ICE in span_to_lines, 'capacity_overflow'

[swgillespie]

Building https://github.com/swgillespie/gccjit.rs/tree/rustc-ice causes this for me.

$ RUST_BACKTRACE=1 cargo build
   Compiling gccjit v0.0.1 (file:///home/sean/Documents/workspace/rust/gccjit-rs/examples/factorial)
/home/sean/Documents/workspace/rust/gccjit-rs/src/rvalue.rs:76:25: 66:79 error: mismatched types:
 expected `gccjit_sys::gcc_jit_binary_op`,
    found `i32`
(expected enum `gccjit_sys::gcc_jit_binary_op`,
    found i32) [E0308]
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: run with `RUST_BACKTRACE=1` for a backtrace
thread 'rustc' panicked at 'capacity overflow', /home/rustbuild/src/rust-buildbot/slave/nightly-dist-rustc-linux/build/src/libcore/option.rs:330

stack backtrace:
   1:     0x7f81efa5af39 - sys::backtrace::write::h7638fca3b07af337rVs
   2:     0x7f81efa62bb6 - panicking::on_panic::h64a1f0366c6b8a23mkx
   3:     0x7f81efa1f912 - rt::unwind::begin_unwind_inner::hcaa5609c9e3078adwZw
   4:     0x7f81efa1fb97 - rt::unwind::begin_unwind_fmt::h1d03ac96c877ea14CYw
   5:     0x7f81efa62796 - rust_begin_unwind
   6:     0x7f81efab4404 - panicking::panic_fmt::hc7c67cbed9e89d8ddTC
   7:     0x7f81ecdb49af - codemap::CodeMap::span_to_lines::hf8f1a35dc982b5e4ahA
   8:     0x7f81ecdf97d7 - diagnostic::emit::h7379a6cfef339f7a7TB
   9:     0x7f81ecdf7624 - diagnostic::EmitterWriter.Emitter::emit::h7d3188d973919325PQB
  10:     0x7f81ecdf5b7b - diagnostic::SpanHandler::span_err_with_code::h4b3154250eb71080pnB
  11:     0x7f81ed89c995 - session::Session::span_err_with_code::h81e7cead23b6ffdb8sp
  12:     0x7f81eda941b9 - middle::infer::error_reporting::InferCtxt<'a, 'tcx>.ErrorReporting<'tcx>::report_type_error::h90db3e78d8bb7e886nq
  13:     0x7f81eda95a26 - middle::infer::error_reporting::InferCtxt<'a, 'tcx>.ErrorReporting<'tcx>::report_and_explain_type_error::h8ba32c89aedde88cUpq
  14:     0x7f81edaee6f3 - middle::infer::InferCtxt<'a, 'tcx>::report_mismatched_types::h2fd9974dc99bf601BRy
  15:     0x7f81ef1aaca6 - check::demand::coerce::h782cae65c398feeaf6f
  16:     0x7f81ef21c17a - check::check_expr_with_unifier::h8593953848767686611
  17:     0x7f81ef1f9518 - check::check_argument_types::hafac6b2d63ad7094Z5p
  18:     0x7f81ef1f6aab - check::callee::confirm_builtin_call::he646cc87182b37cagrm
  19:     0x7f81ef1f53b5 - check::callee::check_call::h4b66c292a82ccddaYhm
  20:     0x7f81ef23fd2b - check::check_expr_with_unifier::h3006517761441790576
  21:     0x7f81ef26568b - check::check_decl_local::hefbaa8208ecc67818bs
  22:     0x7f81ef2103a1 - check::check_block_with_expected::h24feb1297ec9164beis
  23:     0x7f81ef1f3116 - check::check_fn::h1f3e323a3375062bN4n
  24:     0x7f81ef20bd87 - check::check_bare_fn::h3d6f361f6b701b01mUn
  25:     0x7f81ef2148bc - check::check_method_body::h1fba553d1633acb4Rvo
  26:     0x7f81ef209d48 - check::CheckItemBodiesVisitor<'a, 'tcx>.Visitor<'tcx>::visit_item::h65cdf079010f6a6apRn
  27:     0x7f81ef20a0cf - check::CheckItemBodiesVisitor<'a, 'tcx>.Visitor<'tcx>::visit_item::h65cdf079010f6a6apRn
  28:     0x7f81ef2cd0da - check_crate::closure.38363
  29:     0x7f81ef2c8470 - check_crate::h6dcd7dd401f4f117pCC
  30:     0x7f81effc1ae8 - driver::phase_3_run_analysis_passes::h3806bf444cc15f20tGa
  31:     0x7f81effa2e70 - driver::compile_input::h4642f691e22278cbQba
  32:     0x7f81f0063331 - run_compiler::he528ba831532b90aF4b
  33:     0x7f81f0060f82 - boxed::F.FnBox<A>::call_box::h13568337174014462877
  34:     0x7f81f00604b9 - rt::unwind::try::try_fn::h15381261312250239500
  35:     0x7f81efada528 - rust_try_inner
  36:     0x7f81efada515 - rust_try
  37:     0x7f81f0060768 - boxed::F.FnBox<A>::call_box::h6713016946069099629
  38:     0x7f81efa61ac1 - sys::thread::create::thread_start::hbe89fbdfc755452dxjw
  39:     0x7f81e9b09f6d - start_thread
  40:     0x7f81ef6959cc - clone
  41:                0x0 - <unknown>