Rustc panics if a const generic has default value including a const

[zNoctum]

Code

#![allow(incomplete_features)]
#![feature(generic_const_exprs)]

const CONST: u32 = 0;
struct Test<const N: u32, const M: u32 = { CONST/* Must be a const and not a Literal */ }> where [(); N as usize]: , ([u32; N as usize]);

fn main() {
    let _: Test<1>;
}

Meta

rustc --version --verbose:

binary: rustc
commit-hash: e9e1bbc7a820c472b39d3de54b3049bf14050655
commit-date: 2023-05-17
host: x86_64-unknown-linux-gnu
release: 1.71.0-nightly
LLVM version: 16.0.2

Error output

error: internal compiler error: compiler/rustc_middle/src/ty/subst.rs:933:9: const parameter `M/#1` (Const { ty: u32, kind: M/#1 }/1) out of range when substituting substs=[Const { ty: u32, kind: Leaf(0x00000001) }]

Backtrace

   Compiling explody v0.1.0 (/home/user/projects/explody)
error: where clauses are not allowed before tuple struct bodies
 --> src/main.rs:5:53
  |
5 | struct Test<const N: u32, const M: u32 = { CONST }> where [(); N as usize]: , ([u32; N as usize]);
  |        ----                                         ^^^^^^^^^^^^^^^^^^^^^^^^^ ------------------- the struct body
  |        |                                            |
  |        while parsing this tuple struct              unexpected where clause
  |
help: move the body before the where clause
  |
5 - struct Test<const N: u32, const M: u32 = { CONST }> where [(); N as usize]: , ([u32; N as usize]);
5 + struct Test<const N: u32, const M: u32 = { CONST }>([u32; N as usize]) where [(); N as usize]: ;
  |

error: internal compiler error: compiler/rustc_middle/src/ty/subst.rs:933:9: const parameter `M/#1` (Const { ty: u32, kind: M/#1 }/1) out of range when substituting substs=[Const { ty: u32, kind: Leaf(0x00000001) }]

thread 'rustc' panicked at 'Box<dyn Any>', /rustc/e9e1bbc7a820c472b39d3de54b3049bf14050655/compiler/rustc_errors/src/lib.rs:1651:9
stack backtrace:
   0: std::panicking::begin_panic::<rustc_errors::ExplicitBug>
   1: <rustc_errors::HandlerInner>::bug::<alloc::string::String>
   2: <rustc_errors::Handler>::bug::<alloc::string::String>
   3: rustc_middle::util::bug::opt_span_bug_fmt::<rustc_span::span_encoding::Span>::{closure#0}
   4: rustc_middle::ty::context::tls::with_opt::<rustc_middle::util::bug::opt_span_bug_fmt<rustc_span::span_encoding::Span>::{closure#0}, !>::{closure#0}
   5: rustc_middle::ty::context::tls::with_context_opt::<rustc_middle::ty::context::tls::with_opt<rustc_middle::util::bug::opt_span_bug_fmt<rustc_span::span_encoding::Span>::{closure#0}, !>::{closure#0}, !>
   6: rustc_middle::util::bug::bug_fmt
   7: <rustc_middle::ty::subst::SubstFolder>::const_param_out_of_range
   8: <&rustc_middle::ty::list::List<rustc_middle::ty::subst::GenericArg> as rustc_type_ir::fold::TypeFoldable<rustc_middle::ty::context::TyCtxt>>::try_fold_with::<rustc_middle::ty::subst::SubstFolder>
   9: <rustc_middle::ty::consts::Const as rustc_type_ir::fold::TypeSuperFoldable<rustc_middle::ty::context::TyCtxt>>::super_fold_with::<rustc_middle::ty::subst::SubstFolder>
  10: <rustc_middle::ty::Ty as rustc_type_ir::fold::TypeSuperFoldable<rustc_middle::ty::context::TyCtxt>>::super_fold_with::<rustc_middle::ty::subst::SubstFolder>
  11: <rustc_middle::ty::subst::GenericArg as rustc_type_ir::fold::TypeFoldable<rustc_middle::ty::context::TyCtxt>>::try_fold_with::<rustc_middle::ty::subst::SubstFolder>
  12: <alloc::vec::Vec<rustc_middle::ty::Predicate> as alloc::vec::spec_extend::SpecExtend<rustc_middle::ty::Predicate, core::iter::adapters::map::Map<core::slice::iter::Iter<(rustc_middle::ty::Predicate, rustc_span::span_encoding::Span)>, <rustc_middle::ty::generics::GenericPredicates>::instantiate_into::{closure#0}>>>::spec_extend
  13: <rustc_middle::ty::generics::GenericPredicates>::instantiate_into
  14: <rustc_trait_selection::traits::wf::WfPredicates>::nominal_obligations_inner
  15: <rustc_trait_selection::traits::wf::WfPredicates>::compute
  16: <rustc_trait_selection::traits::fulfill::FulfillProcessor as rustc_data_structures::obligation_forest::ObligationProcessor>::process_obligation
  17: <rustc_data_structures::obligation_forest::ObligationForest<rustc_trait_selection::traits::fulfill::PendingPredicateObligation>>::process_obligations::<rustc_trait_selection::traits::fulfill::FulfillProcessor>
  18: <rustc_hir_typeck::fn_ctxt::FnCtxt>::type_inference_fallback
  19: rustc_hir_typeck::typeck
  20: <rustc_query_impl::dynamic_query::typeck::{closure#2} as core::ops::function::FnOnce<(rustc_middle::ty::context::TyCtxt, rustc_span::def_id::LocalDefId)>>::call_once
  21: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::DynamicConfig<rustc_query_system::query::caches::VecCache<rustc_span::def_id::LocalDefId, rustc_middle::query::erase::Erased<[u8; 8]>>, false, false, false>, rustc_query_impl::plumbing::QueryCtxt, true>
  22: rustc_query_system::query::plumbing::force_query::<rustc_query_impl::DynamicConfig<rustc_query_system::query::caches::VecCache<rustc_span::def_id::LocalDefId, rustc_middle::query::erase::Erased<[u8; 8]>>, false, false, false>, rustc_query_impl::plumbing::QueryCtxt>
  23: <rustc_query_impl::plumbing::query_callback<rustc_query_impl::queries::typeck>::{closure#0} as core::ops::function::FnOnce<(rustc_middle::ty::context::TyCtxt, rustc_query_system::dep_graph::dep_node::DepNode<rustc_middle::dep_graph::dep_node::DepKind>)>>::call_once
  24: <rustc_query_system::dep_graph::graph::DepGraphData<rustc_middle::dep_graph::dep_node::DepKind>>::try_mark_previous_green::<rustc_query_impl::plumbing::QueryCtxt>
  25: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::DynamicConfig<rustc_query_system::query::caches::VecCache<rustc_span::def_id::LocalDefId, rustc_middle::query::erase::Erased<[u8; 8]>>, false, false, false>, rustc_query_impl::plumbing::QueryCtxt, true>
  26: rustc_hir_analysis::check_crate
  27: rustc_interface::passes::analysis
  28: <rustc_query_impl::dynamic_query::analysis::{closure#2} as core::ops::function::FnOnce<(rustc_middle::ty::context::TyCtxt, ())>>::call_once
  29: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::DynamicConfig<rustc_query_system::query::caches::SingleCache<rustc_middle::query::erase::Erased<[u8; 1]>>, false, false, false>, rustc_query_impl::plumbing::QueryCtxt, true>
  30: rustc_query_impl::get_query_incr::analysis
  31: <rustc_interface::queries::QueryResult<&rustc_middle::ty::context::GlobalCtxt>>::enter::<core::result::Result<(), rustc_span::ErrorGuaranteed>, rustc_driver_impl::run_compiler::{closure#1}::{closure#2}::{closure#4}>
  32: <rustc_interface::interface::Compiler>::enter::<rustc_driver_impl::run_compiler::{closure#1}::{closure#2}, core::result::Result<core::option::Option<rustc_interface::queries::Linker>, rustc_span::ErrorGuaranteed>>
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

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 1.71.0-nightly (e9e1bbc7a 2023-05-17) running on x86_64-unknown-linux-gnu

note: compiler flags: --crate-type bin -C embed-bitcode=no -C debuginfo=2 -C incremental=[REDACTED]

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

query stack during panic:
#0 [typeck] type-checking `main`
#1 [used_trait_imports] finding used_trait_imports `main`
#2 [analysis] running analysis passes on this crate
end of query stack
there was a panic while trying to force a dep node
try_mark_green dep node stack:
#0 used_trait_imports(explody[44bf]::main)
end of try_mark_green dep node stack
error: could not compile `explody` (bin "explody") due to previous error

[gurry]

Duplicate of #106994

Perhaps we can close this one in favour of that.