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// run-pass
#![feature(specialization)] //~ WARN the feature `specialization` is incomplete
// Test that default methods are cascaded correctly
// First, test only use of explicit `default` items:
trait Foo {
fn foo(&self) -> bool;
}
// Specialization tree for Foo:
//
// T
// / \
// i32 i64
impl<T> Foo for T {
default fn foo(&self) -> bool { false }
}
impl Foo for i32 {}
impl Foo for i64 {
fn foo(&self) -> bool { true }
}
fn test_foo() {
assert!(!0i8.foo());
assert!(!0i32.foo());
assert!(0i64.foo());
}
// Next, test mixture of explicit `default` and provided methods:
trait Bar {
fn bar(&self) -> i32 { 0 }
}
// Specialization tree for Bar.
// Uses of $ designate that method is provided
//
// $Bar (the trait)
// |
// T
// /|\
// / | \
// / | \
// / | \
// / | \
// / | \
// $i32 &str $Vec<T>
// /\
// / \
// Vec<i32> $Vec<i64>
impl<T> Bar for T {
default fn bar(&self) -> i32 { 0 }
}
impl Bar for i32 {
fn bar(&self) -> i32 { 1 }
}
impl<'a> Bar for &'a str {}
impl<T> Bar for Vec<T> {
default fn bar(&self) -> i32 { 2 }
}
impl Bar for Vec<i32> {}
impl Bar for Vec<i64> {
fn bar(&self) -> i32 { 3 }
}
fn test_bar() {
assert!(0u8.bar() == 0);
assert!(0i32.bar() == 1);
assert!("hello".bar() == 0);
assert!(vec![()].bar() == 2);
assert!(vec![0i32].bar() == 2);
assert!(vec![0i64].bar() == 3);
}
fn main() {
test_foo();
test_bar();
}
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