ICE with const generics: llvm failed to get layout for [i32; _] #61936
Description
Hi, I'm trying to learn how to use the new const generics stuff and I ICEd the compiler. Here's the code:
#![feature(const_generics)] trait SliceExt<T: Clone> { fn array_windows<'a, const N: usize>(&'a self) -> ArrayWindows<'a, T, {N}>; } impl <T: Clone> SliceExt<T> for [T] { fn array_windows<'a, const N: usize>(&'a self) -> ArrayWindows<'a, T, {N}> { ArrayWindows{ idx: 0, slice: &self } } } struct ArrayWindows<'a, T, const N: usize> { slice: &'a [T], idx: usize, } impl <'a, T: Clone, const N: usize> Iterator for ArrayWindows<'a, T, {N}> { type Item = [T; N]; fn next(&mut self) -> Option<Self::Item> { let mut res = unsafe{ std::mem::zeroed() }; let mut ptr = &mut res as *mut [T; N] as *mut T; for i in 0..N { match self.slice[i..].get(i) { None => return None, Some(elem) => unsafe { std::ptr::write_volatile(ptr, elem.clone())}, }; ptr = ptr.wrapping_add(1); self.idx += 1; } Some(res) } } const FOUR: usize = 4; fn main() { let v = vec![100; 0usize]; for array in v.as_slice().array_windows::<{FOUR}>() { // println!("{:?}", array); } } I can't give you the verbose compiler info because this was done on play.rust-lang.org but here's the version:
note: rustc 1.37.0-nightly (b25ee6449 2019-06-17) running on x86_64-unknown-linux-gnu note: compiler flags: -C codegen-units=1 -C debuginfo=2 --crate-type bin