ICE with wrong method receiver as second parameter

[jfrimmel]

The following code (on compiler explorer) leads to an ICE:

struct Foo;
impl Foo {
    // mind the missing `>` of the receiver
    pub fn foo(_: i32, self: Box<Self) {}
}

Broken since 1.32.0 up to the current nightly, earlier versions are not affected.

Backtrace of the nightly build

error: internal compiler error: Error constructed but not emitted

thread 'rustc' panicked at 'explicit panic', src/librustc_errors/diagnostic_builder.rs:387:13
stack backtrace:
   0: backtrace::backtrace::libunwind::trace
             at /cargo/registry/src/github.com-1ecc6299db9ec823/backtrace-0.3.29/src/backtrace/libunwind.rs:88
   1: backtrace::backtrace::trace_unsynchronized
             at /cargo/registry/src/github.com-1ecc6299db9ec823/backtrace-0.3.29/src/backtrace/mod.rs:66
   2: std::sys_common::backtrace::_print
             at src/libstd/sys_common/backtrace.rs:47
   3: std::sys_common::backtrace::print
             at src/libstd/sys_common/backtrace.rs:36
   4: std::panicking::default_hook::{{closure}}
             at src/libstd/panicking.rs:200
   5: std::panicking::default_hook
             at src/libstd/panicking.rs:214
   6: rustc::util::common::panic_hook
   7: std::panicking::rust_panic_with_hook
             at src/libstd/panicking.rs:481
   8: std::panicking::begin_panic
   9: <rustc_errors::diagnostic_builder::DiagnosticBuilder as core::ops::drop::Drop>::drop
  10: syntax::parse::parser::Parser::parse_arg_general
  11: syntax::parse::parser::Parser::parse_seq_to_before_tokens
  12: syntax::parse::parser::Parser::parse_impl_method
  13: syntax::parse::parser::Parser::parse_impl_item
  14: syntax::parse::parser::Parser::parse_item_implementation
  15: syntax::parse::parser::Parser::parse_item_
  16: syntax::parse::parser::Parser::parse_item
  17: syntax::parse::parser::Parser::parse_mod_items
  18: syntax::parse::parser::Parser::parse_crate_mod
  19: syntax::parse::parse_crate_from_file
  20: rustc_interface::passes::parse::{{closure}}
  21: rustc::util::common::time
  22: rustc_interface::passes::parse
  23: rustc_interface::queries::Query<T>::compute
  24: rustc_interface::queries::<impl rustc_interface::interface::Compiler>::parse
  25: rustc_interface::interface::run_compiler_in_existing_thread_pool
  26: std::thread::local::LocalKey<T>::with
  27: scoped_tls::ScopedKey<T>::set
  28: syntax::with_globals
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.
query stack during panic:
end of query stack
error: aborting due to previous error


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/blob/master/CONTRIBUTING.md#bug-reports

note: rustc 1.38.0-nightly (71f9384e3 2019-07-12) running on x86_64-unknown-linux-gnu

note: compiler flags: -C debuginfo=2 -C incremental --crate-type bin

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

[goodmanjonathan]

@rustbot claim

[estebank]

@goodmanjonathan you will need to change the line

rust/src/libsyntax/parse/parser.rs

Line 1501 in cc481a4

if let Ok(Some(mut arg)) = self.parse_self_arg() {

to bubble the parse_self_arg error up:

if let Some(mut arg) = self.parse_self_arg()? {

Once you've done that code change create a new test file in src/test/ui/parser/issue-62660.rs.