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// Copyright (C) 2024-2025 Free Software Foundation, Inc.
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.
#![allow(dead_code)]
#![allow(unused_variables)]
#![allow(unused_assignments)]
fn ignore<T>(x: T) { }
// A generic struct that is unsized if T is unsized.
pub struct MaybeUnsizedStruct<T: ?Sized> {
pub regular: u32,
pub rest: T,
}
// Same but without an ordinary part.
pub struct MaybeUnsizedStruct2<T: ?Sized> {
value: T,
}
fn main() {
// This struct is still sized because T is a fixed-length array
let sized_struct = &MaybeUnsizedStruct {
regular: 23,
rest: [5, 6, 7],
};
// This struct is still sized because T is sized
let nested_sized_struct = &MaybeUnsizedStruct {
regular: 91,
rest: MaybeUnsizedStruct {
regular: 23,
rest: [5, 6, 7],
},
};
// This will be a fat pointer, containing the length of the final
// field.
let unsized_struct: &MaybeUnsizedStruct<[u32]> = sized_struct;
// This will also be a fat pointer, containing the length of the
// final field.
let nested_unsized_struct:
&MaybeUnsizedStruct<MaybeUnsizedStruct<[u32]>> = nested_sized_struct;
let alpha: MaybeUnsizedStruct2<[u8; 4]> = MaybeUnsizedStruct2 { value: *b"abc\0" };
let beta: &MaybeUnsizedStruct2<[u8]> = α
let reference = &unsized_struct;
ignore(sized_struct); // set breakpoint here
ignore(nested_sized_struct);
ignore(unsized_struct);
ignore(nested_unsized_struct);
}
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