ICE: gce: `fn_abi_of_instance(..) failed: Layout(Unknown([FlatTree; UnevaluatedConst { .. }: usize]))`

[jxors]

Code

#![feature(generic_const_exprs)]
#[derive(Copy, Clone, Debug, PartialEq, Eq)]
struct FlatTree;

#[derive(Copy, Clone)]
struct TreeLeaf;

#[derive(Copy, Clone)]
struct TreeNode<V, W>(V, W);

const fn const_concat<const A: usize, const B: usize>(_: [FlatTree; A], _: [FlatTree; B]) -> [FlatTree; A + B] {
    [FlatTree; A + B]
}

struct Builder<const N: usize, I> {
    ops: [FlatTree; N],
    builder: I,
}

fn create_node<const N: usize, const M: usize, A, B>(a: Builder<N, A>, b: Builder<M, B>) -> Builder<{ N + M + 1 }, TreeNode<A, B>> {
    Builder {
        ops: const_concat(const_concat::<N, M>(a.ops, b.ops), [FlatTree]),
        builder: TreeNode(a.builder, b.builder),
    }
}

const LEAF: Builder<1, TreeLeaf> = Builder {
    ops: [FlatTree],
    builder: TreeLeaf,
};

static INTERNAL_SIMPLE_BOOLEAN_TEMPLATES: &[fn()] = &[{
    fn eval() {
        create_node(LEAF, create_node(LEAF, LEAF));
    }

    eval
}];

Meta

rustc --version --verbose:

rustc 1.76.0-nightly (9fad68599 2023-12-03)
binary: rustc
commit-hash: 9fad6859925b34f9a0b1af592a7839ccb1e71f60
commit-date: 2023-12-03
host: x86_64-unknown-linux-gnu
release: 1.76.0-nightly
LLVM version: 17.0.5

Error output

   Compiling minimal-rust v0.1.0 (/home/../workspace/repro/minimal-rust)
[..] (warnings removed)
error: internal compiler error: compiler/rustc_codegen_llvm/src/context.rs:1043:21: `fn_abi_of_instance(const_concat::<{const expr}, 1>, [])` failed: Layout(Unknown([FlatTree; UnevaluatedConst { def: DefId(0:8 ~ minimal_rust[599e]::const_concat::{constant#2}), args: [(Add: 1_usize, 3_usize): usize, 1_usize] }: usize]))
  --> minimal-rust/src/lib.rs:11:1
   |
11 | const fn const_concat<const A: usize, const B: usize>(_: [FlatTree; A], _: [FlatTree; B]) -> [FlatTree; A + B] {
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

thread 'rustc' panicked at /rustc/9fad6859925b34f9a0b1af592a7839ccb1e71f60/compiler/rustc_errors/src/lib.rs:995:33:
Box<dyn Any>


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: please attach the file at `/home/../workspace/repro/rustc-ice-2023-12-04T12_27_11-290639.txt` to your bug report

note: compiler flags: --crate-type lib -C opt-level=2 -C embed-bitcode=no -C debuginfo=2 -C debug-assertions=on -C incremental=[REDACTED]

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

query stack during panic:
end of query stack
warning: `minimal-rust` (lib) generated 6 warnings
error: could not compile `minimal-rust` (lib); 6 warnings emitted

Backtrace

thread 'rustc' panicked at /rustc/9fad6859925b34f9a0b1af592a7839ccb1e71f60/compiler/rustc_errors/src/lib.rs:995:33:
Box<dyn Any>
stack backtrace:
   0: std::panicking::begin_panic::<rustc_errors::ExplicitBug>
   1: <rustc_errors::HandlerInner>::span_bug::<rustc_span::span_encoding::Span, alloc::string::String>
   2: <rustc_errors::Handler>::span_bug::<rustc_span::span_encoding::Span, 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::span_bug_fmt::<rustc_span::span_encoding::Span>
   7: <rustc_codegen_llvm::context::CodegenCx as rustc_middle::ty::layout::FnAbiOfHelpers>::handle_fn_abi_err
   8: <rustc_codegen_llvm::context::CodegenCx as rustc_middle::ty::layout::FnAbiOf>::fn_abi_of_instance::{closure#0}
   9: <rustc_codegen_llvm::context::CodegenCx as rustc_codegen_ssa::traits::declare::PreDefineMethods>::predefine_fn
  10: rustc_codegen_llvm::base::compile_codegen_unit::module_codegen
  11: <rustc_codegen_llvm::LlvmCodegenBackend as rustc_codegen_ssa::traits::backend::ExtraBackendMethods>::compile_codegen_unit
  12: rustc_codegen_ssa::base::codegen_crate::<rustc_codegen_llvm::LlvmCodegenBackend>
  13: <rustc_codegen_llvm::LlvmCodegenBackend as rustc_codegen_ssa::traits::backend::CodegenBackend>::codegen_crate
  14: rustc_interface::passes::start_codegen
  15: <rustc_interface::queries::Queries>::codegen_and_build_linker
  16: rustc_interface::interface::run_compiler::<core::result::Result<(), rustc_span::ErrorGuaranteed>, rustc_driver_impl::run_compiler::{closure#0}>::{closure#0}

[jxors]

cargo-bisect-rustc suggests a regression between 2022-11-26 (8681d4c) and 2022-11-27 (80a9646):

finding bors merge commits
found 8 bors merge commits in the specified range
  commit[0] 2022-11-25: Auto merge of #104902 - matthiaskrgr:rollup-oo27a4u, r=matthiaskrgr
  commit[1] 2022-11-25: Auto merge of #99798 - JulianKnodt:ac1, r=BoxyUwU
  commit[2] 2022-11-26: Auto merge of #104431 - alistair23:alistair/rv64-profiler, r=Mark-Simulacrum
  commit[3] 2022-11-26: Auto merge of #104730 - petrochenkov:modchild5, r=cjgillot
  commit[4] 2022-11-26: Auto merge of #103556 - clubby789:specialize-option-partial-eq, r=scottmcm
  commit[5] 2022-11-26: Auto merge of #104935 - matthiaskrgr:rollup-nuca86l, r=matthiaskrgr
  commit[6] 2022-11-26: Auto merge of #104731 - compiler-errors:early-binder-iter-size-hint, r=cjgillot
  commit[7] 2022-11-26: Auto merge of #104945 - GuillaumeGomez:rollup-ygzbpbe, r=GuillaumeGomez
ERROR: no CI builds available between 8681d4cffcd23bbe619984ab62772a91827a40dc and 80a96467ec5675e9f69683b5c075a8b15950c341 within last 167 days

[Luk-ESC]

Minimized:

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

struct Yo<const N: usize>;

const fn add<const A: usize, const B: usize>(_: Yo<A>, _: Yo<B>) -> Yo<{ A + B }> {
    Yo::<{ A + B }>
}

fn create_node<const N: usize>() -> Yo<{ N + N + 1 }> {
    add(add(Yo::<N>, Yo::<N>), Yo::<1>)
}


fn main(){
    create_node::<42>();
}

EDIT: The above is actually a different ICE, but you can get the old one by replacing Yo<N> with [(); N]:

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

const fn add<const A: usize, const B: usize>(_: [(); A], _: [(); B]) -> [(); A + B] {
    [(); { A + B }]
}

fn create_node<const N: usize>() -> [(); N + N + 1] {
    add(add([(); N], [(); N]), [(); 1])
}


fn main(){
    create_node::<42>();
}

[compiler-errors]

No longer ICEs because we added the necessary normalization I think recently?

@rustbot label: E-needs-test

[jxors]

On 1.86.0-nightly (a580b5c37 2025-01-08 it now crashes with:

/rustc/a580b5c379b4fca50dfe5afc0fc0ce00921e4e00/compiler/rustc_middle/src/mir/consts.rs:333:25: Normalization of `ty::ConstKind::Expr` is unimplemented

Edit: #132960 is related or possibly a duplicate