#### 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(); } ```