46 lines
1.2 KiB
Rust
46 lines
1.2 KiB
Rust
// Check that you can cast between different pointers to trait objects
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// whose vtable have the same kind (both lengths, or both trait pointers).
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trait Foo<T> {
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fn foo(&self, _: T) -> u32 { 42 }
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}
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trait Bar {
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fn bar(&self) { println!("Bar!"); }
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}
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impl<T> Foo<T> for () {}
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impl Foo<u32> for u32 { fn foo(&self, _: u32) -> u32 { self+43 } }
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impl Bar for () {}
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unsafe fn round_trip_and_call<'a>(t: *const (Foo<u32>+'a)) -> u32 {
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let foo_e : *const Foo<u16> = t as *const _;
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let r_1 = foo_e as *mut Foo<u32>;
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(&*r_1).foo(0)
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}
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#[repr(C)]
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struct FooS<T:?Sized>(T);
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#[repr(C)]
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struct BarS<T:?Sized>(T);
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fn foo_to_bar<T:?Sized>(u: *const FooS<T>) -> *const BarS<T> {
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u as *const BarS<T>
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}
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fn main() {
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let x = 4u32;
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let y : &Foo<u32> = &x;
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let fl = unsafe { round_trip_and_call(y as *const Foo<u32>) };
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assert_eq!(fl, (43+4));
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let s = FooS([0,1,2]);
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let u: &FooS<[u32]> = &s;
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let u: *const FooS<[u32]> = u;
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let bar_ref : *const BarS<[u32]> = foo_to_bar(u);
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let z : &BarS<[u32]> = unsafe{&*bar_ref};
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assert_eq!(&z.0, &[0,1,2]);
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// If validation fails here, that's likely because an immutable suspension is recovered mutably.
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}
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