ICE when running `cargo +nightly fix --edition` on tokio

[rylev]

When running cargo +nightly fix --edition on tokio, I get the ICE seen below. This seems to happen when compiling benchmarks.

I have been unable so far to reproduce this with a plain cargo or rustc invocation. For example, cargo +nightly c --bench fs works fine.

This also seems to happen in reqwest.

Meta

rustc +nightly --version --verbose:

rustc 1.55.0-nightly (6d820866a 2021-06-29)
binary: rustc
commit-hash: 6d820866a27b1949e237be79b9c8c0145fe728b7
commit-date: 2021-06-29
host: x86_64-unknown-linux-gnu
release: 1.55.0-nightly
LLVM version: 12.0.1

Backtrace

$ RUST_BACKTRACE=1 cargo +nightly fix --edition
    Checking tests-build v0.1.0 (/home/rylevick/crater/tokio/tests-build)
    Checking tokio-macros v1.2.0 (/home/rylevick/crater/tokio/tokio-macros)
    Checking benches v0.0.0 (/home/rylevick/crater/tokio/benches)
   Migrating tests-build/src/lib.rs from 2018 edition to 2021
    Checking tokio-test v0.4.2 (/home/rylevick/crater/tokio/tokio-test)
   Migrating tokio-macros/src/lib.rs from 2018 edition to 2021
   Migrating benches/sync_rwlock.rs from 2018 edition to 2021
   Migrating benches/signal.rs from 2018 edition to 2021
   Migrating benches/sync_semaphore.rs from 2018 edition to 2021
   Migrating tokio-test/src/lib.rs from 2018 edition to 2021
   Migrating benches/spawn.rs from 2018 edition to 2021
   Migrating benches/rt_multi_threaded.rs from 2018 edition to 2021
    Checking stress-test v0.1.0 (/home/rylevick/crater/tokio/stress-test)
   Migrating stress-test/examples/simple_echo_tcp.rs from 2018 edition to 2021
   Migrating benches/fs.rs from 2018 edition to 2021
   Migrating benches/sync_mpsc.rs from 2018 edition to 2021
thread 'rustc' panicked at 'index out of bounds: the len is 0 but the index is 59', /cargo/registry/src/github.com-1ecc6299db9ec823/ena-0.14.0/src/snapshot_vec.rs:199:10
stack backtrace:
   0: rust_begin_unwind
             at /rustc/6d820866a27b1949e237be79b9c8c0145fe728b7/library/std/src/panicking.rs:515:5
   1: core::panicking::panic_fmt
             at /rustc/6d820866a27b1949e237be79b9c8c0145fe728b7/library/core/src/panicking.rs:92:14
   2: core::panicking::panic_bounds_check
             at /rustc/6d820866a27b1949e237be79b9c8c0145fe728b7/library/core/src/panicking.rs:69:5
   3: rustc_infer::infer::InferCtxt::shallow_resolve_ty
   4: <smallvec::SmallVec<A> as core::iter::traits::collect::Extend<<A as smallvec::Array>::Item>>::extend
   5: rustc_middle::ty::fold::TypeFoldable::fold_with
   6: rustc_middle::ty::structural_impls::<impl rustc_middle::ty::fold::TypeFoldable for &rustc_middle::ty::TyS>::super_fold_with
   7: rustc_middle::ty::fold::TypeFoldable::fold_with
   8: rustc_middle::ty::structural_impls::<impl rustc_middle::ty::fold::TypeFoldable for &rustc_middle::ty::TyS>::super_fold_with
   9: rustc_middle::ty::fold::TypeFoldable::fold_with
  10: rustc_middle::ty::structural_impls::<impl rustc_middle::ty::fold::TypeFoldable for &rustc_middle::ty::TyS>::super_fold_with
  11: <smallvec::SmallVec<A> as core::iter::traits::collect::Extend<<A as smallvec::Array>::Item>>::extend
  12: rustc_middle::ty::fold::TypeFoldable::fold_with
  13: rustc_middle::ty::structural_impls::<impl rustc_middle::ty::fold::TypeFoldable for &rustc_middle::ty::TyS>::super_fold_with
  14: rustc_infer::infer::InferCtxtBuilder::enter
  15: core::ops::function::FnOnce::call_once
  16: rustc_query_system::dep_graph::graph::DepGraph<K>::with_task_impl
  17: rustc_data_structures::stack::ensure_sufficient_stack
  18: rustc_query_system::query::plumbing::get_query_impl
  19: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::normalize_generic_arg_after_erasing_regions
  20: <rustc_middle::ty::normalize_erasing_regions::NormalizeAfterErasingRegionsFolder as rustc_middle::ty::fold::TypeFolder>::fold_ty
  21: rustc_middle::ty::normalize_erasing_regions::<impl rustc_middle::ty::context::TyCtxt>::normalize_erasing_regions
  22: rustc_middle::ty::util::<impl rustc_middle::ty::TyS>::has_significant_drop
  23: rustc_typeck::check::upvar::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::analyze_closure
  24: rustc_hir::intravisit::walk_expr
  25: rustc_hir::intravisit::walk_expr
  26: <rustc_typeck::check::upvar::InferBorrowKindVisitor as rustc_hir::intravisit::Visitor>::visit_expr
  27: <rustc_typeck::check::upvar::InferBorrowKindVisitor as rustc_hir::intravisit::Visitor>::visit_expr
  28: rustc_hir::intravisit::walk_stmt
  29: rustc_hir::intravisit::walk_expr
  30: <rustc_typeck::check::upvar::InferBorrowKindVisitor as rustc_hir::intravisit::Visitor>::visit_expr
  31: rustc_hir::intravisit::walk_expr
  32: rustc_hir::intravisit::walk_expr
  33: <rustc_typeck::check::upvar::InferBorrowKindVisitor as rustc_hir::intravisit::Visitor>::visit_expr
  34: <rustc_typeck::check::upvar::InferBorrowKindVisitor as rustc_hir::intravisit::Visitor>::visit_expr
  35: rustc_hir::intravisit::walk_expr
  36: <rustc_typeck::check::upvar::InferBorrowKindVisitor as rustc_hir::intravisit::Visitor>::visit_expr
  37: rustc_hir::intravisit::walk_expr
  38: <rustc_typeck::check::upvar::InferBorrowKindVisitor as rustc_hir::intravisit::Visitor>::visit_expr
  39: rustc_typeck::check::upvar::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::closure_analyze
  40: rustc_infer::infer::InferCtxtBuilder::enter
  41: rustc_typeck::check::typeck
  42: rustc_query_system::dep_graph::graph::DepGraph<K>::with_task_impl
  43: rustc_data_structures::stack::ensure_sufficient_stack
  44: rustc_query_system::query::plumbing::force_query_with_job
  45: rustc_query_system::query::plumbing::get_query_impl
  46: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::typeck
  47: rustc_middle::ty::<impl rustc_middle::ty::context::TyCtxt>::par_body_owners
  48: rustc_typeck::check::typeck_item_bodies
  49: rustc_query_system::dep_graph::graph::DepGraph<K>::with_task_impl
  50: rustc_data_structures::stack::ensure_sufficient_stack
  51: rustc_query_system::query::plumbing::force_query_with_job
  52: rustc_query_system::query::plumbing::get_query_impl
  53: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::typeck_item_bodies
  54: rustc_session::utils::<impl rustc_session::session::Session>::time
  55: rustc_typeck::check_crate
  56: rustc_interface::passes::analysis
  57: rustc_middle::dep_graph::<impl rustc_query_system::dep_graph::DepKind for rustc_middle::dep_graph::dep_node::DepKind>::with_deps
  58: rustc_query_system::dep_graph::graph::DepGraph<K>::with_task_impl
  59: rustc_query_system::dep_graph::graph::DepGraph<K>::with_eval_always_task
  60: rustc_data_structures::stack::ensure_sufficient_stack
  61: rustc_query_system::query::plumbing::force_query_with_job
  62: rustc_query_system::query::plumbing::get_query_impl
  63: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::analysis
  64: rustc_interface::queries::<impl rustc_interface::interface::Compiler>::enter
  65: rustc_span::with_source_map
  66: rustc_interface::interface::create_compiler_and_run
  67: scoped_tls::ScopedKey<T>::set
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

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/issues/new?labels=C-bug%2C+I-ICE%2C+T-compiler&template=ice.md

note: rustc 1.55.0-nightly (6d820866a 2021-06-29) running on x86_64-unknown-linux-gnu

note: compiler flags: -Z unstable-options -C embed-bitcode=no -C debuginfo=2 -C incremental

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

query stack during panic:
#0 [normalize_generic_arg_after_erasing_regions] normalizing `(tokio::future::maybe_done::MaybeDone<impl std::future::Future>, tokio::future::maybe_done::MaybeDone<tokio::task::JoinHandle<()>>, tokio::future::maybe_done::MaybeDone<tokio::task::JoinHandle<()>>, tokio::future::maybe_done::MaybeDone<tokio::task::JoinHandle<()>>, tokio::future::maybe_done::MaybeDone<tokio::task::JoinHandle<()>>, tokio::future::maybe_done::MaybeDone<tokio::task::JoinHandle<()>>)`
#1 [typeck] type-checking `read_concurrent_contended_multi`
#2 [typeck_item_bodies] type-checking all item bodies
#3 [analysis] running analysis passes on this crate
end of query stack
error: could not compile `benches`

To learn more, run the command again with --verbose.
warning: build failed, waiting for other jobs to finish...
thread 'rustc' panicked at 'index out of bounds: the len is 0 but the index is 69', /cargo/registry/src/github.com-1ecc6299db9ec823/ena-0.14.0/src/snapshot_vec.rs:199:10
stack backtrace:
   0: rust_begin_unwind
             at /rustc/6d820866a27b1949e237be79b9c8c0145fe728b7/library/std/src/panicking.rs:515:5
   1: core::panicking::panic_fmt
             at /rustc/6d820866a27b1949e237be79b9c8c0145fe728b7/library/core/src/panicking.rs:92:14
   2: core::panicking::panic_bounds_check
             at /rustc/6d820866a27b1949e237be79b9c8c0145fe728b7/library/core/src/panicking.rs:69:5
   3: rustc_infer::infer::InferCtxt::shallow_resolve_ty
   4: <smallvec::SmallVec<A> as core::iter::traits::collect::Extend<<A as smallvec::Array>::Item>>::extend
   5: rustc_middle::ty::fold::TypeFoldable::fold_with
   6: rustc_middle::ty::structural_impls::<impl rustc_middle::ty::fold::TypeFoldable for &rustc_middle::ty::TyS>::super_fold_with
   7: rustc_middle::ty::fold::TypeFoldable::fold_with
   8: rustc_middle::ty::structural_impls::<impl rustc_middle::ty::fold::TypeFoldable for &rustc_middle::ty::TyS>::super_fold_with
   9: rustc_middle::ty::util::fold_list
  10: rustc_middle::ty::structural_impls::<impl rustc_middle::ty::fold::TypeFoldable for &rustc_middle::ty::TyS>::super_fold_with
  11: <smallvec::SmallVec<A> as core::iter::traits::collect::Extend<<A as smallvec::Array>::Item>>::extend
  12: rustc_middle::ty::fold::TypeFoldable::fold_with
  13: rustc_middle::ty::structural_impls::<impl rustc_middle::ty::fold::TypeFoldable for &rustc_middle::ty::TyS>::super_fold_with
  14: rustc_infer::infer::InferCtxtBuilder::enter
  15: core::ops::function::FnOnce::call_once
  16: rustc_query_system::dep_graph::graph::DepGraph<K>::with_task_impl
  17: rustc_data_structures::stack::ensure_sufficient_stack
  18: rustc_query_system::query::plumbing::get_query_impl
  19: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::normalize_generic_arg_after_erasing_regions
  20: <rustc_middle::ty::normalize_erasing_regions::NormalizeAfterErasingRegionsFolder as rustc_middle::ty::fold::TypeFolder>::fold_ty
  21: rustc_middle::ty::normalize_erasing_regions::<impl rustc_middle::ty::context::TyCtxt>::normalize_erasing_regions
  22: rustc_middle::ty::util::<impl rustc_middle::ty::TyS>::has_significant_drop
  23: rustc_typeck::check::upvar::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::analyze_closure
  24: rustc_hir::intravisit::walk_expr
  25: <rustc_typeck::check::upvar::InferBorrowKindVisitor as rustc_hir::intravisit::Visitor>::visit_expr
  26: rustc_hir::intravisit::walk_expr
  27: <rustc_typeck::check::upvar::InferBorrowKindVisitor as rustc_hir::intravisit::Visitor>::visit_expr
  28: rustc_typeck::check::upvar::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::closure_analyze
  29: rustc_infer::infer::InferCtxtBuilder::enter
  30: rustc_typeck::check::typeck
  31: rustc_query_system::dep_graph::graph::DepGraph<K>::with_task_impl
  32: rustc_data_structures::stack::ensure_sufficient_stack
  33: rustc_query_system::query::plumbing::force_query_with_job
  34: rustc_query_system::query::plumbing::get_query_impl
  35: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::typeck
  36: rustc_middle::ty::<impl rustc_middle::ty::context::TyCtxt>::par_body_owners
  37: rustc_typeck::check::typeck_item_bodies
  38: rustc_query_system::dep_graph::graph::DepGraph<K>::with_task_impl
  39: rustc_data_structures::stack::ensure_sufficient_stack
  40: rustc_query_system::query::plumbing::force_query_with_job
  41: rustc_query_system::query::plumbing::get_query_impl
  42: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::typeck_item_bodies
  43: rustc_session::utils::<impl rustc_session::session::Session>::time
  44: rustc_typeck::check_crate
  45: rustc_interface::passes::analysis
  46: rustc_middle::dep_graph::<impl rustc_query_system::dep_graph::DepKind for rustc_middle::dep_graph::dep_node::DepKind>::with_deps
  47: rustc_query_system::dep_graph::graph::DepGraph<K>::with_task_impl
  48: rustc_query_system::dep_graph::graph::DepGraph<K>::with_eval_always_task
  49: rustc_data_structures::stack::ensure_sufficient_stack
  50: rustc_query_system::query::plumbing::force_query_with_job
  51: rustc_query_system::query::plumbing::get_query_impl
  52: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::analysis
  53: rustc_interface::queries::<impl rustc_interface::interface::Compiler>::enter
  54: rustc_span::with_source_map
  55: rustc_interface::interface::create_compiler_and_run
  56: scoped_tls::ScopedKey<T>::set
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

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/issues/new?labels=C-bug%2C+I-ICE%2C+T-compiler&template=ice.md

note: rustc 1.55.0-nightly (6d820866a 2021-06-29) running on x86_64-unknown-linux-gnu

note: compiler flags: -Z unstable-options -C embed-bitcode=no -C debuginfo=2 -C incremental

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

query stack during panic:
#0 [normalize_generic_arg_after_erasing_regions] normalizing `[closure@benches/fs.rs:66:16: 77:6]`
#1 [typeck] type-checking `async_read_std_file`
#2 [typeck_item_bodies] type-checking all item bodies
#3 [analysis] running analysis passes on this crate
end of query stack
error: build failed

This issue has been assigned to @arora-aman via this comment.

[rylev]

This looks to be related to #86743.

[nikomatsakis]

@rustbot assign @arora-aman

I'm hoping this is the same as #86743!

[lqd]

Reduced the one happening in reqwest

use std::future::Future;
struct Runtime;
impl Runtime {
    pub fn block_on<F: Future>(&self, _future: F) -> F::Output {
        unimplemented!()
    }
}
pub fn http<F, Fut>(_func: F)
where
    F: Fn() -> Fut,
    Fut: Future<Output = ()>,
{
    let rt = Runtime {};
    let srv = rt.block_on(async move { serve(move || async move { unimplemented!() }) });
    let _ = || rt.block_on(async { srv });
}
pub struct Server<S> {
    _marker: std::marker::PhantomData<S>,
}
pub fn serve<S>(_new_service: S) -> Server<S> {
    unimplemented!()
}

rustc +nightly --edition=2018 --crate-type=lib --cap-lints=warn --force-warns rust-2021-compatibility -Zunstable-options main.rs will ICE:

thread 'rustc' panicked at 'index out of bounds: the len is 0 but the index is 21', /cargo/registry/src/github.com-1ecc6299db9ec823/ena-0.14.0/src/snapshot_vec.rs:199:10
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

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/issues/new?labels=C-bug%2C+I-ICE%2C+T-compiler&template=ice.md

note: rustc 1.55.0-nightly (7100b311d 2021-07-01) running on x86_64-unknown-linux-gnu

note: compiler flags: -Z unstable-options --crate-type lib

query stack during panic:
#0 [normalize_generic_arg_after_erasing_regions] normalizing `Server<[closure@main.rs:14:46: 14:85]>`
#1 [typeck] type-checking `http`
end of query stack