span_bug inside of DumpVisitor

[sfackler]

The the problematic crate doesn't compile, but there's no bug reported by a normal rustc invocation.

thread 'rustc' panicked at 'Box<Any>', librustc_errors/lib.rs:482:9
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
   7: rustc_errors::Handler::span_bug
   8: rustc::session::opt_span_bug_fmt::{{closure}}
   9: rustc::ty::context::tls::with_opt::{{closure}}
  10: <std::thread::local::LocalKey<T>>::try_with
  11: <std::thread::local::LocalKey<T>>::with
  12: rustc::ty::context::tls::with
  13: rustc::ty::context::tls::with_opt
  14: rustc::session::opt_span_bug_fmt
  15: rustc::session::span_bug_fmt
  16: <rustc_save_analysis::dump_visitor::DumpVisitor<'l, 'tcx, 'll, O> as syntax::visit::Visitor<'l>>::visit_expr
  17: <rustc_save_analysis::dump_visitor::DumpVisitor<'l, 'tcx, 'll, O> as syntax::visit::Visitor<'l>>::visit_expr
  18: <rustc_save_analysis::dump_visitor::DumpVisitor<'l, 'tcx, 'll, O>>::process_method_call
  19: syntax::visit::walk_expr
  20: <rustc_save_analysis::dump_visitor::DumpVisitor<'l, 'tcx, 'll, O>>::process_method
  21: <rustc_save_analysis::dump_visitor::DumpVisitor<'l, 'tcx, 'll, O>>::process_impl_item
  22: <rustc_save_analysis::dump_visitor::DumpVisitor<'l, 'tcx, 'll, O> as syntax::visit::Visitor<'l>>::visit_item
  23: <rustc_save_analysis::dump_visitor::DumpVisitor<'l, 'tcx, 'll, O> as syntax::visit::Visitor<'l>>::visit_item
  24: <rustc_save_analysis::dump_visitor::DumpVisitor<'l, 'tcx, 'll, O> as syntax::visit::Visitor<'l>>::visit_mod
  25: <rustc_save_analysis::CallbackHandler<'b> as rustc_save_analysis::SaveHandler>::save
  26: <rls::build::rustc::RlsRustcCalls as rustc_driver::CompilerCalls<'a>>::build_controller::{{closure}}
  27: rustc_driver::driver::compile_input::{{closure}}
  28: rustc::ty::context::TyCtxt::create_and_enter
  29: rustc_driver::driver::compile_input
  30: rustc_driver::run_compiler

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 1.26.0-nightly (c9334404f 2018-03-05) running on x86_64-apple-darwin`

[kdy1]

I somehow hit this with cargo check on ubuntu but not on windows. CARGO_INREMENTAL=0 fixed it.

[nrc]

Something must be inlined because there is no span_bug! in visit_expr. Do you have a minimal code example to repro this?

[sfackler]

I don't unfortunately.

[nrc]

Going to close this since it's not actionable, but please open a new issue if there are more details.