ICE: 'discriminant' called on unexpected type Alias(Opaque

[matthiaskrgr]

Code

#![feature(type_alias_impl_trait)]

fn enum_upvar() {
    type T = impl Copy;
    let foo: T = Some((1u32, 2u32));
    let x = move || match foo {
        None => (),
        Some((a, b)) => (),
    };
}

Meta

rustc --version --verbose:

rustc 1.74.0-nightly (c5450191f 2023-09-29)
binary: rustc
commit-hash: c5450191f313658d206dc7539311f665a274947f
commit-date: 2023-09-29
host: x86_64-unknown-linux-gnu
release: 1.74.0-nightly
LLVM version: 17.0.2

Error output

<output>

Backtrace

error: internal compiler error: compiler/rustc_mir_dataflow/src/impls/initialized.rs:770:26: `discriminant` called on unexpected type Alias(Opaque, AliasTy { args: [], def_id: DefId(0:9 ~ issue_96572_unconstrained[d6d8]::enum_upvar::T::{opaque#0}) })

thread 'rustc' panicked at /rustc/c5450191f313658d206dc7539311f665a274947f/compiler/rustc_errors/src/lib.rs:1651:9:
Box<dyn Any>
stack backtrace:
   0:     0x7f59a816433c - std::backtrace_rs::backtrace::libunwind::trace::hb568cd43caaa8089
                               at /rustc/c5450191f313658d206dc7539311f665a274947f/library/std/src/../../backtrace/src/backtrace/libunwind.rs:93:5
   1:     0x7f59a816433c - std::backtrace_rs::backtrace::trace_unsynchronized::h0f2d13a7908f3914
                               at /rustc/c5450191f313658d206dc7539311f665a274947f/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
   2:     0x7f59a816433c - std::sys_common::backtrace::_print_fmt::h6723d6b0ebd2797e
                               at /rustc/c5450191f313658d206dc7539311f665a274947f/library/std/src/sys_common/backtrace.rs:67:5
   3:     0x7f59a816433c - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::h95124a8c06b44298
                               at /rustc/c5450191f313658d206dc7539311f665a274947f/library/std/src/sys_common/backtrace.rs:44:22
   4:     0x7f59a81c9f9c - core::fmt::rt::Argument::fmt::h622e2c6916a5c4d5
                               at /rustc/c5450191f313658d206dc7539311f665a274947f/library/core/src/fmt/rt.rs:138:9
   5:     0x7f59a81c9f9c - core::fmt::write::hcea8acdb83b538a2
                               at /rustc/c5450191f313658d206dc7539311f665a274947f/library/core/src/fmt/mod.rs:1114:21
   6:     0x7f59a81570be - std::io::Write::write_fmt::hee5c75723cef4ed7
                               at /rustc/c5450191f313658d206dc7539311f665a274947f/library/std/src/io/mod.rs:1763:15
   7:     0x7f59a8164124 - std::sys_common::backtrace::_print::h82b258ea59b074e4
                               at /rustc/c5450191f313658d206dc7539311f665a274947f/library/std/src/sys_common/backtrace.rs:47:5
   8:     0x7f59a8164124 - std::sys_common::backtrace::print::h6179e58f626913ed
                               at /rustc/c5450191f313658d206dc7539311f665a274947f/library/std/src/sys_common/backtrace.rs:34:9
   9:     0x7f59a8167003 - std::panicking::default_hook::{{closure}}::h9f2e56e7e949e9ef
                               at /rustc/c5450191f313658d206dc7539311f665a274947f/library/std/src/panicking.rs:272:22
  10:     0x7f59a8166d24 - std::panicking::default_hook::h23bce3c6dc138bb8
                               at /rustc/c5450191f313658d206dc7539311f665a274947f/library/std/src/panicking.rs:292:9
  11:     0x7f59ab2fee5f - std[b4843c1823a37d1]::panicking::update_hook::<alloc[807c770786b1efb8]::boxed::Box<rustc_driver_impl[418485cfdc98bfaa]::install_ice_hook::{closure#0}>>::{closure#0}
  12:     0x7f59a8167831 - <alloc::boxed::Box<F,A> as core::ops::function::Fn<Args>>::call::hec1cb47fd5eca853
                               at /rustc/c5450191f313658d206dc7539311f665a274947f/library/alloc/src/boxed.rs:2021:9
  13:     0x7f59a8167831 - std::panicking::rust_panic_with_hook::h0b9e8e7a1a60c0c6
                               at /rustc/c5450191f313658d206dc7539311f665a274947f/library/std/src/panicking.rs:735:13
  14:     0x7f59ab8386b4 - std[b4843c1823a37d1]::panicking::begin_panic::<rustc_errors[7cbc9798c005d993]::ExplicitBug>::{closure#0}
  15:     0x7f59ab838366 - std[b4843c1823a37d1]::sys_common::backtrace::__rust_end_short_backtrace::<std[b4843c1823a37d1]::panicking::begin_panic<rustc_errors[7cbc9798c005d993]::ExplicitBug>::{closure#0}, !>
  16:     0x7f59ab8c4086 - std[b4843c1823a37d1]::panicking::begin_panic::<rustc_errors[7cbc9798c005d993]::ExplicitBug>
  17:     0x7f59ab82dbb4 - <rustc_errors[7cbc9798c005d993]::HandlerInner>::bug::<alloc[807c770786b1efb8]::string::String>
  18:     0x7f59ab82da66 - <rustc_errors[7cbc9798c005d993]::Handler>::bug::<alloc[807c770786b1efb8]::string::String>
  19:     0x7f59ab89d9dc - rustc_middle[e970cc282ff9b1b5]::util::bug::opt_span_bug_fmt::<rustc_span[b8184c5be003882b]::span_encoding::Span>::{closure#0}
  20:     0x7f59ab89a9fa - rustc_middle[e970cc282ff9b1b5]::ty::context::tls::with_opt::<rustc_middle[e970cc282ff9b1b5]::util::bug::opt_span_bug_fmt<rustc_span[b8184c5be003882b]::span_encoding::Span>::{closure#0}, !>::{closure#0}
  21:     0x7f59ab89a9c8 - rustc_middle[e970cc282ff9b1b5]::ty::context::tls::with_context_opt::<rustc_middle[e970cc282ff9b1b5]::ty::context::tls::with_opt<rustc_middle[e970cc282ff9b1b5]::util::bug::opt_span_bug_fmt<rustc_span[b8184c5be003882b]::span_encoding::Span>::{closure#0}, !>::{closure#0}, !>
  22:     0x7f59a9f84560 - rustc_middle[e970cc282ff9b1b5]::util::bug::bug_fmt
  23:     0x7f59a9985743 - <rustc_mir_dataflow[8cbe94db0a98dfe3]::impls::initialized::MaybeInitializedPlaces as rustc_mir_dataflow[8cbe94db0a98dfe3]::framework::Analysis>::apply_switch_int_edge_effects::<rustc_mir_dataflow[8cbe94db0a98dfe3]::framework::direction::ForwardSwitchIntEdgeEffectsApplier<rustc_mir_dataflow[8cbe94db0a98dfe3]::framework::lattice::MaybeReachable<rustc_index[2c090815ae444856]::bit_set::ChunkedBitSet<rustc_mir_dataflow[8cbe94db0a98dfe3]::move_paths::MovePathIndex>>, <rustc_mir_dataflow[8cbe94db0a98dfe3]::framework::engine::Engine<rustc_mir_dataflow[8cbe94db0a98dfe3]::impls::initialized::MaybeInitializedPlaces>>::iterate_to_fixpoint::{closure#0}>>
  24:     0x7f59a997f94d - <rustc_mir_dataflow[8cbe94db0a98dfe3]::framework::engine::Engine<rustc_mir_dataflow[8cbe94db0a98dfe3]::impls::initialized::MaybeInitializedPlaces>>::iterate_to_fixpoint
  25:     0x7f59a9956f74 - <rustc_mir_transform[f87aab292f3161cd]::elaborate_drops::ElaborateDrops as rustc_middle[e970cc282ff9b1b5]::mir::MirPass>::run_pass
  26:     0x7f59a95ed3fe - rustc_mir_transform[f87aab292f3161cd]::mir_drops_elaborated_and_const_checked
  27:     0x7f59a95ec71e - rustc_query_impl[4980b7cf5b7996c7]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[4980b7cf5b7996c7]::query_impl::mir_drops_elaborated_and_const_checked::dynamic_query::{closure#2}::{closure#0}, rustc_middle[e970cc282ff9b1b5]::query::erase::Erased<[u8; 8usize]>>
  28:     0x7f59a95ec6ee - <rustc_query_impl[4980b7cf5b7996c7]::query_impl::mir_drops_elaborated_and_const_checked::dynamic_query::{closure#2} as core[951439f994106a2d]::ops::function::FnOnce<(rustc_middle[e970cc282ff9b1b5]::ty::context::TyCtxt, rustc_span[b8184c5be003882b]::def_id::LocalDefId)>>::call_once
  29:     0x7f59a9537d38 - rustc_query_system[873a9c0fbeb3d104]::query::plumbing::try_execute_query::<rustc_query_impl[4980b7cf5b7996c7]::DynamicConfig<rustc_query_system[873a9c0fbeb3d104]::query::caches::VecCache<rustc_span[b8184c5be003882b]::def_id::LocalDefId, rustc_middle[e970cc282ff9b1b5]::query::erase::Erased<[u8; 8usize]>>, false, false, false>, rustc_query_impl[4980b7cf5b7996c7]::plumbing::QueryCtxt, false>
  30:     0x7f59aac63151 - rustc_query_impl[4980b7cf5b7996c7]::query_impl::mir_drops_elaborated_and_const_checked::get_query_non_incr::__rust_end_short_backtrace
  31:     0x7f59aa78151c - <rustc_session[dcce3550ca159092]::session::Session>::time::<(), rustc_interface[f0d27452ef10947b]::passes::analysis::{closure#2}>
  32:     0x7f59aa77e96b - rustc_interface[f0d27452ef10947b]::passes::analysis
  33:     0x7f59aa74e3fa - rustc_query_impl[4980b7cf5b7996c7]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[4980b7cf5b7996c7]::query_impl::analysis::dynamic_query::{closure#2}::{closure#0}, rustc_middle[e970cc282ff9b1b5]::query::erase::Erased<[u8; 1usize]>>
  34:     0x7f59aa74e3e9 - <rustc_query_impl[4980b7cf5b7996c7]::query_impl::analysis::dynamic_query::{closure#2} as core[951439f994106a2d]::ops::function::FnOnce<(rustc_middle[e970cc282ff9b1b5]::ty::context::TyCtxt, ())>>::call_once
  35:     0x7f59aa9eca84 - rustc_query_system[873a9c0fbeb3d104]::query::plumbing::try_execute_query::<rustc_query_impl[4980b7cf5b7996c7]::DynamicConfig<rustc_query_system[873a9c0fbeb3d104]::query::caches::SingleCache<rustc_middle[e970cc282ff9b1b5]::query::erase::Erased<[u8; 1usize]>>, false, false, false>, rustc_query_impl[4980b7cf5b7996c7]::plumbing::QueryCtxt, false>
  36:     0x7f59aa9ec7f9 - rustc_query_impl[4980b7cf5b7996c7]::query_impl::analysis::get_query_non_incr::__rust_end_short_backtrace
  37:     0x7f59aa833ce2 - <rustc_middle[e970cc282ff9b1b5]::ty::context::GlobalCtxt>::enter::<rustc_driver_impl[418485cfdc98bfaa]::run_compiler::{closure#1}::{closure#2}::{closure#6}, core[951439f994106a2d]::result::Result<(), rustc_span[b8184c5be003882b]::ErrorGuaranteed>>
  38:     0x7f59aa832761 - rustc_span[b8184c5be003882b]::set_source_map::<core[951439f994106a2d]::result::Result<(), rustc_span[b8184c5be003882b]::ErrorGuaranteed>, rustc_interface[f0d27452ef10947b]::interface::run_compiler<core[951439f994106a2d]::result::Result<(), rustc_span[b8184c5be003882b]::ErrorGuaranteed>, rustc_driver_impl[418485cfdc98bfaa]::run_compiler::{closure#1}>::{closure#0}::{closure#0}>
  39:     0x7f59aa82d340 - std[b4843c1823a37d1]::sys_common::backtrace::__rust_begin_short_backtrace::<rustc_interface[f0d27452ef10947b]::util::run_in_thread_with_globals<rustc_interface[f0d27452ef10947b]::interface::run_compiler<core[951439f994106a2d]::result::Result<(), rustc_span[b8184c5be003882b]::ErrorGuaranteed>, rustc_driver_impl[418485cfdc98bfaa]::run_compiler::{closure#1}>::{closure#0}, core[951439f994106a2d]::result::Result<(), rustc_span[b8184c5be003882b]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[951439f994106a2d]::result::Result<(), rustc_span[b8184c5be003882b]::ErrorGuaranteed>>
  40:     0x7f59aab5bb6e - <<std[b4843c1823a37d1]::thread::Builder>::spawn_unchecked_<rustc_interface[f0d27452ef10947b]::util::run_in_thread_with_globals<rustc_interface[f0d27452ef10947b]::interface::run_compiler<core[951439f994106a2d]::result::Result<(), rustc_span[b8184c5be003882b]::ErrorGuaranteed>, rustc_driver_impl[418485cfdc98bfaa]::run_compiler::{closure#1}>::{closure#0}, core[951439f994106a2d]::result::Result<(), rustc_span[b8184c5be003882b]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[951439f994106a2d]::result::Result<(), rustc_span[b8184c5be003882b]::ErrorGuaranteed>>::{closure#1} as core[951439f994106a2d]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  41:     0x7f59a8172395 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h3bfe3c242a461003
                               at /rustc/c5450191f313658d206dc7539311f665a274947f/library/alloc/src/boxed.rs:2007:9
  42:     0x7f59a8172395 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h9293481db72dd923
                               at /rustc/c5450191f313658d206dc7539311f665a274947f/library/alloc/src/boxed.rs:2007:9
  43:     0x7f59a8172395 - std::sys::unix::thread::Thread::new::thread_start::h643847fe85be950e
                               at /rustc/c5450191f313658d206dc7539311f665a274947f/library/std/src/sys/unix/thread.rs:108:17
  44:     0x7f59a7e8c9eb - <unknown>
  45:     0x7f59a7f10dfc - <unknown>
  46:                0x0 - <unknown>

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: please attach the file at `/tmp/im/rustc-ice-2023-09-29T14:12:02.343060416Z-1922983.txt` to your bug report

query stack during panic:
#0 [mir_drops_elaborated_and_const_checked] elaborating drops for `enum_upvar::{closure#0}`
#1 [analysis] running analysis passes on this crate
end of query stack
error: aborting due to previous error; 4 warnings emitted

[matthiaskrgr]

probably #115759 cc @oli-obk

[matthiaskrgr]

Heh, so this code is from tests/ui/type-alias-impl-trait/issue-96572-unconstrained.rs and I can't figure out why the test did not fail in ci :|

[lqd]

Has there been a nightly with this PR?

[matthiaskrgr]

not yet, only master[1] toolchain has it, 2023-09-29 will be the next nightly that has it, if you can wait a couple hours

[1] https://github.com/kennytm/rustup-toolchain-install-master

[lqd]

Yeah that's fun, the test passes on master for me. It ICEs "late" via codegen or something: a check build works (the test is a check-pass), while a build ICEs.