about summary refs log tree commit diff
path: root/compiler/rustc_error_codes/src/error_codes/E0724.md
blob: bcefd0a74798bc38643dc6c0cb79f17a41d5e434 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
#### Note: this error code is no longer emitted by the compiler.


`#[ffi_returns_twice]` was used on something other than a foreign function
declaration.

Erroneous code example:

```compile_fail
#![feature(ffi_returns_twice)]
#![crate_type = "lib"]

#[ffi_returns_twice] // error!
pub fn foo() {}
```

`#[ffi_returns_twice]` can only be used on foreign function declarations.
For example, we might correct the previous example by declaring
the function inside of an `extern` block.

```compile_fail
#![feature(ffi_returns_twice)]

extern "C" {
   #[ffi_returns_twice] // ok!
   pub fn foo();
}
```