Closed
Description
Playing around with the new trait aliases I encountered a compiler panic. This is a minimized example (play.rust-lang.org):
#![feature(trait_alias)]
use std::ops::Neg;
trait Number = Sized + Neg<Output = Self>;Error message:
internal compiler error: librustc_metadata/encoder.rs:1158: cannot encode info for item Item { name: Number, id: NodeId(17), hir_id: HirId { owner: DefIndex(0:4), local_id: 0 }, attrs: [], node: TraitAlias(Generics { params: [], where_clause: WhereClause { id: NodeId(18), predicates: [] }, span: src/lib.rs:1:1: 1:1 }, [Trait(PolyTraitRef { bound_generic_params: [], trait_ref: TraitRef { path: path(Sized), ref_id: NodeId(19), hir_ref_id: HirId { owner: DefIndex(0:4), local_id: 3 } }, span: src/lib.rs:5:16: 5:21 }, None), Trait(PolyTraitRef { bound_generic_params: [], trait_ref: TraitRef { path: path(Neg<Output = Self>), ref_id: NodeId(21), hir_ref_id: HirId { owner: DefIndex(0:4), local_id: 8 } }, span: src/lib.rs:5:24: 5:42 }, None)]), vis: Spanned { node: Inherited, span: src/lib.rs:5:1: 5:1 }, span: src/lib.rs:5:1: 5:43 }
Update: even smaller repro case
Another update: see here (even more minimal)
Meta
$ rustc --version --verbose
rustc 1.32.0-nightly (f37247f88 2018-11-17)
binary: rustc
commit-hash: f37247f885026d29bf26fd4aed6e9135e4f32ebf
commit-date: 2018-11-17
host: x86_64-unknown-linux-gnu
release: 1.32.0-nightly
LLVM version: 8.0
Backtrace:
thread 'main' panicked at 'Box<Any>', librustc_errors/lib.rs:600:9
stack backtrace:
0: std::sys::unix::backtrace::tracing::imp::unwind_backtrace
at libstd/sys/unix/backtrace/tracing/gcc_s.rs:49
1: std::sys_common::backtrace::_print
at libstd/sys_common/backtrace.rs:71
2: std::panicking::default_hook::{{closure}}
at libstd/sys_common/backtrace.rs:59
at libstd/panicking.rs:211
3: std::panicking::default_hook
at libstd/panicking.rs:227
4: rustc::util::common::panic_hook
5: std::panicking::rust_panic_with_hook
at libstd/panicking.rs:480
6: std::panicking::begin_panic
7: rustc_errors::Handler::bug
8: rustc::util::bug::opt_span_bug_fmt::{{closure}}
9: rustc::ty::context::tls::with_opt::{{closure}}
10: rustc::ty::context::tls::with_context_opt
11: rustc::ty::context::tls::with_opt
12: rustc::util::bug::opt_span_bug_fmt
13: rustc::util::bug::bug_fmt
14: rustc_metadata::encoder::<impl rustc_metadata::isolated_encoder::IsolatedEncoder<'a, 'b, 'tcx>>::encode_info_for_item
15: rustc::ty::context::tls::with_context
16: <rustc_metadata::encoder::EncodeVisitor<'a, 'b, 'tcx> as rustc::hir::intravisit::Visitor<'tcx>>::visit_item
17: rustc::hir::Crate::visit_all_item_likes
18: rustc_metadata::encoder::encode_metadata
19: rustc_metadata::cstore_impl::<impl rustc::middle::cstore::CrateStore for rustc_metadata::cstore::CStore>::encode_metadata
20: rustc::ty::context::TyCtxt::encode_metadata
21: <rustc_codegen_llvm::LlvmCodegenBackend as rustc_codegen_ssa::traits::backend::ExtraBackendMethods>::write_metadata
22: rustc::util::common::time
23: rustc_codegen_ssa::base::codegen_crate
24: <rustc_codegen_llvm::LlvmCodegenBackend as rustc_codegen_utils::codegen_backend::CodegenBackend>::codegen_crate
25: rustc::util::common::time
26: rustc_driver::driver::phase_4_codegen
27: rustc_driver::driver::compile_input::{{closure}}
28: rustc::ty::context::tls::enter_context
29: <std::thread::local::LocalKey<T>>::with
30: rustc::ty::context::TyCtxt::create_and_enter
31: rustc_driver::driver::compile_input
32: rustc_driver::run_compiler_with_pool
33: <scoped_tls::ScopedKey<T>>::set
34: rustc_driver::run_compiler
35: syntax::with_globals
36: __rust_maybe_catch_panic
at libpanic_unwind/lib.rs:102
37: rustc_driver::run
38: rustc_driver::main
39: std::rt::lang_start::{{closure}}
40: std::panicking::try::do_call
at libstd/rt.rs:59
at libstd/panicking.rs:310
41: __rust_maybe_catch_panic
at libpanic_unwind/lib.rs:102
42: std::rt::lang_start_internal
at libstd/panicking.rs:289
at libstd/panic.rs:398
at libstd/rt.rs:58
43: main
44: __libc_start_main
45: <unknown>
query stack during panic:
end of query stack
error: aborting due to previous error