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Zenithsiz opened this issue Apr 14, 2025 · 0 comments · Fixed by #139818
Closed

ICE with (only) coerce_unsized in find_vtable_types_for_unsizing #139812

Zenithsiz opened this issue Apr 14, 2025 · 0 comments · Fixed by #139818
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@compiler-errors
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C-bug Category: This is a bug. F-coerce_unsized The `CoerceUnsized` trait I-ICE Issue: The compiler panicked, giving an Internal Compilation Error (ICE) ❄️ T-compiler Relevant to the compiler team, which will review and decide on the PR/issue.

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@Zenithsiz
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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>;
}

Playground

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.

rustc-ice-2025-04-14T15_52_16-261430.txt
@Zenithsiz Zenithsiz added C-bug Category: This is a bug. I-ICE Issue: The compiler panicked, giving an Internal Compilation Error (ICE) ❄️ T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Apr 14, 2025
@rustbot rustbot added the needs-triage This issue may need triage. Remove it if it has been sufficiently triaged. label Apr 14, 2025
@compiler-errors compiler-errors self-assigned this Apr 14, 2025
@compiler-errors compiler-errors mentioned this issue Apr 14, 2025
Merged
@jieyouxu jieyouxu added F-coerce_unsized The `CoerceUnsized` trait and removed needs-triage This issue may need triage. Remove it if it has been sufficiently triaged. labels Apr 15, 2025
Zalathar added a commit to Zalathar/rust that referenced this issue Apr 15, 2025
@Zalathar
Rollup merge of rust-lang#139818 - compiler-errors:normalize-tails, r…
076d2a4 
…=oli-obk

Normalize ADT field in `find_tails_for_unsizing`

See the comment inline and in the test.

TL;DR is that we're getting getting a type from a `type_of` query and then matching on it structurally in codegen, so we're obligated to normalize it. The fact that this wasn't triggered earlier is that all of the types that have `CoerceUnsized` implementations never encounter aliases when peeling the ADT down to their base reference/ptr type.

**NOTE**: I also renamed some things and reorganized the function a bit.

Fixes rust-lang#139812
Fixes rust-lang#74451, which I didn't think was interesting enough to add another test.

r? oli-obk
@bors bors closed this as completed in 27f1f4d Apr 15, 2025
rust-timer added a commit to rust-lang-ci/rust that referenced this issue Apr 15, 2025
@rust-timer
Unrolled build for rust-lang#139818
e55ff8f 
Rollup merge of rust-lang#139818 - compiler-errors:normalize-tails, r=oli-obk

Normalize ADT field in `find_tails_for_unsizing`

See the comment inline and in the test.

TL;DR is that we're getting getting a type from a `type_of` query and then matching on it structurally in codegen, so we're obligated to normalize it. The fact that this wasn't triggered earlier is that all of the types that have `CoerceUnsized` implementations never encounter aliases when peeling the ADT down to their base reference/ptr type.

**NOTE**: I also renamed some things and reorganized the function a bit.

Fixes rust-lang#139812
Fixes rust-lang#74451, which I didn't think was interesting enough to add another test.

r? oli-obk
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Labels
C-bug Category: This is a bug. F-coerce_unsized The `CoerceUnsized` trait I-ICE Issue: The compiler panicked, giving an Internal Compilation Error (ICE) ❄️ T-compiler Relevant to the compiler team, which will review and decide on the PR/issue.
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Normalize ADT field in find_tails_for_unsizing compiler-errors/rust
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@compiler-errors @Zenithsiz @jieyouxu @rustbot