35 lines
1007 B
Rust
35 lines
1007 B
Rust
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// A dummy iface/impl that work close over any type. The iface will
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// be parameterized by a region due to the &self/int constraint.
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iface foo {
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fn foo(i: &self/int) -> int;
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}
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impl<T:copy> of foo for T {
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fn foo(i: &self/int) -> int {*i}
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}
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fn to_foo<T:copy>(t: T) {
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// This version is ok because, although T may contain borrowed
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// pointers, it never escapes the fn body. We know this because
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// the type of foo includes a region which will be resolved to
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// the fn body itself.
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let v = &3;
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let x = {f:t} as foo;
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assert x.foo(v) == 3;
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}
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fn to_foo_2<T:copy>(t: T) -> foo {
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// Not OK---T may contain borrowed ptrs and it is going to escape
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// as part of the returned foo value
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{f:t} as foo //~ ERROR value may contain borrowed pointers; use `owned` bound
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}
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fn to_foo_3<T:copy owned>(t: T) -> foo {
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// OK---T may escape as part of the returned foo value, but it is
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// owned and hence does not contain borrowed ptrs
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{f:t} as foo
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}
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fn main() {
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}
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