rust/src/test/compile-fail/regions-ret-borrowed.rs
2012-07-30 18:38:15 -07:00

21 lines
644 B
Rust

// Ensure that you cannot use generic types to return a region outside
// of its bound. Here, in the `return_it()` fn, we call with() but
// with R bound to &int from the return_it. Meanwhile, with()
// provides a value that is only good within its own stack frame. This
// used to successfully compile because we failed to account for the
// fact that fn(x: &int) rebound the region &.
fn with<R>(f: fn(x: &int) -> R) -> R {
f(&3)
}
fn return_it() -> &int {
with(|o| o) //~ ERROR mismatched types
//~^ ERROR reference is not valid outside of its lifetime
}
fn main() {
let x = return_it();
debug!{"foo=%d", *x};
}