Panic compiling `multiplex-rs`

[eira-fransham]

Index out of bounds ICE while compiling multiplex-rs. I don't know enough about why this could happen to produce a minimal reproduction. Backtrace:

thread 'rustc' panicked at 'index out of bounds: the len is 136 but the index is 146', /checkout/src/liballoc/vec.rs:1548:10
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
             at /checkout/src/libstd/sys/unix/backtrace/tracing/gcc_s.rs:49
   1: std::sys_common::backtrace::print
             at /checkout/src/libstd/sys_common/backtrace.rs:68
             at /checkout/src/libstd/sys_common/backtrace.rs:57
   2: std::panicking::default_hook::{{closure}}
             at /checkout/src/libstd/panicking.rs:381
   3: std::panicking::default_hook
             at /checkout/src/libstd/panicking.rs:391
   4: std::panicking::rust_panic_with_hook
             at /checkout/src/libstd/panicking.rs:577
   5: std::panicking::begin_panic
             at /checkout/src/libstd/panicking.rs:538
   6: std::panicking::begin_panic_fmt
             at /checkout/src/libstd/panicking.rs:522
   7: rust_begin_unwind
             at /checkout/src/libstd/panicking.rs:498
   8: core::panicking::panic_fmt
             at /checkout/src/libcore/panicking.rs:71
   9: core::panicking::panic_bounds_check
             at /checkout/src/libcore/panicking.rs:58
  10: <rustc::ty::maps::on_disk_cache::CacheDecoder<'a, 'tcx, 'x> as serialize::serialize::SpecializedDecoder<syntax_pos::span_encoding::Span>>::specialized_decode
  11: serialize::serialize::Decoder::read_struct
  12: serialize::serialize::Decoder::read_struct
  13: serialize::serialize::Decoder::read_struct
  14: serialize::serialize::Decoder::read_seq
  15: <rustc::mir::Mir<'tcx> as serialize::serialize::Decodable>::decode::{{closure}}
  16: rustc::ty::maps::on_disk_cache::OnDiskCache::try_load_query_result
  17: rustc::ty::maps::<impl rustc::ty::maps::queries::optimized_mir<'tcx>>::try_get
  18: rustc::ty::maps::TyCtxtAt::optimized_mir
  19: rustc::ty::maps::<impl rustc::ty::context::TyCtxt<'a, 'tcx, 'lcx>>::optimized_mir
  20: rustc_metadata::encoder::<impl rustc_metadata::isolated_encoder::IsolatedEncoder<'a, 'b, 'tcx>>::encode_optimized_mir
  21: rustc_metadata::encoder::<impl rustc_metadata::isolated_encoder::IsolatedEncoder<'a, 'b, 'tcx>>::encode_info_for_impl_item
  22: rustc_metadata::encoder::<impl rustc_metadata::index_builder::IndexBuilder<'a, 'b, 'tcx>>::encode_addl_info_for_item
  23: rustc::hir::Crate::visit_all_item_likes
  24: rustc_metadata::encoder::encode_metadata
  25: rustc_metadata::cstore_impl::<impl rustc::middle::cstore::CrateStore for rustc_metadata::cstore::CStore>::encode_metadata
  26: rustc::ty::context::TyCtxt::encode_metadata
  27: rustc_trans::base::write_metadata
  28: rustc::util::common::time
  29: rustc_trans::base::trans_crate
  30: <rustc_trans::LlvmTransCrate as rustc_trans_utils::trans_crate::TransCrate>::trans_crate
  31: rustc_driver::driver::phase_4_translate_to_llvm
  32: rustc_driver::driver::compile_input::{{closure}}
  33: <std::thread::local::LocalKey<T>>::with
  34: <std::thread::local::LocalKey<T>>::with
  35: rustc::ty::context::TyCtxt::create_and_enter
  36: rustc_driver::driver::compile_input
  37: rustc_driver::run_compiler

[aep]

here's a test case. i got this ICE by random (un)luck and i can't remove any further code or it won't reproduce. at least it's a single file.

cannot reproduce with rustc, must be called from cargo.
Cargo toml has no dependencies tho

use std::io;

enum Tree {
    Leaf(
        Vec<u8>
    ),
    Branch(
        Vec<BlockRef>,
    ),
}

struct Block {
    tree: Tree
}

enum BlockRef {
    StoreRef(Vec<u8>),
    Memory(Block),
}


trait Blockstore {
    fn store(&mut self, block: Block) -> io::Result<Block>;
}

struct FilesystemStore {
}

impl FilesystemStore {
    pub fn open<P: AsRef<Path>>(path: P) -> Result<Self> {
        Ok(Self{})
    }
}

impl Blockstore for FilesystemStore {
    fn store(&mut self, block: Block) -> io::Result<Block> {
    }
}

fn main() {
    let some_file = include_bytes!("main.rs");
}

[aep]

at least i think its related, since its in CacheDecoder as well

stack backtrace:
   0: std::sys::unix::backtrace::tracing::imp::unwind_backtrace
             at libstd/sys/unix/backtrace/tracing/gcc_s.rs:49
   1: std::sys_common::backtrace::print
             at libstd/sys_common/backtrace.rs:71
             at libstd/sys_common/backtrace.rs:59
   2: std::panicking::default_hook::{{closure}}
             at libstd/panicking.rs:207
   3: std::panicking::default_hook
             at libstd/panicking.rs:223
   4: core::ops::function::Fn::call
   5: std::panicking::rust_panic_with_hook
             at libstd/panicking.rs:403
   6: std::panicking::begin_panic_fmt
             at libstd/panicking.rs:349
   7: rust_begin_unwind
             at libstd/panicking.rs:325
   8: core::panicking::panic_fmt
             at libcore/panicking.rs:72
   9: core::panicking::panic_bounds_check
             at libcore/panicking.rs:58
  10: <rustc::ty::maps::on_disk_cache::CacheDecoder<'a, 'tcx, 'x> as serialize::serialize::SpecializedDecoder<syntax_pos::span_encoding::Span>>::specialized_decode
  11: serialize::serialize::Decoder::read_struct
  12: rustc::ty::maps::on_disk_cache::OnDiskCache::try_load_query_result
  13: rustc::ty::maps::<impl rustc::ty::maps::queries::generics_of<'tcx>>::try_get
  14: rustc::ty::maps::TyCtxtAt::generics_of
  15: rustc::ty::maps::<impl rustc::ty::context::TyCtxt<'a, 'tcx, 'lcx>>::generics_of
  16: <rustc_typeck::collect::CollectItemTypesVisitor<'a, 'tcx> as rustc::hir::intravisit::Visitor<'tcx>>::visit_trait_item
  17: rustc::hir::Crate::visit_all_item_likes
  18: rustc::session::Session::track_errors
  19: rustc_typeck::check_crate
  20: <std::thread::local::LocalKey<T>>::with
  21: <std::thread::local::LocalKey<T>>::with
  22: rustc::ty::context::TyCtxt::create_and_enter
  23: rustc_driver::driver::compile_input
  24: rustc_driver::run_compiler_impl
  25: syntax::with_globals

[aep]

cannot reproduce after cargo clean, so attached is the entire project. linux x86_64 rustc 1.26.2 (594fb25 2018-06-01)

46744.zip