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//@ edition: 2018
#![feature(arbitrary_self_types)]
// tests that the referent type of a reference must be known to call methods on it
struct SmartPtr<T>(T);
impl<T> core::ops::Receiver for SmartPtr<T> {
type Target = T;
}
impl<T> SmartPtr<T> {
fn foo(&self) {}
}
fn main() {
let val = 1_u32;
let ptr = &val;
let _a: i32 = (ptr as &_).read();
//~^ ERROR type annotations needed
// Same again, but with a smart pointer type
let val2 = 1_u32;
let rc = std::rc::Rc::new(val2);
let _b = (rc as std::rc::Rc<_>).read();
//~^ ERROR type annotations needed
// Same again, but with a smart pointer type
let ptr = SmartPtr(val);
// We can call unambiguous outer-type methods on this
(ptr as SmartPtr<_>).foo();
// ... but we can't follow the Receiver chain to the inner type
// because we end up with _.
// Because SmartPtr implements Receiver, it's arguable which of the
// following two diagnostics we'd want in this case:
// (a) "type annotations needed" (because the inner type is _)
// (b) "no method named `read` found for struct `SmartPtr`"
// (ignoring the fact that there might have been methods on the
// inner type, had it not been _)
// At present we produce error type (b), which is necessary because
// our resolution logic needs to be able to call methods such as foo()
// on the outer type even if the inner type is ambiguous.
let _c = (ptr as SmartPtr<_>).read();
//~^ ERROR no method named `read` found for struct `SmartPtr`
}
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