ICE: index out of bounds: the len is 1 but the index is 1: layout.rs

[matthiaskrgr]

Code

// build-pass
// compile-flags: -Z mir-opt-level=3

#![crate_type="lib"]
#![feature(lang_items)]
#![no_std]

#[lang = "owned_box"]
pub struct Box<T: ?Sized>(*mut T);

impl<T: ?Sized> Drop for Box<T> {
    fn drop(&mut self) {
    }
}

#[lang = "box_free"]
#[inline(always)]
unsafe fn box_free<T: ?Sized>(ptr: *mut T) {
    dealloc(ptr)
}

#[inline(never)]
fn dealloc<T: ?Sized>(_: *mut T) {
}

pub struct Foo<T>(T);

pub fn foo(a: Option<Box<Foo<usize>>>) -> usize {
    let f = match a {
        None => Foo(0),
        Some(vec) => *vec,
    };
    f.0
}

Meta

rustc --version --verbose:

rustc 1.62.0-nightly (ec77f2524 2022-04-17)
binary: rustc
commit-hash: ec77f252434a532fdb5699ae4f21a3072d211edd
commit-date: 2022-04-17
host: x86_64-unknown-linux-gnu
release: 1.62.0-nightly
LLVM version: 14.0.0

Error output

<output>

Backtrace

thread 'rustc' panicked at 'index out of bounds: the len is 1 but the index is 1', /rustc/ec77f252434a532fdb5699ae4f21a3072d211edd/compiler/rustc_middle/src/ty/layout.rs:2408:51
stack backtrace:
   0:     0x7fa4c7c9d83d - std::backtrace_rs::backtrace::libunwind::trace::hdc1f21fb71c845ee
                               at /rustc/ec77f252434a532fdb5699ae4f21a3072d211edd/library/std/src/../../backtrace/src/backtrace/libunwind.rs:93:5
   1:     0x7fa4c7c9d83d - std::backtrace_rs::backtrace::trace_unsynchronized::h825695a1eac7e4dc
                               at /rustc/ec77f252434a532fdb5699ae4f21a3072d211edd/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
   2:     0x7fa4c7c9d83d - std::sys_common::backtrace::_print_fmt::h201cc1fed0ce4598
                               at /rustc/ec77f252434a532fdb5699ae4f21a3072d211edd/library/std/src/sys_common/backtrace.rs:66:5
   3:     0x7fa4c7c9d83d - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::h4c86a2fdb08a33f9
                               at /rustc/ec77f252434a532fdb5699ae4f21a3072d211edd/library/std/src/sys_common/backtrace.rs:45:22
   4:     0x7fa4c7cf8f1c - core::fmt::write::hee99b3f0c63f5ca9
                               at /rustc/ec77f252434a532fdb5699ae4f21a3072d211edd/library/core/src/fmt/mod.rs:1194:17
   5:     0x7fa4c7c8f031 - std::io::Write::write_fmt::hfa56cdeea03f4b89
                               at /rustc/ec77f252434a532fdb5699ae4f21a3072d211edd/library/std/src/io/mod.rs:1655:15
   6:     0x7fa4c7ca0555 - std::sys_common::backtrace::_print::hbd75018aef718598
                               at /rustc/ec77f252434a532fdb5699ae4f21a3072d211edd/library/std/src/sys_common/backtrace.rs:48:5
   7:     0x7fa4c7ca0555 - std::sys_common::backtrace::print::hc594da4af1e8ead7
                               at /rustc/ec77f252434a532fdb5699ae4f21a3072d211edd/library/std/src/sys_common/backtrace.rs:35:9
   8:     0x7fa4c7ca0555 - std::panicking::default_hook::{{closure}}::h0602100d469ef01e
                               at /rustc/ec77f252434a532fdb5699ae4f21a3072d211edd/library/std/src/panicking.rs:295:22
   9:     0x7fa4c7ca01c9 - std::panicking::default_hook::hc7ef6a8909090411
                               at /rustc/ec77f252434a532fdb5699ae4f21a3072d211edd/library/std/src/panicking.rs:314:9
  10:     0x7fa4c84d0521 - rustc_driver[8e3c698622bece67]::DEFAULT_HOOK::{closure#0}::{closure#0}
  11:     0x7fa4c7ca0d26 - std::panicking::rust_panic_with_hook::hb9245fe7222caa6e
                               at /rustc/ec77f252434a532fdb5699ae4f21a3072d211edd/library/std/src/panicking.rs:702:17
  12:     0x7fa4c7ca0b27 - std::panicking::begin_panic_handler::{{closure}}::he83bcf9a0c850a85
                               at /rustc/ec77f252434a532fdb5699ae4f21a3072d211edd/library/std/src/panicking.rs:588:13
  13:     0x7fa4c7c9dcf4 - std::sys_common::backtrace::__rust_end_short_backtrace::h465a02e71d825eac
                               at /rustc/ec77f252434a532fdb5699ae4f21a3072d211edd/library/std/src/sys_common/backtrace.rs:138:18
  14:     0x7fa4c7ca0859 - rust_begin_unwind
                               at /rustc/ec77f252434a532fdb5699ae4f21a3072d211edd/library/std/src/panicking.rs:584:5
  15:     0x7fa4c7c65c33 - core::panicking::panic_fmt::h23e69d1ae62ab6cd
                               at /rustc/ec77f252434a532fdb5699ae4f21a3072d211edd/library/core/src/panicking.rs:142:14
  16:     0x7fa4c7c65b72 - core::panicking::panic_bounds_check::h8691db1ad4a2a4b5
                               at /rustc/ec77f252434a532fdb5699ae4f21a3072d211edd/library/core/src/panicking.rs:84:5
  17:     0x7fa4c97ce917 - <rustc_middle[c02e249562e6ab88]::ty::Ty as rustc_target[707938acfa23df7d]::abi::TyAbiInterface<_>>::ty_and_layout_field::field_ty_or_layout::<rustc_codegen_llvm[b528a78dcf849805]::context::CodegenCx>
  18:     0x7fa4c97e941f - <rustc_target[707938acfa23df7d]::abi::TyAndLayout<rustc_middle[c02e249562e6ab88]::ty::Ty>>::field::<rustc_codegen_llvm[b528a78dcf849805]::context::CodegenCx>
  19:     0x7fa4c981e8bb - <rustc_codegen_ssa[a235b737831fdbb2]::mir::FunctionCx<rustc_codegen_llvm[b528a78dcf849805]::builder::Builder>>::codegen_place
  20:     0x7fa4c9815481 - <rustc_codegen_ssa[a235b737831fdbb2]::mir::FunctionCx<rustc_codegen_llvm[b528a78dcf849805]::builder::Builder>>::codegen_rvalue
  21:     0x7fa4c97fbbf9 - rustc_codegen_ssa[a235b737831fdbb2]::mir::codegen_mir::<rustc_codegen_llvm[b528a78dcf849805]::builder::Builder>
  22:     0x7fa4c97c7503 - rustc_codegen_llvm[b528a78dcf849805]::base::compile_codegen_unit::module_codegen
  23:     0x7fa4ca594716 - <rustc_query_system[b98794630d07627]::dep_graph::graph::DepGraph<rustc_middle[c02e249562e6ab88]::dep_graph::dep_node::DepKind>>::with_task::<rustc_middle[c02e249562e6ab88]::ty::context::TyCtxt, rustc_span[e15e523c5f5ffbde]::symbol::Symbol, rustc_codegen_ssa[a235b737831fdbb2]::ModuleCodegen<rustc_codegen_llvm[b528a78dcf849805]::ModuleLlvm>>
  24:     0x7fa4ca5941f9 - rustc_codegen_llvm[b528a78dcf849805]::base::compile_codegen_unit
  25:     0x7fa4ca565f35 - rustc_codegen_ssa[a235b737831fdbb2]::base::codegen_crate::<rustc_codegen_llvm[b528a78dcf849805]::LlvmCodegenBackend>
  26:     0x7fa4ca5b90fe - <rustc_codegen_llvm[b528a78dcf849805]::LlvmCodegenBackend as rustc_codegen_ssa[a235b737831fdbb2]::traits::backend::CodegenBackend>::codegen_crate
  27:     0x7fa4ca540327 - <rustc_session[8619e56cac793b58]::session::Session>::time::<alloc[8d468ea801fd4f9]::boxed::Box<dyn core[f08f6a517a2b1407]::any::Any>, rustc_interface[b4fe925d1e8786a0]::passes::start_codegen::{closure#0}>
  28:     0x7fa4ca53c0ec - <rustc_interface[b4fe925d1e8786a0]::passes::QueryContext>::enter::<<rustc_interface[b4fe925d1e8786a0]::queries::Queries>::ongoing_codegen::{closure#0}::{closure#0}, core[f08f6a517a2b1407]::result::Result<alloc[8d468ea801fd4f9]::boxed::Box<dyn core[f08f6a517a2b1407]::any::Any>, rustc_errors[dbef8fecc23abfce]::ErrorGuaranteed>>
  29:     0x7fa4ca55e58f - <rustc_interface[b4fe925d1e8786a0]::queries::Queries>::ongoing_codegen
  30:     0x7fa4ca505dcb - <rustc_interface[b4fe925d1e8786a0]::interface::Compiler>::enter::<rustc_driver[8e3c698622bece67]::run_compiler::{closure#1}::{closure#2}, core[f08f6a517a2b1407]::result::Result<core[f08f6a517a2b1407]::option::Option<rustc_interface[b4fe925d1e8786a0]::queries::Linker>, rustc_errors[dbef8fecc23abfce]::ErrorGuaranteed>>
  31:     0x7fa4ca52eeef - rustc_span[e15e523c5f5ffbde]::with_source_map::<core[f08f6a517a2b1407]::result::Result<(), rustc_errors[dbef8fecc23abfce]::ErrorGuaranteed>, rustc_interface[b4fe925d1e8786a0]::interface::create_compiler_and_run<core[f08f6a517a2b1407]::result::Result<(), rustc_errors[dbef8fecc23abfce]::ErrorGuaranteed>, rustc_driver[8e3c698622bece67]::run_compiler::{closure#1}>::{closure#1}>
  32:     0x7fa4ca5069b7 - <scoped_tls[ed206aee8c9203a6]::ScopedKey<rustc_span[e15e523c5f5ffbde]::SessionGlobals>>::set::<rustc_interface[b4fe925d1e8786a0]::interface::run_compiler<core[f08f6a517a2b1407]::result::Result<(), rustc_errors[dbef8fecc23abfce]::ErrorGuaranteed>, rustc_driver[8e3c698622bece67]::run_compiler::{closure#1}>::{closure#0}, core[f08f6a517a2b1407]::result::Result<(), rustc_errors[dbef8fecc23abfce]::ErrorGuaranteed>>
  33:     0x7fa4ca51bf0f - std[7eb92d5d5059ff02]::sys_common::backtrace::__rust_begin_short_backtrace::<rustc_interface[b4fe925d1e8786a0]::util::run_in_thread_pool_with_globals<rustc_interface[b4fe925d1e8786a0]::interface::run_compiler<core[f08f6a517a2b1407]::result::Result<(), rustc_errors[dbef8fecc23abfce]::ErrorGuaranteed>, rustc_driver[8e3c698622bece67]::run_compiler::{closure#1}>::{closure#0}, core[f08f6a517a2b1407]::result::Result<(), rustc_errors[dbef8fecc23abfce]::ErrorGuaranteed>>::{closure#0}, core[f08f6a517a2b1407]::result::Result<(), rustc_errors[dbef8fecc23abfce]::ErrorGuaranteed>>
  34:     0x7fa4ca51c049 - <<std[7eb92d5d5059ff02]::thread::Builder>::spawn_unchecked_<rustc_interface[b4fe925d1e8786a0]::util::run_in_thread_pool_with_globals<rustc_interface[b4fe925d1e8786a0]::interface::run_compiler<core[f08f6a517a2b1407]::result::Result<(), rustc_errors[dbef8fecc23abfce]::ErrorGuaranteed>, rustc_driver[8e3c698622bece67]::run_compiler::{closure#1}>::{closure#0}, core[f08f6a517a2b1407]::result::Result<(), rustc_errors[dbef8fecc23abfce]::ErrorGuaranteed>>::{closure#0}, core[f08f6a517a2b1407]::result::Result<(), rustc_errors[dbef8fecc23abfce]::ErrorGuaranteed>>::{closure#1} as core[f08f6a517a2b1407]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  35:     0x7fa4c7caabd3 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::hd2056160a42acd52
                               at /rustc/ec77f252434a532fdb5699ae4f21a3072d211edd/library/alloc/src/boxed.rs:1866:9
  36:     0x7fa4c7caabd3 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h99c5b980edefbf69
                               at /rustc/ec77f252434a532fdb5699ae4f21a3072d211edd/library/alloc/src/boxed.rs:1866:9
  37:     0x7fa4c7caabd3 - std::sys::unix::thread::Thread::new::thread_start::h42961cfa146716e3
                               at /rustc/ec77f252434a532fdb5699ae4f21a3072d211edd/library/std/src/sys/unix/thread.rs:108:17
  38:     0x7fa4c7a835c2 - start_thread
  39:     0x7fa4c7b08584 - __clone
  40:                0x0 - <unknown>

error: internal compiler error: unexpected panic

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 1.62.0-nightly (ec77f2524 2022-04-17) running on x86_64-unknown-linux-gnu

query stack during panic:
end of query stack

[asquared31415]

@rustbot label +A-lang-item

[beepster4096]

This is because some of the code related to dereferencing Box now assumes that Box contains a Unique field. You can prevent the ICE by adding a separate Unique struct or by putting the pointer into a tuple like (*mut T,).

[beepster4096]

Actually you would need ((*mut T,),) because Unique has NonNull now and that is also assumed by the compiler. Would be more readable to copy over the Unique struct.

[Noratrieb]

Now errors with

error: internal compiler error: compiler/rustc_mir_transform/src/elaborate_box_derefs.rs:97:17: expected Box to contain Unique

This seems good and correct, modifying lang items like this is not supported.