ICE: type mismatch when copying

[matthiaskrgr]

Code

// build-pass
// compile-flags: -Z mir-opt-level=4

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

struct NonNull<T: ?Sized>(*mut T);

struct Unique<T: ?Sized>(NonNull<T>);

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

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

#[lang = "box_free"]
#[inline(always)]
unsafe fn box_free<T: ?Sized>(ptr: Unique<T>) {
    dealloc(ptr.0.0)
}

#[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
}

EDIT:
reduced:

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

struct NonNull<T>(*mut T);

struct Unique<T>(NonNull<T>);

#[lang = "owned_box"]
pub struct Box<T>(Unique<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 1.66.0-nightly (5253b0a0a 2022-09-17)
binary: rustc
commit-hash: 5253b0a0a1f366fad0ebed57597fcf2703b9e893
commit-date: 2022-09-17
host: x86_64-unknown-linux-gnu
release: 1.66.0-nightly
LLVM version: 15.0.0

Error output

<output>

Backtrace

error: internal compiler error: /rustc/5253b0a0a1f366fad0ebed57597fcf2703b9e893/compiler/rustc_const_eval/src/interpret/place.rs:631:13: type mismatch when copying!
                                src: *mut Foo<usize>,
                                dest: *const Foo<usize>
  --> 8e9c14a03c386623fed51bea2843c68ff16ca8d1.rs:33:22
   |
33 |         Some(vec) => *vec,
   |                      ^^^^

thread 'rustc' panicked at 'Box<dyn Any>', /rustc/5253b0a0a1f366fad0ebed57597fcf2703b9e893/compiler/rustc_errors/src/lib.rs:1400:9
stack backtrace:
   0:     0x7f7b75a66d50 - std::backtrace_rs::backtrace::libunwind::trace::hfb79018b8124bd7c
                               at /rustc/5253b0a0a1f366fad0ebed57597fcf2703b9e893/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
   1:     0x7f7b75a66d50 - std::backtrace_rs::backtrace::trace_unsynchronized::hea6348aacfc825bf
                               at /rustc/5253b0a0a1f366fad0ebed57597fcf2703b9e893/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
   2:     0x7f7b75a66d50 - std::sys_common::backtrace::_print_fmt::h3218c5762799b817
                               at /rustc/5253b0a0a1f366fad0ebed57597fcf2703b9e893/library/std/src/sys_common/backtrace.rs:66:5
   3:     0x7f7b75a66d50 - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::h181c78d6d7624e10
                               at /rustc/5253b0a0a1f366fad0ebed57597fcf2703b9e893/library/std/src/sys_common/backtrace.rs:45:22
   4:     0x7f7b75ac1aae - core::fmt::write::ha340c24d0927f08a
                               at /rustc/5253b0a0a1f366fad0ebed57597fcf2703b9e893/library/core/src/fmt/mod.rs:1202:17
   5:     0x7f7b75a57865 - std::io::Write::write_fmt::h4630979fc72cb761
                               at /rustc/5253b0a0a1f366fad0ebed57597fcf2703b9e893/library/std/src/io/mod.rs:1679:15
   6:     0x7f7b75a69a03 - std::sys_common::backtrace::_print::hd2ccf5d61648e037
                               at /rustc/5253b0a0a1f366fad0ebed57597fcf2703b9e893/library/std/src/sys_common/backtrace.rs:48:5
   7:     0x7f7b75a69a03 - std::sys_common::backtrace::print::hd0f2f0fedf9931f4
                               at /rustc/5253b0a0a1f366fad0ebed57597fcf2703b9e893/library/std/src/sys_common/backtrace.rs:35:9
   8:     0x7f7b75a69a03 - std::panicking::default_hook::{{closure}}::h2244b279de173624
                               at /rustc/5253b0a0a1f366fad0ebed57597fcf2703b9e893/library/std/src/panicking.rs:295:22
   9:     0x7f7b75a696ef - std::panicking::default_hook::hcca6f76171fccd3c
                               at /rustc/5253b0a0a1f366fad0ebed57597fcf2703b9e893/library/std/src/panicking.rs:314:9
  10:     0x7f7b7828e7b1 - <rustc_driver[72e0105baa36f7cf]::DEFAULT_HOOK::{closure#0}::{closure#0} as core[ec2fec875cdc804]::ops::function::FnOnce<(&core[ec2fec875cdc804]::panic::panic_info::PanicInfo,)>>::call_once::{shim:vtable#0}
  11:     0x7f7b75a6a23d - std::panicking::rust_panic_with_hook::ha693bd81668665fa
                               at /rustc/5253b0a0a1f366fad0ebed57597fcf2703b9e893/library/std/src/panicking.rs:702:17
  12:     0x7f7b78529051 - std[8229d8ca295b5814]::panicking::begin_panic::<rustc_errors[7b8d156defe7df9c]::ExplicitBug>::{closure#0}
  13:     0x7f7b78526ce6 - std[8229d8ca295b5814]::sys_common::backtrace::__rust_end_short_backtrace::<std[8229d8ca295b5814]::panicking::begin_panic<rustc_errors[7b8d156defe7df9c]::ExplicitBug>::{closure#0}, !>
  14:     0x7f7b7849a666 - std[8229d8ca295b5814]::panicking::begin_panic::<rustc_errors[7b8d156defe7df9c]::ExplicitBug>
  15:     0x7f7b78543206 - std[8229d8ca295b5814]::panic::panic_any::<rustc_errors[7b8d156defe7df9c]::ExplicitBug>
  16:     0x7f7b7854154f - <rustc_errors[7b8d156defe7df9c]::HandlerInner>::span_bug::<rustc_span[541efa118ade656b]::span_encoding::Span, &alloc[6ca9daef4cd1a959]::string::String>
  17:     0x7f7b785412d0 - <rustc_errors[7b8d156defe7df9c]::Handler>::span_bug::<rustc_span[541efa118ade656b]::span_encoding::Span, &alloc[6ca9daef4cd1a959]::string::String>
  18:     0x7f7b7856eb38 - rustc_middle[3d6e05987d135e92]::ty::context::tls::with_context_opt::<rustc_middle[3d6e05987d135e92]::ty::context::tls::with_opt<rustc_middle[3d6e05987d135e92]::util::bug::opt_span_bug_fmt<rustc_span[541efa118ade656b]::span_encoding::Span>::{closure#0}, ()>::{closure#0}, ()>
  19:     0x7f7b7856df26 - rustc_middle[3d6e05987d135e92]::util::bug::opt_span_bug_fmt::<rustc_span[541efa118ade656b]::span_encoding::Span>
  20:     0x7f7b7856dee4 - rustc_middle[3d6e05987d135e92]::util::bug::span_bug_fmt::<rustc_span[541efa118ade656b]::span_encoding::Span>
  21:     0x7f7b778f3a22 - <rustc_const_eval[e3e04f79ad77013b]::interpret::eval_context::InterpCx<rustc_mir_transform[7aeef426106e0faf]::const_prop::ConstPropMachine>>::eval_rvalue_into_place
  22:     0x7f7b776a3b2a - <rustc_mir_transform[7aeef426106e0faf]::const_prop_lint::ConstPropagator as rustc_middle[3d6e05987d135e92]::mir::visit::Visitor>::visit_body
  23:     0x7f7b7769b568 - <rustc_mir_transform[7aeef426106e0faf]::const_prop_lint::ConstProp as rustc_mir_transform[7aeef426106e0faf]::pass_manager::MirLint>::run_lint
  24:     0x7f7b76e247e5 - rustc_mir_transform[7aeef426106e0faf]::pass_manager::run_passes_no_validate
  25:     0x7f7b76e21ad4 - rustc_mir_transform[7aeef426106e0faf]::run_analysis_to_runtime_passes
  26:     0x7f7b76e20ae2 - rustc_mir_transform[7aeef426106e0faf]::mir_drops_elaborated_and_const_checked
  27:     0x7f7b77859493 - rustc_query_system[608e370b752ac82e]::query::plumbing::try_execute_query::<rustc_query_impl[fcea84a614a56b3b]::plumbing::QueryCtxt, rustc_query_system[608e370b752ac82e]::query::caches::DefaultCache<rustc_middle[3d6e05987d135e92]::ty::WithOptConstParam<rustc_span[541efa118ade656b]::def_id::LocalDefId>, &rustc_data_structures[3c4e9a6ddd2ce539]::steal::Steal<rustc_middle[3d6e05987d135e92]::mir::Body>>>
  28:     0x7f7b781d5dfe - <rustc_query_impl[fcea84a614a56b3b]::Queries as rustc_middle[3d6e05987d135e92]::ty::query::QueryEngine>::mir_drops_elaborated_and_const_checked
  29:     0x7f7b76e6be0b - rustc_mir_transform[7aeef426106e0faf]::optimized_mir
  30:     0x7f7b7768923b - rustc_query_system[608e370b752ac82e]::query::plumbing::try_execute_query::<rustc_query_impl[fcea84a614a56b3b]::plumbing::QueryCtxt, rustc_query_system[608e370b752ac82e]::query::caches::DefaultCache<rustc_span[541efa118ade656b]::def_id::DefId, &rustc_middle[3d6e05987d135e92]::mir::Body>>
  31:     0x7f7b781d61ef - <rustc_query_impl[fcea84a614a56b3b]::Queries as rustc_middle[3d6e05987d135e92]::ty::query::QueryEngine>::optimized_mir
  32:     0x7f7b76eb10e5 - <rustc_middle[3d6e05987d135e92]::ty::context::TyCtxt>::instance_mir
  33:     0x7f7b76ea65fc - rustc_monomorphize[5e15c09026669cb]::collector::collect_neighbours
  34:     0x7f7b76ea4192 - rustc_monomorphize[5e15c09026669cb]::collector::collect_items_rec
  35:     0x7f7b77a59210 - <rustc_session[7ea819359e1dc160]::session::Session>::time::<(), rustc_monomorphize[5e15c09026669cb]::collector::collect_crate_mono_items::{closure#1}>
  36:     0x7f7b77a58da9 - rustc_monomorphize[5e15c09026669cb]::collector::collect_crate_mono_items
  37:     0x7f7b77a57c96 - rustc_monomorphize[5e15c09026669cb]::partitioning::collect_and_partition_mono_items
  38:     0x7f7b78049049 - rustc_query_system[608e370b752ac82e]::query::plumbing::try_execute_query::<rustc_query_impl[fcea84a614a56b3b]::plumbing::QueryCtxt, rustc_query_system[608e370b752ac82e]::query::caches::DefaultCache<(), (&std[8229d8ca295b5814]::collections::hash::set::HashSet<rustc_span[541efa118ade656b]::def_id::DefId, core[ec2fec875cdc804]::hash::BuildHasherDefault<rustc_hash[f62f8fd144a94afc]::FxHasher>>, &[rustc_middle[3d6e05987d135e92]::mir::mono::CodegenUnit])>>
  39:     0x7f7b78048d3b - rustc_query_system[608e370b752ac82e]::query::plumbing::get_query::<rustc_query_impl[fcea84a614a56b3b]::queries::collect_and_partition_mono_items, rustc_query_impl[fcea84a614a56b3b]::plumbing::QueryCtxt>
  40:     0x7f7b78048c7e - <rustc_query_impl[fcea84a614a56b3b]::Queries as rustc_middle[3d6e05987d135e92]::ty::query::QueryEngine>::collect_and_partition_mono_items
  41:     0x7f7b78083ad6 - rustc_codegen_ssa[ccbc7b85aa3cd]::back::symbol_export::exported_symbols_provider_local
  42:     0x7f7b77f261d4 - rustc_query_system[608e370b752ac82e]::query::plumbing::try_execute_query::<rustc_query_impl[fcea84a614a56b3b]::plumbing::QueryCtxt, rustc_query_system[608e370b752ac82e]::query::caches::DefaultCache<rustc_span[541efa118ade656b]::def_id::CrateNum, &[(rustc_middle[3d6e05987d135e92]::middle::exported_symbols::ExportedSymbol, rustc_middle[3d6e05987d135e92]::middle::exported_symbols::SymbolExportInfo)]>>
  43:     0x7f7b77f25e69 - rustc_query_system[608e370b752ac82e]::query::plumbing::get_query::<rustc_query_impl[fcea84a614a56b3b]::queries::exported_symbols, rustc_query_impl[fcea84a614a56b3b]::plumbing::QueryCtxt>
  44:     0x7f7b7764518a - <rustc_metadata[f2051a5928ead7ba]::rmeta::encoder::EncodeContext>::encode_crate_root
  45:     0x7f7b770d7ef2 - rustc_metadata[f2051a5928ead7ba]::rmeta::encoder::encode_metadata_impl
  46:     0x7f7b770b979e - rustc_data_structures[3c4e9a6ddd2ce539]::sync::join::<rustc_metadata[f2051a5928ead7ba]::rmeta::encoder::encode_metadata::{closure#0}, rustc_metadata[f2051a5928ead7ba]::rmeta::encoder::encode_metadata::{closure#1}, (), ()>
  47:     0x7f7b770b9689 - rustc_metadata[f2051a5928ead7ba]::rmeta::encoder::encode_metadata
  48:     0x7f7b770b8773 - rustc_metadata[f2051a5928ead7ba]::fs::encode_and_write_metadata
  49:     0x7f7b770ac512 - <rustc_interface[c871b29908bd8039]::passes::QueryContext>::enter::<<rustc_interface[c871b29908bd8039]::queries::Queries>::ongoing_codegen::{closure#0}::{closure#0}, core[ec2fec875cdc804]::result::Result<alloc[6ca9daef4cd1a959]::boxed::Box<dyn core[ec2fec875cdc804]::any::Any>, rustc_errors[7b8d156defe7df9c]::ErrorGuaranteed>>
  50:     0x7f7b7706c323 - <rustc_interface[c871b29908bd8039]::queries::Queries>::ongoing_codegen
  51:     0x7f7b7706a77a - rustc_interface[c871b29908bd8039]::interface::create_compiler_and_run::<core[ec2fec875cdc804]::result::Result<(), rustc_errors[7b8d156defe7df9c]::ErrorGuaranteed>, rustc_driver[72e0105baa36f7cf]::run_compiler::{closure#1}>
  52:     0x7f7b77069072 - <scoped_tls[d2169369cda87714]::ScopedKey<rustc_span[541efa118ade656b]::SessionGlobals>>::set::<rustc_interface[c871b29908bd8039]::interface::run_compiler<core[ec2fec875cdc804]::result::Result<(), rustc_errors[7b8d156defe7df9c]::ErrorGuaranteed>, rustc_driver[72e0105baa36f7cf]::run_compiler::{closure#1}>::{closure#0}, core[ec2fec875cdc804]::result::Result<(), rustc_errors[7b8d156defe7df9c]::ErrorGuaranteed>>
  53:     0x7f7b77068d5f - std[8229d8ca295b5814]::sys_common::backtrace::__rust_begin_short_backtrace::<rustc_interface[c871b29908bd8039]::util::run_in_thread_pool_with_globals<rustc_interface[c871b29908bd8039]::interface::run_compiler<core[ec2fec875cdc804]::result::Result<(), rustc_errors[7b8d156defe7df9c]::ErrorGuaranteed>, rustc_driver[72e0105baa36f7cf]::run_compiler::{closure#1}>::{closure#0}, core[ec2fec875cdc804]::result::Result<(), rustc_errors[7b8d156defe7df9c]::ErrorGuaranteed>>::{closure#0}, core[ec2fec875cdc804]::result::Result<(), rustc_errors[7b8d156defe7df9c]::ErrorGuaranteed>>
  54:     0x7f7b780fb2c0 - <<std[8229d8ca295b5814]::thread::Builder>::spawn_unchecked_<rustc_interface[c871b29908bd8039]::util::run_in_thread_pool_with_globals<rustc_interface[c871b29908bd8039]::interface::run_compiler<core[ec2fec875cdc804]::result::Result<(), rustc_errors[7b8d156defe7df9c]::ErrorGuaranteed>, rustc_driver[72e0105baa36f7cf]::run_compiler::{closure#1}>::{closure#0}, core[ec2fec875cdc804]::result::Result<(), rustc_errors[7b8d156defe7df9c]::ErrorGuaranteed>>::{closure#0}, core[ec2fec875cdc804]::result::Result<(), rustc_errors[7b8d156defe7df9c]::ErrorGuaranteed>>::{closure#1} as core[ec2fec875cdc804]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  55:     0x7f7b75a74013 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::hdce79cf9300fb363
                               at /rustc/5253b0a0a1f366fad0ebed57597fcf2703b9e893/library/alloc/src/boxed.rs:1940:9
  56:     0x7f7b75a74013 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h430f90c9a59126a4
                               at /rustc/5253b0a0a1f366fad0ebed57597fcf2703b9e893/library/alloc/src/boxed.rs:1940:9
  57:     0x7f7b75a74013 - std::sys::unix::thread::Thread::new::thread_start::h08d74d71e885bab7
                               at /rustc/5253b0a0a1f366fad0ebed57597fcf2703b9e893/library/std/src/sys/unix/thread.rs:108:17
  58:     0x7f7b757cc78d - <unknown>
  59:     0x7f7b7584d8e4 - clone
  60:                0x0 - <unknown>

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 1.66.0-nightly (5253b0a0a 2022-09-17) running on x86_64-unknown-linux-gnu

query stack during panic:
#0 [mir_drops_elaborated_and_const_checked] elaborating drops for `foo`
#1 [optimized_mir] optimizing MIR for `foo`
#2 [collect_and_partition_mono_items] collect_and_partition_mono_items
#3 [exported_symbols] exported_symbols
end of query stack
error: aborting due to previous error

[matthiaskrgr]

There is a similar file in the rustc repo src/test/ui/mir/ssa-analysis-regression-50041.rs which does not crash:

--- src/test/ui/mir/ssa-analysis-regression-50041.rs	2022-07-17 12:25:49.238091488 +0200
+++ /tmp/im/8e9c14a03c386623fed51bea2843c68ff16ca8d1.rs	2022-09-18 05:59:43.438071009 +0200
@@ -5,7 +5,7 @@
 #![feature(lang_items)]
 #![no_std]

-struct NonNull<T: ?Sized>(*const T);
+struct NonNull<T: ?Sized>(*mut T);

 struct Unique<T: ?Sized>(NonNull<T>);

@@ -23,7 +23,7 @@
 }

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

 pub struct Foo<T>(T);

[JohnTitor]

Triage: Fixed on the latest nightly, @rustbot labels: +E-needs-test