new realloc bug reproducer #190

#![feature(autodiff)]
use std::autodiff::autodiff;

#[autodiff(sin_vec, Reverse, Duplicated, Const, Active)]
fn cos_vec(x: &mut Vec<f32>, y: usize) -> f32 {
    // uses enum internally and breaks
    for i in 0..y {
        x.push(i as f32);
    }
    let res = x.into_iter().collect::<Vec<&mut f32>>();

    *res[0]
}

fn main() {
    let mut x = vec![1.0, 1.0, 1.0];
    let mut d_x = vec![0.0; 3];

    sin_vec(&mut x, &mut d_x, 4, 1.0);

    dbg!(&d_x, &x);
}

alloc::raw_vec::finish_grow::hce1ff89b620ba31c
alloc::raw_vec::RawVecInner<A>::grow_amortized::h6d11486032b72786
alloc::raw_vec::RawVecInner<A>::reserve::do_reserve_and_handle::hf69592d80ba560b8
alloc::vec::Vec<T,A>::reserve::hfbf4bb7fa5035d73
alloc::vec::Vec<T,A>::extend_trusted::h9fccf647fedf83c0

pub struct Vec<T, A: Allocator = Global> {
    buf: RawVec<T, A>,
    len: usize,
}

    pub fn reserve(&mut self, additional: usize) {
        self.buf.reserve(self.len, additional);
    }