[rustc.git] / compiler / rustc_error_codes / src / error_codes / E0687.md

#### Note: this error code is no longer emitted by the compiler.

In-band lifetimes cannot be used in `fn`/`Fn` syntax.

Erroneous code examples:

```ignore (feature got removed)
#![feature(in_band_lifetimes)]

fn foo(x: fn(&'a u32)) {} // error!

fn bar(x: &Fn(&'a u32)) {} // error!

fn baz(x: fn(&'a u32), y: &'a u32) {} // error!

struct Foo<'a> { x: &'a u32 }

impl Foo<'a> {
    fn bar(&self, x: fn(&'a u32)) {} // error!
}
```

Lifetimes used in `fn` or `Fn` syntax must be explicitly
declared using `<...>` binders. For example:

```
fn foo<'a>(x: fn(&'a u32)) {} // ok!

fn bar<'a>(x: &Fn(&'a u32)) {} // ok!

fn baz<'a>(x: fn(&'a u32), y: &'a u32) {} // ok!

struct Foo<'a> { x: &'a u32 }

impl<'a> Foo<'a> {
    fn bar(&self, x: fn(&'a u32)) {} // ok!
}
```
Commit	Line	Data
5e7ed085 FG	1	#### Note: this error code is no longer emitted by the compiler.
5e7ed085 FG	2
f035d41b XL	3	In-band lifetimes cannot be used in `fn`/`Fn` syntax.
	4
	5	Erroneous code examples:
	6
5e7ed085	7	```ignore (feature got removed)
f035d41b XL	8	#![feature(in_band_lifetimes)]
	9
	10	fn foo(x: fn(&'a u32)) {} // error!
	11
	12	fn bar(x: &Fn(&'a u32)) {} // error!
	13
	14	fn baz(x: fn(&'a u32), y: &'a u32) {} // error!
	15
	16	struct Foo<'a> { x: &'a u32 }
	17
	18	impl Foo<'a> {
	19	fn bar(&self, x: fn(&'a u32)) {} // error!
	20	}
	21	```
	22
	23	Lifetimes used in `fn` or `Fn` syntax must be explicitly
	24	declared using `<...>` binders. For example:
	25
	26	```
	27	fn foo<'a>(x: fn(&'a u32)) {} // ok!
	28
	29	fn bar<'a>(x: &Fn(&'a u32)) {} // ok!
	30
	31	fn baz<'a>(x: fn(&'a u32), y: &'a u32) {} // ok!
	32
	33	struct Foo<'a> { x: &'a u32 }
	34
	35	impl<'a> Foo<'a> {
	36	fn bar(&self, x: fn(&'a u32)) {} // ok!
	37	}
	38	```