ICE: `invalid pointer unsizing` &str -> str

[Naserume]

Code

#![feature(coerce_unsized)]
use std::ops;

trait Trait3<A> {}
impl<A> ops::CoerceUnsized<A> for A where A: ?Sized {}

fn main() {
    println!("Hello, world!");
}

Command: rustc ./03FC8.rs

Meta

rustc --version --verbose:

rustc 1.83.0-nightly (7608018cb 2024-09-29)
binary: rustc
commit-hash: 7608018cbdac9e55d0d13529cf43adc33d53efcf
commit-date: 2024-09-29
host: x86_64-apple-darwin
release: 1.83.0-nightly
LLVM version: 19.1.0

Error output

error[E0210]: type parameter `A` must be used as the type parameter for some local type (e.g., `MyStruct<A>`)
 --> ./03FC8.rs:9:6
  |
9 | impl<A> ops::CoerceUnsized<A> for A where A: ?Sized {}
  |      ^ type parameter `A` must be used as the type parameter for some local type
  |
  = note: implementing a foreign trait is only possible if at least one of the types for which it is implemented is local
  = note: only traits defined in the current crate can be implemented for a type parameter

error[E0376]: the trait `CoerceUnsized` may only be implemented for a coercion between structures
 --> ./03FC8.rs:9:1
  |
9 | impl<A> ops::CoerceUnsized<A> for A where A: ?Sized {}
  | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error: internal compiler error: compiler/rustc_const_eval/src/interpret/cast.rs:465:17: invalid pointer unsizing &str -> str
  --> ./03FC8.rs:14:14
   |
14 |     println!("Hello, world!");
   |              ^^^^^^^^^^^^^^^

Backtrace

thread 'rustc' panicked at compiler/rustc_const_eval/src/interpret/cast.rs:465:17:
Box<dyn Any>
stack backtrace:
   0:        0x113f193e7 - std::backtrace::Backtrace::create::h697070a74b47c5a1
   1:        0x113f19335 - std::backtrace::Backtrace::force_capture::hd4e20dc44637c239
   2:        0x111d3a7ce - std[a533c313b02b6cfe]::panicking::update_hook::<alloc[3194a7a73d70d243]::boxed::Box<rustc_driver_impl[e0e0c21a20d76ec4]::install_ice_hook::{closure#0}>>::{closure#0}
   3:        0x113f34af8 - std::panicking::rust_panic_with_hook::h9b093984c0b2ae3e
   4:        0x111dbb617 - std[a533c313b02b6cfe]::panicking::begin_panic::<rustc_errors[e7c766416e916d12]::ExplicitBug>::{closure#0}
   5:        0x111da7139 - std[a533c313b02b6cfe]::sys::backtrace::__rust_end_short_backtrace::<std[a533c313b02b6cfe]::panicking::begin_panic<rustc_errors[e7c766416e916d12]::ExplicitBug>::{closure#0}, !>
   6:        0x116bf2f08 - std[a533c313b02b6cfe]::panicking::begin_panic::<rustc_errors[e7c766416e916d12]::ExplicitBug>
   7:        0x111dd0806 - <rustc_errors[e7c766416e916d12]::diagnostic::BugAbort as rustc_errors[e7c766416e916d12]::diagnostic::EmissionGuarantee>::emit_producing_guarantee
   8:        0x111baecb1 - <rustc_errors[e7c766416e916d12]::DiagCtxtHandle>::span_bug::<rustc_span[51e7cf5b04f4660f]::span_encoding::Span, alloc[3194a7a73d70d243]::string::String>
   9:        0x111be2a98 - rustc_middle[3d266d78c9b198e4]::util::bug::opt_span_bug_fmt::<rustc_span[51e7cf5b04f4660f]::span_encoding::Span>::{closure#0}
  10:        0x111be2ad7 - rustc_middle[3d266d78c9b198e4]::ty::context::tls::with_opt::<rustc_middle[3d266d78c9b198e4]::util::bug::opt_span_bug_fmt<rustc_span[51e7cf5b04f4660f]::span_encoding::Span>::{closure#0}, !>::{closure#0}
  11:        0x111bc9975 - rustc_middle[3d266d78c9b198e4]::ty::context::tls::with_context_opt::<rustc_middle[3d266d78c9b198e4]::ty::context::tls::with_opt<rustc_middle[3d266d78c9b198e4]::util::bug::opt_span_bug_fmt<rustc_span[51e7cf5b04f4660f]::span_encoding::Span>::{closure#0}, !>::{closure#0}, !>
  12:        0x116be1932 - rustc_middle[3d266d78c9b198e4]::util::bug::span_bug_fmt::<rustc_span[51e7cf5b04f4660f]::span_encoding::Span>
  13:        0x111c6eba7 - <rustc_const_eval[298ced3d0b3bd135]::interpret::eval_context::InterpCx<rustc_const_eval[298ced3d0b3bd135]::const_eval::machine::CompileTimeMachine>>::unsize_into_ptr
  14:        0x111c9d0bd - <rustc_const_eval[298ced3d0b3bd135]::interpret::eval_context::InterpCx<rustc_const_eval[298ced3d0b3bd135]::const_eval::machine::CompileTimeMachine>>::eval_statement
  15:        0x111cb9c6c - rustc_const_eval[298ced3d0b3bd135]::const_eval::eval_queries::eval_to_allocation_raw_provider
  16:        0x113580cfc - rustc_query_impl[75f1704df0e38289]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[75f1704df0e38289]::query_impl::eval_to_allocation_raw::dynamic_query::{closure#2}::{closure#0}, rustc_middle[3d266d78c9b198e4]::query::erase::Erased<[u8; 24usize]>>
  17:        0x11353173e - <rustc_query_impl[75f1704df0e38289]::query_impl::eval_to_allocation_raw::dynamic_query::{closure#2} as core[907a20686bf8bf7a]::ops::function::FnOnce<(rustc_middle[3d266d78c9b198e4]::ty::context::TyCtxt, rustc_middle[3d266d78c9b198e4]::ty::ParamEnvAnd<rustc_middle[3d266d78c9b198e4]::mir::interpret::GlobalId>)>>::call_once
  18:        0x113348579 - rustc_query_system[13e780f7d1d88911]::query::plumbing::try_execute_query::<rustc_query_impl[75f1704df0e38289]::DynamicConfig<rustc_query_system[13e780f7d1d88911]::query::caches::DefaultCache<rustc_middle[3d266d78c9b198e4]::ty::ParamEnvAnd<rustc_middle[3d266d78c9b198e4]::mir::interpret::GlobalId>, rustc_middle[3d266d78c9b198e4]::query::erase::Erased<[u8; 24usize]>>, false, false, false>, rustc_query_impl[75f1704df0e38289]::plumbing::QueryCtxt, false>
  19:        0x1135b823c - rustc_query_impl[75f1704df0e38289]::query_impl::eval_to_allocation_raw::get_query_non_incr::__rust_end_short_backtrace
  20:        0x111bc62a2 - rustc_middle[3d266d78c9b198e4]::query::plumbing::query_get_at::<rustc_query_system[13e780f7d1d88911]::query::caches::DefaultCache<rustc_middle[3d266d78c9b198e4]::ty::ParamEnvAnd<rustc_middle[3d266d78c9b198e4]::mir::interpret::GlobalId>, rustc_middle[3d266d78c9b198e4]::query::erase::Erased<[u8; 24usize]>>>
  21:        0x111cb6763 - rustc_const_eval[298ced3d0b3bd135]::const_eval::eval_queries::eval_to_const_value_raw_provider
  22:        0x11358141c - rustc_query_impl[75f1704df0e38289]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[75f1704df0e38289]::query_impl::eval_to_const_value_raw::dynamic_query::{closure#2}::{closure#0}, rustc_middle[3d266d78c9b198e4]::query::erase::Erased<[u8; 24usize]>>
  23:        0x11353704e - <rustc_query_impl[75f1704df0e38289]::query_impl::eval_to_const_value_raw::dynamic_query::{closure#2} as core[907a20686bf8bf7a]::ops::function::FnOnce<(rustc_middle[3d266d78c9b198e4]::ty::context::TyCtxt, rustc_middle[3d266d78c9b198e4]::ty::ParamEnvAnd<rustc_middle[3d266d78c9b198e4]::mir::interpret::GlobalId>)>>::call_once
  24:        0x113348579 - rustc_query_system[13e780f7d1d88911]::query::plumbing::try_execute_query::<rustc_query_impl[75f1704df0e38289]::DynamicConfig<rustc_query_system[13e780f7d1d88911]::query::caches::DefaultCache<rustc_middle[3d266d78c9b198e4]::ty::ParamEnvAnd<rustc_middle[3d266d78c9b198e4]::mir::interpret::GlobalId>, rustc_middle[3d266d78c9b198e4]::query::erase::Erased<[u8; 24usize]>>, false, false, false>, rustc_query_impl[75f1704df0e38289]::plumbing::QueryCtxt, false>
  25:        0x1135b8e2c - rustc_query_impl[75f1704df0e38289]::query_impl::eval_to_const_value_raw::get_query_non_incr::__rust_end_short_backtrace
  26:        0x112b74b88 - rustc_middle[3d266d78c9b198e4]::query::plumbing::query_get_at::<rustc_query_system[13e780f7d1d88911]::query::caches::DefaultCache<rustc_middle[3d266d78c9b198e4]::ty::ParamEnvAnd<rustc_middle[3d266d78c9b198e4]::mir::interpret::GlobalId>, rustc_middle[3d266d78c9b198e4]::query::erase::Erased<[u8; 24usize]>>>
  27:        0x112b79563 - <rustc_middle[3d266d78c9b198e4]::ty::context::TyCtxt>::const_eval_global_id
  28:        0x112b78e50 - <rustc_middle[3d266d78c9b198e4]::ty::context::TyCtxt>::const_eval_resolve
  29:        0x112dbf811 - <rustc_const_eval[298ced3d0b3bd135]::interpret::eval_context::InterpCx<rustc_const_eval[298ced3d0b3bd135]::const_eval::dummy_machine::DummyMachine>>::eval_mir_constant::{closure#0}
  30:        0x112ec3849 - <rustc_mir_transform[f683d3911b24b415]::known_panics_lint::ConstPropagator>::eval_constant
  31:        0x112ec47e6 - <rustc_mir_transform[f683d3911b24b415]::known_panics_lint::ConstPropagator as rustc_middle[3d266d78c9b198e4]::mir::visit::Visitor>::visit_assign
  32:        0x112ec9df2 - <rustc_mir_transform[f683d3911b24b415]::known_panics_lint::ConstPropagator as rustc_middle[3d266d78c9b198e4]::mir::visit::Visitor>::visit_basic_block_data
  33:        0x112ec41bc - <rustc_mir_transform[f683d3911b24b415]::known_panics_lint::ConstPropagator as rustc_middle[3d266d78c9b198e4]::mir::visit::Visitor>::visit_body
  34:        0x112ec0b70 - <rustc_mir_transform[f683d3911b24b415]::known_panics_lint::KnownPanicsLint as rustc_mir_transform[f683d3911b24b415]::pass_manager::MirLint>::run_lint
  35:        0x112e652fa - rustc_mir_transform[f683d3911b24b415]::pass_manager::run_passes_inner
  36:        0x112f155c9 - rustc_mir_transform[f683d3911b24b415]::run_analysis_to_runtime_passes
  37:        0x112f1517a - rustc_mir_transform[f683d3911b24b415]::mir_drops_elaborated_and_const_checked
  38:        0x11358265a - rustc_query_impl[75f1704df0e38289]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[75f1704df0e38289]::query_impl::mir_drops_elaborated_and_const_checked::dynamic_query::{closure#2}::{closure#0}, rustc_middle[3d266d78c9b198e4]::query::erase::Erased<[u8; 8usize]>>
  39:        0x1133d8f4e - rustc_query_system[13e780f7d1d88911]::query::plumbing::try_execute_query::<rustc_query_impl[75f1704df0e38289]::DynamicConfig<rustc_query_system[13e780f7d1d88911]::query::caches::VecCache<rustc_span[51e7cf5b04f4660f]::def_id::LocalDefId, rustc_middle[3d266d78c9b198e4]::query::erase::Erased<[u8; 8usize]>>, false, false, false>, rustc_query_impl[75f1704df0e38289]::plumbing::QueryCtxt, false>
  40:        0x1135982ea - rustc_query_impl[75f1704df0e38289]::query_impl::mir_drops_elaborated_and_const_checked::get_query_non_incr::__rust_end_short_backtrace
  41:        0x11270ae48 - rustc_interface[ee26b89eef7e70ed]::passes::run_required_analyses
  42:        0x11270d170 - rustc_interface[ee26b89eef7e70ed]::passes::analysis
  43:        0x113582aca - rustc_query_impl[75f1704df0e38289]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[75f1704df0e38289]::query_impl::analysis::dynamic_query::{closure#2}::{closure#0}, rustc_middle[3d266d78c9b198e4]::query::erase::Erased<[u8; 1usize]>>
  44:        0x1133388ee - rustc_query_system[13e780f7d1d88911]::query::plumbing::try_execute_query::<rustc_query_impl[75f1704df0e38289]::DynamicConfig<rustc_query_system[13e780f7d1d88911]::query::caches::SingleCache<rustc_middle[3d266d78c9b198e4]::query::erase::Erased<[u8; 1usize]>>, false, false, false>, rustc_query_impl[75f1704df0e38289]::plumbing::QueryCtxt, false>
  45:        0x11358f177 - rustc_query_impl[75f1704df0e38289]::query_impl::analysis::get_query_non_incr::__rust_end_short_backtrace
  46:        0x111ce3e77 - <rustc_interface[ee26b89eef7e70ed]::queries::QueryResult<&rustc_middle[3d266d78c9b198e4]::ty::context::GlobalCtxt>>::enter::<core[907a20686bf8bf7a]::result::Result<(), rustc_span[51e7cf5b04f4660f]::ErrorGuaranteed>, rustc_driver_impl[e0e0c21a20d76ec4]::run_compiler::{closure#0}::{closure#1}::{closure#5}>
  47:        0x111d4195d - rustc_interface[ee26b89eef7e70ed]::interface::run_compiler::<core[907a20686bf8bf7a]::result::Result<(), rustc_span[51e7cf5b04f4660f]::ErrorGuaranteed>, rustc_driver_impl[e0e0c21a20d76ec4]::run_compiler::{closure#0}>::{closure#1}
  48:        0x111d2d59c - std[a533c313b02b6cfe]::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface[ee26b89eef7e70ed]::util::run_in_thread_with_globals<rustc_interface[ee26b89eef7e70ed]::util::run_in_thread_pool_with_globals<rustc_interface[ee26b89eef7e70ed]::interface::run_compiler<core[907a20686bf8bf7a]::result::Result<(), rustc_span[51e7cf5b04f4660f]::ErrorGuaranteed>, rustc_driver_impl[e0e0c21a20d76ec4]::run_compiler::{closure#0}>::{closure#1}, core[907a20686bf8bf7a]::result::Result<(), rustc_span[51e7cf5b04f4660f]::ErrorGuaranteed>>::{closure#0}, core[907a20686bf8bf7a]::result::Result<(), rustc_span[51e7cf5b04f4660f]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[907a20686bf8bf7a]::result::Result<(), rustc_span[51e7cf5b04f4660f]::ErrorGuaranteed>>
  49:        0x111d43f1a - <<std[a533c313b02b6cfe]::thread::Builder>::spawn_unchecked_<rustc_interface[ee26b89eef7e70ed]::util::run_in_thread_with_globals<rustc_interface[ee26b89eef7e70ed]::util::run_in_thread_pool_with_globals<rustc_interface[ee26b89eef7e70ed]::interface::run_compiler<core[907a20686bf8bf7a]::result::Result<(), rustc_span[51e7cf5b04f4660f]::ErrorGuaranteed>, rustc_driver_impl[e0e0c21a20d76ec4]::run_compiler::{closure#0}>::{closure#1}, core[907a20686bf8bf7a]::result::Result<(), rustc_span[51e7cf5b04f4660f]::ErrorGuaranteed>>::{closure#0}, core[907a20686bf8bf7a]::result::Result<(), rustc_span[51e7cf5b04f4660f]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[907a20686bf8bf7a]::result::Result<(), rustc_span[51e7cf5b04f4660f]::ErrorGuaranteed>>::{closure#1} as core[907a20686bf8bf7a]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  50:        0x113f3f95b - std::sys::pal::unix::thread::Thread::new::thread_start::hc5e64771570de417
  51:     0x7ff801f5318b - __pthread_start


rustc version: 1.83.0-nightly (7608018cb 2024-09-29)
platform: x86_64-apple-darwin

query stack during panic:
#0 [eval_to_allocation_raw] const-evaluating + checking `main::promoted[0]`
#1 [eval_to_const_value_raw] simplifying constant for the type system `main::promoted[0]`
#2 [mir_drops_elaborated_and_const_checked] elaborating drops for `main`
#3 [analysis] running analysis passes on this crate
end of query stack

Note

Ice location:

rust/compiler/rustc_const_eval/src/interpret/cast.rs

Lines 460 to 471 in 7608018

	_ => {
	// Do not ICE if we are not monomorphic enough.
	ensure_monomorphic_enough(*self.tcx, src.layout.ty)?;
	ensure_monomorphic_enough(*self.tcx, cast_ty)?;
	span_bug!(
	self.cur_span(),
	"invalid pointer unsizing {} -> {}",
	src.layout.ty,
	cast_ty
	)
	}

@rustbot label +F-coerce_unsized

[cyrgani]

Reduced:

impl<A> std::ops::CoerceUnsized<A> for A {}

fn main() {
    format_args!("Hello, world!");
}