ICE when calling method on generic impl constrained by unmet trait alias

[eggyal]

Similar to #108072, but when the method cannot be found.

Code

#![feature(trait_alias)]

trait IteratorAlias = Iterator;

struct Foo<I>(I);

impl<I: IteratorAlias> Foo<I> {
    fn f() {}
}

fn main() {
    Foo::<()>::f()
}

Playground

Meta

rustc --version --verbose:

rustc 1.69.0-nightly (2d14db321 2023-02-15)
binary: rustc
commit-hash: 2d14db321b043ffc579a7461464c88d7e3f54f83
commit-date: 2023-02-15
host: x86_64-unknown-linux-gnu
release: 1.69.0-nightly
LLVM version: 15.0.7

Error output

thread 'rustc' panicked at 'internal error: entered unreachable code: encountered `Item(Item { ident: IteratorAlias#0, owner_id: DefId(0:3 ~ playground[d092]::IteratorAlias), kind: TraitAlias(Generics { params: [], predicates: [], has_where_clause_predicates: false, where_clause_span: src/main.rs:3:31: 3:31 (#0), span: src/main.rs:3:20: 3:20 (#0) }, [Trait(PolyTraitRef { bound_generic_params: [], trait_ref: TraitRef { path: Path { span: src/main.rs:3:23: 3:31 (#0), res: Def(Trait, DefId(2:7197 ~ core[f0a8]::iter::traits::iterator::Iterator)), segments: [PathSegment { ident: Iterator#0, hir_id: HirId(DefId(0:3 ~ playground[d092]::IteratorAlias).1), res: Def(Trait, DefId(2:7197 ~ core[f0a8]::iter::traits::iterator::Iterator)), args: None, infer_args: false }] }, hir_ref_id: HirId(DefId(0:3 ~ playground[d092]::IteratorAlias).2) }, span: src/main.rs:3:23: 3:31 (#0) }, None)]), span: src/main.rs:3:1: 3:32 (#0), vis_span: src/main.rs:3:1: 3:1 (#0) })`', compiler/rustc_hir_typeck/src/method/suggest.rs:729:35

Backtrace

   0:     0x7f7b110769ea - std::backtrace_rs::backtrace::libunwind::trace::h3a20221a56d872e6
                               at /rustc/2d14db321b043ffc579a7461464c88d7e3f54f83/library/std/src/../../backtrace/src/backtrace/libunwind.rs:93:5
   1:     0x7f7b110769ea - std::backtrace_rs::backtrace::trace_unsynchronized::h23863182fd4b4481
                               at /rustc/2d14db321b043ffc579a7461464c88d7e3f54f83/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
   2:     0x7f7b110769ea - std::sys_common::backtrace::_print_fmt::hde799c83b2fa8ddb
                               at /rustc/2d14db321b043ffc579a7461464c88d7e3f54f83/library/std/src/sys_common/backtrace.rs:65:5
   3:     0x7f7b110769ea - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::hb1ed906e28a16738
                               at /rustc/2d14db321b043ffc579a7461464c88d7e3f54f83/library/std/src/sys_common/backtrace.rs:44:22
   4:     0x7f7b110d6afe - core::fmt::write::hee7bc8dd2696f088
                               at /rustc/2d14db321b043ffc579a7461464c88d7e3f54f83/library/core/src/fmt/mod.rs:1232:17
   5:     0x7f7b11067005 - std::io::Write::write_fmt::h031e716f6e3d1f66
                               at /rustc/2d14db321b043ffc579a7461464c88d7e3f54f83/library/std/src/io/mod.rs:1684:15
   6:     0x7f7b110767b5 - std::sys_common::backtrace::_print::h8cea91a8dc3abdb3
                               at /rustc/2d14db321b043ffc579a7461464c88d7e3f54f83/library/std/src/sys_common/backtrace.rs:47:5
   7:     0x7f7b110767b5 - std::sys_common::backtrace::print::hcd9f90783d8afb1f
                               at /rustc/2d14db321b043ffc579a7461464c88d7e3f54f83/library/std/src/sys_common/backtrace.rs:34:9
   8:     0x7f7b1107954f - std::panicking::default_hook::{{closure}}::hdf7c561ea2419acd
                               at /rustc/2d14db321b043ffc579a7461464c88d7e3f54f83/library/std/src/panicking.rs:267:22
   9:     0x7f7b1107928b - std::panicking::default_hook::h9669759e65745add
                               at /rustc/2d14db321b043ffc579a7461464c88d7e3f54f83/library/std/src/panicking.rs:286:9
  10:     0x7f7b143c4c44 - <rustc_driver_impl[cf5be2d75a70ff02]::DEFAULT_HOOK::{closure#0}::{closure#0} as core[f0a84df7292b9247]::ops::function::FnOnce<(&core[f0a84df7292b9247]::panic::panic_info::PanicInfo,)>>::call_once::{shim:vtable#0}
  11:     0x7f7b11079d8a - <alloc::boxed::Box<F,A> as core::ops::function::Fn<Args>>::call::h71e54ddf4b01f8ef
                               at /rustc/2d14db321b043ffc579a7461464c88d7e3f54f83/library/alloc/src/boxed.rs:2002:9
  12:     0x7f7b11079d8a - std::panicking::rust_panic_with_hook::h96419a4a3670d907
                               at /rustc/2d14db321b043ffc579a7461464c88d7e3f54f83/library/std/src/panicking.rs:692:13
  13:     0x7f7b11079b09 - std::panicking::begin_panic_handler::{{closure}}::h17c261a3ff4b53aa
                               at /rustc/2d14db321b043ffc579a7461464c88d7e3f54f83/library/std/src/panicking.rs:579:13
  14:     0x7f7b11076e8c - std::sys_common::backtrace::__rust_end_short_backtrace::h6f10911888b9e113
                               at /rustc/2d14db321b043ffc579a7461464c88d7e3f54f83/library/std/src/sys_common/backtrace.rs:137:18
  15:     0x7f7b11079812 - rust_begin_unwind
                               at /rustc/2d14db321b043ffc579a7461464c88d7e3f54f83/library/std/src/panicking.rs:575:5
  16:     0x7f7b110d34a3 - core::panicking::panic_fmt::hdb483708f9fb42ab
                               at /rustc/2d14db321b043ffc579a7461464c88d7e3f54f83/library/core/src/panicking.rs:64:14
  17:     0x7f7b1456dda0 - <rustc_hir_typeck[d1f10db731357cb4]::fn_ctxt::FnCtxt>::report_no_match_method_error
  18:     0x7f7b1457dd88 - <rustc_hir_typeck[d1f10db731357cb4]::fn_ctxt::FnCtxt>::report_method_error
  19:     0x7f7b1248c30a - <rustc_hir_typeck[d1f10db731357cb4]::fn_ctxt::FnCtxt>::check_expr_path
  20:     0x7f7b126636c5 - <rustc_hir_typeck[d1f10db731357cb4]::fn_ctxt::FnCtxt>::check_call
  21:     0x7f7b1243af78 - <rustc_hir_typeck[d1f10db731357cb4]::fn_ctxt::FnCtxt>::check_expr_with_expectation_and_args
  22:     0x7f7b1247c1fd - <rustc_hir_typeck[d1f10db731357cb4]::fn_ctxt::FnCtxt>::check_block_with_expected
  23:     0x7f7b1243b600 - <rustc_hir_typeck[d1f10db731357cb4]::fn_ctxt::FnCtxt>::check_expr_with_expectation_and_args
  24:     0x7f7b12f0322b - <rustc_hir_typeck[d1f10db731357cb4]::fn_ctxt::FnCtxt>::check_return_expr
  25:     0x7f7b12efabb5 - rustc_hir_typeck[d1f10db731357cb4]::check::check_fn
  26:     0x7f7b12edf0ce - rustc_hir_typeck[d1f10db731357cb4]::typeck
  27:     0x7f7b12522a83 - rustc_query_system[9c20c97984254eda]::query::plumbing::try_execute_query::<rustc_query_impl[e25e6056fa54423]::queries::typeck, rustc_query_impl[e25e6056fa54423]::plumbing::QueryCtxt>
  28:     0x7f7b13b02dfb - rustc_data_structures[4cb054fd51de001a]::sync::par_for_each_in::<&[rustc_span[ff2b83d94cd5766c]::def_id::LocalDefId], <rustc_middle[bd03a598433729a4]::hir::map::Map>::par_body_owners<rustc_hir_typeck[d1f10db731357cb4]::typeck_item_bodies::{closure#0}>::{closure#0}>
  29:     0x7f7b13b02bf1 - rustc_hir_typeck[d1f10db731357cb4]::typeck_item_bodies
  30:     0x7f7b1396b423 - rustc_query_system[9c20c97984254eda]::query::plumbing::try_execute_query::<rustc_query_impl[e25e6056fa54423]::queries::typeck_item_bodies, rustc_query_impl[e25e6056fa54423]::plumbing::QueryCtxt>
  31:     0x7f7b13d4f42b - <rustc_query_impl[e25e6056fa54423]::Queries as rustc_middle[bd03a598433729a4]::ty::query::QueryEngine>::typeck_item_bodies
  32:     0x7f7b138061fe - <rustc_session[130bf05e2988f5fc]::session::Session>::time::<(), rustc_hir_analysis[7e2943bc0d9db6d0]::check_crate::{closure#7}>
  33:     0x7f7b13803420 - rustc_hir_analysis[7e2943bc0d9db6d0]::check_crate
  34:     0x7f7b137f69d4 - rustc_interface[e19372daae8a4d61]::passes::analysis
  35:     0x7f7b13b56a02 - rustc_query_system[9c20c97984254eda]::query::plumbing::try_execute_query::<rustc_query_impl[e25e6056fa54423]::queries::analysis, rustc_query_impl[e25e6056fa54423]::plumbing::QueryCtxt>
  36:     0x7f7b13d4750a - <rustc_query_impl[e25e6056fa54423]::Queries as rustc_middle[bd03a598433729a4]::ty::query::QueryEngine>::analysis
  37:     0x7f7b13a58e79 - <rustc_middle[bd03a598433729a4]::ty::context::GlobalCtxt>::enter::<rustc_driver_impl[cf5be2d75a70ff02]::run_compiler::{closure#1}::{closure#2}::{closure#3}, core[f0a84df7292b9247]::result::Result<(), rustc_errors[580ee8295c6eeddb]::ErrorGuaranteed>>
  38:     0x7f7b135d2a19 - <rustc_interface[e19372daae8a4d61]::interface::Compiler>::enter::<rustc_driver_impl[cf5be2d75a70ff02]::run_compiler::{closure#1}::{closure#2}, core[f0a84df7292b9247]::result::Result<core[f0a84df7292b9247]::option::Option<rustc_interface[e19372daae8a4d61]::queries::Linker>, rustc_errors[580ee8295c6eeddb]::ErrorGuaranteed>>
  39:     0x7f7b135d0b04 - rustc_span[ff2b83d94cd5766c]::with_source_map::<core[f0a84df7292b9247]::result::Result<(), rustc_errors[580ee8295c6eeddb]::ErrorGuaranteed>, rustc_interface[e19372daae8a4d61]::interface::run_compiler<core[f0a84df7292b9247]::result::Result<(), rustc_errors[580ee8295c6eeddb]::ErrorGuaranteed>, rustc_driver_impl[cf5be2d75a70ff02]::run_compiler::{closure#1}>::{closure#0}::{closure#0}>
  40:     0x7f7b135d0614 - <scoped_tls[94748c71a964531c]::ScopedKey<rustc_span[ff2b83d94cd5766c]::SessionGlobals>>::set::<rustc_interface[e19372daae8a4d61]::interface::run_compiler<core[f0a84df7292b9247]::result::Result<(), rustc_errors[580ee8295c6eeddb]::ErrorGuaranteed>, rustc_driver_impl[cf5be2d75a70ff02]::run_compiler::{closure#1}>::{closure#0}, core[f0a84df7292b9247]::result::Result<(), rustc_errors[580ee8295c6eeddb]::ErrorGuaranteed>>
  41:     0x7f7b135cfd12 - std[f1e96740c585910a]::sys_common::backtrace::__rust_begin_short_backtrace::<rustc_interface[e19372daae8a4d61]::util::run_in_thread_pool_with_globals<rustc_interface[e19372daae8a4d61]::interface::run_compiler<core[f0a84df7292b9247]::result::Result<(), rustc_errors[580ee8295c6eeddb]::ErrorGuaranteed>, rustc_driver_impl[cf5be2d75a70ff02]::run_compiler::{closure#1}>::{closure#0}, core[f0a84df7292b9247]::result::Result<(), rustc_errors[580ee8295c6eeddb]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[f0a84df7292b9247]::result::Result<(), rustc_errors[580ee8295c6eeddb]::ErrorGuaranteed>>
  42:     0x7f7b135cfabc - <<std[f1e96740c585910a]::thread::Builder>::spawn_unchecked_<rustc_interface[e19372daae8a4d61]::util::run_in_thread_pool_with_globals<rustc_interface[e19372daae8a4d61]::interface::run_compiler<core[f0a84df7292b9247]::result::Result<(), rustc_errors[580ee8295c6eeddb]::ErrorGuaranteed>, rustc_driver_impl[cf5be2d75a70ff02]::run_compiler::{closure#1}>::{closure#0}, core[f0a84df7292b9247]::result::Result<(), rustc_errors[580ee8295c6eeddb]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[f0a84df7292b9247]::result::Result<(), rustc_errors[580ee8295c6eeddb]::ErrorGuaranteed>>::{closure#1} as core[f0a84df7292b9247]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  43:     0x7f7b11083d23 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h6f3268749d03f717
                               at /rustc/2d14db321b043ffc579a7461464c88d7e3f54f83/library/alloc/src/boxed.rs:1988:9
  44:     0x7f7b11083d23 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::he030b34c5a5b9772
                               at /rustc/2d14db321b043ffc579a7461464c88d7e3f54f83/library/alloc/src/boxed.rs:1988:9
  45:     0x7f7b11083d23 - std::sys::unix::thread::Thread::new::thread_start::h3f952212e35a76cc
                               at /rustc/2d14db321b043ffc579a7461464c88d7e3f54f83/library/std/src/sys/unix/thread.rs:108:17
  46:     0x7f7b10f46609 - start_thread
  47:     0x7f7b10e69133 - clone
  48:                0x0 - <unknown>

@rustbot label +F-trait_alias

[eggyal]

searched nightlies: from nightly-2023-01-01 to nightly-2023-02-16
regressed nightly: nightly-2023-01-15
searched commit range: 0b90256...afaf3e0
regressed commit: 4b51adf

bisected with cargo-bisect-rustc v0.6.5

Host triple: x86_64-unknown-linux-gnu
Reproduce with:

cargo bisect-rustc --regress ice --start 2023-01-01 --preserve --without-cargo 

Of that rollup, #106788 looks most likely responsible to me. cc @estebank

I think the ICE arises from https://github.com/rust-lang/rust/pull/106788/files#diff-fa9d26c02df9437e1b198df6ffd387a476adbb27a18b0a65dbed20c1fc8bd6d1R154-R165, where the DefId of trait aliases get stored in the impl_def_id of an ImplDerivedObligationCause (again cc @compiler-errors), which is a state that is later unexpected in report_no_match_method_error.

@rustbot claim