Closed
Description
Code
#![feature(adt_const_params, generic_const_exprs)]
#![allow(incomplete_features)]
mod lib {
const N_ISLANDS: usize = 4;
const N_BRIDGES: usize = 7;
const BRIDGES: [(usize, usize); 7] = [(0, 1), (0, 1), (0, 2), (0, 3), (0, 3), (1, 2), (2, 3)];
pub type Matrix = [[usize; N_ISLANDS]; N_ISLANDS];
const EMPTY_MATRIX: Matrix = [[0; N_ISLANDS]; N_ISLANDS];
const fn build(mut matrix: Matrix, (to, from): (usize, usize)) -> Matrix {
matrix[to][from] += 1;
matrix[from][to] += 1;
matrix
}
pub const fn walk(mut matrix: Matrix, from: usize, to: usize) -> Matrix {
matrix[from][to] -= 1;
matrix[to][from] -= 1;
matrix
}
const fn to_matrix(bridges: [(usize, usize); N_BRIDGES]) -> Matrix {
let matrix = EMPTY_MATRIX;
let matrix = build(matrix, bridges[0]);
let matrix = build(matrix, bridges[1]);
let matrix = build(matrix, bridges[2]);
let matrix = build(matrix, bridges[3]);
let matrix = build(matrix, bridges[4]);
let matrix = build(matrix, bridges[5]);
let matrix = build(matrix, bridges[6]);
matrix
}
const BRIDGE_MATRIX: [[usize; N_ISLANDS]; N_ISLANDS] = to_matrix(BRIDGES);
pub struct Walk<const CURRENT: usize, const REMAINING: Matrix> {
_p: (),
}
impl Walk<0, BRIDGE_MATRIX> {
pub const fn new() -> Self {
Self { _p: () }
}
}
impl<const CURRENT: usize, const REMAINING: Matrix> Walk<CURRENT, REMAINING> {
pub fn proceed_to<const NEXT: usize>(
self,
) -> Walk<NEXT, { walk(REMAINING, CURRENT, NEXT) }> {
Walk { _p: () }
}
}
pub struct Trophy {
_p: (),
}
impl<const CURRENT: usize> Walk<CURRENT, EMPTY_MATRIX> {
pub fn collect_prize(self) -> Trophy {
Trophy { _p: () }
}
}
}
pub use lib::{Trophy, Walk};
fn main() {
// Example, taking the first step
let _ = Walk::new().proceed_to::<1>();
// Don't be so eager to collect the trophy
// let trophy = Walk::new()
// .proceed_to::<1>()
// .proceed_to::<0>()
// .collect_prize();
// Can't just make a Trophy out of thin air, you must earn it
// let trophy: Trophy = Trophy { _p: () };
// Can you collect the Trophy?
}Note that this does not occur if you replace N_ISLAND with hard-coded values
https://play.rust-lang.org/?version=nightly&mode=debug&edition=2021&gist=448c65a5c73a76d832c510cfe8e269bc
Meta
rustc --version --verbose:
rustc 1.62.0-nightly (a5ad0d29a 2022-05-12)
binary: rustc
commit-hash: a5ad0d29a401007b51715852cc702e441ac2248c
commit-date: 2022-05-12
host: x86_64-unknown-linux-gnu
release: 1.62.0-nightly
LLVM version: 14.0.1
Error output
error: internal compiler error: no errors encountered even though `delay_span_bug` issued
error: internal compiler error: cannot relate constants of different types: [[usize; 4]; 4] != [[usize; _]; _]
|
= note: delayed at /rustc/a5ad0d29a401007b51715852cc702e441ac2248c/compiler/rustc_middle/src/ty/relate.rs:586:29
thread 'rustc' panicked at 'Box<dyn Any>', compiler/rustc_errors/src/lib.rs:1369:13
stack backtrace:
0: 0x7fc2d402ef4d - std::backtrace_rs::backtrace::libunwind::trace::h422c4077f8744b89
at /rustc/a5ad0d29a401007b51715852cc702e441ac2248c/library/std/src/../../backtrace/src/backtrace/libunwind.rs:93:5
1: 0x7fc2d402ef4d - std::backtrace_rs::backtrace::trace_unsynchronized::hcccf40e0ba174c1f
at /rustc/a5ad0d29a401007b51715852cc702e441ac2248c/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
2: 0x7fc2d402ef4d - std::sys_common::backtrace::_print_fmt::h24f1d3a1e85b1a8c
at /rustc/a5ad0d29a401007b51715852cc702e441ac2248c/library/std/src/sys_common/backtrace.rs:66:5
3: 0x7fc2d402ef4d - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::h3f1c8f1337fe72ac
at /rustc/a5ad0d29a401007b51715852cc702e441ac2248c/library/std/src/sys_common/backtrace.rs:45:22
4: 0x7fc2d408abdc - core::fmt::write::h983f1d8ba31b3bfc
at /rustc/a5ad0d29a401007b51715852cc702e441ac2248c/library/core/src/fmt/mod.rs:1196:17
5: 0x7fc2d40206d1 - std::io::Write::write_fmt::h8846f6583b6c4f19
at /rustc/a5ad0d29a401007b51715852cc702e441ac2248c/library/std/src/io/mod.rs:1654:15
6: 0x7fc2d4031c65 - std::sys_common::backtrace::_print::h32315dd1001d90fe
at /rustc/a5ad0d29a401007b51715852cc702e441ac2248c/library/std/src/sys_common/backtrace.rs:48:5
7: 0x7fc2d4031c65 - std::sys_common::backtrace::print::heeb247c299d00082
at /rustc/a5ad0d29a401007b51715852cc702e441ac2248c/library/std/src/sys_common/backtrace.rs:35:9
8: 0x7fc2d4031c65 - std::panicking::default_hook::{{closure}}::h37d2e0f8d04e2807
at /rustc/a5ad0d29a401007b51715852cc702e441ac2248c/library/std/src/panicking.rs:295:22
9: 0x7fc2d40318d9 - std::panicking::default_hook::h7d44d6054314ffd4
at /rustc/a5ad0d29a401007b51715852cc702e441ac2248c/library/std/src/panicking.rs:314:9
10: 0x7fc2d47f5fc1 - rustc_driver[66b06878ed46bf5e]::DEFAULT_HOOK::{closure#0}::{closure#0}
11: 0x7fc2d4032436 - std::panicking::rust_panic_with_hook::hbe27fc2544734249
at /rustc/a5ad0d29a401007b51715852cc702e441ac2248c/library/std/src/panicking.rs:702:17
12: 0x7fc2d5966731 - std[d36776c608d00fa8]::panicking::begin_panic::<rustc_errors[36b154f54aa4db46]::ExplicitBug>::{closure#0}
13: 0x7fc2d5965526 - std[d36776c608d00fa8]::sys_common::backtrace::__rust_end_short_backtrace::<std[d36776c608d00fa8]::panicking::begin_panic<rustc_errors[36b154f54aa4db46]::ExplicitBug>::{closure#0}, !>
14: 0x7fc2d59774a6 - std[d36776c608d00fa8]::panicking::begin_panic::<rustc_errors[36b154f54aa4db46]::ExplicitBug>
15: 0x7fc2d597b576 - std[d36776c608d00fa8]::panic::panic_any::<rustc_errors[36b154f54aa4db46]::ExplicitBug>
16: 0x7fc2d7133c31 - <rustc_errors[36b154f54aa4db46]::HandlerInner as core[243e706900b6a3ef]::ops::drop::Drop>::drop
17: 0x7fc2d6886578 - core[243e706900b6a3ef]::ptr::drop_in_place::<rustc_session[47fb6eda20aa98eb]::parse::ParseSess>
18: 0x7fc2d68887e3 - <alloc[adcee9b7ba6963a2]::rc::Rc<rustc_session[47fb6eda20aa98eb]::session::Session> as core[243e706900b6a3ef]::ops::drop::Drop>::drop
19: 0x7fc2d68854ed - core[243e706900b6a3ef]::ptr::drop_in_place::<rustc_interface[6d9aef74e1383607]::interface::Compiler>
20: 0x7fc2d6884de4 - rustc_span[f40da2bae013e884]::with_source_map::<core[243e706900b6a3ef]::result::Result<(), rustc_errors[36b154f54aa4db46]::ErrorGuaranteed>, rustc_interface[6d9aef74e1383607]::interface::create_compiler_and_run<core[243e706900b6a3ef]::result::Result<(), rustc_errors[36b154f54aa4db46]::ErrorGuaranteed>, rustc_driver[66b06878ed46bf5e]::run_compiler::{closure#1}>::{closure#1}>
21: 0x7fc2d6870524 - rustc_interface[6d9aef74e1383607]::interface::create_compiler_and_run::<core[243e706900b6a3ef]::result::Result<(), rustc_errors[36b154f54aa4db46]::ErrorGuaranteed>, rustc_driver[66b06878ed46bf5e]::run_compiler::{closure#1}>
22: 0x7fc2d685aab2 - <scoped_tls[13ae6aa9ead709d8]::ScopedKey<rustc_span[f40da2bae013e884]::SessionGlobals>>::set::<rustc_interface[6d9aef74e1383607]::interface::run_compiler<core[243e706900b6a3ef]::result::Result<(), rustc_errors[36b154f54aa4db46]::ErrorGuaranteed>, rustc_driver[66b06878ed46bf5e]::run_compiler::{closure#1}>::{closure#0}, core[243e706900b6a3ef]::result::Result<(), rustc_errors[36b154f54aa4db46]::ErrorGuaranteed>>
23: 0x7fc2d6871bcf - std[d36776c608d00fa8]::sys_common::backtrace::__rust_begin_short_backtrace::<rustc_interface[6d9aef74e1383607]::util::run_in_thread_pool_with_globals<rustc_interface[6d9aef74e1383607]::interface::run_compiler<core[243e706900b6a3ef]::result::Result<(), rustc_errors[36b154f54aa4db46]::ErrorGuaranteed>, rustc_driver[66b06878ed46bf5e]::run_compiler::{closure#1}>::{closure#0}, core[243e706900b6a3ef]::result::Result<(), rustc_errors[36b154f54aa4db46]::ErrorGuaranteed>>::{closure#0}, core[243e706900b6a3ef]::result::Result<(), rustc_errors[36b154f54aa4db46]::ErrorGuaranteed>>
24: 0x7fc2d6871d09 - <<std[d36776c608d00fa8]::thread::Builder>::spawn_unchecked_<rustc_interface[6d9aef74e1383607]::util::run_in_thread_pool_with_globals<rustc_interface[6d9aef74e1383607]::interface::run_compiler<core[243e706900b6a3ef]::result::Result<(), rustc_errors[36b154f54aa4db46]::ErrorGuaranteed>, rustc_driver[66b06878ed46bf5e]::run_compiler::{closure#1}>::{closure#0}, core[243e706900b6a3ef]::result::Result<(), rustc_errors[36b154f54aa4db46]::ErrorGuaranteed>>::{closure#0}, core[243e706900b6a3ef]::result::Result<(), rustc_errors[36b154f54aa4db46]::ErrorGuaranteed>>::{closure#1} as core[243e706900b6a3ef]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
25: 0x7fc2d403c353 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::hca3fa30b248623a6
at /rustc/a5ad0d29a401007b51715852cc702e441ac2248c/library/alloc/src/boxed.rs:1872:9
26: 0x7fc2d403c353 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h4df27390e550c728
at /rustc/a5ad0d29a401007b51715852cc702e441ac2248c/library/alloc/src/boxed.rs:1872:9
27: 0x7fc2d403c353 - std::sys::unix::thread::Thread::new::thread_start::h02c78c50592aaddf
at /rustc/a5ad0d29a401007b51715852cc702e441ac2248c/library/std/src/sys/unix/thread.rs:108:17
28: 0x7fc2d3f54609 - start_thread
at /build/glibc-sMfBJT/glibc-2.31/nptl/pthread_create.c:477:8
29: 0x7fc2d3e6d163 - clone
at /build/glibc-sMfBJT/glibc-2.31/misc/../sysdeps/unix/sysv/linux/x86_64/clone.S:95
30: 0x0 - <unknown>
note: the compiler unexpectedly panicked. this is a bug.
note: we would appreciate a bug report: https://github.com/rust-lang/rust/issues/new?labels=C-bug%2C+I-ICE%2C+T-compiler&template=ice.md
note: rustc 1.62.0-nightly (a5ad0d29a 2022-05-12) running on x86_64-unknown-linux-gnu
note: compiler flags: --crate-type bin -C embed-bitcode=no -C debuginfo=2 -C incremental
note: some of the compiler flags provided by cargo are hidden
query stack during panic:
end of query stack
Backtrace
error: internal compiler error: no errors encountered even though `delay_span_bug` issued
error: internal compiler error: cannot relate constants of different types: [[usize; 4]; 4] != [[usize; _]; _]
|
= note: delayed at /rustc/a5ad0d29a401007b51715852cc702e441ac2248c/compiler/rustc_middle/src/ty/relate.rs:586:29
thread 'rustc' panicked at 'Box<dyn Any>', compiler/rustc_errors/src/lib.rs:1369:13
stack backtrace:
0: std::panicking::begin_panic::<rustc_errors::ExplicitBug>
1: std::panic::panic_any::<rustc_errors::ExplicitBug>
2: <rustc_errors::HandlerInner as core::ops::drop::Drop>::drop
3: core::ptr::drop_in_place::<rustc_session::parse::ParseSess>
4: <alloc::rc::Rc<rustc_session::session::Session> as core::ops::drop::Drop>::drop
5: core::ptr::drop_in_place::<rustc_interface::interface::Compiler>
6: rustc_span::with_source_map::<core::result::Result<(), rustc_errors::ErrorGuaranteed>, rustc_interface::interface::create_compiler_and_run<core::result::Result<(), rustc_errors::ErrorGuaranteed>, rustc_driver::run_compiler::{closure#1}>::{closure#1}>
7: rustc_interface::interface::create_compiler_and_run::<core::result::Result<(), rustc_errors::ErrorGuaranteed>, rustc_driver::run_compiler::{closure#1}>
8: <scoped_tls::ScopedKey<rustc_span::SessionGlobals>>::set::<rustc_interface::interface::run_compiler<core::result::Result<(), rustc_errors::ErrorGuaranteed>, rustc_driver::run_compiler::{closure#1}>::{closure#0}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.
note: the compiler unexpectedly panicked. this is a bug.
note: we would appreciate a bug report: https://github.com/rust-lang/rust/issues/new?labels=C-bug%2C+I-ICE%2C+T-compiler&template=ice.md
note: rustc 1.62.0-nightly (a5ad0d29a 2022-05-12) running on x86_64-unknown-linux-gnu
note: compiler flags: --crate-type bin -C embed-bitcode=no -C debuginfo=2 -C incremental
note: some of the compiler flags provided by cargo are hidden
query stack during panic:
end of query stack