Closed
Description
Code
#![feature(coerce_unsized)]
use std::any::Any;
use std::ops::CoerceUnsized;
trait RcFamily {
type Rc<T: ?Sized>;
}
struct R;
impl RcFamily for R {
type Rc<T: ?Sized> = std::rc::Rc<T>;
}
// ICEs
type Rc<T> = <R as RcFamily>::Rc<T>;
// Does not ICE
//type Rc<T> = std::rc::Rc<T>;
struct Signal<T: ?Sized>(Rc<T>);
impl CoerceUnsized<Signal<dyn Any>> for Signal<i32> {}
fn main() {
Signal(Rc::new(5_i32)) as Signal<dyn Any>;
}Meta
rustc --version --verbose:
rustc 1.88.0-nightly (0fe8f3454 2025-04-10)
binary: rustc
commit-hash: 0fe8f3454dbe9dda52a254991347e96bec579a6f
commit-date: 2025-04-10
host: x86_64-unknown-linux-gnu
release: 1.88.0-nightly
LLVM version: 20.1.2
Error output
error: internal compiler error: compiler/rustc_monomorphize/src/collector.rs:1093:14: find_vtable_types_for_unsizing: invalid coercion Alias(Projection, AliasTy { args: [R, i32], def_id: DefId(0:6 ~ test[48ef]::RcFamily::Rc), .. }) -> Alias(Projection, AliasTy { args: [R, dyn [Binder { value: Trait(std::any::Any), bound_vars: [] }] + '{erased}], def_id: DefId(0:6 ~ test[48ef]::RcFamily::Rc), .. })
thread 'rustc' panicked at compiler/rustc_monomorphize/src/collector.rs:1093:14:
Box<dyn Any>
stack backtrace:
0: 0x7f90c1ca3003 - <std::sys::backtrace::BacktraceLock::print::DisplayBacktrace as core::fmt::Display>::fmt::h7686682c5480ba78
1: 0x7f90c2406091 - core::fmt::write::hf1e231fde889384f
2: 0x7f90c3818b51 - std::io::Write::write_fmt::hcc89e08516f58cda
3: 0x7f90c1ca2e62 - std::sys::backtrace::BacktraceLock::print::hc42ae0f3d83336fc
4: 0x7f90c1ca694a - std::panicking::default_hook::{{closure}}::hf08c95cde50909c9
5: 0x7f90c1ca64cf - std::panicking::default_hook::h857accdf112ffe33
6: 0x7f90c0d00c43 - std[5a4a45264b2b22b8]::panicking::update_hook::<alloc[b673e4f92a898af7]::boxed::Box<rustc_driver_impl[e5eb260dc8961db4]::install_ice_hook::{closure#1}>>::{closure#0}
7: 0x7f90c1ca71c3 - std::panicking::rust_panic_with_hook::ha8b882f4d13e028f
8: 0x7f90c0d3f981 - std[5a4a45264b2b22b8]::panicking::begin_panic::<rustc_errors[97cfdff8159a699f]::ExplicitBug>::{closure#0}
9: 0x7f90c0d33896 - std[5a4a45264b2b22b8]::sys::backtrace::__rust_end_short_backtrace::<std[5a4a45264b2b22b8]::panicking::begin_panic<rustc_errors[97cfdff8159a699f]::ExplicitBug>::{closure#0}, !>
10: 0x7f90c0d300d9 - std[5a4a45264b2b22b8]::panicking::begin_panic::<rustc_errors[97cfdff8159a699f]::ExplicitBug>
11: 0x7f90c0d49d51 - <rustc_errors[97cfdff8159a699f]::diagnostic::BugAbort as rustc_errors[97cfdff8159a699f]::diagnostic::EmissionGuarantee>::emit_producing_guarantee
12: 0x7f90c139dfba - rustc_middle[c35ac5c4e9820b71]::util::bug::opt_span_bug_fmt::<rustc_span[5498c1e576460479]::span_encoding::Span>::{closure#0}
13: 0x7f90c1378e9a - rustc_middle[c35ac5c4e9820b71]::ty::context::tls::with_opt::<rustc_middle[c35ac5c4e9820b71]::util::bug::opt_span_bug_fmt<rustc_span[5498c1e576460479]::span_encoding::Span>::{closure#0}, !>::{closure#0}
14: 0x7f90c1378d0b - rustc_middle[c35ac5c4e9820b71]::ty::context::tls::with_context_opt::<rustc_middle[c35ac5c4e9820b71]::ty::context::tls::with_opt<rustc_middle[c35ac5c4e9820b71]::util::bug::opt_span_bug_fmt<rustc_span[5498c1e576460479]::span_encoding::Span>::{closure#0}, !>::{closure#0}, !>
15: 0x7f90be6867b0 - rustc_middle[c35ac5c4e9820b71]::util::bug::bug_fmt
16: 0x7f90c3e40814 - rustc_monomorphize[3e638de941efb25f]::collector::find_vtable_types_for_unsizing.cold
17: 0x7f90c39ab456 - rustc_monomorphize[3e638de941efb25f]::collector::find_vtable_types_for_unsizing.warm
18: 0x7f90bf3ddb8f - rustc_monomorphize[3e638de941efb25f]::collector::items_of_instance
19: 0x7f90c2ec82b2 - rustc_query_impl[cda7d84f80c9103c]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[cda7d84f80c9103c]::query_impl::items_of_instance::dynamic_query::{closure#2}::{closure#0}, rustc_middle[c35ac5c4e9820b71]::query::erase::Erased<[u8; 32usize]>>
20: 0x7f90c2ec8614 - rustc_query_system[6b3ea517af74fad7]::query::plumbing::try_execute_query::<rustc_query_impl[cda7d84f80c9103c]::DynamicConfig<rustc_query_system[6b3ea517af74fad7]::query::caches::DefaultCache<(rustc_middle[c35ac5c4e9820b71]::ty::instance::Instance, rustc_middle[c35ac5c4e9820b71]::mir::mono::CollectionMode), rustc_middle[c35ac5c4e9820b71]::query::erase::Erased<[u8; 32usize]>>, false, false, false>, rustc_query_impl[cda7d84f80c9103c]::plumbing::QueryCtxt, false>
21: 0x7f90c2ec822b - rustc_query_impl[cda7d84f80c9103c]::query_impl::items_of_instance::get_query_non_incr::__rust_end_short_backtrace
22: 0x7f90c2ec9d30 - rustc_monomorphize[3e638de941efb25f]::collector::collect_items_rec::{closure#0}
23: 0x7f90c2ecac2c - rustc_monomorphize[3e638de941efb25f]::collector::collect_items_rec
24: 0x7f90c2ed19e8 - rustc_monomorphize[3e638de941efb25f]::partitioning::collect_and_partition_mono_items
25: 0x7f90c2ed15a4 - rustc_query_impl[cda7d84f80c9103c]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[cda7d84f80c9103c]::query_impl::collect_and_partition_mono_items::dynamic_query::{closure#2}::{closure#0}, rustc_middle[c35ac5c4e9820b71]::query::erase::Erased<[u8; 40usize]>>
26: 0x7f90c2ed1589 - <rustc_query_impl[cda7d84f80c9103c]::query_impl::collect_and_partition_mono_items::dynamic_query::{closure#2} as core[56f6e271b4871ecd]::ops::function::FnOnce<(rustc_middle[c35ac5c4e9820b71]::ty::context::TyCtxt, ())>>::call_once
27: 0x7f90c2ed75b4 - rustc_query_system[6b3ea517af74fad7]::query::plumbing::try_execute_query::<rustc_query_impl[cda7d84f80c9103c]::DynamicConfig<rustc_query_system[6b3ea517af74fad7]::query::caches::SingleCache<rustc_middle[c35ac5c4e9820b71]::query::erase::Erased<[u8; 40usize]>>, false, false, false>, rustc_query_impl[cda7d84f80c9103c]::plumbing::QueryCtxt, false>
28: 0x7f90c2ed7344 - rustc_query_impl[cda7d84f80c9103c]::query_impl::collect_and_partition_mono_items::get_query_non_incr::__rust_end_short_backtrace
29: 0x7f90c3622627 - <rustc_codegen_llvm[7e8954d3ae8f9fa2]::LlvmCodegenBackend as rustc_codegen_ssa[244d404b982eb0b8]::traits::backend::CodegenBackend>::codegen_crate
30: 0x7f90c360e69d - <rustc_interface[c746d0abdacc4b70]::queries::Linker>::codegen_and_build_linker
31: 0x7f90c360c22c - rustc_interface[c746d0abdacc4b70]::passes::create_and_enter_global_ctxt::<core[56f6e271b4871ecd]::option::Option<rustc_interface[c746d0abdacc4b70]::queries::Linker>, rustc_driver_impl[e5eb260dc8961db4]::run_compiler::{closure#0}::{closure#2}>::{closure#2}::{closure#0}
32: 0x7f90c3558db9 - rustc_interface[c746d0abdacc4b70]::interface::run_compiler::<(), rustc_driver_impl[e5eb260dc8961db4]::run_compiler::{closure#0}>::{closure#1}
33: 0x7f90c352c88f - std[5a4a45264b2b22b8]::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface[c746d0abdacc4b70]::util::run_in_thread_with_globals<rustc_interface[c746d0abdacc4b70]::util::run_in_thread_pool_with_globals<rustc_interface[c746d0abdacc4b70]::interface::run_compiler<(), rustc_driver_impl[e5eb260dc8961db4]::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>
34: 0x7f90c352d16b - <<std[5a4a45264b2b22b8]::thread::Builder>::spawn_unchecked_<rustc_interface[c746d0abdacc4b70]::util::run_in_thread_with_globals<rustc_interface[c746d0abdacc4b70]::util::run_in_thread_pool_with_globals<rustc_interface[c746d0abdacc4b70]::interface::run_compiler<(), rustc_driver_impl[e5eb260dc8961db4]::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>::{closure#1} as core[56f6e271b4871ecd]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
35: 0x7f90c352e56b - std::sys::pal::unix::thread::Thread::new::thread_start::h0924f76e10405c90
36: 0x7f90bd2a370a - <unknown>
37: 0x7f90bd327aac - <unknown>
38: 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 make sure that you have updated to the latest nightly
note: please attach the file at `/tmp/rustc-ice-2025-04-14T15_52_16-261430.txt` to your bug report
query stack during panic:
#0 [items_of_instance] collecting items used by `main`
#1 [collect_and_partition_mono_items] collect_and_partition_mono_items
end of query stack
error: aborting due to 1 previous error
Backtrace
error: internal compiler error: compiler/rustc_monomorphize/src/collector.rs:1093:14: find_vtable_types_for_unsizing: invalid coercion Alias(Projection, AliasTy { args: [R, i32], def_id: DefId(0:6 ~ test[48ef]::RcFamily::Rc), .. }) -> Alias(Projection, AliasTy { args: [R, dyn [Binder { value: Trait(std::any::Any), bound_vars: [] }] + '{erased}], def_id: DefId(0:6 ~ test[48ef]::RcFamily::Rc), .. })
thread 'rustc' panicked at compiler/rustc_monomorphize/src/collector.rs:1093:14:
Box<dyn Any>
stack backtrace:
0: std::panicking::begin_panic::<rustc_errors::ExplicitBug>
1: <rustc_errors::diagnostic::BugAbort as rustc_errors::diagnostic::EmissionGuarantee>::emit_producing_guarantee
2: rustc_middle::util::bug::opt_span_bug_fmt::<rustc_span::span_encoding::Span>::{closure#0}
3: rustc_middle::ty::context::tls::with_opt::<rustc_middle::util::bug::opt_span_bug_fmt<rustc_span::span_encoding::Span>::{closure#0}, !>::{closure#0}
4: rustc_middle::ty::context::tls::with_context_opt::<rustc_middle::ty::context::tls::with_opt<rustc_middle::util::bug::opt_span_bug_fmt<rustc_span::span_encoding::Span>::{closure#0}, !>::{closure#0}, !>
5: rustc_middle::util::bug::bug_fmt
6: rustc_monomorphize::collector::find_vtable_types_for_unsizing.cold
7: rustc_monomorphize::collector::find_vtable_types_for_unsizing.warm
8: rustc_monomorphize::collector::items_of_instance
[... omitted 1 frame ...]
9: rustc_monomorphize::collector::collect_items_rec::{closure#0}
10: rustc_monomorphize::collector::collect_items_rec
11: rustc_monomorphize::partitioning::collect_and_partition_mono_items
[... omitted 2 frames ...]
12: <rustc_codegen_llvm::LlvmCodegenBackend as rustc_codegen_ssa::traits::backend::CodegenBackend>::codegen_crate
13: <rustc_interface::queries::Linker>::codegen_and_build_linker
14: rustc_interface::passes::create_and_enter_global_ctxt::<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure#2}>::{closure#2}::{closure#0}
15: rustc_interface::interface::run_compiler::<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.
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 make sure that you have updated to the latest nightly
note: please attach the file at `/tmp/rustc-ice-2025-04-14T15_50_25-261287.txt` to your bug report
query stack during panic:
#0 [items_of_instance] collecting items used by `main`
#1 [collect_and_partition_mono_items] collect_and_partition_mono_items
end of query stack
error: aborting due to 1 previous error
This is similar to #74451, but it seems that one requires specialization, while this one ICEs with just coerce_unsized.