Suggest replacing named lifetime with 'static
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,41 @@ | ||
| // Copyright 2018 The Rust Project Developers. See the COPYRIGHT | ||
| // file at the top-level directory of this distribution and at | ||
| // http://rust-lang.org/COPYRIGHT. | ||
| // | ||
| // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or | ||
| // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license | ||
| // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your | ||
| // option. This file may not be copied, modified, or distributed | ||
| // except according to those terms. | ||
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| struct Foo<'a>(&'a str); | ||
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| fn _foo<'a: 'static, 'b>(_x: &'a str, _y: &'b str) -> &'a str { | ||
| //~^ WARNING unnecessary lifetime parameter `'a` | ||
| "" | ||
| } | ||
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| fn _foo1<'b, 'a: 'static>(_x: &'a str, _y: Foo<'a>) -> &'a str { | ||
| //~^ WARNING unnecessary lifetime parameter `'a` | ||
| "" | ||
| } | ||
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| fn _foo2<'c, 'a: 'static, 'b>(_x: &'a str, _y: &'b str) -> &'a str { | ||
| //~^ WARNING unnecessary lifetime parameter `'a` | ||
| "" | ||
| } | ||
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| fn _foo3<'c, 'a: 'static, 'b: 'a, 'd>(_x: &'a str, _y: &'b str) -> &'a str { | ||
| //~^ WARNING unnecessary lifetime parameter `'a` | ||
| "" | ||
| } | ||
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| fn _foo4<'a: 'static>(_x: &'a str, _y: &str) -> &'a str { | ||
| //~^ WARNING unnecessary lifetime parameter `'a` | ||
| "" | ||
| } | ||
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| fn _foo5<'a: 'static, 'b>(_x: &'a str, _y: &'b str) -> &'b str { | ||
| //~^ WARNING unnecessary lifetime parameter `'a` | ||
| "" | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,67 @@ | ||
| error[E0601]: `main` function not found in crate `static_lifetime` | ||
| | | ||
| = note: consider adding a `main` function to `$DIR/static-lifetime.rs` | ||
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| warning: unnecessary lifetime parameter `'a` | ||
| --> $DIR/static-lifetime.rs:13:9 | ||
| | | ||
| LL | fn _foo<'a: 'static, 'b>(_x: &'a str, _y: &'b str) -> &'a str { | ||
| | ^^^^^^^^^^^ | ||
| help: you can use the `'static` lifetime directly, in place of `'a` | ||
| | | ||
| LL | fn _foo<'b>(_x: &'static str, _y: &'b str) -> &'static str { | ||
| | -- ^^^^^^^ ^^^^^^^ | ||
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| warning: unnecessary lifetime parameter `'a` | ||
| --> $DIR/static-lifetime.rs:18:14 | ||
| | | ||
| LL | fn _foo1<'b, 'a: 'static>(_x: &'a str, _y: Foo<'a>) -> &'a str { | ||
| | ^^^^^^^^^^^ | ||
| help: you can use the `'static` lifetime directly, in place of `'a` | ||
| | | ||
| LL | fn _foo1<'b>(_x: &'static str, _y: Foo<'static>) -> &'static str { | ||
| | -- ^^^^^^^ ^^^^^^^ ^^^^^^^ | ||
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| warning: unnecessary lifetime parameter `'a` | ||
| --> $DIR/static-lifetime.rs:23:14 | ||
| | | ||
| LL | fn _foo2<'c, 'a: 'static, 'b>(_x: &'a str, _y: &'b str) -> &'a str { | ||
| | ^^^^^^^^^^^ | ||
| help: you can use the `'static` lifetime directly, in place of `'a` | ||
| | | ||
| LL | fn _foo2<'c, 'b>(_x: &'static str, _y: &'b str) -> &'static str { | ||
| | -- ^^^^^^^ ^^^^^^^ | ||
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| warning: unnecessary lifetime parameter `'a` | ||
| --> $DIR/static-lifetime.rs:28:14 | ||
| | | ||
| LL | fn _foo3<'c, 'a: 'static, 'b: 'a, 'd>(_x: &'a str, _y: &'b str) -> &'a str { | ||
| | ^^^^^^^^^^^ | ||
| help: you can use the `'static` lifetime directly, in place of `'a` | ||
| | | ||
| LL | fn _foo3<'c, 'b: 'static, 'd>(_x: &'static str, _y: &'b str) -> &'static str { | ||
| | -- ^^^^^^^ ^^^^^^^ ^^^^^^^ | ||
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| warning: unnecessary lifetime parameter `'a` | ||
| --> $DIR/static-lifetime.rs:33:10 | ||
| | | ||
| LL | fn _foo4<'a: 'static>(_x: &'a str, _y: &str) -> &'a str { | ||
| | ^^^^^^^^^^^ | ||
| help: you can use the `'static` lifetime directly, in place of `'a` | ||
| | | ||
| LL | fn _foo4(_x: &'static str, _y: &str) -> &'static str { | ||
| | -- ^^^^^^^ ^^^^^^^ | ||
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| warning: unnecessary lifetime parameter `'a` | ||
| --> $DIR/static-lifetime.rs:38:10 | ||
| | | ||
| LL | fn _foo5<'a: 'static, 'b>(_x: &'a str, _y: &'b str) -> &'b str { | ||
| | ^^^^^^^^^^^ | ||
| help: you can use the `'static` lifetime directly, in place of `'a` | ||
| | | ||
| LL | fn _foo5<'b>(_x: &'static str, _y: &'b str) -> &'b str { | ||
| | -- ^^^^^^^ | ||
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| error: aborting due to previous error | ||
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| For more information about this error, try `rustc --explain E0601`. |
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Can't we use a visitor for this?
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Also, what is this used for? It seems like it doesn't handle shadowing (which, I guess, we disallow at present, so maybe that's ok).
(I was thinking of types like
for<'a> fn(&'a u32), which mention'a, but not the same'aas might be in scope outside... but as I said at present we do disallow such shadowing)There was a problem hiding this comment.
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It's only used to gather all the lifetime spans in the argument and return tys that match the name being checked.