Code change:
<ins> error[E0261]: use of undeclared lifetime name `'a` --> $DIR/ice-unexpected-inference-var-122549.rs:5:70 | LL |     fn const_chunks_exact<const N: usize>(&self) -> ConstChunksExact<'a, T, { N }>; |                                                                      ^^ undeclared lifetime | help: consider introducing lifetime `'a` here | LL |     fn const_chunks_exact<'a, const N: usize>(&self) -> ConstChunksExact<'a, T, { N }>; |                           +++ help: consider introducing lifetime `'a` here | LL | trait ConstChunksExactTrait<'a, T> { |                             +++ error[E0261]: use of undeclared lifetime name `'a` --> $DIR/ice-unexpected-inference-var-122549.rs:11:34 | LL | struct ConstChunksExact<'rem, T: 'a, const N: usize> {} |                         -        ^^ undeclared lifetime |                         | |                         help: consider introducing lifetime `'a` here: `'a,` error[E0046]: not all trait items implemented, missing: `const_chunks_exact` --> $DIR/ice-unexpected-inference-var-122549.rs:9:1 | LL |     fn const_chunks_exact<const N: usize>(&self) -> ConstChunksExact<'a, T, { N }>; |     ------------------------------------------------------------------------------- `const_chunks_exact` from trait ... LL | impl<T> ConstChunksExactTrait<T> for [T] {} | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ missing `const_chunks_exact` in implementation error[E0392]: lifetime parameter `'rem` is never used --> $DIR/ice-unexpected-inference-var-122549.rs:11:25 | LL | struct ConstChunksExact<'rem, T: 'a, const N: usize> {} |                         ^^^^ unused lifetime parameter | = help: consider removing `'rem`, referring to it in a field, or using a marker such as `PhantomData` error[E0392]: type parameter `T` is never used --> $DIR/ice-unexpected-inference-var-122549.rs:11:31 | LL | struct ConstChunksExact<'rem, T: 'a, const N: usize> {} |                               ^ unused type parameter | = help: consider removing `T`, referring to it in a field, or using a marker such as `PhantomData` error[E0207]: the const parameter `N` is not constrained by the impl trait, self type, or predicates --> $DIR/ice-unexpected-inference-var-122549.rs:15:13 | LL | impl<'a, T, const N: usize> Iterator for ConstChunksExact<'a, T, {}> { |             ^^^^^^^^^^^^^^ unconstrained const parameter | = note: expressions using a const parameter must map each value to a distinct output value = note: proving the result of expressions other than the parameter are unique is not supported error[E0308]: mismatched types --> $DIR/ice-unexpected-inference-var-122549.rs:15:66 | LL | impl<'a, T, const N: usize> Iterator for ConstChunksExact<'a, T, {}> { |                                                                  ^^ expected `usize`, found `()` error: aborting due to 7 previous errors Some errors have detailed explanations: E0046, E0207, E0261, E0308, E0392. For more information about an error, try `rustc --explain E0046`. </ins>

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text: ?0c: usize]stack backtrace: 0: 0x7ff8073a4912 - std::backtracers::backtrace::libunwind::trace::h2da6c6ec1776ed1b at 1: 0x7ff8073a4912 - std::backtracers::backtrace::traceunsynchronized::h0cb696e9cf0107ba at 2: 0x7ff8073a4912 - std::syscommon::backtrace::printfmt::hfb11ed7a7d38a028 at 3: 0x7ff8073a4912 - <std::syscommon::backtrace::print::DisplayBacktrace as core::fmt::Display::fmt::h1048d052a888b26c at 4: 0x7ff8073f5c8c - core::fmt::rt::Argument::fmt::hcf8265a03a389e34 at 5: 0x7ff8073f5c8c - core::fmt::write::hd12c3a84e62e1cec at 6: 0x7ff80739980f - std::io::Write::writefmt::h236993be0d5d91de at 7: 0x7ff8073a46e4 - std::syscommon::backtrace::print::he44e9b7b149d34c3 at 8: 0x7ff8073a46e4 - std::syscommon::backtrace::print::h6f8e8e3b9f052551 at 9: 0x7ff8073a73eb - std::panicking::defaulthook::{{closure}}::h321d04c9179dccca 10: 0x7ff8073a7143 - std::panicking::defaulthook::hd949d1362c2e5565 at 11: 0x7ff803fa68ef - std[]::panicking::updatehook::<alloc[]::boxed::Box<rustcdriverimpl[]::installicehook::{closure}::{closure} 12: 0x7ff8073a7b50 - <alloc::boxed::Box<F,