ICE: Unexpected unsized type tail: &ReStatic [u8]

[matthiaskrgr]

auto-reduced (treereduce-rust):

use std::ops::Deref;

struct ArenaSet<U: Deref, V: ?Sized = <U as Deref>::Target>(V, U);

const DATA: *const ArenaSet<Vec<u8>> = std::ptr::null_mut();

original code / tests/ui/issues/issue-39367.rs

original:

//@ run-pass

use std::ops::Deref;

struct ArenaSet<U: Deref, V=<U as Deref>::Target>(V, &'static V)
    where V: 'static + ?Sized;

static Z: [u8; 3] = [1,2,3,4];

fn arena() -> &'static ArenaSet<Vec<u8>> {
    fn transmute() -> ArenaSet<Vec<u8>> {
        ArenaSet(|| {
                DATA = transmute
                    ::<ArenaSet<ArenaSet<Vec<u8>>>, *const ArenaSet<Vec<u8>>>
                    (Box::new(__static_ref_initialize(vec![], &Z)));
            })
    }
    unsafe {
        use std::sync::Once;
        fn arena<T: Sync>(_: &T) { }
        unsafe fn __stability() -> &'static ArenaSet<Vec<u8>> {
            use std::mem::transmute;
            static mut DATA: *const ArenaSet<Vec<u8>> = std::ptr::null_mut();

            static mut ONCE: Once = Once::new();
            ONCE.call_once(|| {
                unsafe {
        use std::sync::Once;
        fn require_sync<T: Sync>(_: &T) { }
        unsafe fn __stability() -> &'static ArenaSet<Vec<u8>> {
            use std::mem::transmute;
            static mut DATA: *const ArenaSet<Vec<u8>> = std::ptr::null_mut();

            static mut ONCE: Once = Once::new();
            ONCE.call_once(|| {
                DATA = transmute
                    ::<Box<ArenaSet<Vec<u8>>>, *const ArenaSet<Vec<u8>>>
                    (Box::new(__static_ref_initialize()));
            });

            &*DATA
        }
        let static_ref = __stability();
        require_sync(static_ref);
        static_ref
    }
            });

            &*DATA
        }
        let static_ref = __stability();
        require_sync(static_ref);
        static_ref
    }
}

fn main() {
    let &ArenaSet(ref u, v) = arena();
    assert!(u.is_empty());
    assert_eq!(v, Z);
}

Version information

rustc 1.78.0-nightly (6f3eb1ce3 2024-03-14)
binary: rustc
commit-hash: 6f3eb1ce3d50246b2cbc5de3107c0f34889f5cc6
commit-date: 2024-03-14
host: x86_64-unknown-linux-gnu
release: 1.78.0-nightly
LLVM version: 18.1.0

Command:
/home/matthias/.rustup/toolchains/master/bin/rustc

Program output

error[E0425]: cannot find value `static_ref` in this scope
  --> /tmp/icemaker_global_tempdir.NZlyzSctY1fd/rustc_testrunner_tmpdir_reporting.UHHGSMyDtFiG/mvce.rs:15:9
   |
15 |         static_ref
   |         ^^^^^^^^^^ not found in this scope

error[E0601]: `main` function not found in crate `mvce`
  --> /tmp/icemaker_global_tempdir.NZlyzSctY1fd/rustc_testrunner_tmpdir_reporting.UHHGSMyDtFiG/mvce.rs:17:2
   |
17 | }
   |  ^ consider adding a `main` function to `/tmp/icemaker_global_tempdir.NZlyzSctY1fd/rustc_testrunner_tmpdir_reporting.UHHGSMyDtFiG/mvce.rs`

error[E0277]: the size for values of type `V` cannot be known at compilation time
 --> /tmp/icemaker_global_tempdir.NZlyzSctY1fd/rustc_testrunner_tmpdir_reporting.UHHGSMyDtFiG/mvce.rs:3:53
  |
3 | struct ArenaSet<U: Deref, V = <U as Deref>::Target>(V, &'static V)
  |                           ------------------------  ^ doesn't have a size known at compile-time
  |                           |
  |                           this type parameter needs to be `Sized`
  |
  = note: only the last field of a struct may have a dynamically sized type
  = help: change the field's type to have a statically known size
help: consider removing the `?Sized` bound to make the type parameter `Sized`
  |
5 -     V: 'static + ?Sized;
5 +     V: 'static;
  |
help: borrowed types always have a statically known size
  |
3 | struct ArenaSet<U: Deref, V = <U as Deref>::Target>(&V, &'static V)
  |                                                     +
help: the `Box` type always has a statically known size and allocates its contents in the heap
  |
3 | struct ArenaSet<U: Deref, V = <U as Deref>::Target>(Box<V>, &'static V)
  |                                                     ++++ +

error[E0392]: type parameter `U` is never used
 --> /tmp/icemaker_global_tempdir.NZlyzSctY1fd/rustc_testrunner_tmpdir_reporting.UHHGSMyDtFiG/mvce.rs:3:17
  |
3 | struct ArenaSet<U: Deref, V = <U as Deref>::Target>(V, &'static V)
  |                 ^ unused type parameter
  |
  = help: consider removing `U`, referring to it in a field, or using a marker such as `PhantomData`

error: internal compiler error: compiler/rustc_const_eval/src/interpret/validity.rs:362:18: Unexpected unsized type tail: &ReStatic [u8]

thread 'rustc' panicked at compiler/rustc_middle/src/util/bug.rs:35:44:
Box<dyn Any>
stack backtrace:
   0:     0x7ffa2538cc22 - std::backtrace_rs::backtrace::libunwind::trace::h51bf9b6011ecfe46
                               at /rustc/6f3eb1ce3d50246b2cbc5de3107c0f34889f5cc6/library/std/src/../../backtrace/src/backtrace/libunwind.rs:105:5
   1:     0x7ffa2538cc22 - std::backtrace_rs::backtrace::trace_unsynchronized::ha7a99e8dfe87a5f1
                               at /rustc/6f3eb1ce3d50246b2cbc5de3107c0f34889f5cc6/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
   2:     0x7ffa2538cc22 - std::sys_common::backtrace::_print_fmt::h553275cb9152f9b7
                               at /rustc/6f3eb1ce3d50246b2cbc5de3107c0f34889f5cc6/library/std/src/sys_common/backtrace.rs:68:5
   3:     0x7ffa2538cc22 - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::h8630fe2600383786
                               at /rustc/6f3eb1ce3d50246b2cbc5de3107c0f34889f5cc6/library/std/src/sys_common/backtrace.rs:44:22
   4:     0x7ffa253ddeac - core::fmt::rt::Argument::fmt::h3a63bdd93942d79d
                               at /rustc/6f3eb1ce3d50246b2cbc5de3107c0f34889f5cc6/library/core/src/fmt/rt.rs:142:9
   5:     0x7ffa253ddeac - core::fmt::write::had61d91578b9cacb
                               at /rustc/6f3eb1ce3d50246b2cbc5de3107c0f34889f5cc6/library/core/src/fmt/mod.rs:1153:17
   6:     0x7ffa25381a1f - std::io::Write::write_fmt::hae3d824a3cf88f9d
                               at /rustc/6f3eb1ce3d50246b2cbc5de3107c0f34889f5cc6/library/std/src/io/mod.rs:1843:15
   7:     0x7ffa2538c9f4 - std::sys_common::backtrace::_print::h0314863ea3443f50
                               at /rustc/6f3eb1ce3d50246b2cbc5de3107c0f34889f5cc6/library/std/src/sys_common/backtrace.rs:47:5
   8:     0x7ffa2538c9f4 - std::sys_common::backtrace::print::hbb8fe6c998935be0
                               at /rustc/6f3eb1ce3d50246b2cbc5de3107c0f34889f5cc6/library/std/src/sys_common/backtrace.rs:34:9
   9:     0x7ffa2538f6fb - std::panicking::default_hook::{{closure}}::he3b999a7524899ad
  10:     0x7ffa2538f453 - std::panicking::default_hook::hf1ab3997598997ad
                               at /rustc/6f3eb1ce3d50246b2cbc5de3107c0f34889f5cc6/library/std/src/panicking.rs:292:9
  11:     0x7ffa282f8b2f - std[51808fdf74a5b252]::panicking::update_hook::<alloc[bb6d84cceaf892b5]::boxed::Box<rustc_driver_impl[5ed4bc6caf392c18]::install_ice_hook::{closure#0}>>::{closure#0}
  12:     0x7ffa2538fe60 - <alloc::boxed::Box<F,A> as core::ops::function::Fn<Args>>::call::h77828d88808d1300
                               at /rustc/6f3eb1ce3d50246b2cbc5de3107c0f34889f5cc6/library/alloc/src/boxed.rs:2034:9
  13:     0x7ffa2538fe60 - std::panicking::rust_panic_with_hook::hf855f69e938f97bf
                               at /rustc/6f3eb1ce3d50246b2cbc5de3107c0f34889f5cc6/library/std/src/panicking.rs:783:13
  14:     0x7ffa283255d4 - std[51808fdf74a5b252]::panicking::begin_panic::<rustc_errors[225c6794f4585fe9]::ExplicitBug>::{closure#0}
  15:     0x7ffa28322226 - std[51808fdf74a5b252]::sys_common::backtrace::__rust_end_short_backtrace::<std[51808fdf74a5b252]::panicking::begin_panic<rustc_errors[225c6794f4585fe9]::ExplicitBug>::{closure#0}, !>
  16:     0x7ffa2831d736 - std[51808fdf74a5b252]::panicking::begin_panic::<rustc_errors[225c6794f4585fe9]::ExplicitBug>
  17:     0x7ffa2832ea41 - <rustc_errors[225c6794f4585fe9]::diagnostic::BugAbort as rustc_errors[225c6794f4585fe9]::diagnostic::EmissionGuarantee>::emit_producing_guarantee
  18:     0x7ffa287af7b1 - rustc_middle[7492fbb28f48ec2e]::util::bug::opt_span_bug_fmt::<rustc_span[ba0d7ae542c94e2e]::span_encoding::Span>::{closure#0}
  19:     0x7ffa287933ca - rustc_middle[7492fbb28f48ec2e]::ty::context::tls::with_opt::<rustc_middle[7492fbb28f48ec2e]::util::bug::opt_span_bug_fmt<rustc_span[ba0d7ae542c94e2e]::span_encoding::Span>::{closure#0}, !>::{closure#0}
  20:     0x7ffa28793248 - rustc_middle[7492fbb28f48ec2e]::ty::context::tls::with_context_opt::<rustc_middle[7492fbb28f48ec2e]::ty::context::tls::with_opt<rustc_middle[7492fbb28f48ec2e]::util::bug::opt_span_bug_fmt<rustc_span[ba0d7ae542c94e2e]::span_encoding::Span>::{closure#0}, !>::{closure#0}, !>
  21:     0x7ffa26f59ee0 - rustc_middle[7492fbb28f48ec2e]::util::bug::bug_fmt
  22:     0x7ffa282b3637 - <rustc_const_eval[c77aacba90eb860b]::interpret::validity::ValidityVisitor<rustc_const_eval[c77aacba90eb860b]::const_eval::machine::CompileTimeInterpreter>>::check_wide_ptr_meta
  23:     0x7ffa296d0953 - <rustc_const_eval[c77aacba90eb860b]::interpret::validity::ValidityVisitor<rustc_const_eval[c77aacba90eb860b]::const_eval::machine::CompileTimeInterpreter> as rustc_const_eval[c77aacba90eb860b]::interpret::visitor::ValueVisitor<rustc_const_eval[c77aacba90eb860b]::const_eval::machine::CompileTimeInterpreter>>::visit_value
  24:     0x7ffa2a4a8db1 - rustc_const_eval[c77aacba90eb860b]::const_eval::eval_queries::eval_in_interpreter
  25:     0x7ffa29f60393 - rustc_const_eval[c77aacba90eb860b]::const_eval::eval_queries::eval_static_initializer_provider
  26:     0x7ffa29f60195 - rustc_query_impl[c8e011bed631d2ff]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[c8e011bed631d2ff]::query_impl::eval_static_initializer::dynamic_query::{closure#2}::{closure#0}, rustc_middle[7492fbb28f48ec2e]::query::erase::Erased<[u8; 16usize]>>
  27:     0x7ffa29f60167 - <rustc_query_impl[c8e011bed631d2ff]::query_impl::eval_static_initializer::dynamic_query::{closure#2} as core[f643d38b75b51528]::ops::function::FnOnce<(rustc_middle[7492fbb28f48ec2e]::ty::context::TyCtxt, rustc_span[ba0d7ae542c94e2e]::def_id::DefId)>>::call_once
  28:     0x7ffa29929a41 - rustc_query_system[33ba2b8a2c2ab98f]::query::plumbing::try_execute_query::<rustc_query_impl[c8e011bed631d2ff]::DynamicConfig<rustc_query_system[33ba2b8a2c2ab98f]::query::caches::DefIdCache<rustc_middle[7492fbb28f48ec2e]::query::erase::Erased<[u8; 16usize]>>, false, false, false>, rustc_query_impl[c8e011bed631d2ff]::plumbing::QueryCtxt, false>
  29:     0x7ffa2a5b3b71 - rustc_query_impl[c8e011bed631d2ff]::query_impl::eval_static_initializer::get_query_non_incr::__rust_end_short_backtrace
  30:     0x7ffa297cbe83 - <rustc_middle[7492fbb28f48ec2e]::hir::map::Map>::par_body_owners::<rustc_hir_analysis[49ec76ea6559053a]::check_crate::{closure#3}>::{closure#0}
  31:     0x7ffa297ca5c6 - rustc_hir_analysis[49ec76ea6559053a]::check_crate
  32:     0x7ffa29cc4e6a - rustc_interface[b4344970d0253b12]::passes::analysis
  33:     0x7ffa29cc4aa5 - rustc_query_impl[c8e011bed631d2ff]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[c8e011bed631d2ff]::query_impl::analysis::dynamic_query::{closure#2}::{closure#0}, rustc_middle[7492fbb28f48ec2e]::query::erase::Erased<[u8; 1usize]>>
  34:     0x7ffa2a425c25 - rustc_query_system[33ba2b8a2c2ab98f]::query::plumbing::try_execute_query::<rustc_query_impl[c8e011bed631d2ff]::DynamicConfig<rustc_query_system[33ba2b8a2c2ab98f]::query::caches::SingleCache<rustc_middle[7492fbb28f48ec2e]::query::erase::Erased<[u8; 1usize]>>, false, false, false>, rustc_query_impl[c8e011bed631d2ff]::plumbing::QueryCtxt, false>
  35:     0x7ffa2a425989 - rustc_query_impl[c8e011bed631d2ff]::query_impl::analysis::get_query_non_incr::__rust_end_short_backtrace
  36:     0x7ffa2a12fd04 - rustc_interface[b4344970d0253b12]::interface::run_compiler::<core[f643d38b75b51528]::result::Result<(), rustc_span[ba0d7ae542c94e2e]::ErrorGuaranteed>, rustc_driver_impl[5ed4bc6caf392c18]::run_compiler::{closure#0}>::{closure#0}
  37:     0x7ffa2a62ef45 - std[51808fdf74a5b252]::sys_common::backtrace::__rust_begin_short_backtrace::<rustc_interface[b4344970d0253b12]::util::run_in_thread_with_globals<rustc_interface[b4344970d0253b12]::util::run_in_thread_pool_with_globals<rustc_interface[b4344970d0253b12]::interface::run_compiler<core[f643d38b75b51528]::result::Result<(), rustc_span[ba0d7ae542c94e2e]::ErrorGuaranteed>, rustc_driver_impl[5ed4bc6caf392c18]::run_compiler::{closure#0}>::{closure#0}, core[f643d38b75b51528]::result::Result<(), rustc_span[ba0d7ae542c94e2e]::ErrorGuaranteed>>::{closure#0}, core[f643d38b75b51528]::result::Result<(), rustc_span[ba0d7ae542c94e2e]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[f643d38b75b51528]::result::Result<(), rustc_span[ba0d7ae542c94e2e]::ErrorGuaranteed>>
  38:     0x7ffa2a62ed72 - <<std[51808fdf74a5b252]::thread::Builder>::spawn_unchecked_<rustc_interface[b4344970d0253b12]::util::run_in_thread_with_globals<rustc_interface[b4344970d0253b12]::util::run_in_thread_pool_with_globals<rustc_interface[b4344970d0253b12]::interface::run_compiler<core[f643d38b75b51528]::result::Result<(), rustc_span[ba0d7ae542c94e2e]::ErrorGuaranteed>, rustc_driver_impl[5ed4bc6caf392c18]::run_compiler::{closure#0}>::{closure#0}, core[f643d38b75b51528]::result::Result<(), rustc_span[ba0d7ae542c94e2e]::ErrorGuaranteed>>::{closure#0}, core[f643d38b75b51528]::result::Result<(), rustc_span[ba0d7ae542c94e2e]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[f643d38b75b51528]::result::Result<(), rustc_span[ba0d7ae542c94e2e]::ErrorGuaranteed>>::{closure#1} as core[f643d38b75b51528]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  39:     0x7ffa25399505 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h97ea3917b3b3035c
                               at /rustc/6f3eb1ce3d50246b2cbc5de3107c0f34889f5cc6/library/alloc/src/boxed.rs:2020:9
  40:     0x7ffa25399505 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::hf2f1ed3ae326d6aa
                               at /rustc/6f3eb1ce3d50246b2cbc5de3107c0f34889f5cc6/library/alloc/src/boxed.rs:2020:9
  41:     0x7ffa25399505 - std::sys::pal::unix::thread::Thread::new::thread_start::h2c562c9f4cefc069
                               at /rustc/6f3eb1ce3d50246b2cbc5de3107c0f34889f5cc6/library/std/src/sys/pal/unix/thread.rs:108:17
  42:     0x7ffa2514b55a - <unknown>
  43:     0x7ffa251c8a3c - <unknown>
  44:                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: rustc 1.78.0-nightly (6f3eb1ce3 2024-03-14) running on x86_64-unknown-linux-gnu

query stack during panic:
#0 [eval_static_initializer] evaluating initializer of static `arena::__stability::DATA`
#1 [analysis] running analysis passes on this crate
end of query stack
error: aborting due to 5 previous errors

Some errors have detailed explanations: E0277, E0392, E0425, E0601.
For more information about an error, try `rustc --explain E0277`.

[matthiaskrgr]

#121087 cc @oli-obk

[matthiaskrgr]

maybe fixed by #121546

[gurry]

It is indeed fixed by #121546 . Does not ICE with the latest nightly.