ICE: resolution failed during building vtable representation trait_alias

[matthiaskrgr]

Code

#![feature(trait_alias)]

trait Alias = A where i32: B;

trait A {}

trait B {
    fn test(&self);
}

trait C: Alias {}

impl A for () {}

impl C for () {}

impl B for i32 {
    fn test(&self) {}
}

fn main() {
    let x: &C = &();
}

Meta

rustc --version --verbose:

rustc 1.70.0-nightly (1db9c061d 2023-03-21)
binary: rustc
commit-hash: 1db9c061d387a66ab16a90ec5a1b90adf216e2da
commit-date: 2023-03-21
host: x86_64-unknown-linux-gnu
release: 1.70.0-nightly
LLVM version: 15.0.7

Error output

<output>

Backtrace

warning: trait objects without an explicit `dyn` are deprecated
  --> melted.rs:22:13
   |
22 |     let x: &C = &();
   |             ^
   |
   = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
   = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
   = note: `#[warn(bare_trait_objects)]` on by default
help: use `dyn`
   |
22 |     let x: &dyn C = &();
   |             +++

warning: unused variable: `x`
  --> melted.rs:22:9
   |
22 |     let x: &C = &();
   |         ^ help: if this is intentional, prefix it with an underscore: `_x`
   |
   = note: `#[warn(unused_variables)]` on by default

thread 'rustc' panicked at 'resolution failed during building vtable representation', compiler/rustc_trait_selection/src/traits/vtable.rs:278:22
stack backtrace:
   0:     0x7f770804b65a - std::backtrace_rs::backtrace::libunwind::trace::h6885d9c02b85e679
                               at /rustc/1db9c061d387a66ab16a90ec5a1b90adf216e2da/library/std/src/../../backtrace/src/backtrace/libunwind.rs:93:5
   1:     0x7f770804b65a - std::backtrace_rs::backtrace::trace_unsynchronized::he3b2669200f72ece
                               at /rustc/1db9c061d387a66ab16a90ec5a1b90adf216e2da/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
   2:     0x7f770804b65a - std::sys_common::backtrace::_print_fmt::h8e8a9af758807679
                               at /rustc/1db9c061d387a66ab16a90ec5a1b90adf216e2da/library/std/src/sys_common/backtrace.rs:65:5
   3:     0x7f770804b65a - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::h38510c1ea4b1ecd1
                               at /rustc/1db9c061d387a66ab16a90ec5a1b90adf216e2da/library/std/src/sys_common/backtrace.rs:44:22
   4:     0x7f77080aefde - core::fmt::write::hc62f02881e1f07c1
                               at /rustc/1db9c061d387a66ab16a90ec5a1b90adf216e2da/library/core/src/fmt/mod.rs:1254:17
   5:     0x7f770803e2d5 - std::io::Write::write_fmt::hdace46740a33e745
                               at /rustc/1db9c061d387a66ab16a90ec5a1b90adf216e2da/library/std/src/io/mod.rs:1698:15
   6:     0x7f770804b425 - std::sys_common::backtrace::_print::hb03a3a0983d6f821
                               at /rustc/1db9c061d387a66ab16a90ec5a1b90adf216e2da/library/std/src/sys_common/backtrace.rs:47:5
   7:     0x7f770804b425 - std::sys_common::backtrace::print::ha68a6a98b1278679
                               at /rustc/1db9c061d387a66ab16a90ec5a1b90adf216e2da/library/std/src/sys_common/backtrace.rs:34:9
   8:     0x7f770804e19f - std::panicking::default_hook::{{closure}}::hf02923da46f3a3dc
                               at /rustc/1db9c061d387a66ab16a90ec5a1b90adf216e2da/library/std/src/panicking.rs:271:22
   9:     0x7f770804dedb - std::panicking::default_hook::he5a627c7eca3cd2a
                               at /rustc/1db9c061d387a66ab16a90ec5a1b90adf216e2da/library/std/src/panicking.rs:290:9
  10:     0x7f7706e36a15 - rustc_driver_impl[c8bf87673e33b5bb]::DEFAULT_HOOK::{closure#0}::{closure#0}
  11:     0x7f770804e9dd - <alloc::boxed::Box<F,A> as core::ops::function::Fn<Args>>::call::hdb8354f09c16b90c
                               at /rustc/1db9c061d387a66ab16a90ec5a1b90adf216e2da/library/alloc/src/boxed.rs:2002:9
  12:     0x7f770804e9dd - std::panicking::rust_panic_with_hook::ha6218529e5f05d2b
                               at /rustc/1db9c061d387a66ab16a90ec5a1b90adf216e2da/library/std/src/panicking.rs:696:13
  13:     0x7f770804e759 - std::panicking::begin_panic_handler::{{closure}}::h7eb84f4007bd2944
                               at /rustc/1db9c061d387a66ab16a90ec5a1b90adf216e2da/library/std/src/panicking.rs:583:13
  14:     0x7f770804bac6 - std::sys_common::backtrace::__rust_end_short_backtrace::h48c70ea8e6c4f5c0
                               at /rustc/1db9c061d387a66ab16a90ec5a1b90adf216e2da/library/std/src/sys_common/backtrace.rs:150:18
  15:     0x7f770804e462 - rust_begin_unwind
                               at /rustc/1db9c061d387a66ab16a90ec5a1b90adf216e2da/library/std/src/panicking.rs:579:5
  16:     0x7f77080ab323 - core::panicking::panic_fmt::h0e90db0c940dfbcc
                               at /rustc/1db9c061d387a66ab16a90ec5a1b90adf216e2da/library/core/src/panicking.rs:64:14
  17:     0x7f77080ab491 - core::panicking::panic_display::hc7ffdbd5b14c6adc
                               at /rustc/1db9c061d387a66ab16a90ec5a1b90adf216e2da/library/core/src/panicking.rs:147:5
  18:     0x7f77080ab43b - core::panicking::panic_str::hbbabf43062e5cee3
                               at /rustc/1db9c061d387a66ab16a90ec5a1b90adf216e2da/library/core/src/panicking.rs:131:5
  19:     0x7f77080ab0a6 - core::option::expect_failed::hc65688ea4e841b28
                               at /rustc/1db9c061d387a66ab16a90ec5a1b90adf216e2da/library/core/src/option.rs:2091:5
  20:     0x7f7705d635fd - <core[674372366ba6bd14]::iter::adapters::copied::Copied<core[674372366ba6bd14]::slice::iter::Iter<rustc_span[9ae650a2a6c0da86]::def_id::DefId>> as core[674372366ba6bd14]::iter::traits::iterator::Iterator>::fold::<(), core[674372366ba6bd14]::iter::adapters::map::map_fold<rustc_span[9ae650a2a6c0da86]::def_id::DefId, rustc_middle[f2c5526360e5c8cb]::ty::vtable::VtblEntry, (), rustc_trait_selection[ad86a979c94cdd0e]::traits::vtable::vtable_entries::{closure#0}::{closure#1}, core[674372366ba6bd14]::iter::traits::iterator::Iterator::for_each::call<rustc_middle[f2c5526360e5c8cb]::ty::vtable::VtblEntry, <alloc[575cea9fff30d964]::vec::Vec<rustc_middle[f2c5526360e5c8cb]::ty::vtable::VtblEntry>>::extend_trusted<core[674372366ba6bd14]::iter::adapters::map::Map<core[674372366ba6bd14]::iter::adapters::copied::Copied<core[674372366ba6bd14]::slice::iter::Iter<rustc_span[9ae650a2a6c0da86]::def_id::DefId>>, rustc_trait_selection[ad86a979c94cdd0e]::traits::vtable::vtable_entries::{closure#0}::{closure#1}>>::{closure#0}>::{closure#0}>::{closure#0}>
  21:     0x7f7705d60bda - rustc_trait_selection[ad86a979c94cdd0e]::traits::vtable::vtable_entries::{closure#0}
  22:     0x7f7705d600b6 - rustc_trait_selection[ad86a979c94cdd0e]::traits::vtable::vtable_entries
  23:     0x7f77062f8f0c - rustc_query_system[96d69ef80f10e645]::query::plumbing::try_execute_query::<rustc_query_impl[7b9961ca59d7bba3]::queries::vtable_entries, rustc_query_impl[7b9961ca59d7bba3]::plumbing::QueryCtxt>
  24:     0x7f77062f8b31 - <rustc_query_impl[7b9961ca59d7bba3]::Queries as rustc_middle[f2c5526360e5c8cb]::ty::query::QueryEngine>::vtable_entries
  25:     0x7f770622d6f0 - rustc_middle[f2c5526360e5c8cb]::ty::vtable::vtable_allocation_provider
  26:     0x7f770637d282 - rustc_query_system[96d69ef80f10e645]::query::plumbing::try_execute_query::<rustc_query_impl[7b9961ca59d7bba3]::queries::vtable_allocation, rustc_query_impl[7b9961ca59d7bba3]::plumbing::QueryCtxt>
  27:     0x7f770637ced9 - <rustc_query_impl[7b9961ca59d7bba3]::Queries as rustc_middle[f2c5526360e5c8cb]::ty::query::QueryEngine>::vtable_allocation
  28:     0x7f770622dc71 - rustc_middle[f2c5526360e5c8cb]::ty::vtable::vtable_allocation_provider
  29:     0x7f770637d282 - rustc_query_system[96d69ef80f10e645]::query::plumbing::try_execute_query::<rustc_query_impl[7b9961ca59d7bba3]::queries::vtable_allocation, rustc_query_impl[7b9961ca59d7bba3]::plumbing::QueryCtxt>
  30:     0x7f770637ced9 - <rustc_query_impl[7b9961ca59d7bba3]::Queries as rustc_middle[f2c5526360e5c8cb]::ty::query::QueryEngine>::vtable_allocation
  31:     0x7f7705672570 - rustc_codegen_ssa[1b6c701da86ec12d]::meth::get_vtable::<rustc_codegen_llvm[c341e14ca1f71b5b]::context::CodegenCx>
  32:     0x7f77056699b5 - rustc_codegen_ssa[1b6c701da86ec12d]::base::unsized_info::<rustc_codegen_llvm[c341e14ca1f71b5b]::builder::Builder>
  33:     0x7f77056629a3 - rustc_codegen_ssa[1b6c701da86ec12d]::base::unsize_ptr::<rustc_codegen_llvm[c341e14ca1f71b5b]::builder::Builder>
  34:     0x7f77056404c6 - <rustc_codegen_ssa[1b6c701da86ec12d]::mir::FunctionCx<rustc_codegen_llvm[c341e14ca1f71b5b]::builder::Builder>>::codegen_rvalue_operand
  35:     0x7f770561005c - rustc_codegen_ssa[1b6c701da86ec12d]::mir::codegen_mir::<rustc_codegen_llvm[c341e14ca1f71b5b]::builder::Builder>
  36:     0x7f77063afc53 - rustc_codegen_llvm[c341e14ca1f71b5b]::base::compile_codegen_unit::module_codegen
  37:     0x7f77063ad6cf - <rustc_codegen_llvm[c341e14ca1f71b5b]::LlvmCodegenBackend as rustc_codegen_ssa[1b6c701da86ec12d]::traits::backend::ExtraBackendMethods>::compile_codegen_unit
  38:     0x7f77063ab838 - rustc_codegen_ssa[1b6c701da86ec12d]::base::codegen_crate::<rustc_codegen_llvm[c341e14ca1f71b5b]::LlvmCodegenBackend>
  39:     0x7f77063ab14e - <rustc_codegen_llvm[c341e14ca1f71b5b]::LlvmCodegenBackend as rustc_codegen_ssa[1b6c701da86ec12d]::traits::backend::CodegenBackend>::codegen_crate
  40:     0x7f7705fa76b1 - <rustc_session[946294f1a07ac87a]::session::Session>::time::<alloc[575cea9fff30d964]::boxed::Box<dyn core[674372366ba6bd14]::any::Any>, rustc_interface[300e6cb95854dc34]::passes::start_codegen::{closure#0}>
  41:     0x7f7705fa71d9 - rustc_interface[300e6cb95854dc34]::passes::start_codegen
  42:     0x7f7705fa33e8 - <rustc_middle[f2c5526360e5c8cb]::ty::context::GlobalCtxt>::enter::<<rustc_interface[300e6cb95854dc34]::queries::Queries>::ongoing_codegen::{closure#0}::{closure#0}, core[674372366ba6bd14]::result::Result<alloc[575cea9fff30d964]::boxed::Box<dyn core[674372366ba6bd14]::any::Any>, rustc_span[9ae650a2a6c0da86]::ErrorGuaranteed>>
  43:     0x7f7705fa1a14 - <rustc_interface[300e6cb95854dc34]::queries::Queries>::ongoing_codegen
  44:     0x7f7705fa0fe1 - <rustc_interface[300e6cb95854dc34]::interface::Compiler>::enter::<rustc_driver_impl[c8bf87673e33b5bb]::run_compiler::{closure#1}::{closure#2}, core[674372366ba6bd14]::result::Result<core[674372366ba6bd14]::option::Option<rustc_interface[300e6cb95854dc34]::queries::Linker>, rustc_span[9ae650a2a6c0da86]::ErrorGuaranteed>>
  45:     0x7f7705f9c180 - rustc_span[9ae650a2a6c0da86]::with_source_map::<core[674372366ba6bd14]::result::Result<(), rustc_span[9ae650a2a6c0da86]::ErrorGuaranteed>, rustc_interface[300e6cb95854dc34]::interface::run_compiler<core[674372366ba6bd14]::result::Result<(), rustc_span[9ae650a2a6c0da86]::ErrorGuaranteed>, rustc_driver_impl[c8bf87673e33b5bb]::run_compiler::{closure#1}>::{closure#0}::{closure#0}>
  46:     0x7f7705f9b729 - std[6e758b2c95f8c60a]::sys_common::backtrace::__rust_begin_short_backtrace::<rustc_interface[300e6cb95854dc34]::util::run_in_thread_pool_with_globals<rustc_interface[300e6cb95854dc34]::interface::run_compiler<core[674372366ba6bd14]::result::Result<(), rustc_span[9ae650a2a6c0da86]::ErrorGuaranteed>, rustc_driver_impl[c8bf87673e33b5bb]::run_compiler::{closure#1}>::{closure#0}, core[674372366ba6bd14]::result::Result<(), rustc_span[9ae650a2a6c0da86]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[674372366ba6bd14]::result::Result<(), rustc_span[9ae650a2a6c0da86]::ErrorGuaranteed>>
  47:     0x7f77066e2aaa - <<std[6e758b2c95f8c60a]::thread::Builder>::spawn_unchecked_<rustc_interface[300e6cb95854dc34]::util::run_in_thread_pool_with_globals<rustc_interface[300e6cb95854dc34]::interface::run_compiler<core[674372366ba6bd14]::result::Result<(), rustc_span[9ae650a2a6c0da86]::ErrorGuaranteed>, rustc_driver_impl[c8bf87673e33b5bb]::run_compiler::{closure#1}>::{closure#0}, core[674372366ba6bd14]::result::Result<(), rustc_span[9ae650a2a6c0da86]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[674372366ba6bd14]::result::Result<(), rustc_span[9ae650a2a6c0da86]::ErrorGuaranteed>>::{closure#1} as core[674372366ba6bd14]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  48:     0x7f77080589a3 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h862118ca57b80f77
                               at /rustc/1db9c061d387a66ab16a90ec5a1b90adf216e2da/library/alloc/src/boxed.rs:1988:9
  49:     0x7f77080589a3 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h98de3b2171a6b9a2
                               at /rustc/1db9c061d387a66ab16a90ec5a1b90adf216e2da/library/alloc/src/boxed.rs:1988:9
  50:     0x7f77080589a3 - std::sys::unix::thread::Thread::new::thread_start::h31cc71e5d7fb3209
                               at /rustc/1db9c061d387a66ab16a90ec5a1b90adf216e2da/library/std/src/sys/unix/thread.rs:108:17
  51:     0x7f7703a67bb5 - <unknown>
  52:     0x7f7703ae9d90 - <unknown>
  53:                0x0 - <unknown>

error: 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 1.70.0-nightly (1db9c061d 2023-03-21) running on x86_64-unknown-linux-gnu

query stack during panic:
#0 [vtable_entries] finding all vtable entries for trait `B`
#1 [vtable_allocation] vtable const allocation for <() as B>
#2 [vtable_allocation] vtable const allocation for <() as C>
end of query stack
warning: 2 warnings emitted

[compiler-errors]

This should be fixed by #107614

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