ICE: thread 'rustc' panicked at 'index out of bounds: the len is 0 but the index is 0', compiler/rustc_middle/src/ty/mod.rs:893:14

[chengniansun]

Code

fn sof<T>() -> T {}
fn test<T>() {
    let _: [u8; sof::<T>()];
}

Meta

rustc --version --verbose:

rustc 1.49.0-nightly (adef9da30 2020-10-13)

binary: rustc

commit-hash: adef9da30f1ecbfeb81312d01ed94ac53f7161ba

commit-date: 2020-10-13

host: x86_64-unknown-linux-gnu

release: 1.49.0-nightly

LLVM version: 11.0

Error output

error[E0601]: `main` function not found in crate `reduced_mutant`
 --> reduced_mutant.rs:1:1
  |
1 | / fn sof<T>() -> T {}
2 | | fn test<T>() {
3 | |     let _: [u8; sof::<T>()];
4 | | }
  | |_^ consider adding a `main` function to `reduced_mutant.rs`

error[E0308]: mismatched types
 --> reduced_mutant.rs:1:16
  |
1 | fn sof<T>() -> T {}
  |    --- -       ^ expected type parameter `T`, found `()`
  |    |   |
  |    |   this type parameter
  |    implicitly returns `()` as its body has no tail or `return` expression
  |
  = note: expected type parameter `T`
                  found unit type `()`

error[E0277]: the size for values of type `T` cannot be known at compilation time
 --> reduced_mutant.rs:3:23
  |
1 | fn sof<T>() -> T {}
  |        - required by this bound in `sof`
2 | fn test<T>() {
  |         - this type parameter needs to be `Sized`
3 |     let _: [u8; sof::<T>()];
  |                       ^ doesn't have a size known at compile-time
  |
help: consider relaxing the implicit `Sized` restriction
  |
1 | fn sof<T: ?Sized>() -> T {}
  |         ^^^^^^^^

thread 'rustc' panicked at 'index out of bounds: the len is 0 but the index is 0', compiler/rustc_middle/src/ty/mod.rs:893:14
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 1.49.0-nightly (dd7fc54eb 2020-10-15) running on x86_64-unknown-linux-gnu

error: aborting due to 3 previous errors

Some errors have detailed explanations: E0277, E0308, E0601.
For more information about an error, try `rustc --explain E0277`.

Backtrace

thread 'rustc' panicked at 'index out of bounds: the len is 0 but the index is 0', compiler/rustc_middle/src/ty/mod.rs:893:14
stack backtrace:
   0: rust_begin_unwind
             at /rustc/dd7fc54ebdca419ad9d3ab1e9f5ed14e770768ea/library/std/src/panicking.rs:483:5
   1: core::panicking::panic_fmt
             at /rustc/dd7fc54ebdca419ad9d3ab1e9f5ed14e770768ea/library/core/src/panicking.rs:85:14
   2: core::panicking::panic_bounds_check
             at /rustc/dd7fc54ebdca419ad9d3ab1e9f5ed14e770768ea/library/core/src/panicking.rs:62:5
   3: rustc_middle::ty::Generics::param_at
   4: rustc_middle::ty::error::<impl rustc_middle::ty::context::TyCtxt>::note_and_explain_type_err
   5: rustc_infer::infer::error_reporting::<impl rustc_infer::infer::InferCtxt>::note_type_err
   6: rustc_infer::infer::error_reporting::<impl rustc_infer::infer::InferCtxt>::report_and_explain_type_error
   7: rustc_infer::infer::InferCtxt::report_mismatched_types
   8: rustc_typeck::check::demand::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::demand_coerce_diag
   9: rustc_typeck::check::expr::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::check_expr_coercable_to_type
  10: rustc_infer::infer::InferCtxtBuilder::enter
  11: rustc_typeck::check::typeck
  12: rustc_query_system::dep_graph::graph::DepGraph<K>::with_task_impl
  13: rustc_data_structures::stack::ensure_sufficient_stack
  14: rustc_query_system::query::plumbing::get_query_impl
  15: rustc_middle::ty::context::TyCtxt::typeck_opt_const_arg
  16: rustc_mir::const_eval::eval_queries::eval_to_allocation_raw_provider
  17: rustc_middle::ty::query::<impl rustc_query_system::query::config::QueryAccessors<rustc_middle::ty::context::TyCtxt> for rustc_middle::ty::query::queries::eval_to_allocation_raw>::compute
  18: rustc_query_system::dep_graph::graph::DepGraph<K>::with_task_impl
  19: rustc_data_structures::stack::ensure_sufficient_stack
  20: rustc_query_system::query::plumbing::get_query_impl
  21: rustc_mir::const_eval::eval_queries::eval_to_const_value_raw_provider
  22: rustc_middle::ty::query::<impl rustc_query_system::query::config::QueryAccessors<rustc_middle::ty::context::TyCtxt> for rustc_middle::ty::query::queries::eval_to_const_value_raw>::compute
  23: rustc_query_system::dep_graph::graph::DepGraph<K>::with_task_impl
  24: rustc_data_structures::stack::ensure_sufficient_stack
  25: rustc_query_system::query::plumbing::get_query_impl
  26: rustc_mir::const_eval::eval_queries::eval_to_const_value_raw_provider
  27: rustc_middle::ty::query::<impl rustc_query_system::query::config::QueryAccessors<rustc_middle::ty::context::TyCtxt> for rustc_middle::ty::query::queries::eval_to_const_value_raw>::compute
  28: rustc_query_system::dep_graph::graph::DepGraph<K>::with_task_impl
  29: rustc_data_structures::stack::ensure_sufficient_stack
  30: rustc_query_system::query::plumbing::get_query_impl
  31: rustc_middle::mir::interpret::queries::<impl rustc_middle::ty::context::TyCtxt>::const_eval_global_id
  32: rustc_middle::mir::interpret::queries::<impl rustc_middle::ty::context::TyCtxt>::const_eval_resolve
  33: <rustc_trait_selection::traits::project::AssocTypeNormalizer as rustc_middle::ty::fold::TypeFolder>::fold_const
  34: rustc_middle::ty::structural_impls::<impl rustc_middle::ty::fold::TypeFoldable for &rustc_middle::ty::TyS>::super_fold_with
  35: <rustc_trait_selection::traits::project::AssocTypeNormalizer as rustc_middle::ty::fold::TypeFolder>::fold_ty
  36: rustc_data_structures::stack::ensure_sufficient_stack
  37: rustc_trait_selection::traits::project::normalize
  38: <rustc_infer::infer::InferCtxt as rustc_trait_selection::infer::InferCtxtExt>::partially_normalize_associated_types_in
  39: rustc_typeck::check::inherited::Inherited::normalize_associated_types_in
  40: <rustc_typeck::check::fn_ctxt::FnCtxt as rustc_typeck::astconv::AstConv>::normalize_ty
  41: <dyn rustc_typeck::astconv::AstConv>::ast_ty_to_ty_inner
  42: <rustc_typeck::check::gather_locals::GatherLocalsVisitor as rustc_hir::intravisit::Visitor>::visit_local
  43: rustc_hir::intravisit::walk_expr
  44: rustc_typeck::check::check::check_fn
  45: rustc_infer::infer::InferCtxtBuilder::enter
  46: rustc_typeck::check::typeck
  47: rustc_middle::ty::query::<impl rustc_query_system::query::config::QueryAccessors<rustc_middle::ty::context::TyCtxt> for rustc_middle::ty::query::queries::typeck>::compute
  48: rustc_query_system::dep_graph::graph::DepGraph<K>::with_task_impl
  49: rustc_data_structures::stack::ensure_sufficient_stack
  50: rustc_query_system::query::plumbing::get_query_impl
  51: rustc_query_system::query::plumbing::ensure_query_impl
  52: rustc_typeck::check::typeck_item_bodies
  53: 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
  54: rustc_query_system::dep_graph::graph::DepGraph<K>::with_task_impl
  55: rustc_data_structures::stack::ensure_sufficient_stack
  56: rustc_query_system::query::plumbing::get_query_impl
  57: rustc_typeck::check_crate
  58: rustc_interface::passes::analysis
  59: rustc_middle::ty::query::<impl rustc_query_system::query::config::QueryAccessors<rustc_middle::ty::context::TyCtxt> for rustc_middle::ty::query::queries::analysis>::compute
  60: rustc_query_system::dep_graph::graph::DepGraph<K>::with_task_impl
  61: rustc_data_structures::stack::ensure_sufficient_stack
  62: rustc_query_system::query::plumbing::get_query_impl
  63: rustc_interface::passes::QueryContext::enter
  64: rustc_interface::queries::<impl rustc_interface::interface::Compiler>::enter
  65: rustc_span::with_source_map
  66: scoped_tls::ScopedKey<T>::set
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

[jonas-schievink]

Duplicate of #43408