ice: SizeOf MIR operator called for unsized type dyn Debug

[matthiaskrgr]

Code

rustc --edition=2021 file.rs

#![feature(generic_const_exprs)]

use core::fmt::Debug;

struct Inline<T>
where
    [u8; ::core::mem::size_of::<T>() + 1]:,
{
    _phantom: PhantomData<T>,
}

fn main() {
    let dst = Inline::<dyn Debug>::new(0); // BANG!
}

Meta

rustc --version --verbose:

rustc 1.73.0-nightly (d190d9786 2023-08-09)
binary: rustc
commit-hash: d190d978649a9bee690ab7d489b59e4c3a78dee4
commit-date: 2023-08-09
host: x86_64-unknown-linux-gnu
release: 1.73.0-nightly
LLVM version: 17.0.0

Error output

error[E0412]: cannot find type `PhantomData` in this scope
 --> treereduce.out:9:15
  |
9 |     _phantom: PhantomData<T>,
  |               ^^^^^^^^^^^ not found in this scope
  |
help: consider importing one of these items
  |
3 + use core::marker::PhantomData;
  |
3 + use std::marker::PhantomData;
  |

warning: the feature `generic_const_exprs` is incomplete and may not be safe to use and/or cause compiler crashes
 --> treereduce.out:1:12
  |
1 | #![feature(generic_const_exprs)]
  |            ^^^^^^^^^^^^^^^^^^^
  |
  = note: see issue #76560 <https://github.com/rust-lang/rust/issues/76560> for more information
  = note: `#[warn(incomplete_features)]` on by default

error[E0599]: no function or associated item named `new` found for struct `Inline` in the current scope
  --> treereduce.out:13:36
   |
5  | struct Inline<T>
   | ---------------- function or associated item `new` not found for this struct
...
13 |     let dst = Inline::<dyn Debug>::new(0); // BANG!
   |                                    ^^^ function or associated item not found in `Inline<dyn Debug>`

Backtrace

error: internal compiler error: compiler/rustc_const_eval/src/interpret/step.rs:272:21: SizeOf MIR operator called for unsized type dyn Debug
   --> /home/matthias/.rustup/toolchains/master/lib/rustlib/src/rust/library/core/src/mem/mod.rs:313:5
    |
313 |     intrinsics::size_of::<T>()
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^

thread 'rustc' panicked at /rustc/d190d978649a9bee690ab7d489b59e4c3a78dee4/compiler/rustc_errors/src/lib.rs:979:33:
Box<dyn Any>
stack backtrace:
   0:     0x7f1cc276451c - std::backtrace_rs::backtrace::libunwind::trace::h2e9aca4a2e5f86d8
                               at /rustc/d190d978649a9bee690ab7d489b59e4c3a78dee4/library/std/src/../../backtrace/src/backtrace/libunwind.rs:93:5
   1:     0x7f1cc276451c - std::backtrace_rs::backtrace::trace_unsynchronized::hceadf256d40c4c78
                               at /rustc/d190d978649a9bee690ab7d489b59e4c3a78dee4/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
   2:     0x7f1cc276451c - std::sys_common::backtrace::_print_fmt::h60f2bef4cb0157c0
                               at /rustc/d190d978649a9bee690ab7d489b59e4c3a78dee4/library/std/src/sys_common/backtrace.rs:67:5
   3:     0x7f1cc276451c - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::h6cea472b207925bd
                               at /rustc/d190d978649a9bee690ab7d489b59e4c3a78dee4/library/std/src/sys_common/backtrace.rs:44:22
   4:     0x7f1cc27c9bec - core::fmt::rt::Argument::fmt::h3d728e2a4afb49e2
                               at /rustc/d190d978649a9bee690ab7d489b59e4c3a78dee4/library/core/src/fmt/rt.rs:138:9
   5:     0x7f1cc27c9bec - core::fmt::write::h150aa7e0125aab4c
                               at /rustc/d190d978649a9bee690ab7d489b59e4c3a78dee4/library/core/src/fmt/mod.rs:1094:21
   6:     0x7f1cc27570ce - std::io::Write::write_fmt::hae7410621843cc88
                               at /rustc/d190d978649a9bee690ab7d489b59e4c3a78dee4/library/std/src/io/mod.rs:1714:15
   7:     0x7f1cc2764304 - std::sys_common::backtrace::_print::h86eb33b34d1dc616
                               at /rustc/d190d978649a9bee690ab7d489b59e4c3a78dee4/library/std/src/sys_common/backtrace.rs:47:5
   8:     0x7f1cc2764304 - std::sys_common::backtrace::print::hb84e0252de442567
                               at /rustc/d190d978649a9bee690ab7d489b59e4c3a78dee4/library/std/src/sys_common/backtrace.rs:34:9
   9:     0x7f1cc27673fa - std::panicking::panic_hook_with_disk_dump::{{closure}}::hd11a41cc902c2e97
                               at /rustc/d190d978649a9bee690ab7d489b59e4c3a78dee4/library/std/src/panicking.rs:278:22
  10:     0x7f1cc27670e7 - std::panicking::panic_hook_with_disk_dump::hbeb280462d2abb1f
                               at /rustc/d190d978649a9bee690ab7d489b59e4c3a78dee4/library/std/src/panicking.rs:312:9
  11:     0x7f1cc5949a59 - rustc_driver_impl[610dbdd3eb094fb1]::install_ice_hook::{closure#0}
  12:     0x7f1cc2767ca0 - <alloc::boxed::Box<F,A> as core::ops::function::Fn<Args>>::call::h73ce24f3c392592f
                               at /rustc/d190d978649a9bee690ab7d489b59e4c3a78dee4/library/alloc/src/boxed.rs:2021:9
  13:     0x7f1cc2767ca0 - std::panicking::rust_panic_with_hook::he76476954ff54d04
                               at /rustc/d190d978649a9bee690ab7d489b59e4c3a78dee4/library/std/src/panicking.rs:733:13
  14:     0x7f1cc5926061 - std[84884ff0985ea275]::panicking::begin_panic::<rustc_errors[9d4dd5a6d4bf62d1]::ExplicitBug>::{closure#0}
  15:     0x7f1cc5924c56 - std[84884ff0985ea275]::sys_common::backtrace::__rust_end_short_backtrace::<std[84884ff0985ea275]::panicking::begin_panic<rustc_errors[9d4dd5a6d4bf62d1]::ExplicitBug>::{closure#0}, !>
  16:     0x7f1cc58fd756 - std[84884ff0985ea275]::panicking::begin_panic::<rustc_errors[9d4dd5a6d4bf62d1]::ExplicitBug>
  17:     0x7f1cc58cb36e - <rustc_errors[9d4dd5a6d4bf62d1]::HandlerInner>::span_bug::<rustc_span[2109ecbc79ac056c]::span_encoding::Span, alloc[431bee5c62997671]::string::String>
  18:     0x7f1cc58cb05f - <rustc_errors[9d4dd5a6d4bf62d1]::Handler>::span_bug::<rustc_span[2109ecbc79ac056c]::span_encoding::Span, alloc[431bee5c62997671]::string::String>
  19:     0x7f1cc58d10fb - rustc_middle[317d0c99bf64221a]::util::bug::opt_span_bug_fmt::<rustc_span[2109ecbc79ac056c]::span_encoding::Span>::{closure#0}
  20:     0x7f1cc58d112a - rustc_middle[317d0c99bf64221a]::ty::context::tls::with_opt::<rustc_middle[317d0c99bf64221a]::util::bug::opt_span_bug_fmt<rustc_span[2109ecbc79ac056c]::span_encoding::Span>::{closure#0}, !>::{closure#0}
  21:     0x7f1cc58d0d78 - rustc_middle[317d0c99bf64221a]::ty::context::tls::with_context_opt::<rustc_middle[317d0c99bf64221a]::ty::context::tls::with_opt<rustc_middle[317d0c99bf64221a]::util::bug::opt_span_bug_fmt<rustc_span[2109ecbc79ac056c]::span_encoding::Span>::{closure#0}, !>::{closure#0}, !>
  22:     0x7f1cc3faf1c4 - rustc_middle[317d0c99bf64221a]::util::bug::span_bug_fmt::<rustc_span[2109ecbc79ac056c]::span_encoding::Span>
  23:     0x7f1cc3f27713 - <rustc_const_eval[81b8e6d870518589]::interpret::eval_context::InterpCx<rustc_const_eval[81b8e6d870518589]::const_eval::machine::CompileTimeInterpreter>>::statement
  24:     0x7f1cc3ecdc19 - rustc_const_eval[81b8e6d870518589]::const_eval::eval_queries::eval_to_allocation_raw_provider
  25:     0x7f1cc3a5e007 - rustc_query_impl[8362d19b71b00d]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[8362d19b71b00d]::query_impl::eval_to_allocation_raw::dynamic_query::{closure#2}::{closure#0}, rustc_middle[317d0c99bf64221a]::query::erase::Erased<[u8; 16usize]>>
  26:     0x7f1cc44333c7 - rustc_query_system[46f106d5b822efb7]::query::plumbing::try_execute_query::<rustc_query_impl[8362d19b71b00d]::DynamicConfig<rustc_query_system[46f106d5b822efb7]::query::caches::DefaultCache<rustc_middle[317d0c99bf64221a]::ty::ParamEnvAnd<rustc_middle[317d0c99bf64221a]::mir::interpret::GlobalId>, rustc_middle[317d0c99bf64221a]::query::erase::Erased<[u8; 16usize]>>, false, false, false>, rustc_query_impl[8362d19b71b00d]::plumbing::QueryCtxt, false>
  27:     0x7f1cc4433049 - rustc_query_impl[8362d19b71b00d]::query_impl::eval_to_allocation_raw::get_query_non_incr::__rust_end_short_backtrace
  28:     0x7f1cc5089909 - rustc_const_eval[81b8e6d870518589]::const_eval::eval_to_valtree
  29:     0x7f1cc50897a0 - <rustc_const_eval[81b8e6d870518589]::provide::{closure#0} as core[1b2a3d848a2ec87d]::ops::function::FnOnce<(rustc_middle[317d0c99bf64221a]::ty::context::TyCtxt, rustc_middle[317d0c99bf64221a]::ty::ParamEnvAnd<rustc_middle[317d0c99bf64221a]::mir::interpret::GlobalId>)>>::call_once
  30:     0x7f1cc4da85e9 - rustc_query_impl[8362d19b71b00d]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[8362d19b71b00d]::query_impl::eval_to_valtree::dynamic_query::{closure#2}::{closure#0}, rustc_middle[317d0c99bf64221a]::query::erase::Erased<[u8; 24usize]>>
  31:     0x7f1cc4da8598 - <rustc_query_impl[8362d19b71b00d]::query_impl::eval_to_valtree::dynamic_query::{closure#2} as core[1b2a3d848a2ec87d]::ops::function::FnOnce<(rustc_middle[317d0c99bf64221a]::ty::context::TyCtxt, rustc_middle[317d0c99bf64221a]::ty::ParamEnvAnd<rustc_middle[317d0c99bf64221a]::mir::interpret::GlobalId>)>>::call_once
  32:     0x7f1cc4f327c5 - rustc_query_system[46f106d5b822efb7]::query::plumbing::try_execute_query::<rustc_query_impl[8362d19b71b00d]::DynamicConfig<rustc_query_system[46f106d5b822efb7]::query::caches::DefaultCache<rustc_middle[317d0c99bf64221a]::ty::ParamEnvAnd<rustc_middle[317d0c99bf64221a]::mir::interpret::GlobalId>, rustc_middle[317d0c99bf64221a]::query::erase::Erased<[u8; 24usize]>>, false, false, false>, rustc_query_impl[8362d19b71b00d]::plumbing::QueryCtxt, false>
  33:     0x7f1cc4f3245e - rustc_query_impl[8362d19b71b00d]::query_impl::eval_to_valtree::get_query_non_incr::__rust_end_short_backtrace
  34:     0x7f1cc41478dc - rustc_middle[317d0c99bf64221a]::query::plumbing::query_get_at::<rustc_query_system[46f106d5b822efb7]::query::caches::DefaultCache<rustc_middle[317d0c99bf64221a]::ty::ParamEnvAnd<rustc_middle[317d0c99bf64221a]::mir::interpret::GlobalId>, rustc_middle[317d0c99bf64221a]::query::erase::Erased<[u8; 24usize]>>>
  35:     0x7f1cc4147667 - <rustc_middle[317d0c99bf64221a]::ty::context::TyCtxt>::const_eval_global_id_for_typeck
  36:     0x7f1cc4147190 - <rustc_middle[317d0c99bf64221a]::ty::context::TyCtxt>::const_eval_resolve_for_typeck
  37:     0x7f1cc3dba0cd - <rustc_infer[4964aa7e7a96197b]::infer::InferCtxt>::const_eval_resolve
  38:     0x7f1cc3db7921 - rustc_trait_selection[f5378f77531ecf34]::traits::const_evaluatable::is_const_evaluatable
  39:     0x7f1cc3d3cbaf - <rustc_trait_selection[f5378f77531ecf34]::traits::fulfill::FulfillProcessor as rustc_data_structures[88ad4396f1aa1674]::obligation_forest::ObligationProcessor>::process_obligation
  40:     0x7f1cc3d33f3b - <rustc_data_structures[88ad4396f1aa1674]::obligation_forest::ObligationForest<rustc_trait_selection[f5378f77531ecf34]::traits::fulfill::PendingPredicateObligation>>::process_obligations::<rustc_trait_selection[f5378f77531ecf34]::traits::fulfill::FulfillProcessor>
  41:     0x7f1cc3d33770 - <rustc_trait_selection[f5378f77531ecf34]::traits::fulfill::FulfillmentContext as rustc_infer[4964aa7e7a96197b]::traits::engine::TraitEngine>::select_where_possible
  42:     0x7f1cc3da251b - <rustc_hir_typeck[7e00dffbed43131e]::fn_ctxt::FnCtxt>::demand_coerce
  43:     0x7f1cc3d196d7 - <rustc_hir_typeck[7e00dffbed43131e]::fn_ctxt::FnCtxt>::check_decl
  44:     0x7f1cc3cf9a33 - <rustc_hir_typeck[7e00dffbed43131e]::fn_ctxt::FnCtxt>::check_block_with_expected
  45:     0x7f1cc3cc65fb - <rustc_hir_typeck[7e00dffbed43131e]::fn_ctxt::FnCtxt>::check_expr_with_expectation_and_args
  46:     0x7f1cc496ef58 - <rustc_hir_typeck[7e00dffbed43131e]::fn_ctxt::FnCtxt>::check_return_expr
  47:     0x7f1cc496d798 - rustc_hir_typeck[7e00dffbed43131e]::check::check_fn
  48:     0x7f1cc495e7ed - rustc_hir_typeck[7e00dffbed43131e]::typeck
  49:     0x7f1cc3a1a6cc - rustc_query_impl[8362d19b71b00d]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[8362d19b71b00d]::query_impl::typeck::dynamic_query::{closure#2}::{closure#0}, rustc_middle[317d0c99bf64221a]::query::erase::Erased<[u8; 8usize]>>
  50:     0x7f1cc3a1a6ae - <rustc_query_impl[8362d19b71b00d]::query_impl::typeck::dynamic_query::{closure#2} as core[1b2a3d848a2ec87d]::ops::function::FnOnce<(rustc_middle[317d0c99bf64221a]::ty::context::TyCtxt, rustc_span[2109ecbc79ac056c]::def_id::LocalDefId)>>::call_once
  51:     0x7f1cc3afb2dd - rustc_query_system[46f106d5b822efb7]::query::plumbing::try_execute_query::<rustc_query_impl[8362d19b71b00d]::DynamicConfig<rustc_query_system[46f106d5b822efb7]::query::caches::VecCache<rustc_span[2109ecbc79ac056c]::def_id::LocalDefId, rustc_middle[317d0c99bf64221a]::query::erase::Erased<[u8; 8usize]>>, false, false, false>, rustc_query_impl[8362d19b71b00d]::plumbing::QueryCtxt, false>
  52:     0x7f1cc52bf96f - rustc_query_impl[8362d19b71b00d]::query_impl::typeck::get_query_non_incr::__rust_end_short_backtrace
  53:     0x7f1cc4e2bf7b - rustc_data_structures[88ad4396f1aa1674]::sync::par_for_each_in::<&[rustc_span[2109ecbc79ac056c]::def_id::LocalDefId], <rustc_middle[317d0c99bf64221a]::hir::map::Map>::par_body_owners<rustc_hir_analysis[6e7d8e1705157800]::check_crate::{closure#7}>::{closure#0}>
  54:     0x7f1cc4e2b0ab - rustc_hir_analysis[6e7d8e1705157800]::check_crate
  55:     0x7f1cc4e2567a - rustc_interface[93d7af63a48c5455]::passes::analysis
  56:     0x7f1cc4e64aba - rustc_query_impl[8362d19b71b00d]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[8362d19b71b00d]::query_impl::analysis::dynamic_query::{closure#2}::{closure#0}, rustc_middle[317d0c99bf64221a]::query::erase::Erased<[u8; 1usize]>>
  57:     0x7f1cc4e64aa9 - <rustc_query_impl[8362d19b71b00d]::query_impl::analysis::dynamic_query::{closure#2} as core[1b2a3d848a2ec87d]::ops::function::FnOnce<(rustc_middle[317d0c99bf64221a]::ty::context::TyCtxt, ())>>::call_once
  58:     0x7f1cc4febcd8 - rustc_query_system[46f106d5b822efb7]::query::plumbing::try_execute_query::<rustc_query_impl[8362d19b71b00d]::DynamicConfig<rustc_query_system[46f106d5b822efb7]::query::caches::SingleCache<rustc_middle[317d0c99bf64221a]::query::erase::Erased<[u8; 1usize]>>, false, false, false>, rustc_query_impl[8362d19b71b00d]::plumbing::QueryCtxt, false>
  59:     0x7f1cc4feba67 - rustc_query_impl[8362d19b71b00d]::query_impl::analysis::get_query_non_incr::__rust_end_short_backtrace
  60:     0x7f1cc4fb6e16 - <rustc_middle[317d0c99bf64221a]::ty::context::GlobalCtxt>::enter::<rustc_driver_impl[610dbdd3eb094fb1]::run_compiler::{closure#1}::{closure#2}::{closure#6}, core[1b2a3d848a2ec87d]::result::Result<(), rustc_span[2109ecbc79ac056c]::ErrorGuaranteed>>
  61:     0x7f1cc4be01c1 - rustc_span[2109ecbc79ac056c]::set_source_map::<core[1b2a3d848a2ec87d]::result::Result<(), rustc_span[2109ecbc79ac056c]::ErrorGuaranteed>, rustc_interface[93d7af63a48c5455]::interface::run_compiler<core[1b2a3d848a2ec87d]::result::Result<(), rustc_span[2109ecbc79ac056c]::ErrorGuaranteed>, rustc_driver_impl[610dbdd3eb094fb1]::run_compiler::{closure#1}>::{closure#0}::{closure#0}>
  62:     0x7f1cc4bda690 - std[84884ff0985ea275]::sys_common::backtrace::__rust_begin_short_backtrace::<rustc_interface[93d7af63a48c5455]::util::run_in_thread_pool_with_globals<rustc_interface[93d7af63a48c5455]::interface::run_compiler<core[1b2a3d848a2ec87d]::result::Result<(), rustc_span[2109ecbc79ac056c]::ErrorGuaranteed>, rustc_driver_impl[610dbdd3eb094fb1]::run_compiler::{closure#1}>::{closure#0}, core[1b2a3d848a2ec87d]::result::Result<(), rustc_span[2109ecbc79ac056c]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[1b2a3d848a2ec87d]::result::Result<(), rustc_span[2109ecbc79ac056c]::ErrorGuaranteed>>
  63:     0x7f1cc51baed5 - <<std[84884ff0985ea275]::thread::Builder>::spawn_unchecked_<rustc_interface[93d7af63a48c5455]::util::run_in_thread_pool_with_globals<rustc_interface[93d7af63a48c5455]::interface::run_compiler<core[1b2a3d848a2ec87d]::result::Result<(), rustc_span[2109ecbc79ac056c]::ErrorGuaranteed>, rustc_driver_impl[610dbdd3eb094fb1]::run_compiler::{closure#1}>::{closure#0}, core[1b2a3d848a2ec87d]::result::Result<(), rustc_span[2109ecbc79ac056c]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[1b2a3d848a2ec87d]::result::Result<(), rustc_span[2109ecbc79ac056c]::ErrorGuaranteed>>::{closure#1} as core[1b2a3d848a2ec87d]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  64:     0x7f1cc27722d5 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h24d01bd9757d4365
                               at /rustc/d190d978649a9bee690ab7d489b59e4c3a78dee4/library/alloc/src/boxed.rs:2007:9
  65:     0x7f1cc27722d5 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h3f16bb51567a3163
                               at /rustc/d190d978649a9bee690ab7d489b59e4c3a78dee4/library/alloc/src/boxed.rs:2007:9
  66:     0x7f1cc27722d5 - std::sys::unix::thread::Thread::new::thread_start::h5a67bb2093ddc843
                               at /rustc/d190d978649a9bee690ab7d489b59e4c3a78dee4/library/std/src/sys/unix/thread.rs:108:17
  67:     0x7f1cc250444b - <unknown>
  68:     0x7f1cc2587e40 - <unknown>
  69:                0x0 - <unknown>

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: please attach the file at `/tmp/im/rustc-ice-2023-08-09T17:21:49.851337451Z-2047217.txt` to your bug report

query stack during panic:
#0 [eval_to_allocation_raw] const-evaluating + checking `Inline::{constant#0}`
#1 [eval_to_valtree] evaluating type-level constant
#2 [typeck] type-checking `main`
#3 [analysis] running analysis passes on this crate
end of query stack
error: aborting due to 3 previous errors; 1 warning emitted

Some errors have detailed explanations: E0412, E0599.
For more information about an error, try `rustc --explain E0412`.

[matthiaskrgr]

Original code from #80742
Regression in e3590fc
#114615 cc @RalfJung

[RalfJung]

Yeah this was a deliberate regression (of an incomplete unstable feature): the old fix wasn't a proper fix, there were still tons of other similar ICEs, so just guarding against this particular ICE isn't worth it. This should be closed as a duplicate of #97477.