ICE on nightly 1.56.0 (2021-07-29) when missing semicolon or function body in impl block

[dataphract]

Playground with repro here. Not present in latest stable or beta.

Code

struct Foo {}

impl Foo {
    pub fn bar()
}

fn main() {}

Meta

rustc --version --verbose:

rustc 1.56.0-nightly (492723897 2021-07-29)
binary: rustc
commit-hash: 492723897e9b4db6701b3a75b72618d08a7d5319
commit-date: 2021-07-29
host: x86_64-unknown-linux-gnu
release: 1.56.0-nightly
LLVM version: 12.0.1

Error output

   Compiling ice v0.1.0 ([redacted])
error: expected `;`, found `}`
 --> src/main.rs:4:17
  |
4 |     pub fn bar()
  |                 ^ help: add `;` here
5 | }
  | - unexpected token

thread 'rustc' panicked at 'internal error: entered unreachable code', compiler/rustc_parse/src/parser/item.rs:1723:17
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 1.56.0-nightly (492723897 2021-07-29) 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

query stack during panic:
end of query stack
error: could not compile `ice` due to previous error

Backtrace

stack backtrace:
   0: rust_begin_unwind
             at /rustc/492723897e9b4db6701b3a75b72618d08a7d5319/library/std/src/panicking.rs:516:5
   1: core::panicking::panic_fmt
             at /rustc/492723897e9b4db6701b3a75b72618d08a7d5319/library/core/src/panicking.rs:93:14
   2: core::panicking::panic
             at /rustc/492723897e9b4db6701b3a75b72618d08a7d5319/library/core/src/panicking.rs:50:5
   3: rustc_parse::parser::item::<impl rustc_parse::parser::Parser>::parse_fn
   4: rustc_parse::parser::item::<impl rustc_parse::parser::Parser>::parse_item_kind
   5: rustc_parse::parser::item::<impl rustc_parse::parser::Parser>::parse_item_common
   6: rustc_parse::parser::item::<impl rustc_parse::parser::Parser>::parse_assoc_item
   7: rustc_parse::parser::item::<impl rustc_parse::parser::Parser>::parse_item_impl
   8: rustc_parse::parser::item::<impl rustc_parse::parser::Parser>::parse_item_kind
   9: rustc_parse::parser::item::<impl rustc_parse::parser::Parser>::parse_item_common
  10: rustc_parse::parser::item::<impl rustc_parse::parser::Parser>::parse_mod
  11: rustc_parse::parse_crate_from_file
  12: rustc_session::utils::<impl rustc_session::session::Session>::time
  13: rustc_interface::passes::parse
  14: rustc_interface::queries::Queries::parse
  15: rustc_interface::queries::<impl rustc_interface::interface::Compiler>::enter
  16: rustc_span::with_source_map
  17: rustc_interface::interface::create_compiler_and_run
  18: scoped_tls::ScopedKey<T>::set

[JohnTitor]

Regressed since #87480, I think #87436 is the cause.

[apiraino]

right, this issue can be probably be closed as duplicate of #87647

[steffahn]

@apiraino

I would suggest not closing this issue as long as #87647 literally starts with the statement

This also ICEs, but that's a separate issue: #87635

referencing back to this issue. Furthermore, this issue is older, so if they’d be duplicates, #87647 would be closed.