ICE: `index out of bounds: the len is 0 but the index is 0` snapshot_vec

[matthiaskrgr]

Summary

This will probably need a rustc->clippy sync in order to be reproducible in the clippy repo.
File was added in rust-lang/rust#107772

./tests/ui/dyn-star/llvm-old-style-ptrs.rs

// run-pass
// compile-flags: -Copt-level=0 -Cllvm-args=-opaque-pointers=0

// (opaque-pointers flag is called force-opaque-pointers in LLVM 13...)
// min-llvm-version: 14.0

// This test can be removed once non-opaque pointers are gone from LLVM, maybe.

#![feature(dyn_star, pointer_like_trait)]
#![allow(incomplete_features)]

use std::fmt::Debug;
use std::marker::PointerLike;

fn make_dyn_star<'a>(t: impl PointerLike + Debug + 'a) -> dyn* Debug + 'a {
    t as _
}

fn main() {
    println!("{:?}", make_dyn_star(Box::new(1i32)));
    println!("{:?}", make_dyn_star(2usize));
    println!("{:?}", make_dyn_star((3usize,)));
}

Version

rustc 1.69.0-nightly (4507fdaaa 2023-02-18)
binary: rustc
commit-hash: 4507fdaaa27ea2fb59a41df2ce7d1f290da53dae
commit-date: 2023-02-18
host: x86_64-unknown-linux-gnu
release: 1.69.0-nightly
LLVM version: 15.0.7

Error output

Backtrace

thread 'rustc' panicked at 'index out of bounds: the len is 0 but the index is 0', /cargo/registry/src/index.crates.io-6f17d22bba15001f/ena-0.14.0/src/snapshot_vec.rs:199:10
stack backtrace:
 0:     0x7f111176aa7a - std::backtrace_rs::backtrace::libunwind::trace::h9ab7cd28287cf18f
                             at /rustc/4507fdaaa27ea2fb59a41df2ce7d1f290da53dae/library/std/src/../../backtrace/src/backtrace/libunwind.rs:93:5
 1:     0x7f111176aa7a - std::backtrace_rs::backtrace::trace_unsynchronized::h3e7e6ca06d1d63cf
                             at /rustc/4507fdaaa27ea2fb59a41df2ce7d1f290da53dae/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
 2:     0x7f111176aa7a - std::sys_common::backtrace::_print_fmt::h5b6184fd459f0c71
                             at /rustc/4507fdaaa27ea2fb59a41df2ce7d1f290da53dae/library/std/src/sys_common/backtrace.rs:65:5
 3:     0x7f111176aa7a - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::h8ed5468732b78071
                             at /rustc/4507fdaaa27ea2fb59a41df2ce7d1f290da53dae/library/std/src/sys_common/backtrace.rs:44:22
 4:     0x7f11117ca9fe - core::fmt::write::h89c1e855e81d7a96
                             at /rustc/4507fdaaa27ea2fb59a41df2ce7d1f290da53dae/library/core/src/fmt/mod.rs:1232:17
 5:     0x7f111175af25 - std::io::Write::write_fmt::ha23ba71db044374b
                             at /rustc/4507fdaaa27ea2fb59a41df2ce7d1f290da53dae/library/std/src/io/mod.rs:1684:15
 6:     0x7f111176a845 - std::sys_common::backtrace::_print::h194cdf55c322d5fe
                             at /rustc/4507fdaaa27ea2fb59a41df2ce7d1f290da53dae/library/std/src/sys_common/backtrace.rs:47:5
 7:     0x7f111176a845 - std::sys_common::backtrace::print::h4549e75783bab124
                             at /rustc/4507fdaaa27ea2fb59a41df2ce7d1f290da53dae/library/std/src/sys_common/backtrace.rs:34:9
 8:     0x7f111176d5bf - std::panicking::default_hook::{{closure}}::h04a46ea9ff60bf2c
                             at /rustc/4507fdaaa27ea2fb59a41df2ce7d1f290da53dae/library/std/src/panicking.rs:267:22
 9:     0x7f111176d2fb - std::panicking::default_hook::h6f3c116d48f73fba
                             at /rustc/4507fdaaa27ea2fb59a41df2ce7d1f290da53dae/library/std/src/panicking.rs:286:9
10:     0x55cee00184c0 - clippy_driver[f0dcf01ecd52ed00]::ICE_HOOK::{closure#0}::{closure#0}
11:     0x7f111176ddfd - <alloc::boxed::Box<F,A> as core::ops::function::Fn<Args>>::call::h779d28c2deb011a8
                             at /rustc/4507fdaaa27ea2fb59a41df2ce7d1f290da53dae/library/alloc/src/boxed.rs:2002:9
12:     0x7f111176ddfd - std::panicking::rust_panic_with_hook::h5a936503487f19f5
                             at /rustc/4507fdaaa27ea2fb59a41df2ce7d1f290da53dae/library/std/src/panicking.rs:692:13
13:     0x7f111176db79 - std::panicking::begin_panic_handler::{{closure}}::hf8db4efce7a7f23f
                             at /rustc/4507fdaaa27ea2fb59a41df2ce7d1f290da53dae/library/std/src/panicking.rs:579:13
14:     0x7f111176aee6 - std::sys_common::backtrace::__rust_end_short_backtrace::h668cb6dbbf3929c2
                             at /rustc/4507fdaaa27ea2fb59a41df2ce7d1f290da53dae/library/std/src/sys_common/backtrace.rs:137:18
15:     0x7f111176d882 - rust_begin_unwind
                             at /rustc/4507fdaaa27ea2fb59a41df2ce7d1f290da53dae/library/std/src/panicking.rs:575:5
16:     0x7f11117c73a3 - core::panicking::panic_fmt::h6a86232234ce2127
                             at /rustc/4507fdaaa27ea2fb59a41df2ce7d1f290da53dae/library/core/src/panicking.rs:64:14
17:     0x7f11117c7592 - core::panicking::panic_bounds_check::h71a6710f1af624e4
                             at /rustc/4507fdaaa27ea2fb59a41df2ce7d1f290da53dae/library/core/src/panicking.rs:159:5
18:     0x7f1112a23267 - <ena[e9f14e00eff15fcd]::unify::UnificationTable<ena[e9f14e00eff15fcd]::unify::backing_vec::InPlace<rustc_middle[2a277d44e6a99f4f]::infer::unify_key::RegionVidKey, &mut alloc[d821da156a43ed98]::vec::Vec<ena[e9f14e00eff15fcd]::unify::VarValue<rustc_middle[2a277d44e6a99f4f]::infer::unify_key::RegionVidKey>>, &mut rustc_infer[80d058b2c2e7c69]::infer::undo_log::InferCtxtUndoLogs>>>::uninlined_get_root_key
19:     0x7f1112ae4c7d - <rustc_infer[80d058b2c2e7c69]::infer::canonical::canonicalizer::Canonicalizer as rustc_type_ir[8beb17bdab38ad78]::fold::TypeFolder<rustc_middle[2a277d44e6a99f4f]::ty::context::TyCtxt>>::fold_region
20:     0x7f1112d3a8e8 - rustc_middle[2a277d44e6a99f4f]::ty::util::fold_list::<rustc_infer[80d058b2c2e7c69]::infer::canonical::canonicalizer::Canonicalizer, rustc_middle[2a277d44e6a99f4f]::ty::Predicate, <&rustc_middle[2a277d44e6a99f4f]::ty::list::List<rustc_middle[2a277d44e6a99f4f]::ty::Predicate> as rustc_type_ir[8beb17bdab38ad78]::fold::TypeFoldable<rustc_middle[2a277d44e6a99f4f]::ty::context::TyCtxt>>::try_fold_with<rustc_infer[80d058b2c2e7c69]::infer::canonical::canonicalizer::Canonicalizer>::{closure#0}>
21:     0x7f11133b5838 - <rustc_infer[80d058b2c2e7c69]::infer::InferCtxt as rustc_trait_selection[56e02159555b3df4]::traits::query::evaluate_obligation::InferCtxtExt>::predicate_must_hold_modulo_regions
22:     0x7f11133b503b - rustc_trait_selection[56e02159555b3df4]::traits::type_known_to_meet_bound_modulo_regions
23:     0x7f11133b4cdc - rustc_ty_utils[ee275bd23a42692]::common_traits::is_sized_raw
24:     0x7f1113703e0b - <rustc_middle[2a277d44e6a99f4f]::ty::Ty>::is_sized
25:     0x7f111346d39b - rustc_ty_utils[ee275bd23a42692]::layout::layout_of
26:     0x7f111362dac9 - rustc_query_system[46560f6823c6ac3e]::query::plumbing::get_query::<rustc_query_impl[34788ad4354c9a05]::queries::layout_of, rustc_query_impl[34788ad4354c9a05]::plumbing::QueryCtxt, rustc_middle[2a277d44e6a99f4f]::dep_graph::dep_node::DepKind>
27:     0x7f111362d6b3 - <rustc_query_impl[34788ad4354c9a05]::Queries as rustc_middle[2a277d44e6a99f4f]::ty::query::QueryEngine>::layout_of
28:     0x7f11130cd123 - <rustc_trait_selection[56e02159555b3df4]::traits::select::SelectionContext>::assemble_candidate_for_ptr_sized
29:     0x7f11130a9e84 - <rustc_trait_selection[56e02159555b3df4]::traits::select::SelectionContext>::assemble_candidates
30:     0x7f1112bdd1fe - <rustc_trait_selection[56e02159555b3df4]::traits::select::SelectionContext>::candidate_from_obligation_no_cache
31:     0x7f1112bdc5df - <rustc_query_system[46560f6823c6ac3e]::dep_graph::graph::DepGraph<rustc_middle[2a277d44e6a99f4f]::dep_graph::dep_node::DepKind>>::with_anon_task::<rustc_middle[2a277d44e6a99f4f]::ty::context::TyCtxt, <rustc_trait_selection[56e02159555b3df4]::traits::select::SelectionContext>::in_task<<rustc_trait_selection[56e02159555b3df4]::traits::select::SelectionContext>::candidate_from_obligation::{closure#0}::{closure#0}, core[69c2f5c35675f1ee]::result::Result<core[69c2f5c35675f1ee]::option::Option<rustc_middle[2a277d44e6a99f4f]::traits::select::SelectionCandidate>, rustc_middle[2a277d44e6a99f4f]::traits::SelectionError>>::{closure#0}, core[69c2f5c35675f1ee]::result::Result<core[69c2f5c35675f1ee]::option::Option<rustc_middle[2a277d44e6a99f4f]::traits::select::SelectionCandidate>, rustc_middle[2a277d44e6a99f4f]::traits::SelectionError>>
32:     0x7f1112bd5a97 - <rustc_trait_selection[56e02159555b3df4]::traits::select::SelectionContext>::evaluate_stack
33:     0x7f1113626cdf - <rustc_trait_selection[56e02159555b3df4]::traits::select::SelectionContext>::evaluate_predicate_recursively
34:     0x7f1113624883 - <rustc_infer[80d058b2c2e7c69]::infer::InferCtxt>::probe::<core[69c2f5c35675f1ee]::result::Result<rustc_middle[2a277d44e6a99f4f]::traits::select::EvaluationResult, rustc_middle[2a277d44e6a99f4f]::traits::select::OverflowError>, <rustc_trait_selection[56e02159555b3df4]::traits::select::SelectionContext>::evaluation_probe<<rustc_trait_selection[56e02159555b3df4]::traits::select::SelectionContext>::evaluate_root_obligation::{closure#0}>::{closure#0}>
35:     0x7f11132dfe02 - rustc_traits[92224ab987017c6]::evaluate_obligation::evaluate_obligation
36:     0x7f11132dd096 - rustc_query_system[46560f6823c6ac3e]::query::plumbing::get_query::<rustc_query_impl[34788ad4354c9a05]::queries::evaluate_obligation, rustc_query_impl[34788ad4354c9a05]::plumbing::QueryCtxt, rustc_middle[2a277d44e6a99f4f]::dep_graph::dep_node::DepKind>
37:     0x7f111338c815 - <rustc_infer[80d058b2c2e7c69]::infer::InferCtxt as rustc_trait_selection[56e02159555b3df4]::traits::query::evaluate_obligation::InferCtxtExt>::evaluate_obligation
38:     0x55cee0409cba - clippy_utils[a5661489ba05b5cc]::ty::implements_trait
39:     0x55cee033e99f - <clippy_lints[4079790fda0cdfd1]::needless_pass_by_value::NeedlessPassByValue as rustc_lint[d21e6d472070f61c]::passes::LateLintPass>::check_fn
40:     0x7f1114e515ad - <rustc_lint[d21e6d472070f61c]::late::RuntimeCombinedLateLintPass as rustc_lint[d21e6d472070f61c]::passes::LateLintPass>::check_fn
41:     0x7f1114e18569 - <rustc_lint[d21e6d472070f61c]::late::LateContextAndPass<rustc_lint[d21e6d472070f61c]::late::RuntimeCombinedLateLintPass> as rustc_hir[1e8fd85835ba83b0]::intravisit::Visitor>::visit_fn
42:     0x7f1114deda5d - rustc_hir[1e8fd85835ba83b0]::intravisit::walk_item::<rustc_lint[d21e6d472070f61c]::late::LateContextAndPass<rustc_lint[d21e6d472070f61c]::late::RuntimeCombinedLateLintPass>>
43:     0x7f1114e189c0 - <rustc_lint[d21e6d472070f61c]::late::LateContextAndPass<rustc_lint[d21e6d472070f61c]::late::RuntimeCombinedLateLintPass> as rustc_hir[1e8fd85835ba83b0]::intravisit::Visitor>::visit_nested_item
44:     0x7f1114ded2b8 - rustc_hir[1e8fd85835ba83b0]::intravisit::walk_mod::<rustc_lint[d21e6d472070f61c]::late::LateContextAndPass<rustc_lint[d21e6d472070f61c]::late::RuntimeCombinedLateLintPass>>
45:     0x7f11140a3323 - rustc_lint[d21e6d472070f61c]::late::late_lint_crate::<rustc_lint[d21e6d472070f61c]::BuiltinCombinedLateLintPass>
46:     0x7f11140a2672 - <rustc_session[403a5d4fc02438c2]::session::Session>::time::<(), rustc_lint[d21e6d472070f61c]::late::check_crate<rustc_lint[d21e6d472070f61c]::BuiltinCombinedLateLintPass, rustc_interface[3e6023fe39c52850]::passes::analysis::{closure#6}::{closure#1}::{closure#2}::{closure#0}::{closure#0}>::{closure#0}::{closure#0}>
47:     0x7f11140a24d2 - <rustc_session[403a5d4fc02438c2]::session::Session>::time::<(), rustc_interface[3e6023fe39c52850]::passes::analysis::{closure#6}::{closure#1}::{closure#2}::{closure#0}>
48:     0x7f11140a215b - <core[69c2f5c35675f1ee]::panic::unwind_safe::AssertUnwindSafe<rustc_interface[3e6023fe39c52850]::passes::analysis::{closure#6}::{closure#1}> as core[69c2f5c35675f1ee]::ops::function::FnOnce<()>>::call_once
49:     0x7f1112efff4d - <rustc_session[403a5d4fc02438c2]::session::Session>::time::<(), rustc_interface[3e6023fe39c52850]::passes::analysis::{closure#6}>
50:     0x7f1112efec8a - rustc_interface[3e6023fe39c52850]::passes::analysis
51:     0x7f1114258e62 - rustc_query_system[46560f6823c6ac3e]::query::plumbing::try_execute_query::<rustc_query_impl[34788ad4354c9a05]::queries::analysis, rustc_query_impl[34788ad4354c9a05]::plumbing::QueryCtxt>
52:     0x7f111442ed8a - <rustc_query_impl[34788ad4354c9a05]::Queries as rustc_middle[2a277d44e6a99f4f]::ty::query::QueryEngine>::analysis
53:     0x7f1113cc79f6 - <rustc_middle[2a277d44e6a99f4f]::ty::context::GlobalCtxt>::enter::<rustc_driver_impl[48a98004e06292cf]::run_compiler::{closure#1}::{closure#2}::{closure#3}, core[69c2f5c35675f1ee]::result::Result<(), rustc_errors[abf5e0320c3520e7]::ErrorGuaranteed>>
54:     0x7f1113cc68e6 - <rustc_interface[3e6023fe39c52850]::interface::Compiler>::enter::<rustc_driver_impl[48a98004e06292cf]::run_compiler::{closure#1}::{closure#2}, core[69c2f5c35675f1ee]::result::Result<core[69c2f5c35675f1ee]::option::Option<rustc_interface[3e6023fe39c52850]::queries::Linker>, rustc_errors[abf5e0320c3520e7]::ErrorGuaranteed>>
55:     0x7f1113cc49c4 - rustc_span[97beb3ced854c2e2]::with_source_map::<core[69c2f5c35675f1ee]::result::Result<(), rustc_errors[abf5e0320c3520e7]::ErrorGuaranteed>, rustc_interface[3e6023fe39c52850]::interface::run_compiler<core[69c2f5c35675f1ee]::result::Result<(), rustc_errors[abf5e0320c3520e7]::ErrorGuaranteed>, rustc_driver_impl[48a98004e06292cf]::run_compiler::{closure#1}>::{closure#0}::{closure#0}>
56:     0x7f1113cc3f2d - std[d6315e0f51da5517]::sys_common::backtrace::__rust_begin_short_backtrace::<rustc_interface[3e6023fe39c52850]::util::run_in_thread_pool_with_globals<rustc_interface[3e6023fe39c52850]::interface::run_compiler<core[69c2f5c35675f1ee]::result::Result<(), rustc_errors[abf5e0320c3520e7]::ErrorGuaranteed>, rustc_driver_impl[48a98004e06292cf]::run_compiler::{closure#1}>::{closure#0}, core[69c2f5c35675f1ee]::result::Result<(), rustc_errors[abf5e0320c3520e7]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[69c2f5c35675f1ee]::result::Result<(), rustc_errors[abf5e0320c3520e7]::ErrorGuaranteed>>
57:     0x7f1113cc397c - <<std[d6315e0f51da5517]::thread::Builder>::spawn_unchecked_<rustc_interface[3e6023fe39c52850]::util::run_in_thread_pool_with_globals<rustc_interface[3e6023fe39c52850]::interface::run_compiler<core[69c2f5c35675f1ee]::result::Result<(), rustc_errors[abf5e0320c3520e7]::ErrorGuaranteed>, rustc_driver_impl[48a98004e06292cf]::run_compiler::{closure#1}>::{closure#0}, core[69c2f5c35675f1ee]::result::Result<(), rustc_errors[abf5e0320c3520e7]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[69c2f5c35675f1ee]::result::Result<(), rustc_errors[abf5e0320c3520e7]::ErrorGuaranteed>>::{closure#1} as core[69c2f5c35675f1ee]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
58:     0x7f1111777c83 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::heeffe32503a99aa5
                             at /rustc/4507fdaaa27ea2fb59a41df2ce7d1f290da53dae/library/alloc/src/boxed.rs:1988:9
59:     0x7f1111777c83 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h5085270dbf970bb4
                             at /rustc/4507fdaaa27ea2fb59a41df2ce7d1f290da53dae/library/alloc/src/boxed.rs:1988:9
60:     0x7f1111777c83 - std::sys::unix::thread::Thread::new::thread_start::h76c3abd575e0d195
                             at /rustc/4507fdaaa27ea2fb59a41df2ce7d1f290da53dae/library/std/src/sys/unix/thread.rs:108:17
61:     0x7f11113e8bb5 - <unknown>
62:     0x7f111146ad90 - <unknown>
63:                0x0 - <unknown>

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-clippy/issues/new

note: Clippy version: clippy 0.1.69 (4507fda 2023-02-18)

query stack during panic:
#0 [is_sized_raw] computing whether `impl PointerLike + Debug + 'a` is `Sized`
#1 [layout_of] computing layout of `&impl PointerLike + Debug + 'a`
#2 [evaluate_obligation] evaluating trait selection obligation `&impl PointerLike + Debug + 'a: core::marker::PointerLike`
#3 [analysis] running analysis passes on this crate
end of query stack

[matthiaskrgr]

Reduced to

#![feature(pointer_like_trait)]
#![allow(incomplete_features)]

fn make_dyn_star<'a>(t: impl std::marker::PointerLike + 'a)  {
    todo!();
}

fn main() {}

[Jarcho]

I'm not sure if that's a clippy bug. The obligation it's failing on is valid and shouldn't crash. Unless we set the ParamEnv wrong somehow.

The ParamEnv is set correctly.

Somehow a RegionKind::ReVar(_) is ending up in the query. Only way I can see that happening is through the predicates contained in the ParamEnv. Current code has an obligation of the form &'erased T: std::marker::PointerLike which evaluates a second obligation T: Sized. Not sure where the stray region variable comes from.

[Jarcho]

This no longer crashes on 2024-08-02