ICE in const_prop.rs:633: 'index out of bounds: the len is 1 but the index is 1'

[bytwise]

This code results in an ICE when compiling using -Z mir-opt-level=3.

trait Write {
    fn write();
}

impl Write for () {
    fn write() {
        let none = |_| { None };
        let _: Option<()> = none("blink");
    }
}

thread 'rustc' panicked at 'index out of bounds: the len is 1 but the index is 1', src/librustc_mir/transform/const_prop.rs:633:42
stack backtrace:
   0: <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt
   1: core::fmt::write
   2: std::io::Write::write_fmt
   3: std::panicking::default_hook::{{closure}}
   4: std::panicking::default_hook
   5: rustc_driver::report_ice
   6: std::panicking::rust_panic_with_hook
   7: std::panicking::continue_panic_fmt
   8: rust_begin_unwind
   9: core::panicking::panic_fmt
  10: core::panicking::panic_bounds_check
  11: <rustc_mir::transform::const_prop::ConstPropagator as rustc::mir::visit::MutVisitor>::visit_statement
  12: <rustc_mir::transform::const_prop::ConstProp as rustc_mir::transform::MirPass>::run_pass
  13: rustc_mir::transform::run_passes
  14: rustc_mir::transform::run_optimization_passes
  15: rustc_mir::transform::optimized_mir
  16: rustc::ty::query::<impl rustc::ty::query::config::QueryAccessors for rustc::ty::query::queries::optimized_mir>::compute
  17: rustc::dep_graph::graph::DepGraph::with_task_impl
  18: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt>::get_query
  19: rustc_mir::monomorphize::collector::collect_items_rec
  20: rustc_mir::monomorphize::collector::collect_crate_mono_items::{{closure}}
  21: rustc::util::common::time
  22: rustc_mir::monomorphize::collector::collect_crate_mono_items
  23: rustc::util::common::time
  24: rustc_mir::monomorphize::partitioning::collect_and_partition_mono_items
  25: rustc::ty::query::__query_compute::collect_and_partition_mono_items
  26: rustc::dep_graph::graph::DepGraph::with_task_impl
  27: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt>::get_query
  28: rustc_codegen_ssa::base::codegen_crate
  29: <rustc_codegen_llvm::LlvmCodegenBackend as rustc_codegen_utils::codegen_backend::CodegenBackend>::codegen_crate
  30: rustc_interface::passes::start_codegen::{{closure}}
  31: rustc_interface::passes::start_codegen
  32: rustc::ty::context::tls::enter_global
  33: rustc_interface::passes::BoxedGlobalCtxt::access::{{closure}}
  34: rustc_interface::passes::create_global_ctxt::{{closure}}
  35: rustc_interface::passes::BoxedGlobalCtxt::enter
  36: rustc_interface::queries::Query<T>::compute
  37: rustc_interface::queries::<impl rustc_interface::interface::Compiler>::ongoing_codegen
  38: rustc_interface::interface::run_compiler_in_existing_thread_pool
  39: std::thread::local::LocalKey<T>::with
  40: scoped_tls::ScopedKey<T>::set
  41: syntax::with_globals
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/blob/master/CONTRIBUTING.md#bug-reports

note: rustc 1.40.0-nightly (3fc30d884 2019-11-10) running on x86_64-apple-darwin

note: compiler flags: -Z mir-opt-level=3 -C opt-level=3 --crate-type lib

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

query stack during panic:
#0 [optimized_mir] processing `<() as Write>::write`
#1 [collect_and_partition_mono_items] collect_and_partition_mono_items
end of query stack

[Centril]

cc @wesleywiser @oli-obk

[VirrageS]

Reduced:

fn foo() {
    let bar = |_| { };
    let _ = bar("a");
}

But this compiles:

fn foo() {
    let bar = |_, _| { };
    let _ = bar("a", "b");
}