ICE: index out of bounds

[ubsan]

   Compiling pinkc v0.1.0 (file:///Users/ubsan/src/workspace/rust/pink)
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
thread 'rustc' panicked at 'index out of bounds: the len is 15 but the index is 17', ../src/libcollections/vec.rs:1179
stack backtrace:
   1:        0x10c8de518 - sys::backtrace::tracing::imp::write::hd929d4e27d7189acGvv
   2:        0x10c8e7979 - panicking::default_handler::_$u7b$$u7b$closure$u7d$$u7d$::closure.44460
   3:        0x10c8e7497 - panicking::default_handler::h323e24f308b387b4U6z
   4:        0x10c8ac576 - sys_common::unwind::begin_unwind_inner::h3bfd460d0d96a1d2suu
   5:        0x10c8ad06e - sys_common::unwind::begin_unwind_fmt::he7cb7c739b04da34ytu
   6:        0x10c8dbdd7 - rust_begin_unwind
   7:        0x10c920c20 - panicking::panic_fmt::h8917bddd72ecec2e7mM
   8:        0x10c920e30 - panicking::panic_bounds_check::h93a3522a76b40c57dmM
   9:        0x10931b9e0 - middle::infer::InferCtxt<'a, 'tcx>::shallow_resolve::hd3812351ab4bfbe02jE
  10:        0x1093f59eb - middle::traits::fulfill::process_predicate::h825292a03af2b183FnU
  11:        0x1093f47d3 - obligation_forest::ObligationForest<O, T>::process_obligations::h12431531188540138369
  12:        0x1093efebc - middle::traits::fulfill::FulfillmentContext<'tcx>::select_where_possible::hdd4f708f72da3cd5KfU
  13:        0x1086a6694 - check::FnCtxt<'a, 'tcx>::select_obligations_where_possible::hb66eedf8825bdea3VIq
  14:        0x1086ba14c - check::FnCtxt<'a, 'tcx>::resolve_type_vars_if_possible::h71a8db5364f9d703jPp
  15:        0x1086d052a - check::demand::coerce::h246de84530e7134eWCf
  16:        0x1086cdf30 - check::check_argument_types::h1700393ff797f022T8q
  17:        0x1087483cd - check::callee::confirm_builtin_call::hc9f0878ba333a19fNkm
  18:        0x1086e6cb6 - check::callee::check_call::hd35b84bf2d6b58f7Sbm
  19:        0x1086d178a - check::check_expr_with_expectation_and_lvalue_pref::he337646483dc09cd8Hr
  20:        0x1087014bd - check::check_decl_initializer::h4ab29c1087c52ea8RUs
  21:        0x108701590 - check::check_decl_local::he9d8dbcafd84118f3Vs
  22:        0x108701825 - check::check_stmt::h9f0320269d23967cNXs
  23:        0x1086acd1a - check::check_block_with_expected::h8b413e75ec65de5eA1s
  24:        0x1086a3688 - check::check_fn::h3fd8a6bec4190345XWo
  25:        0x1086a0d6f - check::check_bare_fn::h245a5fd39660f1ecqMo
  26:        0x1086b1daa - check::check_method_body::he0085f6ddf3109464mp
  27:        0x10869bda9 - check::check_item_body::hb2b3af44521a0307Xbp
  28:        0x108694928 - check::check_item_bodies::h756f6be30ffaa021dKo
  29:        0x10868c405 - check_crate::h288f4573dd9eece3IGC
  30:        0x1084135b1 - driver::phase_3_run_analysis_passes::_$u7b$$u7b$closure$u7d$$u7d$::closure.29921
  31:        0x108411be9 - middle::ty::context::TyCtxt<'tcx>::create_and_enter::h14982197898393062399
  32:        0x10840e5ad - driver::phase_3_run_analysis_passes::h10469946015979689481
  33:        0x1083e178e - driver::compile_input::hfe917584d5fff413Pca
  34:        0x1083cedb7 - run_compiler::h01319ef2912a48felQc
  35:        0x1083cc462 - sys_common::unwind::try::try_fn::h5286116259890539823
  36:        0x10c8dbd6b - __rust_try
  37:        0x10c8dbcf3 - sys_common::unwind::inner_try::hab8f8e132b20c6f3uru
  38:        0x1083cccf9 - boxed::F.FnBox<A>::call_box::h2979158220400435295
  39:        0x10c8e67ec - sys::thread::Thread::new::thread_start::h78b200bc5c33e143Rkz
  40:     0x7fff89c0bc12 - _pthread_body
  41:     0x7fff89c0bb8f - _pthread_start

Could not compile `pinkc`.

To learn more, run the command again with --verbose.

compiling this crate: https://github.com/ubsan/pink/tree/c625d31661e3381f5173d2789ff4c8d809210d2f

[ubsan]

The issue is on src/ast/expr.rs:172. I make a new Vec, instead of a new HashMap.

[ubsan]

Ping @nikomatsakis, because it seems to be a bug in the Forest of Obligation

[nikomatsakis]

triage: P-medium

[allan-simon]

an other code that seems to trigger the same ICE http://is.gd/bZ6QYu