ICE: dyn_star during const eval

[matthiaskrgr]

Code

code from #102544

#![feature(dyn_star)]
#![allow(incomplete_features)]

use core::fmt::Debug;

fn main() {
    let foo = &3;
    let i = foo as dyn* Debug;
}

Meta

rustc --version --verbose:

rustc 1.68.0-nightly (935dc0721 2022-12-19)
binary: rustc
commit-hash: 935dc07218b4bf6e20231e44eb9263b612fd649b
commit-date: 2022-12-19
host: x86_64-unknown-linux-gnu
release: 1.68.0-nightly
LLVM version: 15.0.6

Error output

<output>

Backtrace

Preparing a sysroot for Miri (target: x86_64-unknown-linux-gnu)... done
WARNING: Ignoring `RUSTC_WRAPPER` environment variable, Miri does not support wrapping.
    Finished dev [unoptimized + debuginfo] target(s) in 0.00s
     Running `/home/matthias/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/cargo-miri runner target/miri/x86_64-unknown-linux-gnu/debug/miri_ice`
warning: unused variable: `i`
 --> src/main.rs:8:9
  |
8 |     let i = foo as dyn* Debug;
  |         ^ help: if this is intentional, prefix it with an underscore: `_i`
  |
  = note: `#[warn(unused_variables)]` on by default

thread 'rustc' panicked at 'called `Option::unwrap()` on a `None` value', /rustc/935dc07218b4bf6e20231e44eb9263b612fd649b/compiler/rustc_const_eval/src/interpret/visitor.rs:533:1
stack backtrace:
   0:     0x7f7547bfea7a - std::backtrace_rs::backtrace::libunwind::trace::h06c3ddb908575635
                               at /rustc/935dc07218b4bf6e20231e44eb9263b612fd649b/library/std/src/../../backtrace/src/backtrace/libunwind.rs:93:5
   1:     0x7f7547bfea7a - std::backtrace_rs::backtrace::trace_unsynchronized::h8bfc3753e1cc3345
                               at /rustc/935dc07218b4bf6e20231e44eb9263b612fd649b/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
   2:     0x7f7547bfea7a - std::sys_common::backtrace::_print_fmt::h3c304feda98d6679
                               at /rustc/935dc07218b4bf6e20231e44eb9263b612fd649b/library/std/src/sys_common/backtrace.rs:65:5
   3:     0x7f7547bfea7a - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::h98af9289a7a29dc2
                               at /rustc/935dc07218b4bf6e20231e44eb9263b612fd649b/library/std/src/sys_common/backtrace.rs:44:22
   4:     0x7f7547c617ae - core::fmt::write::h02538848739b7e2a
                               at /rustc/935dc07218b4bf6e20231e44eb9263b612fd649b/library/core/src/fmt/mod.rs:1208:17
   5:     0x7f7547beef45 - std::io::Write::write_fmt::h4aac2f2c3f0128af
                               at /rustc/935dc07218b4bf6e20231e44eb9263b612fd649b/library/std/src/io/mod.rs:1682:15
   6:     0x7f7547bfe845 - std::sys_common::backtrace::_print::h2e2acfe71f2fdb67
                               at /rustc/935dc07218b4bf6e20231e44eb9263b612fd649b/library/std/src/sys_common/backtrace.rs:47:5
   7:     0x7f7547bfe845 - std::sys_common::backtrace::print::h5bf077c253fab052
                               at /rustc/935dc07218b4bf6e20231e44eb9263b612fd649b/library/std/src/sys_common/backtrace.rs:34:9
   8:     0x7f7547c0158f - std::panicking::default_hook::{{closure}}::h0ceeeedebdf177d0
                               at /rustc/935dc07218b4bf6e20231e44eb9263b612fd649b/library/std/src/panicking.rs:267:22
   9:     0x7f7547c012cb - std::panicking::default_hook::h7d6f04e84940bd1d
                               at /rustc/935dc07218b4bf6e20231e44eb9263b612fd649b/library/std/src/panicking.rs:286:9
  10:     0x7f7546a40511 - rustc_driver[3622bb61b1ebe64a]::DEFAULT_HOOK::{closure#0}::{closure#0}
  11:     0x7f7547c01dcd - <alloc::boxed::Box<F,A> as core::ops::function::Fn<Args>>::call::hc60f5ae29562b326
                               at /rustc/935dc07218b4bf6e20231e44eb9263b612fd649b/library/alloc/src/boxed.rs:2032:9
  12:     0x7f7547c01dcd - std::panicking::rust_panic_with_hook::hce0f8648dbfb386b
                               at /rustc/935dc07218b4bf6e20231e44eb9263b612fd649b/library/std/src/panicking.rs:692:13
  13:     0x7f7547c01b02 - std::panicking::begin_panic_handler::{{closure}}::h6ffcdb3a218d0ebe
                               at /rustc/935dc07218b4bf6e20231e44eb9263b612fd649b/library/std/src/panicking.rs:577:13
  14:     0x7f7547bfef2c - std::sys_common::backtrace::__rust_end_short_backtrace::hc576a427f61fdaa5
                               at /rustc/935dc07218b4bf6e20231e44eb9263b612fd649b/library/std/src/sys_common/backtrace.rs:137:18
  15:     0x7f7547c01852 - rust_begin_unwind
                               at /rustc/935dc07218b4bf6e20231e44eb9263b612fd649b/library/std/src/panicking.rs:575:5
  16:     0x7f7547c5e193 - core::panicking::panic_fmt::habc1ee4a9702013e
                               at /rustc/935dc07218b4bf6e20231e44eb9263b612fd649b/library/core/src/panicking.rs:64:14
  17:     0x7f7547c5e26d - core::panicking::panic::h73f802489c27713b
                               at /rustc/935dc07218b4bf6e20231e44eb9263b612fd649b/library/core/src/panicking.rs:111:5
  18:     0x559b24a3b580 - <rustc_const_eval[60209f501fc07249]::interpret::validity::ValidityVisitor<miri[df45d2962384a2a4]::machine::MiriMachine> as rustc_const_eval[60209f501fc07249]::interpret::visitor::ValueVisitor<miri[df45d2962384a2a4]::machine::MiriMachine>>::walk_value
  19:     0x559b2496f434 - <rustc_const_eval[60209f501fc07249]::interpret::eval_context::InterpCx<miri[df45d2962384a2a4]::machine::MiriMachine>>::validate_operand_internal
  20:     0x559b249691dd - <rustc_const_eval[60209f501fc07249]::interpret::eval_context::InterpCx<miri[df45d2962384a2a4]::machine::MiriMachine>>::cast
  21:     0x559b2496a5c7 - <rustc_const_eval[60209f501fc07249]::interpret::eval_context::InterpCx<miri[df45d2962384a2a4]::machine::MiriMachine>>::eval_rvalue_into_place
  22:     0x559b24993178 - <rustc_const_eval[60209f501fc07249]::interpret::eval_context::InterpCx<miri[df45d2962384a2a4]::machine::MiriMachine> as miri[df45d2962384a2a4]::concurrency::thread::EvalContextExt>::run_threads
  23:     0x559b24a40e1d - miri[df45d2962384a2a4]::eval::eval_entry
  24:     0x559b2489c0e4 - <rustc_interface[299971c75fff0058]::passes::QueryContext>::enter::<<miri[2cc0a1151e659598]::MiriCompilerCalls as rustc_driver[3622bb61b1ebe64a]::Callbacks>::after_analysis::{closure#0}, ()>
  25:     0x559b248a1263 - <miri[2cc0a1151e659598]::MiriCompilerCalls as rustc_driver[3622bb61b1ebe64a]::Callbacks>::after_analysis
  26:     0x7f7545cd1661 - <rustc_interface[299971c75fff0058]::interface::Compiler>::enter::<rustc_driver[3622bb61b1ebe64a]::run_compiler::{closure#1}::{closure#2}, core[62c015fcd585be4a]::result::Result<core[62c015fcd585be4a]::option::Option<rustc_interface[299971c75fff0058]::queries::Linker>, rustc_errors[19d12f94925af316]::ErrorGuaranteed>>
  27:     0x7f7545ccc658 - rustc_span[ea560f4838c45ec0]::with_source_map::<core[62c015fcd585be4a]::result::Result<(), rustc_errors[19d12f94925af316]::ErrorGuaranteed>, rustc_interface[299971c75fff0058]::interface::run_compiler<core[62c015fcd585be4a]::result::Result<(), rustc_errors[19d12f94925af316]::ErrorGuaranteed>, rustc_driver[3622bb61b1ebe64a]::run_compiler::{closure#1}>::{closure#0}::{closure#0}>
  28:     0x7f7545ccc145 - <scoped_tls[6f6de2f0677d8068]::ScopedKey<rustc_span[ea560f4838c45ec0]::SessionGlobals>>::set::<rustc_interface[299971c75fff0058]::interface::run_compiler<core[62c015fcd585be4a]::result::Result<(), rustc_errors[19d12f94925af316]::ErrorGuaranteed>, rustc_driver[3622bb61b1ebe64a]::run_compiler::{closure#1}>::{closure#0}, core[62c015fcd585be4a]::result::Result<(), rustc_errors[19d12f94925af316]::ErrorGuaranteed>>
  29:     0x7f7545ccb732 - std[688abfdbcfe52504]::sys_common::backtrace::__rust_begin_short_backtrace::<rustc_interface[299971c75fff0058]::util::run_in_thread_pool_with_globals<rustc_interface[299971c75fff0058]::interface::run_compiler<core[62c015fcd585be4a]::result::Result<(), rustc_errors[19d12f94925af316]::ErrorGuaranteed>, rustc_driver[3622bb61b1ebe64a]::run_compiler::{closure#1}>::{closure#0}, core[62c015fcd585be4a]::result::Result<(), rustc_errors[19d12f94925af316]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[62c015fcd585be4a]::result::Result<(), rustc_errors[19d12f94925af316]::ErrorGuaranteed>>
  30:     0x7f7546303aba - <<std[688abfdbcfe52504]::thread::Builder>::spawn_unchecked_<rustc_interface[299971c75fff0058]::util::run_in_thread_pool_with_globals<rustc_interface[299971c75fff0058]::interface::run_compiler<core[62c015fcd585be4a]::result::Result<(), rustc_errors[19d12f94925af316]::ErrorGuaranteed>, rustc_driver[3622bb61b1ebe64a]::run_compiler::{closure#1}>::{closure#0}, core[62c015fcd585be4a]::result::Result<(), rustc_errors[19d12f94925af316]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[62c015fcd585be4a]::result::Result<(), rustc_errors[19d12f94925af316]::ErrorGuaranteed>>::{closure#1} as core[62c015fcd585be4a]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  31:     0x7f7547c0bdc3 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h16c8b1a5112fc07f
                               at /rustc/935dc07218b4bf6e20231e44eb9263b612fd649b/library/alloc/src/boxed.rs:2000:9
  32:     0x7f7547c0bdc3 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h0cc5ff4fc4b4dcff
                               at /rustc/935dc07218b4bf6e20231e44eb9263b612fd649b/library/alloc/src/boxed.rs:2000:9
  33:     0x7f7547c0bdc3 - std::sys::unix::thread::Thread::new::thread_start::ha7c6dff74603472f
                               at /rustc/935dc07218b4bf6e20231e44eb9263b612fd649b/library/std/src/sys/unix/thread.rs:108:17
  34:     0x7f754355d8fd - <unknown>
  35:     0x7f75435dfa60 - <unknown>
  36:                0x0 - <unknown>

error: internal compiler error: unexpected panic

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 1.68.0-nightly (935dc0721 2022-12-19) running on x86_64-unknown-linux-gnu

note: compiler flags: --crate-type bin -C embed-bitcode=no -C debuginfo=2 -C incremental=[REDACTED] -C target-cpu=native

note: some of the compiler flags provided by cargo are hidden

query stack during panic:
end of query stack

Miri caused an ICE during evaluation. Here's the interpreter backtrace at the time of the panic:
note: the place in the program where the ICE was triggered
 --> src/main.rs:8:13
  |
8 |     let i = foo as dyn* Debug;
  |             ^^^
  |
  = note: inside `main` at src/main.rs:8:13: 8:16
  = note: inside `<fn() as std::ops::FnOnce<()>>::call_once - shim(fn())` at /home/matthias/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/ops/function.rs:507:5: 507:71
  = note: inside `std::sys_common::backtrace::__rust_begin_short_backtrace::<fn(), ()>` at /home/matthias/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/sys_common/backtrace.rs:121:18: 121:21
  = note: inside closure at /home/matthias/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/rt.rs:166:18: 166:82
  = note: inside `std::ops::function::impls::<impl std::ops::FnOnce<()> for &dyn std::ops::Fn() -> i32 + std::marker::Sync + std::panic::RefUnwindSafe>::call_once` at /home/matthias/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/ops/function.rs:606:13: 606:31
  = note: inside `std::panicking::r#try::do_call::<&dyn std::ops::Fn() -> i32 + std::marker::Sync + std::panic::RefUnwindSafe, i32>` at /home/matthias/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/panicking.rs:483:40: 483:43
  = note: inside `std::panicking::r#try::<i32, &dyn std::ops::Fn() -> i32 + std::marker::Sync + std::panic::RefUnwindSafe>` at /home/matthias/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/panicking.rs:447:19: 447:81
  = note: inside `std::panic::catch_unwind::<&dyn std::ops::Fn() -> i32 + std::marker::Sync + std::panic::RefUnwindSafe, i32>` at /home/matthias/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/panic.rs:137:14: 137:33
  = note: inside closure at /home/matthias/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/rt.rs:148:48: 148:73
  = note: inside `std::panicking::r#try::do_call::<[closure@std::rt::lang_start_internal::{closure#2}], isize>` at /home/matthias/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/panicking.rs:483:40: 483:43
  = note: inside `std::panicking::r#try::<isize, [closure@std::rt::lang_start_internal::{closure#2}]>` at /home/matthias/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/panicking.rs:447:19: 447:81
  = note: inside `std::panic::catch_unwind::<[closure@std::rt::lang_start_internal::{closure#2}], isize>` at /home/matthias/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/panic.rs:137:14: 137:33
  = note: inside `std::rt::lang_start_internal` at /home/matthias/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/rt.rs:148:20: 148:98
  = note: inside `std::rt::lang_start::<()>` at /home/matthias/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/rt.rs:165:17: 170:6

warning: 1 warning emitted

[compiler-errors]

Since this is a miri-related ICE you're filing against the rust-lang/rust repo, it might be best to not assume people know how to reproduce this. Can you leave repro instructions for people familiar with rustc development?

[matthiaskrgr]

Basically cargo new, copy code into src/main.rs and cargo miri run which will reproduce the ICE.

I think once you have the miri component via rustup, the initial cargo miri run should also run the necessary cargo miri setup on its own.
https://github.com/rust-lang/miri#using-miri

[oli-obk]

Most such issues are reproducible with the const evaluator, too:

#![feature(dyn_star)]
#![allow(incomplete_features)]

use core::fmt::Debug;

const FOO: () = {
    let foo = &3;
    let i = foo as dyn* Debug;
};

[Alexendoo]

Fixed by #109921 / #107728