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#[derive(Copy, Clone, Debug, Eq, PartialEq)]
pub struct Foo {
}
impl Foo {
fn get(&self) -> Option<&Result<String, String>> {
None
}
fn mutate(&mut self) { }
}
fn main() {
let mut foo = Foo { };
// foo.get() returns type Option<&Result<String, String>>, so
// using `string` keeps borrow of `foo` alive. Hence calling
// `foo.mutate()` should be an error.
while let Some(Ok(string)) = foo.get() {
foo.mutate();
//~^ ERROR cannot borrow `foo` as mutable
println!("foo={:?}", *string);
}
}
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