mirror of
https://github.com/rust-lang/rust-clippy
synced 2024-11-24 13:43:17 +00:00
538 lines
13 KiB
Rust
538 lines
13 KiB
Rust
// run-rustfix
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// aux-build:macro_rules.rs
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#![warn(clippy::needless_lifetimes)]
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#![allow(
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unused,
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clippy::boxed_local,
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clippy::extra_unused_type_parameters,
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clippy::needless_pass_by_value,
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clippy::unnecessary_wraps,
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dyn_drop,
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clippy::get_first
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)]
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#[macro_use]
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extern crate macro_rules;
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fn distinct_lifetimes(_x: &u8, _y: &u8, _z: u8) {}
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fn distinct_and_static(_x: &u8, _y: &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(x: &u8, _y: u8) -> &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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// Error; multiple input refs, but the output lifetime is not elided, i.e., the following is valid:
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// fn multiple_in_and_out_2a<'a>(x: &'a u8, _y: &u8) -> &'a u8
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// ^^^
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fn multiple_in_and_out_2a<'a>(x: &'a u8, _y: &u8) -> &'a u8 {
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x
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}
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// Error; multiple input refs, but the output lifetime is not elided, i.e., the following is valid:
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// fn multiple_in_and_out_2b<'b>(_x: &u8, y: &'b u8) -> &'b u8
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// ^^^
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fn multiple_in_and_out_2b<'b>(_x: &u8, y: &'b u8) -> &'b u8 {
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y
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}
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// No error; multiple input refs
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async fn func<'a>(args: &[&'a str]) -> Option<&'a str> {
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args.get(0).cloned()
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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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// Error; multiple input refs, but the output lifetime is not elided, i.e., the following is valid:
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// fn deep_reference_1a<'a>(x: &'a u8, _y: &u8) -> Result<&'a u8, ()>
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// ^^^
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fn deep_reference_1a<'a>(x: &'a u8, _y: &u8) -> Result<&'a u8, ()> {
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Ok(x)
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}
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// Error; multiple input refs, but the output lifetime is not elided, i.e., the following is valid:
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// fn deep_reference_1b<'b>(_x: &u8, y: &'b u8) -> Result<&'b u8, ()>
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// ^^^
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fn deep_reference_1b<'b>(_x: &u8, y: &'b u8) -> Result<&'b u8, ()> {
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Ok(y)
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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(x: &u8, _y: u8) -> Result<&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<T>(x: &u8, _y: u8) -> Result<&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(_x: Ref<'_>, _y: &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<F, I>(_m: Lt<'_, I>, _f: F) -> Lt<'_, 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 { x } else { f() }
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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(&self) -> &u8 {
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&self.x
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}
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// Error; multiple input refs, but the output lifetime is not elided, i.e., the following is valid:
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// fn self_and_in_out_1<'s>(&'s self, _x: &u8) -> &'s u8
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// ^^^
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fn self_and_in_out_1<'s>(&'s self, _x: &u8) -> &'s u8 {
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&self.x
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}
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// Error; multiple input refs, but the output lifetime is not elided, i.e., the following is valid:
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// fn self_and_in_out_2<'t>(&self, x: &'t u8) -> &'t u8
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// ^^^^^
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fn self_and_in_out_2<'t>(&self, x: &'t u8) -> &'t u8 {
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x
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}
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fn distinct_self_and_in(&self, _x: &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(_foo: Foo<'_>) -> &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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// Warning; two input lifetimes, but the output lifetime is not elided, i.e., the following is
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// valid:
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// fn struct_with_lt4a<'a>(_foo: &'a Foo<'_>) -> &'a str
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// ^^
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fn struct_with_lt4a<'a>(_foo: &'a Foo<'_>) -> &'a str {
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unimplemented!()
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}
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// Warning; two input lifetimes, but the output lifetime is not elided, i.e., the following is
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// valid:
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// fn struct_with_lt4b<'b>(_foo: &Foo<'b>) -> &'b str
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// ^^^^
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fn struct_with_lt4b<'b>(_foo: &Foo<'b>) -> &'b 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(_arg: &dyn Drop) -> &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(_foo: FooAlias<'_>) -> &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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// Warning; two input lifetimes, but the output lifetime is not elided, i.e., the following is
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// valid:
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// fn alias_with_lt4a<'a>(_foo: &'a FooAlias<'_>) -> &'a str
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// ^^
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fn alias_with_lt4a<'a>(_foo: &'a FooAlias<'_>) -> &'a str {
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unimplemented!()
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}
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// Warning; two input lifetimes, but the output lifetime is not elided, i.e., the following is
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// valid:
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// fn alias_with_lt4b<'b>(_foo: &FooAlias<'b>) -> &'b str
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// ^^^^^^^^^
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fn alias_with_lt4b<'b>(_foo: &FooAlias<'b>) -> &'b str {
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unimplemented!()
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}
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fn named_input_elided_output(_arg: &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<T: WithLifetime<'static>>(_: &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(e: &str) -> Cow<'_> {
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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(x: &u8) {}
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}
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impl BadTrait for () {
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fn needless_lt(_x: &u8) {}
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}
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}
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mod issue2944 {
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trait Foo {}
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struct Bar;
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struct Baz<'a> {
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bar: &'a Bar,
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}
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impl<'a> Foo for Baz<'a> {}
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impl Bar {
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fn baz(&self) -> impl Foo + '_ {
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Baz { bar: self }
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}
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}
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}
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mod nested_elision_sites {
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// issue #issue2944
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// closure trait bounds subject to nested elision
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// don't lint because they refer to outer lifetimes
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fn trait_fn<'a>(i: &'a i32) -> impl Fn() -> &'a i32 {
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move || i
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}
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fn trait_fn_mut<'a>(i: &'a i32) -> impl FnMut() -> &'a i32 {
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move || i
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}
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fn trait_fn_once<'a>(i: &'a i32) -> impl FnOnce() -> &'a i32 {
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move || i
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}
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// don't lint
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fn impl_trait_in_input_position<'a>(f: impl Fn() -> &'a i32) -> &'a i32 {
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f()
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}
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fn impl_trait_in_output_position<'a>(i: &'a i32) -> impl Fn() -> &'a i32 {
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move || i
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}
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// lint
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fn impl_trait_elidable_nested_named_lifetimes<'a>(i: &'a i32, f: impl for<'b> Fn(&'b i32) -> &'b i32) -> &'a i32 {
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f(i)
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}
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fn impl_trait_elidable_nested_anonymous_lifetimes(i: &i32, f: impl Fn(&i32) -> &i32) -> &i32 {
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f(i)
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}
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// don't lint
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fn generics_not_elidable<'a, T: Fn() -> &'a i32>(f: T) -> &'a i32 {
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f()
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}
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// lint
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fn generics_elidable<T: Fn(&i32) -> &i32>(i: &i32, f: T) -> &i32 {
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f(i)
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}
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// don't lint
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fn where_clause_not_elidable<'a, T>(f: T) -> &'a i32
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where
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T: Fn() -> &'a i32,
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{
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f()
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}
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// lint
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fn where_clause_elidadable<T>(i: &i32, f: T) -> &i32
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where
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T: Fn(&i32) -> &i32,
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{
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f(i)
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}
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// don't lint
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fn pointer_fn_in_input_position<'a>(f: fn(&'a i32) -> &'a i32, i: &'a i32) -> &'a i32 {
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f(i)
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}
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fn pointer_fn_in_output_position<'a>(_: &'a i32) -> fn(&'a i32) -> &'a i32 {
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|i| i
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}
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// lint
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fn pointer_fn_elidable(i: &i32, f: fn(&i32) -> &i32) -> &i32 {
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f(i)
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}
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// don't lint
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fn nested_fn_pointer_1<'a>(_: &'a i32) -> fn(fn(&'a i32) -> &'a i32) -> i32 {
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|f| 42
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}
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fn nested_fn_pointer_2<'a>(_: &'a i32) -> impl Fn(fn(&'a i32)) {
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|f| ()
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}
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// lint
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fn nested_fn_pointer_3(_: &i32) -> fn(fn(&i32) -> &i32) -> i32 {
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|f| 42
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}
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fn nested_fn_pointer_4(_: &i32) -> impl Fn(fn(&i32)) {
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|f| ()
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}
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}
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mod issue6159 {
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use std::ops::Deref;
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pub fn apply_deref<'a, T, F, R>(x: &'a T, f: F) -> R
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where
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T: Deref,
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F: FnOnce(&'a T::Target) -> R,
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{
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f(x.deref())
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}
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}
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mod issue7296 {
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use std::rc::Rc;
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use std::sync::Arc;
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struct Foo;
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impl Foo {
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fn implicit(&self) -> &() {
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&()
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}
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fn implicit_mut(&mut self) -> &() {
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&()
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}
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fn explicit<'a>(self: &'a Arc<Self>) -> &'a () {
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&()
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}
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fn explicit_mut<'a>(self: &'a mut Rc<Self>) -> &'a () {
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&()
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}
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fn lifetime_elsewhere(self: Box<Self>, here: &()) -> &() {
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&()
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}
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}
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trait Bar {
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fn implicit(&self) -> &();
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fn implicit_provided(&self) -> &() {
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&()
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}
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fn explicit<'a>(self: &'a Arc<Self>) -> &'a ();
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fn explicit_provided<'a>(self: &'a Arc<Self>) -> &'a () {
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&()
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}
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fn lifetime_elsewhere(self: Box<Self>, here: &()) -> &();
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fn lifetime_elsewhere_provided(self: Box<Self>, here: &()) -> &() {
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&()
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}
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}
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}
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mod pr_9743_false_negative_fix {
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#![allow(unused)]
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fn foo(x: &u8, y: &'_ u8) {}
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fn bar(x: &u8, y: &'_ u8, z: &'_ u8) {}
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}
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mod pr_9743_output_lifetime_checks {
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#![allow(unused)]
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// lint: only one input
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fn one_input(x: &u8) -> &u8 {
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unimplemented!()
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}
|
|
|
|
// lint: multiple inputs, output would not be elided
|
|
fn multiple_inputs_output_not_elided<'b>(x: &u8, y: &'b u8, z: &'b u8) -> &'b u8 {
|
|
unimplemented!()
|
|
}
|
|
|
|
// don't lint: multiple inputs, output would be elided (which would create an ambiguity)
|
|
fn multiple_inputs_output_would_be_elided<'a, 'b>(x: &'a u8, y: &'b u8, z: &'b u8) -> &'a u8 {
|
|
unimplemented!()
|
|
}
|
|
}
|
|
|
|
mod in_macro {
|
|
macro_rules! local_one_input_macro {
|
|
() => {
|
|
fn one_input(x: &u8) -> &u8 {
|
|
unimplemented!()
|
|
}
|
|
};
|
|
}
|
|
|
|
// lint local macro expands to function with needless lifetimes
|
|
local_one_input_macro!();
|
|
|
|
// no lint on external macro
|
|
macro_rules::needless_lifetime!();
|
|
}
|
|
|
|
mod issue5787 {
|
|
use std::sync::MutexGuard;
|
|
|
|
struct Foo;
|
|
|
|
impl Foo {
|
|
// doesn't get linted without async
|
|
pub async fn wait<'a, T>(&self, guard: MutexGuard<'a, T>) -> MutexGuard<'a, T> {
|
|
guard
|
|
}
|
|
}
|
|
|
|
async fn foo<'a>(_x: &i32, y: &'a str) -> &'a str {
|
|
y
|
|
}
|
|
}
|
|
|
|
fn main() {}
|