ICE on compiler\rustc_mir\src\monomorphize\collector.rs:894:93

[deprilula28]

Code

The error doesn't specify where in the code caused the issue, making it hard to provide an example.

Meta

rustc --version --verbose:

rustc 1.58.0-nightly (495322d77 2021-11-08)
binary: rustc
commit-hash: 495322d776fd6f679cd8cd4ca02b8fa834da654b
commit-date: 2021-11-08
host: x86_64-pc-windows-msvc
release: 1.58.0-nightly
LLVM version: 13.0.0

It also happens on stable and an on 1.55.0 (which I updated from after I initially ran into this problem).

Error output

thread 'rustc' panicked at 'called `Option::unwrap()` on a `None` value', compiler\rustc_monomorphize\src\collector.rs:903:93
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

error: internal compiler error: unexpected panic

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 1.58.0-nightly (495322d77 2021-11-08) running on x86_64-pc-windows-msvc

note: compiler flags: -C embed-bitcode=no -C debuginfo=2 -C linker=rust-lld.exe -C incremental -C link-arg=-fuse-ld=lld --crate-type lib

note: some of the compiler flags provided by cargo are hidden

query stack during panic:
#0 [collect_and_partition_mono_items] collect_and_partition_mono_items
#1 [exported_symbols] exported_symbols
end of query stack

Backtrace

stack backtrace:
   0:     0x7fff5d2b8c6f - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::hda2ead71f9ecd977
   1:     0x7fff5d2e2eba - core::fmt::write::h8a2c40ddb66ccc71
   2:     0x7fff5d2ab438 - <std::io::IoSlice as core::fmt::Debug>::fmt::h94c9e1851482e651
   3:     0x7fff5d2bc1b6 - std::panicking::take_hook::ha134472c0530875e
   4:     0x7fff5d2bbc9c - std::panicking::take_hook::ha134472c0530875e
   5:     0x7fff45f7b12e - <rustc_lint[fc42b54c9644860b]::BuiltinCombinedPreExpansionLintPass as rustc_lint[fc42b54c9644860b]::passes::EarlyLintPass>::check_crate_post
   6:     0x7fff5d2bcac9 - std::panicking::rust_panic_with_hook::h1142463f499f4e70
   7:     0x7fff5d2bc53f - rust_begin_unwind
   8:     0x7fff5d2b9597 - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::hda2ead71f9ecd977
   9:     0x7fff5d2bc4c9 - rust_begin_unwind
  10:     0x7fff5d317460 - core::panicking::panic_fmt::hc1b1ca620e7a2c9f
  11:     0x7fff5d3173ac - core::panicking::panic::hfef5cee9afdef02a
  12:     0x7fff4857a3c9 - <rustc_monomorphize[4514d9151ad2ce1]::collector::MirNeighborCollector as rustc_middle[25ed325aece9029c]::mir::visit::Visitor>::visit_terminator
  13:     0x7fff4857d0e7 - <rustc_monomorphize[4514d9151ad2ce1]::collector::RootCollector as rustc_hir[ae23d96f99620364]::itemlikevisit::ItemLikeVisitor>::visit_impl_item
  14:     0x7fff4857622c - <rustc_monomorphize[4514d9151ad2ce1]::partitioning::MonoItemPlacement as core[3b5640218fb446b]::fmt::Debug>::fmt
  15:     0x7fff4857653e - <rustc_monomorphize[4514d9151ad2ce1]::partitioning::MonoItemPlacement as core[3b5640218fb446b]::fmt::Debug>::fmt
  16:     0x7fff4857653e - <rustc_monomorphize[4514d9151ad2ce1]::partitioning::MonoItemPlacement as core[3b5640218fb446b]::fmt::Debug>::fmt
  17:     0x7fff4857653e - <rustc_monomorphize[4514d9151ad2ce1]::partitioning::MonoItemPlacement as core[3b5640218fb446b]::fmt::Debug>::fmt
  18:     0x7fff4857653e - <rustc_monomorphize[4514d9151ad2ce1]::partitioning::MonoItemPlacement as core[3b5640218fb446b]::fmt::Debug>::fmt
  19:     0x7fff4857653e - <rustc_monomorphize[4514d9151ad2ce1]::partitioning::MonoItemPlacement as core[3b5640218fb446b]::fmt::Debug>::fmt
  20:     0x7fff4857653e - <rustc_monomorphize[4514d9151ad2ce1]::partitioning::MonoItemPlacement as core[3b5640218fb446b]::fmt::Debug>::fmt
  21:     0x7fff4857653e - <rustc_monomorphize[4514d9151ad2ce1]::partitioning::MonoItemPlacement as core[3b5640218fb446b]::fmt::Debug>::fmt
  22:     0x7fff4857653e - <rustc_monomorphize[4514d9151ad2ce1]::partitioning::MonoItemPlacement as core[3b5640218fb446b]::fmt::Debug>::fmt
  23:     0x7fff4857653e - <rustc_monomorphize[4514d9151ad2ce1]::partitioning::MonoItemPlacement as core[3b5640218fb446b]::fmt::Debug>::fmt
  24:     0x7fff4857653e - <rustc_monomorphize[4514d9151ad2ce1]::partitioning::MonoItemPlacement as core[3b5640218fb446b]::fmt::Debug>::fmt
  25:     0x7fff4855da0f - <core[3b5640218fb446b]::option::Option<rustc_middle[25ed325aece9029c]::middle::privacy::AccessLevel> as rustc_privacy[4b5d474e1e41ebc0]::VisibilityLike>::new_min
  26:     0x7fff48574752 - <rustc_monomorphize[4514d9151ad2ce1]::partitioning::MonoItemPlacement as core[3b5640218fb446b]::fmt::Debug>::fmt
  27:     0x7fff4857215d - <rustc_monomorphize[4514d9151ad2ce1]::partitioning::default::DefaultPartitioning as rustc_monomorphize[4514d9151ad2ce1]::partitioning::Partitioner>::internalize_symbols
  28:     0x7fff49809ad3 - <rustc_query_impl[fc0b1a80fdfefbde]::on_disk_cache::CacheDecoder as rustc_serialize[e9f3e8e17ec8afb5]::serialize::Decoder>::error
  29:     0x7fff497b0103 - <rustc_query_impl[fc0b1a80fdfefbde]::Queries as rustc_middle[25ed325aece9029c]::ty::query::QueryEngine>::try_mark_green
  30:     0x7fff496f917c - rustc_query_impl[fc0b1a80fdfefbde]::profiling_support::alloc_self_profile_query_strings
  31:     0x7fff495837cc - <rustc_mir_dataflow[21def95b390535c9]::impls::init_locals::MaybeInitializedLocals as rustc_mir_dataflow[21def95b390535c9]::framework::AnalysisDomain>::initialize_start_block
  32:     0x7fff4963343a - <rustc_mir_dataflow[21def95b390535c9]::impls::init_locals::MaybeInitializedLocals as rustc_mir_dataflow[21def95b390535c9]::framework::AnalysisDomain>::initialize_start_block
  33:     0x7fff4974c10e - <rustc_query_impl[fc0b1a80fdfefbde]::Queries as rustc_middle[25ed325aece9029c]::ty::query::QueryEngine>::try_mark_green
  34:     0x7fff49939e85 - rustc_codegen_ssa[e9091bef2ee1db53]::back::symbol_export::crates_export_threshold
  35:     0x7fff49807406 - <rustc_query_impl[fc0b1a80fdfefbde]::on_disk_cache::CacheDecoder as rustc_serialize[e9f3e8e17ec8afb5]::serialize::Decoder>::error
  36:     0x7fff4979d20a - <rustc_query_impl[fc0b1a80fdfefbde]::Queries as rustc_middle[25ed325aece9029c]::ty::query::QueryEngine>::try_mark_green
  37:     0x7fff496f8c48 - rustc_query_impl[fc0b1a80fdfefbde]::profiling_support::alloc_self_profile_query_strings
  38:     0x7fff49551c30 - <rustc_mir_dataflow[21def95b390535c9]::impls::init_locals::MaybeInitializedLocals as rustc_mir_dataflow[21def95b390535c9]::framework::AnalysisDomain>::initialize_start_block
  39:     0x7fff496056d3 - <rustc_mir_dataflow[21def95b390535c9]::impls::init_locals::MaybeInitializedLocals as rustc_mir_dataflow[21def95b390535c9]::framework::AnalysisDomain>::initialize_start_block
  40:     0x7fff49b3e92b - <rustc_metadata[1b6d4e0ca9c23e9d]::rmeta::encoder::EncodeContext as rustc_middle[25ed325aece9029c]::ty::codec::TyEncoder>::encode_alloc_id
  41:     0x7fff49b52916 - rustc_metadata[1b6d4e0ca9c23e9d]::rmeta::encoder::encode_metadata
  42:     0x7fff49bdb095 - <rustc_metadata[1b6d4e0ca9c23e9d]::rmeta::decoder::DecodeContext as rustc_middle[25ed325aece9029c]::ty::codec::TyDecoder>::decode_alloc_id
  43:     0x7fff49b51f73 - rustc_metadata[1b6d4e0ca9c23e9d]::rmeta::encoder::encode_metadata
  44:     0x7fff460f3f8c - <rustc_interface[ede8d86ad4d1922a]::queries::Linker>::link
  45:     0x7fff460db2ff - <rustc_interface[ede8d86ad4d1922a]::queries::Queries>::ongoing_codegen
  46:     0x7fff45fdb0b6 - <rustc_span[7f75108ed1dfc9fc]::symbol::SymbolStr as core[3b5640218fb446b]::fmt::Display>::fmt
  47:     0x7fff45f95096 - rustc_driver[c696c68206e0209d]::pretty::print_after_hir_lowering
  48:     0x7fff45ff7386 - <rustc_span[7f75108ed1dfc9fc]::symbol::SymbolStr as core[3b5640218fb446b]::fmt::Display>::fmt
  49:     0x7fff45f9e853 - rustc_driver[c696c68206e0209d]::pretty::print_after_hir_lowering
  50:     0x7fff460166d8 - <rustc_driver[c696c68206e0209d]::args::Error as core[3b5640218fb446b]::fmt::Debug>::fmt
  51:     0x7fff5d2c97fc - std::sys::windows::thread::Thread::new::h0fc50b675267fa21
  52:     0x7fffd8e854e0 - BaseThreadInitThunk
  53:     0x7fffda38485b - RtlUserThreadStart

error: internal compiler error: unexpected panic

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 1.58.0-nightly (495322d77 2021-11-08) running on x86_64-pc-windows-msvc

note: compiler flags: -C embed-bitcode=no -C debuginfo=2 -C linker=rust-lld.exe -C incremental -C link-arg=-fuse-ld=lld --crate-type lib

note: some of the compiler flags provided by cargo are hidden

query stack during panic:
#0 [collect_and_partition_mono_items] collect_and_partition_mono_items
#1 [exported_symbols] exported_symbols
end of query stack

[bjorn3]

The panic happens on the second .unwrap() at

rust/compiler/rustc_monomorphize/src/collector.rs

Line 903 in 9dbbbb1

ty::Instance::resolve(tcx, ty::ParamEnv::reveal_all(), def_id, substs).unwrap().unwrap()

According to the docs of Instance::resolve this should be impossible:

Returns Ok(None) if we cannot resolve Instance to a specific instance. For example, in a context like this,

fn foo<T: Debug>(t: T) { ... }

trying to resolve Debug::fmt applied to T will yield Ok(None), because we do not know what code ought to run. (Note that this setting is also affected by the RevealMode in the parameter environment.)

Presuming that coherence and type-check have succeeded, if this method is invoked in a monomorphic context (i.e., like during codegen), then it is guaranteed to return Ok(Some(instance)).

The error doesn't specify where in the code caused the issue, making it hard to provide an example.

Is this a public project? If so can you tell which project it is and what commit? Do you roughly know what you last changed before this crash? If it isn't public you could try making a minimal reproducing example. https://blog.pnkfx.org/blog/2019/11/18/rust-bug-minimization-patterns/ is a great post about how to reduce it. You could also try rust-reduce and if you inline all modules creduce. While creduce is written for C, most of the transforms it does work pretty well in any language with a C like syntax, including Rust.

It is possible that someone can find the issue without a reproducing example, but providing one will make finding the issue much easier.

[istankovic]

@deprilula28 is this issue still relevant? If you can't provide a minimal reproducible example, could you please test with a recent rustc and see if the problem is still there?

[kpreid]

Triage: Relabeling issues which don't have a runnable reproduction (as opposed to having a non-minimized one) to the new label S-needs-repro.
@rustbot label +S-needs-repro -E-needs-mcve