ICE with higher order associated types
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A-associated-items
A-GATs
C-bug
fixed-by-next-solver
I-ICE
S-bug-has-test
T-compiler
- Dominant language
- Rust
- Stars
- 119k
- Forks
- 16.1k
- PR merge metrics
- PR metrics pending
Description
Code
pub fn into_vec<'inner>(dummy: impl FromRow<'inner>) {
let _f = dummy.prepare();
}
pub fn test() {
into_vec(Assume(Some("test")));
}
pub trait FromRow<'t> {
type Out<'a>;
fn prepare(self) -> impl for<'a> FnMut(&'a ()) -> Self::Out<'a>;
}
impl<'t, T: Value<'t, Typ: MyTyp>> FromRow<'t> for T {
type Out<'a> = <T::Typ as MyTyp>::Out<'a>;
fn prepare(self) -> impl for<'a> FnMut(&'a ()) -> Self::Out<'a> {
move |_| loop {}
}
}
pub struct Assume<A>(pub(crate) A);
impl<'t, T, A: Value<'t, Typ = Option<T>>> Value<'t> for Assume<A> {
type Typ = T;
}
pub trait Value<'t> {
type Typ;
}
impl<'t> Value<'t> for &str {
type Typ = String;
}
impl<'t, T: Value<'t, Typ = X>, X: MyTyp> Value<'t> for Option<T> {
type Typ = Option<T::Typ>;
}
pub trait MyTyp: 'static {
type Out<'t>;
}
impl MyTyp for String {
type Out<'t> = Self;
}
Meta
rustc --version --verbose:
rustc 1.82.0-nightly (5aea14073 2024-08-20)
binary: rustc
commit-hash: 5aea14073eee9e403c3bb857490cd6aa4a395531
commit-date: 2024-08-20
host: x86_64-unknown-linux-gnu
release: 1.82.0-nightly
LLVM version: 19.1.0
Error output
error: the compiler unexpectedly panicked. this is a bug.
Backtrace
thread 'rustc' panicked at compiler/rustc_codegen_llvm/src/debuginfo/metadata/type_map.rs:52:9:
assertion `left == right` failed
left: Closure(DefId(0:19 ~ rust_query[ff33]::{impl#0}::prepare::{closure#0}), ['{erased}, Assume<std::option::Option<&'{erased} str>>, i16, Binder { value: extern "RustCall" fn((&'^0 (),)) -> Alias(Projection, AliasTy { args: [std::string::String, '^0], def_id: DefId(0:37 ~ rust_query[ff33]::MyTyp::Out), .. }), bound_vars: [Region(BrAnon)] }, ()])
right: Closure(DefId(0:19 ~ rust_query[ff33]::{impl#0}::prepare::{closure#0}), ['{erased}, Assume<std::option::Option<&'{erased} str>>, i16, Binder { value: extern "RustCall" fn((&'^0 (),)) -> std::string::String, bound_vars: [Region(BrAnon)] }, ()])
stack backtrace:
0: rust_begin_unwind
1: core::panicking::panic_fmt
2: core::panicking::assert_failed_inner
3: core::panicking::assert_failed::<rustc_middle::ty::Ty, rustc_middle::ty::Ty>
4: rustc_codegen_llvm::debuginfo::metadata::type_di_node
5: rustc_codegen_ssa::mir::codegen_mir::<rustc_codegen_llvm::builder::Builder>
6: rustc_codegen_llvm::base::compile_codegen_unit::module_codegen
7: <rustc_codegen_llvm::LlvmCodegenBackend as rustc_codegen_ssa::traits::backend::ExtraBackendMethods>::compile_codegen_unit
8: <rustc_codegen_llvm::LlvmCodegenBackend as rustc_codegen_ssa::traits::backend::CodegenBackend>::codegen_crate
9: <rustc_interface::queries::Linker>::codegen_and_build_linker
10: rustc_interface::interface::run_compiler::<core::result::Result<(), rustc_span::ErrorGuaranteed>, rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Reproduce the supplied example with the reported rustc 1.82.0-nightly version and inspect the panic in compiler/rustc_codegen_llvm/src/debuginfo/metadata/type_map.rs. Trace the differing closure types shown in the assertion and verify that compiling the example no longer causes an internal compiler error.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- rust
- Domain
- compilers
- Issue type
- Bug
- Difficulty
- 5/5
- Estimated time
- Over a week
- Activity status
- Quiet
- Clarity
- Needs clarification
- Newbie friendliness
- 35/100