ICE: assertion failed: !self.intercrate

[matthiaskrgr]

Code

#![feature(specialization)]

trait Assoc {
    type Output;
}

default impl<T> Assoc for T {
    type Output = bool;
}

impl Assoc for u8 {}

trait Foo {}
impl Foo for u32 {}
impl Foo for <u8 as Assoc>::Output {}

Meta

rustc --version --verbose:

rustc 1.72.0-nightly (d9c13cd45 2023-07-05)
binary: rustc
commit-hash: d9c13cd4531649c2028a8384cb4d4e54f985380e
commit-date: 2023-07-05
host: x86_64-unknown-linux-gnu
release: 1.72.0-nightly
LLVM version: 16.0.5

Error output

Backtrace

warning: the feature `specialization` is incomplete and may not be safe to use and/or cause compiler crashes
 --> treereduce.out:1:12
  |
1 | #![feature(specialization)]
  |            ^^^^^^^^^^^^^^
  |
  = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
  = help: consider using `min_specialization` instead, which is more stable and complete
  = note: `#[warn(incomplete_features)]` on by default

error[E0601]: `main` function not found in crate `treereduce`
  --> treereduce.out:15:38
   |
15 | impl Foo for <u8 as Assoc>::Output {}
   |                                      ^ consider adding a `main` function to `treereduce.out`

thread 'rustc' panicked at 'assertion failed: !self.intercrate', compiler/rustc_trait_selection/src/traits/query/evaluate_obligation.rs:100:13
stack backtrace:
   0:     0x7f1a5fb63a81 - std::backtrace_rs::backtrace::libunwind::trace::h3c8b1207af9f7dc4
                               at /rustc/d9c13cd4531649c2028a8384cb4d4e54f985380e/library/std/src/../../backtrace/src/backtrace/libunwind.rs:93:5
   1:     0x7f1a5fb63a81 - std::backtrace_rs::backtrace::trace_unsynchronized::h6cc4d1ef12765b77
                               at /rustc/d9c13cd4531649c2028a8384cb4d4e54f985380e/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
   2:     0x7f1a5fb63a81 - std::sys_common::backtrace::_print_fmt::h4b58ac6692087093
                               at /rustc/d9c13cd4531649c2028a8384cb4d4e54f985380e/library/std/src/sys_common/backtrace.rs:65:5
   3:     0x7f1a5fb63a81 - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::h4cfe701aadad59ba
                               at /rustc/d9c13cd4531649c2028a8384cb4d4e54f985380e/library/std/src/sys_common/backtrace.rs:44:22
   4:     0x7f1a5fbc9d8f - core::fmt::rt::Argument::fmt::h017682705ed0d628
                               at /rustc/d9c13cd4531649c2028a8384cb4d4e54f985380e/library/core/src/fmt/rt.rs:138:9
   5:     0x7f1a5fbc9d8f - core::fmt::write::h69b96bfc1fe292d1
                               at /rustc/d9c13cd4531649c2028a8384cb4d4e54f985380e/library/core/src/fmt/mod.rs:1094:21
   6:     0x7f1a5fb563c7 - std::io::Write::write_fmt::h320e7f56f42ea27f
                               at /rustc/d9c13cd4531649c2028a8384cb4d4e54f985380e/library/std/src/io/mod.rs:1714:15
   7:     0x7f1a5fb63895 - std::sys_common::backtrace::_print::h0061961dcfb0fc1f
                               at /rustc/d9c13cd4531649c2028a8384cb4d4e54f985380e/library/std/src/sys_common/backtrace.rs:47:5
   8:     0x7f1a5fb63895 - std::sys_common::backtrace::print::h3caf3df7088e0a43
                               at /rustc/d9c13cd4531649c2028a8384cb4d4e54f985380e/library/std/src/sys_common/backtrace.rs:34:9
   9:     0x7f1a5fb66673 - std::panicking::default_hook::{{closure}}::h77ae45a48b0419f4
                               at /rustc/d9c13cd4531649c2028a8384cb4d4e54f985380e/library/std/src/panicking.rs:269:22
  10:     0x7f1a5fb66404 - std::panicking::default_hook::h1750cbe688cc23cf
                               at /rustc/d9c13cd4531649c2028a8384cb4d4e54f985380e/library/std/src/panicking.rs:288:9
  11:     0x7f1a62e72cab - rustc_driver_impl[c8224e60c583ce9e]::install_ice_hook::{closure#0}
  12:     0x7f1a5fb66e9e - <alloc::boxed::Box<F,A> as core::ops::function::Fn<Args>>::call::h2f7c4b5be15d65f3
                               at /rustc/d9c13cd4531649c2028a8384cb4d4e54f985380e/library/alloc/src/boxed.rs:2024:9
  13:     0x7f1a5fb66e9e - std::panicking::rust_panic_with_hook::hb1e7052d584ca5b8
                               at /rustc/d9c13cd4531649c2028a8384cb4d4e54f985380e/library/std/src/panicking.rs:709:13
  14:     0x7f1a5fb66be1 - std::panicking::begin_panic_handler::{{closure}}::haa7ba27cd61f2c57
                               at /rustc/d9c13cd4531649c2028a8384cb4d4e54f985380e/library/std/src/panicking.rs:595:13
  15:     0x7f1a5fb63ee6 - std::sys_common::backtrace::__rust_end_short_backtrace::hf9f1a9ff381b40f6
                               at /rustc/d9c13cd4531649c2028a8384cb4d4e54f985380e/library/std/src/sys_common/backtrace.rs:151:18
  16:     0x7f1a5fb66972 - rust_begin_unwind
                               at /rustc/d9c13cd4531649c2028a8384cb4d4e54f985380e/library/std/src/panicking.rs:593:5
  17:     0x7f1a5fbc5fe3 - core::panicking::panic_fmt::h7ce7a976d3070fa0
                               at /rustc/d9c13cd4531649c2028a8384cb4d4e54f985380e/library/core/src/panicking.rs:67:14
  18:     0x7f1a5fbc6073 - core::panicking::panic::hc2792b9695c02495
                               at /rustc/d9c13cd4531649c2028a8384cb4d4e54f985380e/library/core/src/panicking.rs:117:5
  19:     0x7f1a610b71fa - <rustc_trait_selection[41dd4520de8bf710]::traits::fulfill::FulfillProcessor as rustc_data_structures[c8b73cf51072de45]::obligation_forest::ObligationProcessor>::process_obligation
  20:     0x7f1a610a8bf4 - <rustc_data_structures[c8b73cf51072de45]::obligation_forest::ObligationForest<rustc_trait_selection[41dd4520de8bf710]::traits::fulfill::PendingPredicateObligation>>::process_obligations::<rustc_trait_selection[41dd4520de8bf710]::traits::fulfill::FulfillProcessor>
  21:     0x7f1a61266dff - <rustc_trait_selection[41dd4520de8bf710]::traits::engine::ObligationCtxt>::select_all_or_error
  22:     0x7f1a6123c7f7 - rustc_trait_selection[41dd4520de8bf710]::traits::specialize::translate_substs
  23:     0x7f1a6122845b - rustc_trait_selection[41dd4520de8bf710]::traits::project::opt_normalize_projection_type
  24:     0x7f1a6122346f - <rustc_trait_selection[41dd4520de8bf710]::traits::project::AssocTypeNormalizer as rustc_type_ir[6aab80a962adc91c]::fold::TypeFolder<rustc_middle[a92143083d338f81]::ty::context::TyCtxt>>::fold_ty
  25:     0x7f1a61b33715 - <rustc_middle[a92143083d338f81]::ty::ImplHeader as rustc_type_ir[6aab80a962adc91c]::fold::TypeFoldable<rustc_middle[a92143083d338f81]::ty::context::TyCtxt>>::fold_with::<rustc_trait_selection[41dd4520de8bf710]::traits::project::AssocTypeNormalizer>
  26:     0x7f1a61b32754 - <rustc_trait_selection[41dd4520de8bf710]::traits::project::AssocTypeNormalizer>::fold::<rustc_middle[a92143083d338f81]::ty::ImplHeader>
  27:     0x7f1a61b32099 - rustc_trait_selection[41dd4520de8bf710]::traits::project::normalize_with_depth::<rustc_middle[a92143083d338f81]::ty::ImplHeader>
  28:     0x7f1a61b31d99 - <rustc_infer[513a04dd9302731b]::infer::at::At as rustc_trait_selection[41dd4520de8bf710]::traits::project::NormalizeExt>::normalize::<rustc_middle[a92143083d338f81]::ty::ImplHeader>
  29:     0x7f1a61b31580 - rustc_trait_selection[41dd4520de8bf710]::traits::coherence::with_fresh_ty_vars
  30:     0x7f1a61b277e6 - rustc_trait_selection[41dd4520de8bf710]::traits::coherence::overlap
  31:     0x7f1a62028c6b - <rustc_middle[a92143083d338f81]::traits::specialization_graph::Children as rustc_trait_selection[41dd4520de8bf710]::traits::specialize::specialization_graph::ChildrenExt>::insert
  32:     0x7f1a62026ec0 - <rustc_middle[a92143083d338f81]::traits::specialization_graph::Graph as rustc_trait_selection[41dd4520de8bf710]::traits::specialize::specialization_graph::GraphExt>::insert
  33:     0x7f1a62025a83 - rustc_trait_selection[41dd4520de8bf710]::traits::specialize::specialization_graph_provider
  34:     0x7f1a6226317b - rustc_query_impl[7a314159d938cad9]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[7a314159d938cad9]::query_impl::specialization_graph_of::dynamic_query::{closure#2}::{closure#0}, rustc_middle[a92143083d338f81]::query::erase::Erased<[u8; 8usize]>>
  35:     0x7f1a62263151 - <rustc_query_impl[7a314159d938cad9]::query_impl::specialization_graph_of::dynamic_query::{closure#2} as core[39f2cadfad9b7192]::ops::function::FnOnce<(rustc_middle[a92143083d338f81]::ty::context::TyCtxt, rustc_span[c131c644fb7cb5fa]::def_id::DefId)>>::call_once
  36:     0x7f1a60e88d55 - rustc_query_system[fcf123a786d6e0bc]::query::plumbing::try_execute_query::<rustc_query_impl[7a314159d938cad9]::DynamicConfig<rustc_query_system[fcf123a786d6e0bc]::query::caches::DefaultCache<rustc_span[c131c644fb7cb5fa]::def_id::DefId, rustc_middle[a92143083d338f81]::query::erase::Erased<[u8; 8usize]>>, false, false, false>, rustc_query_impl[7a314159d938cad9]::plumbing::QueryCtxt, false>
  37:     0x7f1a627f86a4 - rustc_query_impl[7a314159d938cad9]::query_impl::specialization_graph_of::get_query_non_incr::__rust_end_short_backtrace
  38:     0x7f1a621c50b1 - rustc_hir_analysis[58a31f7655e3c3]::coherence::coherent_trait
  39:     0x7f1a61b0e3b1 - rustc_query_impl[7a314159d938cad9]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[7a314159d938cad9]::query_impl::coherent_trait::dynamic_query::{closure#2}::{closure#0}, rustc_middle[a92143083d338f81]::query::erase::Erased<[u8; 0usize]>>
  40:     0x7f1a61b0e391 - <rustc_query_impl[7a314159d938cad9]::query_impl::coherent_trait::dynamic_query::{closure#2} as core[39f2cadfad9b7192]::ops::function::FnOnce<(rustc_middle[a92143083d338f81]::ty::context::TyCtxt, rustc_span[c131c644fb7cb5fa]::def_id::DefId)>>::call_once
  41:     0x7f1a6238a960 - rustc_query_system[fcf123a786d6e0bc]::query::plumbing::try_execute_query::<rustc_query_impl[7a314159d938cad9]::DynamicConfig<rustc_query_system[fcf123a786d6e0bc]::query::caches::DefaultCache<rustc_span[c131c644fb7cb5fa]::def_id::DefId, rustc_middle[a92143083d338f81]::query::erase::Erased<[u8; 0usize]>>, false, false, false>, rustc_query_impl[7a314159d938cad9]::plumbing::QueryCtxt, false>
  42:     0x7f1a6238a6ce - rustc_query_impl[7a314159d938cad9]::query_impl::coherent_trait::get_query_non_incr::__rust_end_short_backtrace
  43:     0x7f1a622b1433 - <rustc_session[ba0171e1a42d92f9]::session::Session>::track_errors::<rustc_hir_analysis[58a31f7655e3c3]::check_crate::{closure#3}, ()>
  44:     0x7f1a622aed0e - rustc_hir_analysis[58a31f7655e3c3]::check_crate
  45:     0x7f1a622a5dda - rustc_interface[6ebb3a637cfebd5]::passes::analysis
  46:     0x7f1a6233368a - rustc_query_impl[7a314159d938cad9]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[7a314159d938cad9]::query_impl::analysis::dynamic_query::{closure#2}::{closure#0}, rustc_middle[a92143083d338f81]::query::erase::Erased<[u8; 1usize]>>
  47:     0x7f1a62333679 - <rustc_query_impl[7a314159d938cad9]::query_impl::analysis::dynamic_query::{closure#2} as core[39f2cadfad9b7192]::ops::function::FnOnce<(rustc_middle[a92143083d338f81]::ty::context::TyCtxt, ())>>::call_once
  48:     0x7f1a624ad878 - rustc_query_system[fcf123a786d6e0bc]::query::plumbing::try_execute_query::<rustc_query_impl[7a314159d938cad9]::DynamicConfig<rustc_query_system[fcf123a786d6e0bc]::query::caches::SingleCache<rustc_middle[a92143083d338f81]::query::erase::Erased<[u8; 1usize]>>, false, false, false>, rustc_query_impl[7a314159d938cad9]::plumbing::QueryCtxt, false>
  49:     0x7f1a624ad649 - rustc_query_impl[7a314159d938cad9]::query_impl::analysis::get_query_non_incr::__rust_end_short_backtrace
  50:     0x7f1a6205d455 - <rustc_middle[a92143083d338f81]::ty::context::GlobalCtxt>::enter::<rustc_driver_impl[c8224e60c583ce9e]::run_compiler::{closure#1}::{closure#2}::{closure#4}, core[39f2cadfad9b7192]::result::Result<(), rustc_span[c131c644fb7cb5fa]::ErrorGuaranteed>>
  51:     0x7f1a6205ca82 - <rustc_interface[6ebb3a637cfebd5]::interface::Compiler>::enter::<rustc_driver_impl[c8224e60c583ce9e]::run_compiler::{closure#1}::{closure#2}, core[39f2cadfad9b7192]::result::Result<core[39f2cadfad9b7192]::option::Option<rustc_interface[6ebb3a637cfebd5]::queries::Linker>, rustc_span[c131c644fb7cb5fa]::ErrorGuaranteed>>
  52:     0x7f1a62053795 - rustc_span[c131c644fb7cb5fa]::set_source_map::<core[39f2cadfad9b7192]::result::Result<(), rustc_span[c131c644fb7cb5fa]::ErrorGuaranteed>, rustc_interface[6ebb3a637cfebd5]::interface::run_compiler<core[39f2cadfad9b7192]::result::Result<(), rustc_span[c131c644fb7cb5fa]::ErrorGuaranteed>, rustc_driver_impl[c8224e60c583ce9e]::run_compiler::{closure#1}>::{closure#0}::{closure#0}>
  53:     0x7f1a62053206 - <scoped_tls[8bf4edb3452830f]::ScopedKey<rustc_span[c131c644fb7cb5fa]::SessionGlobals>>::set::<rustc_interface[6ebb3a637cfebd5]::interface::run_compiler<core[39f2cadfad9b7192]::result::Result<(), rustc_span[c131c644fb7cb5fa]::ErrorGuaranteed>, rustc_driver_impl[c8224e60c583ce9e]::run_compiler::{closure#1}>::{closure#0}, core[39f2cadfad9b7192]::result::Result<(), rustc_span[c131c644fb7cb5fa]::ErrorGuaranteed>>
  54:     0x7f1a620527cc - std[fa0d0b5c306c9702]::sys_common::backtrace::__rust_begin_short_backtrace::<rustc_interface[6ebb3a637cfebd5]::util::run_in_thread_pool_with_globals<rustc_interface[6ebb3a637cfebd5]::interface::run_compiler<core[39f2cadfad9b7192]::result::Result<(), rustc_span[c131c644fb7cb5fa]::ErrorGuaranteed>, rustc_driver_impl[c8224e60c583ce9e]::run_compiler::{closure#1}>::{closure#0}, core[39f2cadfad9b7192]::result::Result<(), rustc_span[c131c644fb7cb5fa]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[39f2cadfad9b7192]::result::Result<(), rustc_span[c131c644fb7cb5fa]::ErrorGuaranteed>>
  55:     0x7f1a62052595 - <<std[fa0d0b5c306c9702]::thread::Builder>::spawn_unchecked_<rustc_interface[6ebb3a637cfebd5]::util::run_in_thread_pool_with_globals<rustc_interface[6ebb3a637cfebd5]::interface::run_compiler<core[39f2cadfad9b7192]::result::Result<(), rustc_span[c131c644fb7cb5fa]::ErrorGuaranteed>, rustc_driver_impl[c8224e60c583ce9e]::run_compiler::{closure#1}>::{closure#0}, core[39f2cadfad9b7192]::result::Result<(), rustc_span[c131c644fb7cb5fa]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[39f2cadfad9b7192]::result::Result<(), rustc_span[c131c644fb7cb5fa]::ErrorGuaranteed>>::{closure#1} as core[39f2cadfad9b7192]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  56:     0x7f1a5fb71315 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h21ee91033946694b
                               at /rustc/d9c13cd4531649c2028a8384cb4d4e54f985380e/library/alloc/src/boxed.rs:2010:9
  57:     0x7f1a5fb71315 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::hdf07228f28997b56
                               at /rustc/d9c13cd4531649c2028a8384cb4d4e54f985380e/library/alloc/src/boxed.rs:2010:9
  58:     0x7f1a5fb71315 - std::sys::unix::thread::Thread::new::thread_start::h79fe093c0599c14c
                               at /rustc/d9c13cd4531649c2028a8384cb4d4e54f985380e/library/std/src/sys/unix/thread.rs:108:17
  59:     0x7f1a5f90244b - <unknown>
  60:     0x7f1a5f985e40 - <unknown>
  61:                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 1.72.0-nightly (d9c13cd45 2023-07-05) running on x86_64-unknown-linux-gnu

query stack during panic:
#0 [specialization_graph_of] building specialization graph of trait `Foo`
#1 [coherent_trait] coherence checking all impls of trait `Foo`
#2 [analysis] running analysis passes on this crate
end of query stack
error: aborting due to previous error; 1 warning emitted

For more information about this error, try `rustc --explain E0601`.

[compiler-errors]

cc @lcnr, you added this assertion 😃

[matthiaskrgr]

Regression in nightly-2023-07-06
Regression in 5dac6b3

[lcnr]

so this was clearly buggy before and I expect it to be an issue limited to specialization. Going to not look into this further myself for now.