mirror of https://github.com/rust-lang/rust
44 lines
1.0 KiB
Rust
44 lines
1.0 KiB
Rust
//@ run-pass
|
|
#![allow(dead_code)]
|
|
#![allow(unused_variables)]
|
|
// This is an example where the older inference algorithm failed. The
|
|
// specifics of why it failed are somewhat, but not entirely, tailed
|
|
// to the algorithm. Ultimately the problem is that when computing the
|
|
// mutual supertype of both sides of the `if` it would be faced with a
|
|
// choice of tightening bounds or unifying variables and it took the
|
|
// wrong path. The new algorithm avoids this problem and hence this
|
|
// example typechecks correctly.
|
|
|
|
//@ pretty-expanded FIXME #23616
|
|
|
|
enum ScopeChain<'a> {
|
|
Link(Scope<'a>),
|
|
End
|
|
}
|
|
|
|
type Scope<'a> = &'a ScopeChain<'a>;
|
|
|
|
struct OuterContext;
|
|
|
|
struct Context<'a> {
|
|
foo: &'a OuterContext
|
|
}
|
|
|
|
impl<'a> Context<'a> {
|
|
fn foo(&mut self, scope: Scope) {
|
|
let link = if 1 < 2 {
|
|
let l = ScopeChain::Link(scope);
|
|
self.take_scope(&l);
|
|
l
|
|
} else {
|
|
ScopeChain::Link(scope)
|
|
};
|
|
self.take_scope(&link);
|
|
}
|
|
|
|
fn take_scope(&mut self, x: Scope) {
|
|
}
|
|
}
|
|
|
|
fn main() { }
|