ICE: `SizeSkeleton::compute` layout errored in `layout.rs`

Code

(hand-reduced)

#![feature(impl_trait_in_assoc_type)]

trait Trait: Sized {
    type Assoc2;
}

impl Trait for Bar {
    type Assoc2 = impl std::fmt::Debug;
}

struct Foo {
    field: <Bar as Trait>::Assoc2,
}

enum Bar {
    C = 42,
    D = 99,
}

static BAR: u8 = 42;

static FOO2: (&Foo, &<Bar as Trait>::Assoc2) =
    unsafe { (std::mem::transmute(&BAR), std::mem::transmute(&BAR)) };

fn main() {}

(original)

```Rust //! This test demonstrates a bug where we accidentally //! detected opaque types in struct fields, but only if nested //! in projections of another opaque type. #![feature(impl_trait_in_assoc_type)] struct Bar; trait Trait: Sized { type Assoc2; type Assoc; fn foo() -> Self::Assoc; } impl Trait for Bar { type Assoc2 = impl std::fmt::Debug; type Assoc = impl Iterator; fn foo() -> Self::Assoc { vec![Foo { field: () }].into_iter() //~^ ERROR mismatched types } } struct Foo { field: ::Assoc2, } fn main() {} //@ check-pass enum Foo { A = 5, B = 42, } enum Bar { C = 42, D = 99, } #[repr(C)] union Union { foo: &'static Foo, bar: &'static Bar, u8: &'static u8, } static BAR: u8 = 42; static FOO: (&Foo, &Bar) = unsafe {( Union { u8: &BAR }.foo, Union { u8: &BAR }.bar, )}; static FOO2: (&Foo, &::Assoc2) = unsafe {(std::mem::transmute(&BAR), std::mem::transmute(&BAR))}; fn main() {} ```

Error output

Command: rustc

error: unconstrained opaque type
 --> r_layout_4A229A.rs:8:19
  |
8 |     type Assoc2 = impl std::fmt::Debug;
  |                   ^^^^^^^^^^^^^^^^^^^^
  |
  = note: `Assoc2` must be used in combination with a concrete type within the same impl

Backtrace

``` error: internal compiler error: compiler/rustc_middle/src/ty/layout.rs:382:26: SizeSkeleton::compute(&Foo): layout errored (Unknown(Alias(Projection, AliasTy { args: [Foo], def_id: DefId(2:2141 ~ core[cbba]::ptr::metadata::Pointee::Metadata) }))), yet tail `::Assoc2` is not a type parameter or a projection thread 'rustc' panicked at compiler/rustc_middle/src/ty/layout.rs:382:26: Box stack backtrace: 0: std::panicking::begin_panic:: 1: ::emit_producing_guarantee 2: rustc_middle::util::bug::opt_span_bug_fmt::::{closure#0} 3: rustc_middle::ty::context::tls::with_opt::::{closure#0}, !>::{closure#0} 4: rustc_middle::ty::context::tls::with_context_opt::::{closure#0}, !>::{closure#0}, !> 5: rustc_middle::util::bug::bug_fmt 6: ::compute 7: ::check_transmutes 8: rustc_hir_typeck::typeck [... omitted 1 frame ...] 9: rustc_hir_analysis::check::check::check_item_type 10: rustc_hir_analysis::check::wfcheck::check_well_formed [... omitted 1 frame ...] 11: rustc_middle::query::plumbing::query_ensure_error_guaranteed::>, ()> 12: rustc_hir_analysis::check::wfcheck::check_mod_type_wf [... omitted 1 frame ...] 13: rustc_hir_analysis::check_crate 14: rustc_interface::passes::run_required_analyses 15: rustc_interface::passes::analysis [... omitted 1 frame ...] 16: >::enter::, rustc_driver_impl::run_compiler::{closure#0}::{closure#1}::{closure#3}> 17: rustc_interface::interface::run_compiler::, rustc_driver_impl::run_compiler::{closure#0}>::{closure#1} 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: please make sure that you have updated to the latest nightly note: please attach the file at `/Volumes/T7/workspace/240529_100chaos_tree_combine_typ/icefiles/rustc-ice-2024-05-30T06_54_29-96455.txt` to your bug report query stack during panic: #0 [typeck] type-checking `FOO2` #1 [check_well_formed] checking that `FOO2` is well-formed #2 [check_mod_type_wf] checking that types are well-formed in top-level module #3 [analysis] running analysis passes on this crate end of query stack error: aborting due to 2 previous errors ```

Note

ICE location: compiler/rustc_middle/src/ty/layout.rs L382-L385 https://github.com/rust-lang/rust/blob/debd22da66cfa97c74040ebf68e420672ac8560e/compiler/rustc_middle/src/ty/layout.rs#L373-L385
Related ICE issues that points to identical ICE location:
- 124031 (Fixed)
- 109078 (Fixed)

rust-lang / rust