rust/tests/crashes/121575.rs
2024-04-14 11:21:51 +02:00

108 lines
2.6 KiB
Rust

//@ known-bug: #121575
// ignore-tidy-linelength
#![feature(generic_const_exprs)]
use std::array;
trait PrimRec<const N: usize, const O: usize> {
fn eval(&self, x: [usize; N]) -> [usize; O];
}
struct Zero;
impl<const N: usize> PrimRec<N, 1> for Zero {
fn eval(&self, _: [usize; N]) -> [usize; 1] {
[0]
}
}
struct Const(usize);
impl<const N: usize> PrimRec<N, 1> for Const {
fn eval(&self, _: [usize; N]) -> [usize; 1] {
[self.0]
}
}
struct S;
impl PrimRec<1, 1> for S {
fn eval(&self, x: [usize; 1]) -> [usize; 1] {
[x[0] + 1]
}
}
struct Proj<const I: usize>;
impl<const N: usize, const I: usize> PrimRec<N, 1> for Proj<I> {
fn eval(&self, x: [usize; N]) -> [usize; 1] {
[x[I]]
}
}
struct Merge<const N: usize, const O1: usize, const O2: usize, A: PrimRec<N, O1>, B: PrimRec<N, O2>>(
A,
B,
);
fn concat<const M: usize, const N: usize>(a: [usize; M], b: [usize; N]) -> [usize; M + N] {
array::from_fn(|i| if i < M { a[i] } else { b[i - M] })
}
impl<const N: usize, const O1: usize, const O2: usize, A: PrimRec<N, O1>, B: PrimRec<N, O2>>
PrimRec<N, { O1 + O2 }> for Merge<N, O1, O2, A, B>
{
fn eval(&self, x: [usize; N]) -> [usize; O1 + O2] {
concat(self.0.eval(x), self.1.eval(x))
}
}
struct Compose<const N: usize, const I: usize, const O: usize, A: PrimRec<N, I>, B: PrimRec<I, O>>(
A,
B,
);
impl<const N: usize, const I: usize, const O: usize, A: PrimRec<N, I>, B: PrimRec<I, O>>
PrimRec<N, O> for Compose<N, I, O, A, B>
{
fn eval(&self, x: [usize; N]) -> [usize; O] {
self.1.eval(self.0.eval(x))
}
}
struct Rec<const N: usize, const O: usize, Base: PrimRec<N, O>, F: PrimRec<{ O + (N + 1) }, O>>(
Base,
F,
);
fn tail<const N: usize>(x: [usize; N + 1]) -> [usize; N] {
array::from_fn(|i| x[i + 1])
}
fn cons<const N: usize>(x: usize, xs: [usize; N]) -> [usize; N + 1] {
array::from_fn(|i| if i == 0 { x } else { xs[i - 1] })
}
impl<const N: usize, const O: usize, Base: PrimRec<N, O>, F: PrimRec<{ O + (N + 1) }, O>>
PrimRec<{ N + 1 }, O> for Rec<N, O, Base, F>
{
fn eval(&self, x: [usize; N + 1]) -> [usize; O] {
match (x[0], tail(x)) {
(0, x) => self.0.eval(x),
(y, x) => {
let xy = cons(y - 1, x);
let input = concat(self.eval(xy), xy);
self.1.eval(input)
}
}
}
}
fn main() {
let one = Compose(Zero, S);
dbg!(one.eval([]));
let add: Rec<1, 1, Proj<0>, Compose<3, 1, 1, Proj<0>, S>> =
Rec(Proj::<0>, Compose(Proj::<0>, S));
dbg!(add.eval([3, 2]));
}