer lifetimes + fn trait_fn<'a>(i: &'a i32) -> impl Fn() -> &'a i32 { + move || i + } + fn trait_fn_mut<'a>(i: &'a i32) -> impl FnMut() -> &'a i32 { + move || i + } + fn trait_fn_once<'a>(i: &'a i32) -> impl FnOnce() -> &'a i32 { + move || i + } + + // don't lint + fn impl_trait_in_input_position<'a>(f: impl Fn() -> &'a i32) -> &'a i32 { + f() + } + fn impl_trait_in_output_position<'a>(i: &'a i32) -> impl Fn() -> &'a i32 { + move || i + } + // lint + fn impl_trait_elidable_nested_named_lifetimes<'a>(i: &'a i32, f: impl for<'b> Fn(&'b i32) -> &'b i32) -> &'a i32 { + f(i) + } + fn impl_trait_elidable_nested_anonymous_lifetimes<'a>(i: &'a i32, f: impl Fn(&i32) -> &i32) -> &'a i32 { + f(i) + } + + // don't lint + fn generics_not_elidable<'a, T: Fn() -> &'a i32>(f: T) -> &'a i32 { + f() + } + // lint + fn generics_elidable<'a, T: Fn(&i32) -> &i32>(i: &'a i32, f: T) -> &'a i32 { + f(i) + } + + // don't lint + fn where_clause_not_elidable<'a, T>(f: T) -> &'a i32 + where + T: Fn() -> &'a i32, + { + f() + } + // lint + fn where_clause_elidadable<'a, T>(i: &'a i32, f: T) -> &'a i32 + where + T: Fn(&i32) -> &i32, + { + f(i) + } + + // don't lint + fn pointer_fn_in_input_position<'a>(f: fn(&'a i32) -> &'a i32, i: &'a i32) -> &'a i32 { + f(i) + } + fn pointer_fn_in_output_position<'a>(_: &'a i32) -> fn(&'a i32) -> &'a i32 { + |i| i + } + // lint + fn pointer_fn_elidable<'a>(i: &'a i32, f: fn(&i32) -> &i32) -> &'a i32 { + f(i) + } + + // don't lint + fn nested_fn_pointer_1<'a>(_: &'a i32) -> fn(fn(&'a i32) -> &'a i32) -> i32 { + |f| 42 + } + fn nested_fn_pointer_2<'a>(_: &'a i32) -> impl Fn(fn(&'a i32)) { + |f| () + } + + // lint + fn nested_fn_pointer_3<'a>(_: &'a i32) -> fn(fn(&i32) -> &i32) -> i32 { + |f| 42 + } + fn nested_fn_pointer_4<'a>(_: &'a i32) -> impl Fn(fn(&i32)) { + |f| () + } +} + +mod issue6159 { + use std::ops::Deref; + pub fn apply_deref<'a, T, F, R>(x: &'a T, f: F) -> R + where + T: Deref, + F: FnOnce(&'a T::Target) -> R, + { + f(x.deref()) + } +} + +mod issue7296 { + use std::rc::Rc; + use std::sync::Arc; + + struct Foo; + impl Foo { + fn implicit<'a>(&'a self) -> &'a () { + &() + } + fn implicit_mut<'a>(&'a mut self) -> &'a () { + &() + } + + fn explicit<'a>(self: &'a Arc<Self>) -> &'a () { + &() + } + fn explicit_mut<'a>(self: &'a mut Rc<Self>) -> &'a () { + &() + } + + fn lifetime_elsewhere<'a>(self: Box<Self>, here: &'a ()) -> &'a () { + &() + } + } + + trait Bar { + fn implicit<'a>(&'a self) -> &'a (); + fn implicit_provided<'a>(&'a self) -> &'a () { + &() + } + + fn explicit<'a>(self: &'a Arc<Self>) -> &'a (); + fn explicit_provided<'a>(self: &'a Arc<Self>) -> &'a () { + &() + } + + fn lifetime_elsewhere<'a>(self: Box<Self>, here: &'a ()) -> &'a (); + fn lifetime_elsewhere_provided<'a>(self: Box<Self>, here: &'a ()) -> &'a () { + &() + } + } +} + +fn main() {} |