const panic ICE: ref_to_mplace called on non-ptr type

[DutchGhost]

The following ICE's:

#![feature(const_if_match)]
#![feature(const_fn)]
#![feature(const_panic)]

const fn bug(mut array: &[isize], mut ip: usize) {
    match array[ip] {
        _ => panic!(1),
    }
    
}

const _: () = bug(&[1], 0);

Backtrace:

 Compiling playground v0.0.1 (/playground)
warning: function is never used: `bug`
 --> src/lib.rs:5:10
  |
5 | const fn bug(array: &[isize], ip: usize) {
  |          ^^^
  |
  = note: `#[warn(dead_code)]` on by default

thread 'rustc' panicked at '`ref_to_mplace` called on non-ptr type', src/librustc_mir/interpret/place.rs:309:13
stack backtrace:
   0: backtrace::backtrace::libunwind::trace
             at /cargo/registry/src/github.com-1ecc6299db9ec823/backtrace-0.3.40/src/backtrace/libunwind.rs:88
   1: backtrace::backtrace::trace_unsynchronized
             at /cargo/registry/src/github.com-1ecc6299db9ec823/backtrace-0.3.40/src/backtrace/mod.rs:66
   2: std::sys_common::backtrace::_print_fmt
             at src/libstd/sys_common/backtrace.rs:77
   3: <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt
             at src/libstd/sys_common/backtrace.rs:59
   4: core::fmt::write
             at src/libcore/fmt/mod.rs:1052
   5: std::io::Write::write_fmt
             at src/libstd/io/mod.rs:1428
   6: std::sys_common::backtrace::_print
             at src/libstd/sys_common/backtrace.rs:62
   7: std::sys_common::backtrace::print
             at src/libstd/sys_common/backtrace.rs:49
   8: std::panicking::default_hook::{{closure}}
             at src/libstd/panicking.rs:204
   9: std::panicking::default_hook
             at src/libstd/panicking.rs:224
  10: rustc_driver::report_ice
  11: std::panicking::rust_panic_with_hook
             at src/libstd/panicking.rs:474
  12: rust_begin_unwind
             at src/libstd/panicking.rs:378
  13: core::panicking::panic_fmt
             at src/libcore/panicking.rs:85
  14: core::option::expect_failed
             at src/libcore/option.rs:1191
  15: rustc_mir::interpret::place::<impl rustc_mir::interpret::eval_context::InterpCx<M>>::ref_to_mplace
  16: rustc_mir::interpret::place::<impl rustc_mir::interpret::eval_context::InterpCx<M>>::deref_operand
  17: rustc_mir::interpret::intrinsics::<impl rustc_mir::interpret::eval_context::InterpCx<M>>::hook_panic_fn
  18: <rustc_mir::const_eval::machine::CompileTimeInterpreter as rustc_mir::interpret::machine::Machine>::find_mir_or_eval_fn
  19: rustc_mir::interpret::terminator::<impl rustc_mir::interpret::eval_context::InterpCx<M>>::eval_fn_call
  20: rustc_mir::interpret::step::<impl rustc_mir::interpret::eval_context::InterpCx<M>>::run
  21: rustc_mir::const_eval::eval_queries::const_eval_raw_provider
  22: rustc::ty::query::__query_compute::const_eval_raw
  23: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt>::get_query
  24: rustc_mir::const_eval::eval_queries::const_eval_validated_provider
  25: rustc::ty::query::__query_compute::const_eval_validated
  26: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt>::get_query
  27: rustc_mir::const_eval::eval_queries::const_eval_validated_provider
  28: rustc::ty::query::__query_compute::const_eval_validated
  29: rustc::ty::query::<impl rustc::ty::query::config::QueryAccessors for rustc::ty::query::queries::const_eval_validated>::compute
  30: rustc::dep_graph::graph::DepGraph::with_task_impl
  31: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt>::get_query
  32: rustc::mir::interpret::queries::<impl rustc::ty::context::TyCtxt>::const_eval_poly
  33: <rustc_lint::BuiltinCombinedLateLintPass as rustc_lint::passes::LateLintPass>::check_item
  34: rustc_hir::intravisit::Visitor::visit_nested_item
  35: rustc_hir::intravisit::walk_crate
  36: rustc_session::utils::<impl rustc_session::session::Session>::time
  37: __rust_maybe_catch_panic
             at src/libpanic_unwind/lib.rs:86
  38: <std::panic::AssertUnwindSafe<F> as core::ops::function::FnOnce<()>>::call_once
  39: __rust_maybe_catch_panic
             at src/libpanic_unwind/lib.rs:86
  40: rustc_session::utils::<impl rustc_session::session::Session>::time
  41: rustc_interface::passes::analysis
  42: rustc::ty::query::__query_compute::analysis
  43: rustc::dep_graph::graph::DepGraph::with_task_impl
  44: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt>::get_query
  45: rustc::ty::context::tls::enter_global
  46: rustc_interface::interface::run_compiler_in_existing_thread_pool
  47: scoped_tls::ScopedKey<T>::set
  48: syntax::attr::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 1.42.0-nightly (13db6501c 2020-02-01) running on x86_64-unknown-linux-gnu

note: compiler flags: -C codegen-units=1 -C debuginfo=2 --crate-type lib

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

query stack during panic:
#0 [const_eval_raw] const-evaluating `_`
#1 [const_eval_validated] const-evaluating + checking `_`
#2 [const_eval_validated] const-evaluating + checking `_`
#3 [analysis] running analysis passes on this crate
end of query stack
error: could not compile `playground`.

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

[jonas-schievink]

Duplicate of #66693