Typecheck panics feat. a closure and a struct with a private field and a public method

[skatbude]

Code

mod m {
  pub struct S { foo: i32 }
  impl S {
    pub fn foo(&self) -> i32 { 42 }
  }
}

fn bar(s: &m::S) {
  || s.foo() + s.foo;
}

fn main() {}

Meta

rustc --version --verbose:

rustc 1.56.0 (09c42c458 2021-10-18)
binary: rustc
commit-hash: 09c42c45858d5f3aedfa670698275303a3d19afa
commit-date: 2021-10-18
host: x86_64-unknown-linux-gnu
release: 1.56.0
LLVM version: 13.0.0

Also checked beta and nightly at https://play.rust-lang.org:

rustc 1.57.0-beta.2 (7e4c9eebd 2021-10-22) running on x86_64-unknown-linux-gnu
rustc 1.58.0-nightly (ff0e14829 2021-10-31) running on x86_64-unknown-linux-gnu

Error output

error[E0616]: field `foo` of struct `S` is private
 --> bug.rs:9:18
  |
9 |   || s.foo() + s.foo;
  |                  ^^^ private field
  |
help: a method `foo` also exists, call it with parentheses
  |
9 |   || s.foo() + s.foo();
  |                     ++

error: internal compiler error: compiler/rustc_typeck/src/check/upvar.rs:641:30: ProjectionKinds Deref and Field were mismatched: (Field(0, 0), Deref)

thread 'rustc' panicked at 'Box<dyn Any>', compiler/rustc_errors/src/lib.rs:1147:9
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 1.56.0 (09c42c458 2021-10-18) running on x86_64-unknown-linux-gnu

query stack during panic:
#0 [typeck] type-checking `bar`
#1 [typeck] type-checking `bar::{closure#0}`
end of query stack
error: aborting due to 2 previous errors

For more information about this error, try `rustc --explain E0616`.

Backtrace

thread 'rustc' panicked at 'Box<dyn Any>', compiler/rustc_errors/src/lib.rs:1147:9
stack backtrace:
   0: std::panicking::begin_panic
   1: std::panic::panic_any
   2: rustc_errors::HandlerInner::bug
   3: rustc_errors::Handler::bug
   4: rustc_middle::ty::context::tls::with_opt
   5: rustc_middle::util::bug::opt_span_bug_fmt
   6: rustc_middle::util::bug::bug_fmt
   7: alloc::slice::<impl [T]>::sort_by::{{closure}}
   8: alloc::slice::merge_sort
   9: rustc_typeck::check::upvar::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::compute_min_captures
  10: rustc_typeck::check::upvar::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::analyze_closure
  11: <rustc_typeck::check::upvar::InferBorrowKindVisitor as rustc_hir::intravisit::Visitor>::visit_expr
  12: rustc_hir::intravisit::walk_expr
  13: <rustc_typeck::check::upvar::InferBorrowKindVisitor as rustc_hir::intravisit::Visitor>::visit_expr
  14: rustc_typeck::check::upvar::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::closure_analyze
  15: rustc_infer::infer::InferCtxtBuilder::enter
  16: rustc_typeck::check::typeck
  17: rustc_query_system::query::plumbing::get_query_impl
  18: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::typeck
  19: rustc_typeck::check::typeck
  20: rustc_query_system::query::plumbing::get_query_impl
  21: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::typeck
  22: rustc_middle::ty::<impl rustc_middle::ty::context::TyCtxt>::par_body_owners
  23: rustc_typeck::check::typeck_item_bodies
  24: rustc_query_system::query::plumbing::get_query_impl
  25: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::typeck_item_bodies
  26: rustc_session::utils::<impl rustc_session::session::Session>::time
  27: rustc_typeck::check_crate
  28: rustc_interface::passes::analysis
  29: rustc_query_system::query::plumbing::get_query_impl
  30: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::analysis
  31: rustc_interface::passes::QueryContext::enter
  32: rustc_interface::queries::<impl rustc_interface::interface::Compiler>::enter
  33: rustc_span::with_source_map
  34: scoped_tls::ScopedKey<T>::set
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

[SNCPlay42]

This does not panic on 1.55. Also, it panics on 1.56 regardless of which edition is used.

@rustbot label regression-from-stable-to-stable

[SNCPlay42]

searched nightlies: from nightly-2021-07-23 to nightly-2021-11-02
regressed nightly: nightly-2021-09-26
searched commit range: 7342213...addb4da
regressed commit: 6867dd2

bisected with cargo-bisect-rustc v0.6.1

Host triple: x86_64-unknown-linux-gnu
Reproduce with:

cargo bisect-rustc --preserve --start=2021-07-23 --regress=ice -- check 

From this rollup, #89208 looks relevant, and it landed in 1.56 via backport.

[nbdd0121]

@rustbot claim

[camelid]

Assigning priority as discussed in the prioritization working group.