ICE: "type parameter out of range when substituting" when accessing non-existent field of struct

[danielbalke]

Code

fn main()
{
    let x = String::new();
    x.y;
}

This doesn't work for all structs, for example using Vec<u8> produces a normal compiler error.

Meta

rustc --version --verbose:

rustc 1.51.0-nightly (d4e3570db 2021-02-01)
binary: rustc
commit-hash: d4e3570db4c007089035b833cc20c7fc2f8cb32f
commit-date: 2021-02-01
host: x86_64-pc-windows-gnu
release: 1.51.0-nightly
LLVM version: 11.0.1

Couldn't reproduce this on 1.49.0 or 1.50.0-beta.8.

Error output

error: internal compiler error: compiler\rustc_middle\src\ty\subst.rs:529:17: type parameter `T/#0` (T/0) out of range when substituting, substs=[]

Backtrace

thread 'rustc' panicked at 'Box<Any>', /rustc/d4e3570db4c007089035b833cc20c7fc2f8cb32f\compiler\rustc_errors\src\lib.rs:904:9
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
   5: rustc_middle::util::bug::opt_span_bug_fmt
   6: rustc_middle::util::bug::span_bug_fmt
   7: <rustc_middle::ty::subst::SubstFolder as rustc_middle::ty::fold::TypeFolder>::fold_ty
   8: rustc_middle::ty::fold::TypeFoldable::fold_with
   9: rustc_middle::ty::structural_impls::<impl rustc_middle::ty::fold::TypeFoldable for &rustc_middle::ty::TyS>::super_fold_with
  10: rustc_middle::ty::FieldDef::ty
  11: rustc_typeck::check::expr::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::check_for_nested_field
  12: rustc_typeck::check::expr::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::check_for_nested_field
  13: rustc_typeck::check::expr::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::check_field
  14: rustc_typeck::check::expr::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::check_expr_kind
  15: rustc_typeck::check::expr::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::check_expr_with_expectation
  16: rustc_typeck::check::fn_ctxt::checks::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::check_stmt
  17: rustc_typeck::check::fn_ctxt::checks::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::check_block_with_expected
  18: rustc_typeck::check::expr::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::check_expr_kind
  19: rustc_typeck::check::expr::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::check_expr_with_expectation
  20: rustc_typeck::check::expr::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::check_return_expr
  21: rustc_typeck::check::check::check_fn
  22: rustc_infer::infer::InferCtxtBuilder::enter
  23: rustc_typeck::check::typeck
  24: rustc_middle::ty::query::<impl rustc_query_system::query::config::QueryAccessors<rustc_middle::ty::context::TyCtxt> for rustc_middle::ty::query::queries::typeck>::compute
  25: rustc_middle::dep_graph::<impl rustc_query_system::dep_graph::DepKind for rustc_middle::dep_graph::dep_node::DepKind>::with_deps
  26: rustc_query_system::dep_graph::graph::DepGraph<K>::with_task_impl
  27: rustc_middle::ty::query::plumbing::<impl rustc_query_system::query::QueryContext for rustc_middle::ty::context::TyCtxt>::start_query::{{closure}}::{{closure}}::{{closure}}
  28: rustc_query_system::query::plumbing::force_query_with_job
  29: rustc_query_system::query::plumbing::get_query_impl
  30: rustc_query_system::query::plumbing::ensure_query_impl
  31: rustc_typeck::check::typeck_item_bodies
  32: 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
  33: rustc_middle::dep_graph::<impl rustc_query_system::dep_graph::DepKind for rustc_middle::dep_graph::dep_node::DepKind>::with_deps
  34: rustc_query_system::dep_graph::graph::DepGraph<K>::with_task_impl
  35: rustc_data_structures::stack::ensure_sufficient_stack
  36: rustc_query_system::query::plumbing::force_query_with_job
  37: rustc_query_system::query::plumbing::get_query_impl
  38: rustc_typeck::check_crate
  39: rustc_interface::passes::analysis
  40: rustc_middle::ty::query::<impl rustc_query_system::query::config::QueryAccessors<rustc_middle::ty::context::TyCtxt> for rustc_middle::ty::query::queries::analysis>::compute
  41: rustc_middle::dep_graph::<impl rustc_query_system::dep_graph::DepKind for rustc_middle::dep_graph::dep_node::DepKind>::with_deps
  42: rustc_query_system::dep_graph::graph::DepGraph<K>::with_task_impl
  43: rustc_middle::ty::query::plumbing::<impl rustc_query_system::query::QueryContext for rustc_middle::ty::context::TyCtxt>::start_query::{{closure}}::{{closure}}::{{closure}}
  44: rustc_query_system::query::plumbing::force_query_with_job
  45: rustc_query_system::query::plumbing::get_query_impl
  46: rustc_interface::passes::QueryContext::enter
  47: rustc_interface::queries::<impl rustc_interface::interface::Compiler>::enter
  48: rustc_span::with_source_map
  49: rustc_interface::interface::create_compiler_and_run

[matthiaskrgr]

duplicate of #81627

[camelid]

A somewhat more realistic example:

fn main() {
    let x = String::new();
    let y = x.char; // typo: they meant `x.chars()`
}

On stable:

error[E0609]: no field `char` on type `String`
 --> src/main.rs:3:15
  |
3 |     let y = x.char;
  |               ^^^^ unknown field

error: aborting due to previous error

On nightly:

error: internal compiler error: compiler/rustc_middle/src/ty/subst.rs:529:17: type parameter `T/#0` (T/0) out of range when substituting, substs=[]

thread 'rustc' panicked at 'Box<Any>', /rustc/368275062fb655c1f36e0398f88b15379a1f3c93/compiler/rustc_errors/src/lib.rs:904:9
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 1.51.0-nightly (368275062 2021-02-02) running on x86_64-unknown-linux-gnu

note: compiler flags: -C embed-bitcode=no -C codegen-units=1 -C debuginfo=2 --crate-type bin

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

query stack during panic:
#0 [typeck] type-checking `main`
#1 [typeck_item_bodies] type-checking all item bodies
end of query stack
error: aborting due to previous error

error: could not compile `playground`

[camelid]

Assigning P-high and removing I-prioritize as discussed in the prioritization working group.