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ICE on unmonomorphized const generics in const eval: eval_const_to_op: Unexpected ConstKind #72819
Description
Amusingly the following ICEs while https://play.rust-lang.org/?version=nightly&mode=debug&edition=2018&gist=67ee1b8218865042e272d1c2c1aa22fe has a compiler error that hints at the const generic actually getting resolved.
#![feature(const_generics)]
#![allow(incomplete_features)]
struct Arr<const N: usize>
where Assert::<{N < usize::max_value() / 2}>: IsTrue,
{
}
enum Assert<const CHECK: bool> {}
trait IsTrue {}
impl IsTrue for Assert<true> {}
fn main() {
let x: Arr<{usize::max_value()}> = Arr {};
}Errors:
Compiling playground v0.0.1 (/playground)
error: internal compiler error: src/librustc_mir/interpret/operand.rs:548: eval_const_to_op: Unexpected ConstKind Const { ty: usize, val: Bound(DebruijnIndex(0), 0) }
thread 'rustc' panicked at 'Box<Any>', src/librustc_errors/lib.rs:907:9
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
note: the compiler unexpectedly panicked. this is a bug.
note: we would appreciate a bug report: https://github.com/rust-lang/rust/blob/master/CONTRIBUTING.md#bug-reports
note: rustc 1.45.0-nightly (74e804683 2020-05-30) running on x86_64-unknown-linux-gnu
note: compiler flags: -C embed-bitcode=no -C codegen-units=1 -C debuginfo=2 --crate-type bin
note: some of the compiler flags provided by cargo are hidden
error: aborting due to previous error
error: could not compile `playground`.
To learn more, run the command again with --verbose.
Activity
jonas-schievink commentedon May 31, 2020
Also happens on stable without the feature gate
JohnTitor commentedon Jun 6, 2020
Triage: This is no longer ICE and emits an error correctly by #70107. Marking as E-needs-test.
fixup! Add regression test for const generic ICE in rust-lang#72819
fixup! Add regression test for const generic ICE in rust-lang#72819
fixup! Add regression test for const generic ICE in rust-lang#72819
Add regression test for const generic ICE in rust-lang#72819
Rollup merge of rust-lang#73070 - ayazhafiz:i/72819, r=nikomatsakis