ICE: panicked at 'RefCell<T> already borrowed', /Users/carllerche/Code/oss/rust/src/libcore/cell.rs:317

[carllerche]

rustc version: rustc 0.13.0-dev (60a669a 2014-11-06 14:06:59 +0000)

Repro:

I have not yet been able to isolate to a small case, but clone the following repo on the "ice-repo2" branch (sorry, typos) and run cargo test, it should ICE

https://github.com/carllerche/astaire/tree/ice-repo2

Backtrace

error: internal compiler error: unexpected panic
note: the compiler unexpectedly panicked. this is a bug.
note: we would appreciate a bug report: http://doc.rust-lang.org/complement-bugreport.html
note: run with `RUST_BACKTRACE=1` for a backtrace
task 'rustc' panicked at 'RefCell<T> already borrowed', /Users/carllerche/Code/oss/rust/src/libcore/cell.rs:317

stack backtrace:
   1:        0x10a9f8b3f - rt::backtrace::imp::write::h2ff90a76b93803d4wdq
   2:        0x10a9fbcc7 - failure::on_fail::hb9446c51627aa852luq
   3:        0x10ac54855 - unwind::begin_unwind_inner::hb06e7f4e8a4318c3NJd
   4:        0x10ac54518 - unwind::begin_unwind_fmt::h06689276fe1886c0fHd
   5:        0x10ac54272 - rust_begin_unwind
   6:        0x10aca40bc - panicking::panic_fmt::hfaf6da97a3eeb8f2y7j
   7:        0x10ac9ab0f - panicking::panic::h02d6408bd2255aa5C4j
   8:        0x10782684b - middle::astencode::decode_side_tables::closure.114678
   9:        0x10a00e7b6 - reader::docs::h468ef2f5473ec55euTa
  10:        0x1076cac6d - middle::astencode::decode_inlined_item::hd744c6fdd78d459asCd
  11:        0x1078e3084 - middle::const_eval::lookup_variant_by_id::closure.118471
  12:        0x107fcecf3 - middle::trans::inline::instantiate_inline::closure.123290
  13:        0x107eba57b - metadata::decoder::maybe_get_item_ast::h9e4d672ed43e14e2bvx
  14:        0x1079ed00f - middle::trans::inline::instantiate_inline::h6de6d9c3889784346M0
  15:        0x107a25943 - middle::trans::callee::trans_fn_ref_with_substs::hdb01074bff7fc08f1c4
  16:        0x107a234e8 - middle::trans::callee::trans_fn_ref::h1a91258cddd65598R03
  17:        0x107a0887d - middle::trans::meth::trans_method_callee::hc75c8689a4447f7au8m
  18:        0x107a2b8cb - middle::trans::callee::trans_method_call::closure.124024
  19:        0x107a06be5 - middle::trans::callee::trans_call_inner::h9815d9afb9e1ec44Ly4
  20:        0x107a2b6fd - middle::trans::callee::trans_method_call::he027fede3ae25373du4
  21:        0x107a390fd - middle::trans::expr::trans_rvalue_dps_unadjusted::h7dbd4d63b7e1f10aEH6
  22:        0x107a37e61 - middle::trans::expr::trans_unadjusted::ha98f989fff991c48B35
  23:        0x107a009dd - middle::trans::expr::trans::he231f09d11f1a48dxm5
  24:        0x1079fe77d - middle::trans::controlflow::trans_stmt_semi::h020e65f758f11838ry1
  25:        0x1079fde80 - middle::trans::controlflow::trans_stmt::hc03c7e6720b2276beu1
  26:        0x1079ff6b8 - middle::trans::controlflow::trans_block::h3b3f26872c4554fbkz1
  27:        0x107a39624 - middle::trans::expr::trans_rvalue_dps_unadjusted::h7dbd4d63b7e1f10aEH6
  28:        0x1079ff469 - middle::trans::expr::trans_into::h00984fb0dd3ef008Di5
  29:        0x1079ff7be - middle::trans::controlflow::trans_block::h3b3f26872c4554fbkz1
  30:        0x107a9f948 - middle::trans::base::trans_closure::h638c8183c6a8c3b1XIh
  31:        0x107a4da90 - middle::trans::closure::trans_unboxed_closure::hb43598d7c59a231bD4l
  32:        0x107a395f2 - middle::trans::expr::trans_rvalue_dps_unadjusted::h7dbd4d63b7e1f10aEH6
  33:        0x107a37e61 - middle::trans::expr::trans_unadjusted::ha98f989fff991c48B35
  34:        0x107a009dd - middle::trans::expr::trans::he231f09d11f1a48dxm5
  35:        0x107a315d0 - middle::trans::callee::trans_args::h26b99096d88adfffWT4
  36:        0x107a07cd0 - middle::trans::callee::trans_call_inner::h9815d9afb9e1ec44Ly4
  37:        0x107a2b6fd - middle::trans::callee::trans_method_call::he027fede3ae25373du4
  38:        0x107a390fd - middle::trans::expr::trans_rvalue_dps_unadjusted::h7dbd4d63b7e1f10aEH6
  39:        0x1079ff469 - middle::trans::expr::trans_into::h00984fb0dd3ef008Di5
  40:        0x107ac717e - middle::trans::_match::store_local::closure.127810
  41:        0x107ac7030 - middle::trans::_match::mk_binding_alloca::h2042705593528179270
  42:        0x107a9735f - middle::trans::_match::store_local::ha914c957ec74fc25cdl
  43:        0x1079fea44 - middle::trans::base::init_local::h9ae72d5affea250csOg
  44:        0x1079fdeb1 - middle::trans::controlflow::trans_stmt::hc03c7e6720b2276beu1
  45:        0x1079ff6b8 - middle::trans::controlflow::trans_block::h3b3f26872c4554fbkz1
  46:        0x107a9f948 - middle::trans::base::trans_closure::h638c8183c6a8c3b1XIh
  47:        0x1079f2f9c - middle::trans::base::trans_fn::ha597ae815301c37bSUh
  48:        0x1079f06a1 - middle::trans::base::trans_item::h7ef8b7e6130a9cb16di
  49:        0x1079f0bd8 - middle::trans::base::trans_item::h7ef8b7e6130a9cb16di
  50:        0x107aa89f9 - middle::trans::base::trans_crate::hdeb74411a2b08c317bj
  51:        0x107ef3445 - driver::driver::phase_4_translate_to_llvm::h75d3ab0b8caab322KwC
  52:        0x107eebcc1 - driver::driver::compile_input::h6d8884a3959ef920E3B
  53:        0x107f6a3ad - driver::run_compiler::h31af41afacc0fe35VTF
  54:        0x107f6883e - driver::run::closure.147439
  55:        0x1076b96ab - task::TaskBuilder<S>::try_future::closure.104811
  56:        0x1076b95a3 - task::TaskBuilder<S>::spawn_internal::closure.104782
  57:        0x10a089d7d - task::NativeSpawner.Spawner::spawn::closure.8538
  58:        0x10acb39cc - rust_try_inner
  59:        0x10acb39b6 - rust_try
  60:        0x10ac52057 - unwind::try::ha62186b67ab65c30vyd
  61:        0x10ac51eec - task::Task::run::hdb6100930f630459iKc
  62:        0x10a089ba3 - task::NativeSpawner.Spawner::spawn::closure.8475
  63:        0x10ac53717 - thread::thread_start::h7c5f82d4ec72fc8cx5c
  64:     0x7fff8e631772 - _pthread_start

[nikomatsakis]

cc me -- note this a refcell failure. first step is probably to figure out which hashmap is being written into, then figure out who is iterating over it etc

[carllerche]

I enabled debug logs, this is what I got when filtering to middle::astencode

DEBUG:rustc::middle::astencode: >< Side table doc loaded
DEBUG:rustc::middle::astencode: >> Side table document with tag 0x49 found for id 15510 (orig 2435)
DEBUG:rustc::middle::astencode: >< Side table doc loaded
DEBUG:rustc::middle::astencode: >> Side table document with tag 0x56 found for id 15510 (orig 2435)
DEBUG:rustc::middle::astencode: >< Side table doc loaded
DEBUG:rustc::middle::astencode: >> Side table document with tag 0x54 found for id 15510 (orig 2435)
DEBUG:rustc::middle::astencode: convert_def_id(source=NominalType, did=DefId { krate: 0, node: 2337 })=DefId { krate: 13, node: 2337 }
DEBUG:rustc::middle::astencode: convert_def_id(source=TypeParameter, did=DefId { krate: 0, node: 2451 })=DefId { krate: 0, node: 15526 }
error: internal compiler error: unexpected panic

[carllerche]

The ICE is happening somewhere here:

https://github.com/rust-lang/rust/blob/master/src/librustc/middle/astencode.rs#L1881-L1889

[bkoropoff]

I think I see the conflicting borrow, it's really silly. Coming up with a reduced test case will probably be harder than fixing it.