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