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//@ run-pass
#![allow(dead_code)]
#![allow(unused_variables)]
#![allow(unreachable_code)]
// A regression test extracted from image-0.3.11. The point of
// failure was in `index_colors` below.
use std::ops::{Deref, DerefMut};
#[derive(Copy, Clone)]
pub struct Luma<T: Primitive> { pub data: [T; 1] }
impl<T: Primitive + 'static> Pixel for Luma<T> {
type Subpixel = T;
}
pub struct ImageBuffer<P: Pixel, Container> {
pixels: P,
c: Container,
}
pub trait GenericImage: Sized {
type Pixel: Pixel;
}
pub trait Pixel: Copy + Clone {
type Subpixel: Primitive;
}
pub trait Primitive: Copy + PartialOrd<Self> + Clone {
}
impl<P, Container> GenericImage for ImageBuffer<P, Container>
where P: Pixel + 'static,
Container: Deref<Target=[P::Subpixel]> + DerefMut,
P::Subpixel: 'static {
type Pixel = P;
}
impl Primitive for u8 { }
impl<P, Container> ImageBuffer<P, Container>
where P: Pixel + 'static,
P::Subpixel: 'static,
Container: Deref<Target=[P::Subpixel]>
{
pub fn pixels<'a>(&'a self) -> Pixels<'a, Self> {
loop { }
}
pub fn pixels_mut(&mut self) -> PixelsMut<P> {
loop { }
}
}
pub struct Pixels<'a, I: 'a> {
image: &'a I,
x: u32,
y: u32,
width: u32,
height: u32
}
impl<'a, I: GenericImage> Iterator for Pixels<'a, I> {
type Item = (u32, u32, I::Pixel);
fn next(&mut self) -> Option<(u32, u32, I::Pixel)> {
loop { }
}
}
pub struct PixelsMut<'a, P: Pixel + 'a> where P::Subpixel: 'a {
chunks: &'a mut P::Subpixel
}
impl<'a, P: Pixel + 'a> Iterator for PixelsMut<'a, P> where P::Subpixel: 'a {
type Item = &'a mut P;
fn next(&mut self) -> Option<&'a mut P> {
loop { }
}
}
pub fn index_colors<Pix>(image: &ImageBuffer<Pix, Vec<u8>>)
-> ImageBuffer<Luma<u8>, Vec<u8>>
where Pix: Pixel<Subpixel=u8> + 'static,
{
// When NLL-enabled, `let mut` below is deemed unnecessary (due to
// the remaining code being unreachable); so ignore that lint.
#![allow(unused_mut)]
let mut indices: ImageBuffer<_,Vec<_>> = loop { };
for (pixel, idx) in image.pixels().zip(indices.pixels_mut()) {
// failure occurred here ^^ because we were requiring that we
// could project Pixel or Subpixel from `T_indices` (type of
// `indices`), but the type is insufficiently constrained
// until we reach the return below.
}
indices
}
fn main() { }
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