ICE: with_negative_coherence + specialization

[matthiaskrgr]

Seems that both these snippets trigger the same ICE
rustc ./43037.rs -Zcrate-attr="feature(with_negative_coherence)"

Code

glacier/fixed/45814.rs

#![feature(specialization)]

pub trait Trait<T> { }

default impl<T, U> Trait<T> for U { }

impl<T> Trait<<T as Iterator>::Item> for T { }

fn main() { }

Code

glacier/fixed/43037.rs

#![crate_type = "lib"]
#![feature(specialization)] // comment this line to get the expected behavior
trait X {}
trait Y: X {}
trait Z { type Assoc: Y; }
struct A<T>(T);

impl<T> Y for T where T: X {}
impl<T: X> Z for A<T> { type Assoc = T; }

// this impl is invalid, but causes an ICE anyway
impl<T> From<<A<T> as Z>::Assoc> for T {}

fn main() {}

Meta

rustc --version --verbose:

rustc 1.64.0-nightly (55f46419a 2022-08-05)
binary: rustc
commit-hash: 55f46419afd2e49acfc6be176ad4aeadaa5686d7
commit-date: 2022-08-05
host: x86_64-unknown-linux-gnu
release: 1.64.0-nightly
LLVM version: 14.0.6

Error output

Backtrace

warning: the feature `specialization` is incomplete and may not be safe to use and/or cause compiler crashes
 --> ./43037.rs:2:12
  |
2 | #![feature(specialization)] // comment this line to get the expected behavior
  |            ^^^^^^^^^^^^^^
  |
  = note: `#[warn(incomplete_features)]` on by default
  = 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

error: internal compiler error: compiler/rustc_trait_selection/src/traits/coherence.rs:311:25: failed to fully normalize DefId(0:16 ~ 43037[6c8e]::{impl#2}): [FulfillmentError(Obligation(predicate=Binder(TraitPredicate(<T as X>, polarity:Positive), []), depth=1),Unimplemented)]

thread 'rustc' panicked at 'Box<dyn Any>', /rustc/55f46419afd2e49acfc6be176ad4aeadaa5686d7/compiler/rustc_errors/src/lib.rs:1392:9
stack backtrace:
   0:     0x7fc3306189f0 - std::backtrace_rs::backtrace::libunwind::trace::he1976fae853ce905
                               at /rustc/55f46419afd2e49acfc6be176ad4aeadaa5686d7/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
   1:     0x7fc3306189f0 - std::backtrace_rs::backtrace::trace_unsynchronized::h3488ea444a1a69dd
                               at /rustc/55f46419afd2e49acfc6be176ad4aeadaa5686d7/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
   2:     0x7fc3306189f0 - std::sys_common::backtrace::_print_fmt::hfad550d850e72213
                               at /rustc/55f46419afd2e49acfc6be176ad4aeadaa5686d7/library/std/src/sys_common/backtrace.rs:66:5
   3:     0x7fc3306189f0 - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::h42d6f8c2d1e8c740
                               at /rustc/55f46419afd2e49acfc6be176ad4aeadaa5686d7/library/std/src/sys_common/backtrace.rs:45:22
   4:     0x7fc3306743bc - core::fmt::write::ha87b736d58259280
                               at /rustc/55f46419afd2e49acfc6be176ad4aeadaa5686d7/library/core/src/fmt/mod.rs:1198:17
   5:     0x7fc330609c35 - std::io::Write::write_fmt::hf60299faac9a8340
                               at /rustc/55f46419afd2e49acfc6be176ad4aeadaa5686d7/library/std/src/io/mod.rs:1672:15
   6:     0x7fc33061b6d1 - std::sys_common::backtrace::_print::h5274cd1faa558544
                               at /rustc/55f46419afd2e49acfc6be176ad4aeadaa5686d7/library/std/src/sys_common/backtrace.rs:48:5
   7:     0x7fc33061b6d1 - std::sys_common::backtrace::print::h184de4772363b29a
                               at /rustc/55f46419afd2e49acfc6be176ad4aeadaa5686d7/library/std/src/sys_common/backtrace.rs:35:9
   8:     0x7fc33061b6d1 - std::panicking::default_hook::{{closure}}::h224bcb75892e6bc7
                               at /rustc/55f46419afd2e49acfc6be176ad4aeadaa5686d7/library/std/src/panicking.rs:295:22
   9:     0x7fc33061b39e - std::panicking::default_hook::hd243a62dc6826477
                               at /rustc/55f46419afd2e49acfc6be176ad4aeadaa5686d7/library/std/src/panicking.rs:314:9
  10:     0x7fc332e93524 - rustc_driver[f6b350ee36914076]::DEFAULT_HOOK::{closure#0}::{closure#0}
  11:     0x7fc33061bf06 - std::panicking::rust_panic_with_hook::he4db359924fe7f6e
                               at /rustc/55f46419afd2e49acfc6be176ad4aeadaa5686d7/library/std/src/panicking.rs:702:17
  12:     0x7fc333e31461 - std[79962577103da855]::panicking::begin_panic::<rustc_errors[42ff641c0a7dbad8]::ExplicitBug>::{closure#0}
  13:     0x7fc333e30956 - std[79962577103da855]::sys_common::backtrace::__rust_end_short_backtrace::<std[79962577103da855]::panicking::begin_panic<rustc_errors[42ff641c0a7dbad8]::ExplicitBug>::{closure#0}, !>
  14:     0x7fc333e12a16 - std[79962577103da855]::panicking::begin_panic::<rustc_errors[42ff641c0a7dbad8]::ExplicitBug>
  15:     0x7fc333e55d36 - std[79962577103da855]::panic::panic_any::<rustc_errors[42ff641c0a7dbad8]::ExplicitBug>
  16:     0x7fc333e55b85 - <rustc_errors[42ff641c0a7dbad8]::HandlerInner>::bug::<&alloc[849470dd3c3c5534]::string::String>
  17:     0x7fc333e558e0 - <rustc_errors[42ff641c0a7dbad8]::Handler>::bug::<&alloc[849470dd3c3c5534]::string::String>
  18:     0x7fc333e7885d - rustc_middle[3ed8dbeb8d00c629]::ty::context::tls::with_context_opt::<rustc_middle[3ed8dbeb8d00c629]::ty::context::tls::with_opt<rustc_middle[3ed8dbeb8d00c629]::util::bug::opt_span_bug_fmt<rustc_span[704994f6531b2995]::span_encoding::Span>::{closure#0}, ()>::{closure#0}, ()>
  19:     0x7fc333e7b916 - rustc_middle[3ed8dbeb8d00c629]::util::bug::opt_span_bug_fmt::<rustc_span[704994f6531b2995]::span_encoding::Span>
  20:     0x7fc3318e9093 - rustc_middle[3ed8dbeb8d00c629]::util::bug::bug_fmt
  21:     0x7fc333c486a4 - <rustc_infer[8ce69979a813aa75]::infer::InferCtxtBuilder>::enter::<bool, rustc_trait_selection[8aa47ea5b5082416]::traits::coherence::negative_impl::{closure#0}>
  22:     0x7fc333d09018 - rustc_trait_selection[8aa47ea5b5082416]::traits::coherence::negative_impl
  23:     0x7fc33299e72b - rustc_trait_selection[8aa47ea5b5082416]::traits::coherence::overlap_within_probe
  24:     0x7fc33299dfa9 - <rustc_infer[8ce69979a813aa75]::infer::InferCtxt>::probe_maybe_skip_leak_check::<core[aa10b8f86cfda392]::option::Option<rustc_trait_selection[8aa47ea5b5082416]::traits::coherence::OverlapResult>, rustc_trait_selection[8aa47ea5b5082416]::traits::coherence::overlap::{closure#0}>
  25:     0x7fc3327e9861 - <rustc_infer[8ce69979a813aa75]::infer::InferCtxtBuilder>::enter::<bool, rustc_trait_selection[8aa47ea5b5082416]::traits::coherence::overlapping_impls<<rustc_middle[3ed8dbeb8d00c629]::traits::specialization_graph::Children as rustc_trait_selection[8aa47ea5b5082416]::traits::specialize::specialization_graph::ChildrenExt>::insert::{closure#2}, <rustc_middle[3ed8dbeb8d00c629]::traits::specialization_graph::Children as rustc_trait_selection[8aa47ea5b5082416]::traits::specialize::specialization_graph::ChildrenExt>::insert::{closure#3}, core[aa10b8f86cfda392]::result::Result<(bool, bool), rustc_trait_selection[8aa47ea5b5082416]::traits::specialize::OverlapError>>::{closure#1}>
  26:     0x7fc3327e7a1c - <rustc_middle[3ed8dbeb8d00c629]::traits::specialization_graph::Children as rustc_trait_selection[8aa47ea5b5082416]::traits::specialize::specialization_graph::ChildrenExt>::insert
  27:     0x7fc3327e4b64 - <rustc_middle[3ed8dbeb8d00c629]::traits::specialization_graph::Graph as rustc_trait_selection[8aa47ea5b5082416]::traits::specialize::specialization_graph::GraphExt>::insert
  28:     0x7fc3327e3e28 - rustc_trait_selection[8aa47ea5b5082416]::traits::specialize::specialization_graph_provider
  29:     0x7fc332784e5a - rustc_query_system[cefe79c3038533a5]::query::plumbing::try_execute_query::<rustc_query_impl[40b4f3c979e2ab16]::plumbing::QueryCtxt, rustc_query_system[cefe79c3038533a5]::query::caches::ArenaCache<rustc_span[704994f6531b2995]::def_id::DefId, rustc_middle[3ed8dbeb8d00c629]::traits::specialization_graph::Graph>>
  30:     0x7fc332784af9 - rustc_query_system[cefe79c3038533a5]::query::plumbing::get_query::<rustc_query_impl[40b4f3c979e2ab16]::queries::specialization_graph_of, rustc_query_impl[40b4f3c979e2ab16]::plumbing::QueryCtxt>
  31:     0x7fc3325ab848 - rustc_typeck[e4000634b4fd5083]::coherence::coherent_trait
  32:     0x7fc3322dc4f5 - rustc_query_system[cefe79c3038533a5]::query::plumbing::try_execute_query::<rustc_query_impl[40b4f3c979e2ab16]::plumbing::QueryCtxt, rustc_query_system[cefe79c3038533a5]::query::caches::DefaultCache<rustc_span[704994f6531b2995]::def_id::DefId, ()>>
  33:     0x7fc332860692 - rustc_query_system[cefe79c3038533a5]::query::plumbing::get_query::<rustc_query_impl[40b4f3c979e2ab16]::queries::coherent_trait, rustc_query_impl[40b4f3c979e2ab16]::plumbing::QueryCtxt>
  34:     0x7fc332872739 - <rustc_session[aa654962c49ecbb3]::session::Session>::track_errors::<rustc_typeck[e4000634b4fd5083]::check_crate::{closure#3}, ()>
  35:     0x7fc33286e7cf - rustc_typeck[e4000634b4fd5083]::check_crate
  36:     0x7fc33286de97 - rustc_interface[1d8565b9d7e787d1]::passes::analysis
  37:     0x7fc332c21c15 - rustc_query_system[cefe79c3038533a5]::query::plumbing::try_execute_query::<rustc_query_impl[40b4f3c979e2ab16]::plumbing::QueryCtxt, rustc_query_system[cefe79c3038533a5]::query::caches::DefaultCache<(), core[aa10b8f86cfda392]::result::Result<(), rustc_errors[42ff641c0a7dbad8]::ErrorGuaranteed>>>
  38:     0x7fc332c2199e - rustc_query_system[cefe79c3038533a5]::query::plumbing::get_query::<rustc_query_impl[40b4f3c979e2ab16]::queries::analysis, rustc_query_impl[40b4f3c979e2ab16]::plumbing::QueryCtxt>
  39:     0x7fc33267130a - <rustc_interface[1d8565b9d7e787d1]::interface::Compiler>::enter::<rustc_driver[f6b350ee36914076]::run_compiler::{closure#1}::{closure#2}, core[aa10b8f86cfda392]::result::Result<core[aa10b8f86cfda392]::option::Option<rustc_interface[1d8565b9d7e787d1]::queries::Linker>, rustc_errors[42ff641c0a7dbad8]::ErrorGuaranteed>>
  40:     0x7fc332664d2a - rustc_span[704994f6531b2995]::with_source_map::<core[aa10b8f86cfda392]::result::Result<(), rustc_errors[42ff641c0a7dbad8]::ErrorGuaranteed>, rustc_interface[1d8565b9d7e787d1]::interface::create_compiler_and_run<core[aa10b8f86cfda392]::result::Result<(), rustc_errors[42ff641c0a7dbad8]::ErrorGuaranteed>, rustc_driver[f6b350ee36914076]::run_compiler::{closure#1}>::{closure#1}>
  41:     0x7fc332664700 - rustc_interface[1d8565b9d7e787d1]::interface::create_compiler_and_run::<core[aa10b8f86cfda392]::result::Result<(), rustc_errors[42ff641c0a7dbad8]::ErrorGuaranteed>, rustc_driver[f6b350ee36914076]::run_compiler::{closure#1}>
  42:     0x7fc332662a71 - <scoped_tls[fc5e344a71e03ad0]::ScopedKey<rustc_span[704994f6531b2995]::SessionGlobals>>::set::<rustc_interface[1d8565b9d7e787d1]::interface::run_compiler<core[aa10b8f86cfda392]::result::Result<(), rustc_errors[42ff641c0a7dbad8]::ErrorGuaranteed>, rustc_driver[f6b350ee36914076]::run_compiler::{closure#1}>::{closure#0}, core[aa10b8f86cfda392]::result::Result<(), rustc_errors[42ff641c0a7dbad8]::ErrorGuaranteed>>
  43:     0x7fc33266275f - std[79962577103da855]::sys_common::backtrace::__rust_begin_short_backtrace::<rustc_interface[1d8565b9d7e787d1]::util::run_in_thread_pool_with_globals<rustc_interface[1d8565b9d7e787d1]::interface::run_compiler<core[aa10b8f86cfda392]::result::Result<(), rustc_errors[42ff641c0a7dbad8]::ErrorGuaranteed>, rustc_driver[f6b350ee36914076]::run_compiler::{closure#1}>::{closure#0}, core[aa10b8f86cfda392]::result::Result<(), rustc_errors[42ff641c0a7dbad8]::ErrorGuaranteed>>::{closure#0}, core[aa10b8f86cfda392]::result::Result<(), rustc_errors[42ff641c0a7dbad8]::ErrorGuaranteed>>
  44:     0x7fc332cb5759 - <<std[79962577103da855]::thread::Builder>::spawn_unchecked_<rustc_interface[1d8565b9d7e787d1]::util::run_in_thread_pool_with_globals<rustc_interface[1d8565b9d7e787d1]::interface::run_compiler<core[aa10b8f86cfda392]::result::Result<(), rustc_errors[42ff641c0a7dbad8]::ErrorGuaranteed>, rustc_driver[f6b350ee36914076]::run_compiler::{closure#1}>::{closure#0}, core[aa10b8f86cfda392]::result::Result<(), rustc_errors[42ff641c0a7dbad8]::ErrorGuaranteed>>::{closure#0}, core[aa10b8f86cfda392]::result::Result<(), rustc_errors[42ff641c0a7dbad8]::ErrorGuaranteed>>::{closure#1} as core[aa10b8f86cfda392]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  45:     0x7fc330625ed3 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h8951f5312048b23c
                               at /rustc/55f46419afd2e49acfc6be176ad4aeadaa5686d7/library/alloc/src/boxed.rs:1935:9
  46:     0x7fc330625ed3 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h45d7e719250fdc91
                               at /rustc/55f46419afd2e49acfc6be176ad4aeadaa5686d7/library/alloc/src/boxed.rs:1935:9
  47:     0x7fc330625ed3 - std::sys::unix::thread::Thread::new::thread_start::h865a7bb40e742e03
                               at /rustc/55f46419afd2e49acfc6be176ad4aeadaa5686d7/library/std/src/sys/unix/thread.rs:108:17
  48:     0x7fc33036454d - <unknown>
  49:     0x7fc3303e9874 - clone
  50:                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 1.64.0-nightly (55f46419a 2022-08-05) running on x86_64-unknown-linux-gnu

note: compiler flags: -Z crate-attr=feature(with_negative_coherence)

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