ICE in const_evaluatable_checked

[DutchGhost]

I got a little excited with #76559 merged, soooo I gave it a try, and I found this rather funny ICE. Notice how I call test::<2>(), without a type parameter, while the function expects a type parameter.

Code

#![feature(const_generics, const_evaluatable_checked)]
#![allow(incomplete_features)]

struct Bool<const B: bool>;

trait True {}

impl True for Bool<true> {}

fn test<T, const P: usize>() where Bool<{core::mem::size_of::<T>() > 4}>: True {
    todo!()
}

fn main() {
    test::<2>();
}

Meta

rustc --version --verbose:

rustc 1.48.0-nightly (a1947b3f9 2020-09-10)

Error output

error: internal compiler error: compiler/rustc_middle/src/ty/layout.rs:1263:17: Layout::compute: unexpected type `^0`

Backtrace

thread 'rustc' panicked at 'Box<Any>', compiler/rustc_errors/src/lib.rs:945:9
stack backtrace:
   0: std::panicking::begin_panic
   1: rustc_errors::HandlerInner::bug
   2: rustc_errors::Handler::bug
   3: rustc_middle::util::bug::opt_span_bug_fmt::{{closure}}
   4: rustc_middle::ty::context::tls::with_opt::{{closure}}
   5: rustc_middle::ty::context::tls::with_opt
   6: rustc_middle::util::bug::opt_span_bug_fmt
   7: rustc_middle::util::bug::bug_fmt
   8: rustc_middle::ty::layout::LayoutCx<rustc_middle::ty::context::TyCtxt>::layout_raw_uncached
   9: rustc_middle::ty::layout::layout_raw
  10: rustc_middle::ty::query::<impl rustc_query_system::query::config::QueryAccessors<rustc_middle::ty::context::TyCtxt> for rustc_middle::ty::query::queries::layout_raw>::compute
  11: rustc_query_system::dep_graph::graph::DepGraph<K>::with_task_impl
  12: rustc_data_structures::stack::ensure_sufficient_stack
  13: rustc_query_system::query::plumbing::get_query_impl
  14: <rustc_middle::ty::layout::LayoutCx<rustc_middle::ty::context::TyCtxt> as rustc_target::abi::LayoutOf>::layout_of
  15: rustc_mir::interpret::intrinsics::eval_nullary_intrinsic
  16: rustc_mir::const_eval::eval_queries::const_eval_validated_provider
  17: rustc_middle::ty::query::<impl rustc_query_system::query::config::QueryAccessors<rustc_middle::ty::context::TyCtxt> for rustc_middle::ty::query::queries::const_eval_validated>::compute
  18: rustc_query_system::dep_graph::graph::DepGraph<K>::with_task_impl
  19: rustc_data_structures::stack::ensure_sufficient_stack
  20: rustc_query_system::query::plumbing::get_query_impl
  21: rustc_middle::mir::interpret::queries::<impl rustc_middle::ty::context::TyCtxt>::const_eval_global_id
  22: rustc_mir::interpret::eval_context::InterpCx<M>::const_eval
  23: rustc_mir::interpret::intrinsics::<impl rustc_mir::interpret::eval_context::InterpCx<M>>::emulate_intrinsic
  24: <rustc_mir::const_eval::machine::CompileTimeInterpreter as rustc_mir::interpret::machine::Machine>::call_intrinsic
  25: rustc_mir::interpret::terminator::<impl rustc_mir::interpret::eval_context::InterpCx<M>>::eval_fn_call
  26: rustc_mir::interpret::step::<impl rustc_mir::interpret::eval_context::InterpCx<M>>::run
  27: rustc_mir::const_eval::eval_queries::const_eval_raw_provider
  28: rustc_middle::ty::query::<impl rustc_query_system::query::config::QueryAccessors<rustc_middle::ty::context::TyCtxt> for rustc_middle::ty::query::queries::const_eval_raw>::compute
  29: rustc_query_system::dep_graph::graph::DepGraph<K>::with_task_impl
  30: rustc_data_structures::stack::ensure_sufficient_stack
  31: rustc_query_system::query::plumbing::get_query_impl
  32: rustc_mir::const_eval::machine::<impl rustc_mir::interpret::eval_context::InterpCx<rustc_mir::const_eval::machine::CompileTimeInterpreter>>::try_eval_const_fn_call
  33: <rustc_mir::const_eval::machine::CompileTimeInterpreter as rustc_mir::interpret::machine::Machine>::find_mir_or_eval_fn
  34: rustc_mir::interpret::terminator::<impl rustc_mir::interpret::eval_context::InterpCx<M>>::eval_fn_call
  35: rustc_mir::interpret::step::<impl rustc_mir::interpret::eval_context::InterpCx<M>>::run
  36: rustc_mir::const_eval::eval_queries::const_eval_raw_provider
  37: rustc_middle::ty::query::<impl rustc_query_system::query::config::QueryAccessors<rustc_middle::ty::context::TyCtxt> for rustc_middle::ty::query::queries::const_eval_raw>::compute
  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::get_query_impl
  41: rustc_mir::const_eval::eval_queries::const_eval_validated_provider
  42: rustc_middle::ty::query::<impl rustc_query_system::query::config::QueryAccessors<rustc_middle::ty::context::TyCtxt> for rustc_middle::ty::query::queries::const_eval_validated>::compute
  43: rustc_query_system::dep_graph::graph::DepGraph<K>::with_task_impl
  44: rustc_data_structures::stack::ensure_sufficient_stack
  45: rustc_query_system::query::plumbing::get_query_impl
  46: rustc_middle::mir::interpret::queries::<impl rustc_middle::ty::context::TyCtxt>::const_eval_global_id
  47: rustc_middle::mir::interpret::queries::<impl rustc_middle::ty::context::TyCtxt>::const_eval_resolve
  48: rustc_infer::infer::InferCtxt::const_eval_resolve
  49: rustc_trait_selection::traits::const_evaluatable::is_const_evaluatable
  50: rustc_data_structures::obligation_forest::ObligationForest<O>::process_obligations
  51: <rustc_trait_selection::traits::fulfill::FulfillmentContext as rustc_infer::traits::engine::TraitEngine>::select_where_possible
  52: rustc_typeck::check::FnCtxt::resolve_vars_with_obligations
  53: rustc_typeck::check::FnCtxt::structurally_resolved_type
  54: rustc_typeck::check::callee::<impl rustc_typeck::check::FnCtxt>::check_call
  55: rustc_typeck::check::expr::<impl rustc_typeck::check::FnCtxt>::check_expr_kind
  56: rustc_typeck::check::expr::<impl rustc_typeck::check::FnCtxt>::check_expr_with_expectation
  57: rustc_typeck::check::FnCtxt::check_stmt
  58: rustc_typeck::check::FnCtxt::check_block_with_expected
  59: rustc_typeck::check::expr::<impl rustc_typeck::check::FnCtxt>::check_expr_kind
  60: rustc_typeck::check::expr::<impl rustc_typeck::check::FnCtxt>::check_expr_with_expectation
  61: rustc_typeck::check::expr::<impl rustc_typeck::check::FnCtxt>::check_return_expr
  62: rustc_typeck::check::check_fn
  63: rustc_infer::infer::InferCtxtBuilder::enter
  64: rustc_typeck::check::typeck
  65: rustc_middle::ty::query::<impl rustc_query_system::query::config::QueryAccessors<rustc_middle::ty::context::TyCtxt> for rustc_middle::ty::query::queries::typeck>::compute
  66: rustc_query_system::dep_graph::graph::DepGraph<K>::with_task_impl
  67: rustc_data_structures::stack::ensure_sufficient_stack
  68: rustc_query_system::query::plumbing::get_query_impl
  69: rustc_query_system::query::plumbing::ensure_query_impl
  70: rustc_typeck::check::typeck_item_bodies
  71: rustc_middle::ty::query::<impl rustc_query_system::query::config::QueryAccessors<rustc_middle::ty::context::TyCtxt> for rustc_middle::ty::query::queries::typeck_item_bodies>::compute
  72: rustc_query_system::dep_graph::graph::DepGraph<K>::with_task_impl
  73: rustc_data_structures::stack::ensure_sufficient_stack
  74: rustc_query_system::query::plumbing::get_query_impl
  75: rustc_typeck::check_crate
  76: rustc_interface::passes::analysis
  77: rustc_middle::ty::query::<impl rustc_query_system::query::config::QueryAccessors<rustc_middle::ty::context::TyCtxt> for rustc_middle::ty::query::queries::analysis>::compute
  78: rustc_query_system::dep_graph::graph::DepGraph<K>::with_task_impl
  79: rustc_data_structures::stack::ensure_sufficient_stack
  80: rustc_query_system::query::plumbing::get_query_impl
  81: rustc_interface::queries::<impl rustc_interface::interface::Compiler>::enter
  82: rustc_span::with_source_map
  83: rustc_interface::interface::create_compiler_and_run
  84: scoped_tls::ScopedKey<T>::set
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

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 1.48.0-nightly (a1947b3f9 2020-09-10) running on x86_64-unknown-linux-gnu

note: compiler flags: -C embed-bitcode=no -C codegen-units=1 -C debuginfo=2 --crate-type bin

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

query stack during panic:
#0 [layout_raw] computing layout of `^0`
#1 [const_eval_validated] const-evaluating + checking `std::intrinsics::size_of`
#2 [const_eval_raw] const-evaluating `std::mem::size_of`
#3 [const_eval_raw] const-evaluating `test::{{constant}}#0`
#4 [const_eval_validated] const-evaluating + checking `test::{{constant}}#0`
#5 [typeck] type-checking `main`
#6 [typeck_item_bodies] type-checking all item bodies
#7 [analysis] running analysis passes on this crate
end of query stack

[lcnr]

yeah, that ICE is interesting 🤔 and why is it only triggered with const-evaluatable_checked?

@rustbot claim