'called Option::unwrap() on a None value' in SaveContext::get_expr_data

[sfackler]

note: rustc 1.26.0-nightly (259e4a678 2018-03-04) running on x86_64-apple-darwin

thread 'rustc' panicked at 'called `Option::unwrap()` on a `None` value', libcore/option.rs:335:21
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.
stack backtrace:
   0: std::sys::unix::backtrace::tracing::imp::unwind_backtrace
   1: std::sys_common::backtrace::_print
   2: std::panicking::default_hook::{{closure}}
   3: std::panicking::default_hook
   4: core::ops::function::Fn::call
   5: std::panicking::rust_panic_with_hook
   6: std::panicking::begin_panic_fmt
   7: rust_begin_unwind
   8: core::panicking::panic_fmt
   9: core::panicking::panic
  10: rustc_save_analysis::SaveContext::get_expr_data
  11: <rustc_save_analysis::dump_visitor::DumpVisitor<'l, 'tcx, 'll, O> as syntax::visit::Visitor<'l>>::visit_expr
  12: syntax::visit::walk_expr
  13: syntax::visit::walk_expr
  14: <rustc_save_analysis::dump_visitor::DumpVisitor<'l, 'tcx, 'll, O>>::nest_tables
  15: <rustc_save_analysis::dump_visitor::DumpVisitor<'l, 'tcx, 'll, O> as syntax::visit::Visitor<'l>>::visit_item
  16: <rustc_save_analysis::dump_visitor::DumpVisitor<'l, 'tcx, 'll, O> as syntax::visit::Visitor<'l>>::visit_item
  17: <rustc_save_analysis::dump_visitor::DumpVisitor<'l, 'tcx, 'll, O> as syntax::visit::Visitor<'l>>::visit_mod
  18: <rustc_save_analysis::CallbackHandler<'b> as rustc_save_analysis::SaveHandler>::save
  19: <rls::build::rustc::RlsRustcCalls as rustc_driver::CompilerCalls<'a>>::build_controller::{{closure}}
  20: rustc_driver::driver::compile_input::{{closure}}
  21: rustc::ty::context::TyCtxt::create_and_enter
  22: rustc_driver::driver::compile_input
  23: rustc_driver::run_compiler

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

[nrc]

Do you have any idea what code caused this to happen? Ideally knowing what the expression looked like which we tried to get info for.

[sfackler]

Not really unfortunately. #755 seems like it's somewhat related. I copied the build errors at the time of the crashes in there.