dyn* ICE primitive read not possible for type: [i32; 4]

[DutchGhost]

Code

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

use core::fmt::Debug;

fn main() {
    let i = [1, 2, 3, 4] as dyn* Debug;
    
    dbg!(i);
}

Meta

rustc --version --verbose:

rustc 1.66.0-nightly (e7119a030 2022-09-22)

Error output

[<output>](error: internal compiler error: /rustc/e7119a0300b87a3d670408ee8e847c6821b3ae80/compiler/rustc_const_eval/src/interpret/operand.rs:390:13: primitive read not possible for type: [i32; 4])

Backtrace

error: internal compiler error: /rustc/e7119a0300b87a3d670408ee8e847c6821b3ae80/compiler/rustc_const_eval/src/interpret/operand.rs:390:13: primitive read not possible for type: [i32; 4]
 --> src/main.rs:7:13
  |
7 |     let i = [1, 2, 3, 4] as dyn* Debug;
  |             ^^^^^^^^^^^^^^^^^^^^^^^^^^

thread 'rustc' panicked at 'Box<dyn Any>', /rustc/e7119a0300b87a3d670408ee8e847c6821b3ae80/compiler/rustc_errors/src/lib.rs:1434:9
stack backtrace:
   0:     0x7f024ef53ff0 - std::backtrace_rs::backtrace::libunwind::trace::hf4e04b2e4313927b
                               at /rustc/e7119a0300b87a3d670408ee8e847c6821b3ae80/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
   1:     0x7f024ef53ff0 - std::backtrace_rs::backtrace::trace_unsynchronized::h2771cf061d4680d1
                               at /rustc/e7119a0300b87a3d670408ee8e847c6821b3ae80/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
   2:     0x7f024ef53ff0 - std::sys_common::backtrace::_print_fmt::h2e413508900ead1c
                               at /rustc/e7119a0300b87a3d670408ee8e847c6821b3ae80/library/std/src/sys_common/backtrace.rs:66:5
   3:     0x7f024ef53ff0 - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::hb886319318f6b897
                               at /rustc/e7119a0300b87a3d670408ee8e847c6821b3ae80/library/std/src/sys_common/backtrace.rs:45:22
   4:     0x7f024efaee1e - core::fmt::write::hd7350cb51945e18c
                               at /rustc/e7119a0300b87a3d670408ee8e847c6821b3ae80/library/core/src/fmt/mod.rs:1202:17
   5:     0x7f024ef44af5 - std::io::Write::write_fmt::ha7bc763f922fc662
                               at /rustc/e7119a0300b87a3d670408ee8e847c6821b3ae80/library/std/src/io/mod.rs:1679:15
   6:     0x7f024ef56d73 - std::sys_common::backtrace::_print::h7ad0003e1b032609
                               at /rustc/e7119a0300b87a3d670408ee8e847c6821b3ae80/library/std/src/sys_common/backtrace.rs:48:5
   7:     0x7f024ef56d73 - std::sys_common::backtrace::print::h6f247b59322d4826
                               at /rustc/e7119a0300b87a3d670408ee8e847c6821b3ae80/library/std/src/sys_common/backtrace.rs:35:9
   8:     0x7f024ef56d73 - std::panicking::default_hook::{{closure}}::h71a394bfa368bc38
                               at /rustc/e7119a0300b87a3d670408ee8e847c6821b3ae80/library/std/src/panicking.rs:267:22
   9:     0x7f024ef56a5f - std::panicking::default_hook::h353829743ca9a29f
                               at /rustc/e7119a0300b87a3d670408ee8e847c6821b3ae80/library/std/src/panicking.rs:286:9
  10:     0x7f025176cef1 - <rustc_driver[7857f239df018eab]::DEFAULT_HOOK::{closure#0}::{closure#0} as core[cde1ce9e21f08391]::ops::function::FnOnce<(&core[cde1ce9e21f08391]::panic::panic_info::PanicInfo,)>>::call_once::{shim:vtable#0}
  11:     0x7f024ef575ab - <alloc::boxed::Box<F,A> as core::ops::function::Fn<Args>>::call::h5c7ac9f6a4be07e2
                               at /rustc/e7119a0300b87a3d670408ee8e847c6821b3ae80/library/alloc/src/boxed.rs:1954:9
  12:     0x7f024ef575ab - std::panicking::rust_panic_with_hook::h6ad4960c15699d95
                               at /rustc/e7119a0300b87a3d670408ee8e847c6821b3ae80/library/std/src/panicking.rs:673:13
  13:     0x7f02519f5b21 - std[35bb8192b5670ad2]::panicking::begin_panic::<rustc_errors[354c2d440e1385ac]::ExplicitBug>::{closure#0}
  14:     0x7f02519f41c6 - std[35bb8192b5670ad2]::sys_common::backtrace::__rust_end_short_backtrace::<std[35bb8192b5670ad2]::panicking::begin_panic<rustc_errors[354c2d440e1385ac]::ExplicitBug>::{closure#0}, !>
  15:     0x7f0251976536 - std[35bb8192b5670ad2]::panicking::begin_panic::<rustc_errors[354c2d440e1385ac]::ExplicitBug>
  16:     0x7f0251a1f4a6 - std[35bb8192b5670ad2]::panic::panic_any::<rustc_errors[354c2d440e1385ac]::ExplicitBug>
  17:     0x7f0251a1eedf - <rustc_errors[354c2d440e1385ac]::HandlerInner>::span_bug::<rustc_span[4a0a9e8ceb64f0f4]::span_encoding::Span, &alloc[70f1755a93720895]::string::String>
  18:     0x7f0251a1ec60 - <rustc_errors[354c2d440e1385ac]::Handler>::span_bug::<rustc_span[4a0a9e8ceb64f0f4]::span_encoding::Span, &alloc[70f1755a93720895]::string::String>
  19:     0x7f0251a4c3e8 - rustc_middle[33a3dc3ec8228005]::ty::context::tls::with_context_opt::<rustc_middle[33a3dc3ec8228005]::ty::context::tls::with_opt<rustc_middle[33a3dc3ec8228005]::util::bug::opt_span_bug_fmt<rustc_span[4a0a9e8ceb64f0f4]::span_encoding::Span>::{closure#0}, ()>::{closure#0}, ()>
  20:     0x7f0251a4b906 - rustc_middle[33a3dc3ec8228005]::util::bug::opt_span_bug_fmt::<rustc_span[4a0a9e8ceb64f0f4]::span_encoding::Span>
  21:     0x7f0251a4b8c4 - rustc_middle[33a3dc3ec8228005]::util::bug::span_bug_fmt::<rustc_span[4a0a9e8ceb64f0f4]::span_encoding::Span>
  22:     0x7f0250e15e82 - <rustc_const_eval[4d5bd7e7607305c4]::interpret::eval_context::InterpCx<rustc_mir_transform[38a49b1d59d53461]::const_prop::ConstPropMachine>>::eval_rvalue_into_place
  23:     0x7f0250bb10c2 - <rustc_mir_transform[38a49b1d59d53461]::const_prop_lint::ConstPropagator as rustc_middle[33a3dc3ec8228005]::mir::visit::Visitor>::visit_body
  24:     0x7f0250ba8c03 - <rustc_mir_transform[38a49b1d59d53461]::const_prop_lint::ConstProp as rustc_mir_transform[38a49b1d59d53461]::pass_manager::MirLint>::run_lint
  25:     0x7f02503013e5 - rustc_mir_transform[38a49b1d59d53461]::pass_manager::run_passes_no_validate
  26:     0x7f02502fe684 - rustc_mir_transform[38a49b1d59d53461]::run_analysis_to_runtime_passes
  27:     0x7f02502fd692 - rustc_mir_transform[38a49b1d59d53461]::mir_drops_elaborated_and_const_checked
  28:     0x7f0250d526a3 - rustc_query_system[d3b2657d85679091]::query::plumbing::try_execute_query::<rustc_query_impl[542bbd4b66bfb449]::plumbing::QueryCtxt, rustc_query_system[d3b2657d85679091]::query::caches::DefaultCache<rustc_middle[33a3dc3ec8228005]::ty::WithOptConstParam<rustc_span[4a0a9e8ceb64f0f4]::def_id::LocalDefId>, &rustc_data_structures[bf19c7e493ef6519]::steal::Steal<rustc_middle[33a3dc3ec8228005]::mir::Body>>>
  29:     0x7f02516ad28e - <rustc_query_impl[542bbd4b66bfb449]::Queries as rustc_middle[33a3dc3ec8228005]::ty::query::QueryEngine>::mir_drops_elaborated_and_const_checked
  30:     0x7f025035b3cb - rustc_mir_transform[38a49b1d59d53461]::optimized_mir
  31:     0x7f0250b744eb - rustc_query_system[d3b2657d85679091]::query::plumbing::try_execute_query::<rustc_query_impl[542bbd4b66bfb449]::plumbing::QueryCtxt, rustc_query_system[d3b2657d85679091]::query::caches::DefaultCache<rustc_span[4a0a9e8ceb64f0f4]::def_id::DefId, &rustc_middle[33a3dc3ec8228005]::mir::Body>>
  32:     0x7f02516ad67f - <rustc_query_impl[542bbd4b66bfb449]::Queries as rustc_middle[33a3dc3ec8228005]::ty::query::QueryEngine>::optimized_mir
  33:     0x7f02503a5735 - <rustc_middle[33a3dc3ec8228005]::ty::context::TyCtxt>::instance_mir
  34:     0x7f025039ab3c - rustc_monomorphize[807358ae657c971c]::collector::collect_neighbours
  35:     0x7f02503986d2 - rustc_monomorphize[807358ae657c971c]::collector::collect_items_rec
  36:     0x7f0250ee534d - <rustc_session[fa757ff4c2b8954a]::session::Session>::time::<(), rustc_monomorphize[807358ae657c971c]::collector::collect_crate_mono_items::{closure#1}>
  37:     0x7f0250ee4ed9 - rustc_monomorphize[807358ae657c971c]::collector::collect_crate_mono_items
  38:     0x7f0250ee3dc6 - rustc_monomorphize[807358ae657c971c]::partitioning::collect_and_partition_mono_items
  39:     0x7f025151c4a9 - rustc_query_system[d3b2657d85679091]::query::plumbing::try_execute_query::<rustc_query_impl[542bbd4b66bfb449]::plumbing::QueryCtxt, rustc_query_system[d3b2657d85679091]::query::caches::DefaultCache<(), (&std[35bb8192b5670ad2]::collections::hash::set::HashSet<rustc_span[4a0a9e8ceb64f0f4]::def_id::DefId, core[cde1ce9e21f08391]::hash::BuildHasherDefault<rustc_hash[56467a0a1e3e166e]::FxHasher>>, &[rustc_middle[33a3dc3ec8228005]::mir::mono::CodegenUnit])>>
  40:     0x7f025151c19b - rustc_query_system[d3b2657d85679091]::query::plumbing::get_query::<rustc_query_impl[542bbd4b66bfb449]::queries::collect_and_partition_mono_items, rustc_query_impl[542bbd4b66bfb449]::plumbing::QueryCtxt>
  41:     0x7f025151c0de - <rustc_query_impl[542bbd4b66bfb449]::Queries as rustc_middle[33a3dc3ec8228005]::ty::query::QueryEngine>::collect_and_partition_mono_items
  42:     0x7f0251263712 - rustc_codegen_ssa[2a18cf2abb0e25f]::base::codegen_crate::<rustc_codegen_llvm[1c20db9e7afb2165]::LlvmCodegenBackend>
  43:     0x7f02512634e2 - <rustc_codegen_llvm[1c20db9e7afb2165]::LlvmCodegenBackend as rustc_codegen_ssa[2a18cf2abb0e25f]::traits::backend::CodegenBackend>::codegen_crate
  44:     0x7f025053f7dc - <rustc_session[fa757ff4c2b8954a]::session::Session>::time::<alloc[70f1755a93720895]::boxed::Box<dyn core[cde1ce9e21f08391]::any::Any>, rustc_interface[f2560d97934cc6f6]::passes::start_codegen::{closure#0}>
  45:     0x7f025053f1ae - <rustc_interface[f2560d97934cc6f6]::passes::QueryContext>::enter::<<rustc_interface[f2560d97934cc6f6]::queries::Queries>::ongoing_codegen::{closure#0}::{closure#0}, core[cde1ce9e21f08391]::result::Result<alloc[70f1755a93720895]::boxed::Box<dyn core[cde1ce9e21f08391]::any::Any>, rustc_errors[354c2d440e1385ac]::ErrorGuaranteed>>
  46:     0x7f02504ff6d3 - <rustc_interface[f2560d97934cc6f6]::queries::Queries>::ongoing_codegen
  47:     0x7f02504fda4a - rustc_interface[f2560d97934cc6f6]::interface::create_compiler_and_run::<core[cde1ce9e21f08391]::result::Result<(), rustc_errors[354c2d440e1385ac]::ErrorGuaranteed>, rustc_driver[7857f239df018eab]::run_compiler::{closure#1}>
  48:     0x7f02504fc342 - <scoped_tls[8ee1aa185b4607e2]::ScopedKey<rustc_span[4a0a9e8ceb64f0f4]::SessionGlobals>>::set::<rustc_interface[f2560d97934cc6f6]::interface::run_compiler<core[cde1ce9e21f08391]::result::Result<(), rustc_errors[354c2d440e1385ac]::ErrorGuaranteed>, rustc_driver[7857f239df018eab]::run_compiler::{closure#1}>::{closure#0}, core[cde1ce9e21f08391]::result::Result<(), rustc_errors[354c2d440e1385ac]::ErrorGuaranteed>>
  49:     0x7f02504fc02f - std[35bb8192b5670ad2]::sys_common::backtrace::__rust_begin_short_backtrace::<rustc_interface[f2560d97934cc6f6]::util::run_in_thread_pool_with_globals<rustc_interface[f2560d97934cc6f6]::interface::run_compiler<core[cde1ce9e21f08391]::result::Result<(), rustc_errors[354c2d440e1385ac]::ErrorGuaranteed>, rustc_driver[7857f239df018eab]::run_compiler::{closure#1}>::{closure#0}, core[cde1ce9e21f08391]::result::Result<(), rustc_errors[354c2d440e1385ac]::ErrorGuaranteed>>::{closure#0}, core[cde1ce9e21f08391]::result::Result<(), rustc_errors[354c2d440e1385ac]::ErrorGuaranteed>>
  50:     0x7f02515d1980 - <<std[35bb8192b5670ad2]::thread::Builder>::spawn_unchecked_<rustc_interface[f2560d97934cc6f6]::util::run_in_thread_pool_with_globals<rustc_interface[f2560d97934cc6f6]::interface::run_compiler<core[cde1ce9e21f08391]::result::Result<(), rustc_errors[354c2d440e1385ac]::ErrorGuaranteed>, rustc_driver[7857f239df018eab]::run_compiler::{closure#1}>::{closure#0}, core[cde1ce9e21f08391]::result::Result<(), rustc_errors[354c2d440e1385ac]::ErrorGuaranteed>>::{closure#0}, core[cde1ce9e21f08391]::result::Result<(), rustc_errors[354c2d440e1385ac]::ErrorGuaranteed>>::{closure#1} as core[cde1ce9e21f08391]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  51:     0x7f024ef61393 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::hbe492c93bea3125c
                               at /rustc/e7119a0300b87a3d670408ee8e847c6821b3ae80/library/alloc/src/boxed.rs:1940:9
  52:     0x7f024ef61393 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h1c6cb812ee67c431
                               at /rustc/e7119a0300b87a3d670408ee8e847c6821b3ae80/library/alloc/src/boxed.rs:1940:9
  53:     0x7f024ef61393 - std::sys::unix::thread::Thread::new::thread_start::hcd53b5f11cecf106
                               at /rustc/e7119a0300b87a3d670408ee8e847c6821b3ae80/library/std/src/sys/unix/thread.rs:108:17
  54:     0x7f024ee34609 - start_thread
  55:     0x7f024ed57133 - clone
  56:                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 1.66.0-nightly (e7119a030 2022-09-22) running on x86_64-unknown-linux-gnu

note: compiler flags: --crate-type bin -C embed-bitcode=no -C codegen-units=1 -C debuginfo=2

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

query stack during panic:
#0 [mir_drops_elaborated_and_const_checked] elaborating drops for `main`
#1 [optimized_mir] optimizing MIR for `main`
#2 [collect_and_partition_mono_items] collect_and_partition_mono_items
end of query stack
error: could not compile `playground`

[eholk]

Thanks for the report!

This test case should not compile because only things that are pointer sized can be converted to dyn*. But, we definitely need a proper error message rather than an ICE.