ICE: unexpected failure

[carllerche]

trait Node {
    fn zomg();
}

trait Graph<N: Node> {
    fn nodes<'a, I: Iterator<&'a N>>(&'a self) -> I;
}

impl<N: Node> Graph<N> for Vec<N> {
    fn nodes<'a, I: Iterator<&'a N>>(&self) -> I {
        self.iter()
    }
}

struct Stuff;

impl Node for Stuff {
    fn zomg() {
        println!("zomg");
    }
}

fn iterate<N: Node, G: Graph<N>>(graph: &G) {
    for node in graph.iter() {
        node.zomg();
    }
}

pub fn main() {
    let graph = Vec::new();

    graph.push(Stuff);

    iterate(graph);
}

backtrace:

RUST_BACKTRACE=1 rustc graph.rs
graph.rs:11:9: 11:20 error: mismatched types: expected `I` but found `std::slice::Items<,N>` (expected type parameter but found struct std::slice::Items)
graph.rs:11         self.iter()
                    ^~~~~~~~~~~
error: internal compiler error: unexpected failure
note: the compiler hit an unexpected failure path. this is a bug.
note: we would appreciate a bug report: http://static.rust-lang.org/doc/master/complement-bugreport.html
note: run with `RUST_BACKTRACE=1` for a backtrace
task 'rustc' failed at 'OwnedSlice: index out of bounds', /Users/carllerche/Code/oss/rust/src/libstd/option.rs:245
stack backtrace:
   1:        0x1124fcbe4 - rt::backtrace::imp::write::hcadb4ca6cf458711WEa::v0.11.pre
   2:        0x11245eafe - rt::unwind::begin_unwind_inner::hca8608d5eeddd58a2ea::v0.11.pre
   3:        0x10f857888 - rt::unwind::begin_unwind::h17449128597888216233::v0.11.pre
   4:        0x10fa04c9c - middle::subst::ty..Region.Subst::subst_spanned::he4ed0aac71e34c93RLQ::v0.11.pre
   5:        0x10fa04f94 - middle::ty_fold::super_fold_sty::h16046759532750779955::v0.11.pre
   6:        0x10fa044c3 - middle::subst::SubstFolder<'a>.TypeFolder::fold_ty::h0538984c9a39e119FwQ::v0.11.pre
   7:        0x10f9d4460 - iter::Iterator::collect::h16000720370100676544::v0.11.pre
   8:        0x10fa05820 - middle::ty_fold::super_fold_sig::h9594554811819343845::v0.11.pre
   9:        0x10fa05029 - middle::ty_fold::super_fold_sty::h16046759532750779955::v0.11.pre
  10:        0x10fa044c3 - middle::subst::SubstFolder<'a>.TypeFolder::fold_ty::h0538984c9a39e119FwQ::v0.11.pre
  11:        0x10f9d4795 - middle::subst::ty..t.Subst::subst_spanned::h2928f17972b9f34fRuQ::v0.11.pre
  12:        0x10fafd280 - middle::typeck::check::compare_impl_method::h7ba2a958f71be34dSK7::v0.11.pre
  13:        0x10fae6595 - middle::typeck::check::check_item::h67823ebe09a4e536lp7::v0.11.pre
  14:        0x10faedb8d - middle::typeck::check::check_item_types::hd2c43c2abe8a4484gS6::v0.11.pre
  15:        0x10fc1d97f - util::common::time::h16635378632434799699::v0.11.pre
  16:        0x10fc1c8ad - middle::typeck::check_crate::he941c106adef2e35Wgu::v0.11.pre
  17:        0x11003840d - driver::driver::phase_3_run_analysis_passes::h297d37f689608467g1e::v0.11.pre
  18:        0x11003e5c2 - driver::driver::compile_input::h6b68b4cbb99b30fb3qf::v0.11.pre
  19:        0x110064312 - run_compiler::h6001e0654ecea84bzUm::v0.11.pre
  20:        0x11007818d - main_args::closure.91224
  21:        0x110076522 - monitor::closure.91099
  22:        0x11007206b - task::TaskBuilder::try::closure.90865
  23:        0x10f8216ec - task::spawn_opts::closure.7106
  24:        0x1124f7ce8 - rt::task::Task::run::closure.40146
  25:        0x112501a5c - rust_try
  26:        0x1124f7b67 - rt::task::Task::run::h7f884ecfbc0c0d44C57::v0.11.pre
  27:        0x10f82156f - task::spawn_opts::closure.7078
  28:        0x1124fb5b6 - rt::thread::thread_start::h46e5de4fe5c37df8PK8::v0.11.pre
  29:     0x7fff8e14e772 - _pthread_start

[carllerche]

Here is a smaller bit of code that causes a compiler error. I am not 100% sure it is the same case though.

trait Graph<N> {
    fn nodes<'a, I: Iterator<&'a N>>(&'a self) -> I;
}

impl<N> Graph<N> for Vec<N> {
    fn nodes<'a, I: Iterator<&'a N>>(&'a self) -> I {
        self.iter()
    }
}

pub fn main() {
}

[alexcrichton]

Another testcase

#![crate_type = "lib"]

enum NodeContents<'a> {
    Children(Vec<Node<'a>>),
}

struct Node<'a> {
    contents: NodeContents<'a>,
}

impl<'a> Node<'a> {
    fn noName(contents: NodeContents<'a>) -> Node<'a> {
        Node{  contents: contents,}
    }
}

[alexcrichton]

Another test case

trait FromStructReader<'a> { }
trait ResponseHook {
     fn get<'a, T: FromStructReader<'a>>(&'a self);
}
fn foo(res : Box<ResponseHook>) { res.get }
fn main() {}

[jdm]

Another testcase:

struct AutoBuilder<'a> {
    context: &'a int
}

impl<'a> Drop for AutoBuilder<'a> {
    fn drop(&mut self) {
    }
}

fn main() {
}

[irauta]

I'm pretty much new at this on many levels (just created this account!), so you should take anything I say with a grain of salt. Anyway, I too hit this bug with essentially the same code as jdm - trying to implement Drop for a struct containing a borrowed pointer.

After some git bisecting looks like the commit 7d6f1aa is the first one where this error happens. That commit changed file src/librustc/middle/subst.rs and the stack traces mention middle::subst so maybe there's something to this?

When testing with the Drop version of the code, the older versions of rustc suggest adding a #["unsafe_destructor"]. It seems to make the error go away on newer versions too - just tested it on rustc 0.11.0-pre-nightly (faa7ba7 2014-05-31 01:06:40 -0700), x86_64-unknown-linux-gnu, and the code compiled without any complaints.

[Valloric]

Motivated by @irauta's findings, I played around with my testcase and provoked what appears to be Yet Another ICE. It looks different, but it might be caused by the same underlying problem so I'm posting it here instead of creating a new issue.

Testcase (notice that only the Drop impl was added):

#![crate_type = "lib"]

enum NodeContents<'a> {
    Children(Vec<Node<'a>>),
}

impl<'a> Drop for NodeContents<'a> {
  fn drop( &mut self ) {
  }
}

struct Node<'a> {
    contents: NodeContents<'a>,
}

impl<'a> Node<'a> {
    fn noName(contents: NodeContents<'a>) -> Node<'a> {
        Node{  contents: contents,}
    }
}

Output:

$ RUST_BACKTRACE=1 rustc testcase.rs
error: internal compiler error: ID not mapped to struct fields: enum NodeContents::NodeContents (id=3)
note: the compiler hit an unexpected failure path. 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' failed at 'Box<Any>', /home/rustbuild/src/rust-buildbot/slave/nightly-linux/build/src/libsyntax/diagnostic.rs:162
stack backtrace:
   1:     0x7ffee7a64c10 - rt::backtrace::imp::write::h4eaa694fcd948704Wrx::v0.11.0.pre
   2:     0x7ffee79e7730 - rt::unwind::begin_unwind_inner::h3b5fcee9a7d12dbfX1w::v0.11.0.pre
   3:     0x7ffee63be2f0 - rt::unwind::begin_unwind::h6952148588903257095::v0.11.0.pre
   4:     0x7ffee63bed30 - diagnostic::Handler::bug::h4b77aa25d705a445P4b::v0.11.0.pre
   5:     0x7ffee850fc70 - driver::session::Session::bug::hfc07277a564612feWGn::v0.11.0.pre
   6:     0x7ffee86200c0 - middle::ty::lookup_struct_fields::hfb681bcf73bb30d2TpQ::v0.11.0.pre
   7:     0x7ffee8561670 - middle::ty::struct_fields::he157a00b7c3060eb1uQ::v0.11.0.pre
   8:     0x7ffee86b1880 - middle::ty::type_contents::tc_ty::hcf3453b2500819dfPCN::v0.11.0.pre
   9:     0x7ffee865b040 - middle::ty::type_contents::h59dcd90524a31605LBN::v0.11.0.pre
  10:     0x7ffee8a28ac0 - middle::kind::check_item::h098689564b21e13a08S::v0.11.0.pre
  11:     0x7ffee8a2b7b0 - middle::kind::check_crate::h9e02f0748a8c41d7dZS::v0.11.0.pre
  12:     0x7ffee8dbcc60 - driver::driver::phase_3_run_analysis_passes::hc9c5bc13cc92c0a5kJm::v0.11.0.pre
  13:     0x7ffee8db6120 - driver::driver::compile_input::he7dad0e3dbb6fee3Uym::v0.11.0.pre
  14:     0x7ffee8e82540 - driver::run_compiler::h96a720220bae0c8cDdp::v0.11.0.pre
  15:     0x7ffee8e82460 - driver::main_args::closure.94809
  16:     0x7ffee8e97600 - driver::monitor::closure.95880
  17:     0x7ffee8e929e0 - task::TaskBuilder::try::closure.95643
  18:     0x7ffee7f97690 - task::spawn_opts::closure.7832
  19:     0x7ffee7a5f0a0 - rt::task::Task::run::closure.25246
  20:     0x7ffee7ac8ea0 - rust_try
  21:     0x7ffee7a5eff0 - rt::task::Task::run::h11c4d2099f444a65AQu::v0.11.0.pre
  22:     0x7ffee7f97440 - task::spawn_opts::closure.7805
  23:     0x7ffee7a63040 - rt::thread::thread_start::h43799e40ebb51dd18zv::v0.11.0.pre
  24:     0x7ffee54f40c0 - start_thread
  25:     0x7ffee76a72d9 - __clone
  26:                0x0 - <unknown>

[Valloric]

As of rustc 0.11.0-pre-nightly (0ee6a8e 2014-06-09 23:41:53 -0700), the testcase from #13853 (comment) doesn't repro anymore; it compiles fine. Every other testcase reported in this issue (including #13853 (comment)) still fails with an ICE.

[erickt]

Another test case that has the same backtrace.

trait Deserializer<'a> { }

trait Deserializable {
    fn deserialize_token<'a, D: Deserializer<'a>>(D, &'a str) -> Self;
}

impl<'a, T: Deserializable> Deserializable for &'a str {
    fn deserialize_token<D: Deserializer<'a>>(_x: D, _y: &'a str) -> &'a str {
    }
}

fn main() {
}