ICE when passing numeric literals to str as generics

[JakeStanger]

Here's a fun one I discovered back in 2019 when I first started learning Rust and forgot to report (sorry!). I figured I'd try the genius idea of making a string of length 3 by passing 3 as a generic. I dug up the code that caused the problem, and it sure enough causes the same crash now.

Code

let test: str<3> = "hello world";

Meta

rustc --version --verbose:

rustc 1.48.0-nightly (d006f5734 2020-08-28)
binary: rustc
commit-hash: d006f5734f49625c34d6fc33bf6b9967243abca8
commit-date: 2020-08-28
host: x86_64-unknown-linux-gnu
release: 1.48.0-nightly
LLVM version: 11.0

Error output

error: internal compiler error: src/librustc_typeck/collect/type_of.rs:114:26: unexpected anon const res PrimTy(Str) in path: Path { span: src/main.rs:14:17: 14:23 (#0), res: PrimTy(Str), segments: [PathSegment { ident: str#0, hir_id: Some(HirId { owner: DefId(0:10 ~ toffee[3d1d]::main[0]), local_id: 9 }), res: Some(Err), args: Some(GenericArgs { args: [Const(ConstArg { value: AnonConst { hir_id: HirId { owner: DefId(0:10 ~ toffee[3d1d]::main[0]), local_id: 7 }, body: BodyId { hir_id: HirId { owner: DefId(0:10 ~ toffee[3d1d]::main[0]), local_id: 8 } } }, span: src/main.rs:14:21: 14:22 (#0) })], bindings: [], parenthesized: false }), infer_args: false }] }

thread 'rustc' panicked at 'Box<Any>', /rustc/d006f5734f49625c34d6fc33bf6b9967243abca8/src/librustc_errors/lib.rs:873:9
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

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 1.48.0-nightly (d006f5734 2020-08-28) running on x86_64-unknown-linux-gnu

note: compiler flags: -C embed-bitcode=no -C debuginfo=2 -C incremental --crate-type bin

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

Backtrace

thread 'rustc' panicked at 'Box<Any>', /rustc/d006f5734f49625c34d6fc33bf6b9967243abca8/src/librustc_errors/lib.rs:873:9
stack backtrace:
   0: std::panicking::begin_panic
   1: rustc_errors::HandlerInner::span_bug
   2: rustc_errors::Handler::span_bug
   3: rustc_middle::util::bug::opt_span_bug_fmt::{{closure}}
   4: rustc_middle::ty::context::tls::with_opt::{{closure}}
   5: rustc_middle::ty::context::tls::with_opt
   6: rustc_middle::util::bug::opt_span_bug_fmt
   7: rustc_middle::util::bug::span_bug_fmt
   8: rustc_typeck::collect::type_of::opt_const_param_of
   9: rustc_middle::ty::query::<impl rustc_query_system::query::config::QueryAccessors<rustc_middle::ty::context::TyCtxt> for rustc_middle::ty::query::queries::opt_const_param_of>::compute
  10: rustc_middle::dep_graph::<impl rustc_query_system::dep_graph::DepKind for rustc_middle::dep_graph::dep_node::DepKind>::with_deps
  11: rustc_query_system::dep_graph::graph::DepGraph<K>::with_task_impl
  12: rustc_data_structures::stack::ensure_sufficient_stack
  13: rustc_query_system::query::plumbing::get_query_impl
  14: rustc_typeck::check::typeck
  15: rustc_middle::ty::query::<impl rustc_query_system::query::config::QueryAccessors<rustc_middle::ty::context::TyCtxt> for rustc_middle::ty::query::queries::typeck>::compute
  16: rustc_middle::dep_graph::<impl rustc_query_system::dep_graph::DepKind for rustc_middle::dep_graph::dep_node::DepKind>::with_deps
  17: rustc_query_system::dep_graph::graph::DepGraph<K>::with_task_impl
  18: rustc_data_structures::stack::ensure_sufficient_stack
  19: rustc_query_system::query::plumbing::get_query_impl
  20: rustc_query_system::query::plumbing::ensure_query_impl
  21: rustc_typeck::check::typeck_item_bodies
  22: rustc_middle::ty::query::<impl rustc_query_system::query::config::QueryAccessors<rustc_middle::ty::context::TyCtxt> for rustc_middle::ty::query::queries::typeck_item_bodies>::compute
  23: rustc_middle::dep_graph::<impl rustc_query_system::dep_graph::DepKind for rustc_middle::dep_graph::dep_node::DepKind>::with_deps
  24: rustc_query_system::dep_graph::graph::DepGraph<K>::with_task_impl
  25: rustc_data_structures::stack::ensure_sufficient_stack
  26: rustc_query_system::query::plumbing::get_query_impl
  27: rustc_typeck::check_crate
  28: rustc_interface::passes::analysis
  29: rustc_middle::ty::query::<impl rustc_query_system::query::config::QueryAccessors<rustc_middle::ty::context::TyCtxt> for rustc_middle::ty::query::queries::analysis>::compute
  30: rustc_middle::dep_graph::<impl rustc_query_system::dep_graph::DepKind for rustc_middle::dep_graph::dep_node::DepKind>::with_deps
  31: rustc_query_system::dep_graph::graph::DepGraph<K>::with_task_impl
  32: rustc_data_structures::stack::ensure_sufficient_stack
  33: rustc_query_system::query::plumbing::get_query_impl
  34: rustc_interface::queries::<impl rustc_interface::interface::Compiler>::enter
  35: rustc_span::with_source_map
  36: rustc_interface::interface::create_compiler_and_run
  37: scoped_tls::ScopedKey<T>::set
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

[jyn514]

1.48-nightly is 6 months old, this is fixed on master. https://play.rust-lang.org/?version=nightly&mode=debug&edition=2018&gist=804b1c50345e46ef1473cd7341a3e1e9

[camelid]

Dang, you beat me to it by 1 minute! 😆

[camelid]

Based on testing with Godbolt, it looks like it was fixed in 1.49.0. Probably work on const generics is what fixed it.

[JakeStanger]

🤦 my bad, I saw my version was nightly and didn't think to update.