mirror of https://github.com/rust-lang/rust
21 lines
632 B
Rust
21 lines
632 B
Rust
// Ensure that you cannot use generic types to return a region outside
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// of its bound. Here, in the `return_it()` fn, we call with() but
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// with R bound to &isize from the return_it. Meanwhile, with()
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// provides a value that is only good within its own stack frame. This
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// used to successfully compile because we failed to account for the
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// fact that fn(x: &isize) rebound the region &.
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fn with<R, F>(f: F) -> R where F: FnOnce(&isize) -> R {
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f(&3)
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}
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fn return_it<'a>() -> &'a isize {
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with(|o| o)
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//~^ ERROR lifetime may not live long enough
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}
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fn main() {
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let x = return_it();
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println!("foo={}", *x);
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}
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