ICE: Cannot create local mono-item within future returned as impl trait

[mathall]

A couple of odd requirements to trigger this one, I'm not sure how to summarize. I've boiled down the case and added comments to the code below, they all mention the circumstances which are necessary to trigger the ICE.

src/lib.rs:

extern crate futures;
extern crate tokio;

// a struct in a submodule, with a method
mod sub {
    pub struct S;

    impl S {
        pub fn meth(&self) {
        }
    }
}

// return impl trait, cannot be Box<dyn trait>
fn fun() -> impl futures::future::Future<Item=(), Error=()> {
    futures::future::lazy(|| {
        // call the method on an instance of S from within the future
        sub::S.meth();
        Ok(())
    })
}

// some trait bound parameter
pub fn run<P: AsRef<std::path::Path>>(_: P) {
    // pass the returned future to tokio
    tokio::run(fun());
}

src/main.rs:

extern crate mylib;

fn main() {
    // make a call
    mylib::run("");
}

Meta

RUST_BACKTRACE=1 cargo build:

error: internal compiler error: librustc_mir/monomorphize/collector.rs:765: Cannot create local mono-item for DefId(10/0:8 ~ mylib[784e]::sub[0]::{{impl}}[0]::meth[0])

thread 'main' panicked at 'Box<Any>', librustc_errors/lib.rs:554:9
stack backtrace:
   0: std::sys::unix::backtrace::tracing::imp::unwind_backtrace
   1: std::sys_common::backtrace::print
   2: std::panicking::default_hook::{{closure}}
   3: std::panicking::default_hook
   4: rustc::util::common::panic_hook
   5: std::panicking::rust_panic_with_hook
   6: std::panicking::begin_panic
   7: rustc_errors::Handler::bug
   8: rustc::session::opt_span_bug_fmt::{{closure}}
   9: rustc::ty::context::tls::with_opt::{{closure}}
  10: rustc::ty::context::tls::with_context_opt
  11: rustc::ty::context::tls::with_opt
  12: rustc::session::opt_span_bug_fmt
  13: rustc::session::bug_fmt
  14: rustc_mir::monomorphize::collector::should_monomorphize_locally
  15: rustc_mir::monomorphize::collector::visit_instance_use
  16: <rustc_mir::monomorphize::collector::MirNeighborCollector<'a, 'tcx> as rustc::mir::visit::Visitor<'tcx>>::visit_terminator_kind
  17: rustc_mir::monomorphize::collector::collect_items_rec
  18: rustc_mir::monomorphize::collector::collect_items_rec
  19: rustc_mir::monomorphize::collector::collect_items_rec
  20: rustc_mir::monomorphize::collector::collect_items_rec
  21: rustc_mir::monomorphize::collector::collect_items_rec
  22: rustc_mir::monomorphize::collector::collect_items_rec
  23: rustc_mir::monomorphize::collector::collect_items_rec
  24: rustc_mir::monomorphize::collector::collect_items_rec
  25: rustc_mir::monomorphize::collector::collect_crate_mono_items::{{closure}}
  26: rustc_mir::monomorphize::collector::collect_crate_mono_items
  27: rustc::util::common::time
  28: rustc_codegen_llvm::base::collect_and_partition_mono_items
  29: rustc::ty::query::<impl rustc::ty::query::config::QueryAccessors<'tcx> for rustc::ty::query::queries::collect_and_partition_mono_items<'tcx>>::compute
  30: rustc::ty::context::tls::with_context
  31: rustc::dep_graph::graph::DepGraph::with_task_impl
  32: rustc::ty::context::tls::with_related_context
  33: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt<'a, 'gcx, 'tcx>>::force_query_with_job
  34: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt<'a, 'gcx, 'tcx>>::get_query
  35: rustc_codegen_llvm::base::codegen_crate
  36: <rustc_codegen_llvm::LlvmCodegenBackend as rustc_codegen_utils::codegen_backend::CodegenBackend>::codegen_crate
  37: rustc::util::common::time
  38: rustc_driver::driver::phase_4_codegen
  39: rustc_driver::driver::compile_input::{{closure}}
  40: rustc::ty::context::tls::enter_context
  41: <std::thread::local::LocalKey<T>>::with
  42: rustc::ty::context::TyCtxt::create_and_enter
  43: rustc_driver::driver::compile_input
  44: rustc_driver::run_compiler_with_pool
  45: <scoped_tls::ScopedKey<T>>::set
  46: syntax::with_globals
  47: <std::panic::AssertUnwindSafe<F> as core::ops::function::FnOnce<()>>::call_once
  48: __rust_maybe_catch_panic
  49: rustc_driver::run
  50: rustc_driver::main
  51: std::rt::lang_start::{{closure}}
  52: std::panicking::try::do_call
  53: __rust_maybe_catch_panic
  54: std::rt::lang_start_internal
  55: main
query stack during panic:
#0 [collect_and_partition_mono_items] collect_and_partition_mono_items
end of query stack
error: aborting due to previous error


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: rustc 1.28.0 (9634041f0 2018-07-30) running on x86_64-apple-darwin

note: compiler flags: -C debuginfo=2 -C incremental --crate-type bin

note: some of the compiler flags provided by cargo are hidden

error: Could not compile `mypack`.

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

rustc --version --verbose:

rustc 1.28.0 (9634041f0 2018-07-30)
binary: rustc
commit-hash: 9634041f0e8c0f3191d2867311276f19d0a42564
commit-date: 2018-07-30
host: x86_64-apple-darwin
release: 1.28.0
LLVM version: 6.0

[hellow554]

note: Run with RUST_BACKTRACE=1 for a backtrace.

Can you do that and edit your post?

[hrvolapeter]

Possibly related to #53468

[c0gent]

Here's another backtrace if at all helpful:

error: internal compiler error: librustc_mir/monomorphize/collector.rs:757: Cannot create local mono-item for DefId(318/0:334 ~ hydrabadger[6497]::peer[0]::{{impl}}[0]::hdb[0])

thread 'main' panicked at 'Box<Any>', librustc_errors/lib.rs:578:9
stack backtrace:
   0:     0x7fd699c0ccbe - std::sys::unix::backtrace::tracing::imp::unwind_backtrace::hc38b730e4fac0255
                               at libstd/sys/unix/backtrace/tracing/gcc_s.rs:49
   1:     0x7fd699be88a6 - std::sys_common::backtrace::print::h14587871a85be1d1
                               at libstd/sys_common/backtrace.rs:71
                               at libstd/sys_common/backtrace.rs:59
   2:     0x7fd699be229d - std::panicking::default_hook::{{closure}}::h3598f21b0ef93330
                               at libstd/panicking.rs:211
   3:     0x7fd699be2010 - std::panicking::default_hook::h8168a325cc2a7e4b
                               at libstd/panicking.rs:227
   4:     0x7fd69633192d - rustc::util::common::panic_hook::h377e19a02109a0d9
   5:     0x7fd699be2a23 - std::panicking::rust_panic_with_hook::hd4f331d1faf6d125
                               at libstd/panicking.rs:479
   6:     0x7fd694fc5d1e - std::panicking::begin_panic::hed18f2dfd78a2f6d
   7:     0x7fd694fe0451 - rustc_errors::Handler::bug::h288e744370c67e9f
   8:     0x7fd695e5eb4c - rustc::session::opt_span_bug_fmt::{{closure}}::h4fcb79e90c410083
   9:     0x7fd695f197b9 - rustc::ty::context::tls::with_opt::{{closure}}::h2f8fc392cd1c03eb
  10:     0x7fd695e5f94f - rustc::ty::context::tls::with_context_opt::hbae69a80d2573e4d
  11:     0x7fd695f19246 - rustc::ty::context::tls::with_opt::hfa24305e0dd1e123
  12:     0x7fd695dbb534 - rustc::session::opt_span_bug_fmt::hfb7915fc33f379ad
  13:     0x7fd695dbb4a6 - rustc::session::bug_fmt::h93f77b183d77c02a
  14:     0x7fd696c761d9 - rustc_mir::monomorphize::collector::should_monomorphize_locally::h64c89d199ca23581
  15:     0x7fd696c75e54 - rustc_mir::monomorphize::collector::visit_instance_use::hbb874cd8dad31ce0
  16:     0x7fd696c75e22 - rustc_mir::monomorphize::collector::visit_fn_use::h9fe7bd383d9f49ad
  17:     0x7fd696c75982 - <rustc_mir::monomorphize::collector::MirNeighborCollector<'a, 'tcx> as rustc::mir::visit::Visitor<'tcx>>::visit_terminator_kind::h361ce6d615c46199
  18:     0x7fd696c74386 - rustc_mir::monomorphize::collector::collect_items_rec::h15cbb74d560a196f
  19:     0x7fd696c749b9 - rustc_mir::monomorphize::collector::collect_items_rec::h15cbb74d560a196f
  20:     0x7fd696c749b9 - rustc_mir::monomorphize::collector::collect_items_rec::h15cbb74d560a196f
  21:     0x7fd696c749b9 - rustc_mir::monomorphize::collector::collect_items_rec::h15cbb74d560a196f
  22:     0x7fd696c749b9 - rustc_mir::monomorphize::collector::collect_items_rec::h15cbb74d560a196f
  23:     0x7fd696c749b9 - rustc_mir::monomorphize::collector::collect_items_rec::h15cbb74d560a196f
  24:     0x7fd696c749b9 - rustc_mir::monomorphize::collector::collect_items_rec::h15cbb74d560a196f
  25:     0x7fd696c749b9 - rustc_mir::monomorphize::collector::collect_items_rec::h15cbb74d560a196f
  26:     0x7fd696c749b9 - rustc_mir::monomorphize::collector::collect_items_rec::h15cbb74d560a196f
  27:     0x7fd696c749b9 - rustc_mir::monomorphize::collector::collect_items_rec::h15cbb74d560a196f
  28:     0x7fd696c749b9 - rustc_mir::monomorphize::collector::collect_items_rec::h15cbb74d560a196f
  29:     0x7fd696c749b9 - rustc_mir::monomorphize::collector::collect_items_rec::h15cbb74d560a196f
  30:     0x7fd696c749b9 - rustc_mir::monomorphize::collector::collect_items_rec::h15cbb74d560a196f
  31:     0x7fd696c749b9 - rustc_mir::monomorphize::collector::collect_items_rec::h15cbb74d560a196f
  32:     0x7fd696c749b9 - rustc_mir::monomorphize::collector::collect_items_rec::h15cbb74d560a196f
  33:     0x7fd696c749b9 - rustc_mir::monomorphize::collector::collect_items_rec::h15cbb74d560a196f
  34:     0x7fd696c749b9 - rustc_mir::monomorphize::collector::collect_items_rec::h15cbb74d560a196f
  35:     0x7fd696c749b9 - rustc_mir::monomorphize::collector::collect_items_rec::h15cbb74d560a196f
  36:     0x7fd696c749b9 - rustc_mir::monomorphize::collector::collect_items_rec::h15cbb74d560a196f
  37:     0x7fd696c749b9 - rustc_mir::monomorphize::collector::collect_items_rec::h15cbb74d560a196f
  38:     0x7fd696c749b9 - rustc_mir::monomorphize::collector::collect_items_rec::h15cbb74d560a196f
  39:     0x7fd696c749b9 - rustc_mir::monomorphize::collector::collect_items_rec::h15cbb74d560a196f
  40:     0x7fd696c749b9 - rustc_mir::monomorphize::collector::collect_items_rec::h15cbb74d560a196f
  41:     0x7fd696c749b9 - rustc_mir::monomorphize::collector::collect_items_rec::h15cbb74d560a196f
  42:     0x7fd696c749b9 - rustc_mir::monomorphize::collector::collect_items_rec::h15cbb74d560a196f
  43:     0x7fd696c749b9 - rustc_mir::monomorphize::collector::collect_items_rec::h15cbb74d560a196f
  44:     0x7fd696c749b9 - rustc_mir::monomorphize::collector::collect_items_rec::h15cbb74d560a196f
  45:     0x7fd696c749b9 - rustc_mir::monomorphize::collector::collect_items_rec::h15cbb74d560a196f
  46:     0x7fd696c749b9 - rustc_mir::monomorphize::collector::collect_items_rec::h15cbb74d560a196f
  47:     0x7fd696c749b9 - rustc_mir::monomorphize::collector::collect_items_rec::h15cbb74d560a196f
  48:     0x7fd696c749b9 - rustc_mir::monomorphize::collector::collect_items_rec::h15cbb74d560a196f
  49:     0x7fd696c749b9 - rustc_mir::monomorphize::collector::collect_items_rec::h15cbb74d560a196f
  50:     0x7fd696c749b9 - rustc_mir::monomorphize::collector::collect_items_rec::h15cbb74d560a196f
  51:     0x7fd696f306f0 - rustc_mir::monomorphize::collector::collect_crate_mono_items::{{closure}}::h42377768293a947b
  52:     0x7fd696f086d4 - rustc::util::common::time::hb3164c62cd6cc215
  53:     0x7fd696c73030 - rustc_mir::monomorphize::collector::collect_crate_mono_items::hc77a074be340e459
  54:     0x7fd68f6f6c86 - rustc::util::common::time::hf1e4990b4a639374
  55:     0x7fd68f7b2274 - rustc_codegen_llvm::base::collect_and_partition_mono_items::hd1a070a2376bb9c5
  56:     0x7fd695f1b348 - rustc::ty::query::<impl rustc::ty::query::config::QueryAccessors<'tcx> for rustc::ty::query::queries::collect_and_partition_mono_items<'tcx>>::compute::hea75f44dc97797d0
  57:     0x7fd695d1274e - rustc::dep_graph::graph::DepGraph::with_task_impl::h835f0a4d2b18bc07
  58:     0x7fd695ec0f5b - rustc::ty::context::tls::with_related_context::h3c83330713b13e99
  59:     0x7fd69601dae7 - rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt<'a, 'gcx, 'tcx>>::force_query_with_job::h5c8689f533db834c
  60:     0x7fd696116298 - rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt<'a, 'gcx, 'tcx>>::get_query::hc459420e2d1f7906
  61:     0x7fd68f7b7350 - <rustc_codegen_llvm::LlvmCodegenBackend as rustc_codegen_utils::codegen_backend::CodegenBackend>::codegen_crate::h16304cb944eb3a10
  62:     0x7fd699f92971 - rustc::util::common::time::h27952c3dcecf4d9d
  63:     0x7fd699f8967c - rustc_driver::driver::phase_4_codegen::h11f31d1ce05dd8cc
  64:     0x7fd69a029f98 - rustc_driver::driver::compile_input::{{closure}}::hbcfd05b05ee10962
  65:     0x7fd69a024ad9 - rustc::ty::context::tls::enter_context::he6792d96b1a8593b
  66:     0x7fd699fd8c5a - <std::thread::local::LocalKey<T>>::with::hff342551e22b97f4
  67:     0x7fd69a0464fd - rustc::ty::context::TyCtxt::create_and_enter::h900d40186934f964
  68:     0x7fd699f82d3c - rustc_driver::driver::compile_input::he3d8ffa7fc6fb0b1
  69:     0x7fd69a02ebd9 - rustc_driver::run_compiler_with_pool::h857bb7f679bff0bc
  70:     0x7fd699f4989c - <scoped_tls::ScopedKey<T>>::set::h5dd3e2bfa44e92e2
  71:     0x7fd699f49591 - <scoped_tls::ScopedKey<T>>::set::h4da18d6fc1a78347
  72:     0x7fd699fe57ba - syntax::with_globals::h0ede7174af3ad87c
  73:     0x7fd699f48012 - <std::panic::AssertUnwindSafe<F> as core::ops::function::FnOnce<()>>::call_once::hb5f73936aff14500
  74:     0x7fd699c22c99 - __rust_maybe_catch_panic
                               at libpanic_unwind/lib.rs:105
  75:     0x7fd69a02bf9e - rustc_driver::run::hcfb204ccb1735e19
  76:     0x7fd69a0398ca - rustc_driver::main::ha16d2705f2f29af0
  77:     0x556fa6531b52 - std::rt::lang_start::{{closure}}::h0dc69d8f000bba40
  78:     0x7fd699be2462 - std::panicking::try::do_call::h09f2e11537387364
                               at libstd/rt.rs:59
                               at libstd/panicking.rs:310
  79:     0x7fd699c22c99 - __rust_maybe_catch_panic
                               at libpanic_unwind/lib.rs:105
  80:     0x7fd699be7175 - std::rt::lang_start_internal::h62ba303339938384
                               at libstd/panicking.rs:289
                               at libstd/panic.rs:392
                               at libstd/rt.rs:58
  81:     0x556fa6531bb3 - main
  82:     0x7fd6997bcb96 - __libc_start_main
  83:     0x556fa6531a38 - <unknown>
query stack during panic:
#0 [collect_and_partition_mono_items] collect_and_partition_mono_items
end of query stack
error: aborting due to previous error


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: rustc 1.29.0-beta.14 (edfc72bc7 2018-09-09) running on x86_64-unknown-linux-gnu

note: compiler flags: -C opt-level=3 --crate-type bin

note: some of the compiler flags provided by cargo are hidden

error: Could not compile `parity-ethereum`.

[FelixMcFelix]

Does the issue persist on nightly?

[c0gent]

This has cleared up on nightly for me.

[bobbobbio]

Perhaps unrelated, but this open issue has a similar failure mode and still fails in 1.30 / 1.31

[Noratrieb]

The issue seems to have been fixed, but there's no mcve to test, so I'm closing this as unactionable. If you encounter further problems, feel free to open new issues.