Hang after encountering overflow errors for huge types

[ym-xie]

Code

fn main() {
    let mut x = None;
    let y = x;
    let z = Default::default();
    let mut w = (&mut x, z, z);
    let a = (&mut None::<fn(&())>, y, None::<fn(&'static ())>);
    w = z;
}

Affected release channels

• Previous Stable
• Current Stable
• Current Beta
• Current Nightly

Rust Version

rustc 1.84.0-nightly (bc5cf99 2024-11-05)
binary: rustc
commit-hash: bc5cf99
commit-date: 2024-11-05
host: x86_64-unknown-linux-gnu
release: 1.84.0-nightly
LLVM version: 19.1.3

Current error output

No response

Backtrace

Anything else?

[fmease]

I can reproduce the hang without any of the provided compiler flags.

[fmease]

RUSTC_LOG=debug, excerpt:

     rustc_trait_selection::traits::fulfill::process_obligation 
       0ms DEBUG rustc_trait_selection::traits::fulfill pre-resolve, obligation=Obligation(predicate=Binder { value: TraitPredicate(<_ as std::marker::Sized>, polarity:Positive), bound_vars: [] }, depth=129)
       rustc_trait_selection::traits::fulfill::process_trait_obligation trait_obligation=Obligation(predicate=Binder { value: TraitPredicate(<(&mut std::option::Option<_>, _, _) as std::marker::Sized>, polarity:Positive), bound_vars: [] }, depth=129)
         rustc_trait_selection::traits::select::poly_select obligation=Obligation(predicate=Binder { value: TraitPredicate(<(&mut std::option::Option<_>, _, _) as std::marker::Sized>, polarity:Positive), bound_vars: [] }, depth=129)
           rustc_trait_selection::traits::select::candidate_from_obligation stack=TraitObligationStack(Obligation(predicate=Binder { value: TraitPredicate(<(&mut std::option::Option<_>, _, _) as std::marker::Sized>, polarity:Positive), bound_vars: [] }, depth=129))
             rustc_middle::ty::print::default_print_def_path def_id=DefId(2:45807 ~ core[add1]::option::Option), args=[?11t]
               0ms DEBUG rustc_middle::ty::print key=DefKey { parent: Some(DefIndex(9544)), disambiguated_data: DisambiguatedDefPathData { data: TypeNs("Option"), disambiguator: 0 } }
             rustc_middle::ty::print::default_print_def_path def_id=DefId(2:36054 ~ core[add1]::marker::Sized), args=[(&'?391 mut std::option::Option<?11t>, ?403t, ?403t)]
               0ms DEBUG rustc_middle::ty::print key=DefKey { parent: Some(DefIndex(3424)), disambiguated_data: DisambiguatedDefPathData { data: TypeNs("Sized"), disambiguator: 0 } }
            14ms DEBUG rustc_errors::diagnostic Created new diagnostic
             rustc_middle::ty::print::default_print_def_path def_id=DefId(2:45807 ~ core[add1]::option::Option), args=[?11t]
               0ms DEBUG rustc_middle::ty::print key=DefKey { parent: Some(DefIndex(9544)), disambiguated_data: DisambiguatedDefPathData { data: TypeNs("Option"), disambiguator: 0 } }
             rustc_middle::ty::print::default_print_def_path def_id=DefId(2:45807 ~ core[add1]::option::Option), args=[?11t]
               0ms DEBUG rustc_middle::ty::print key=DefKey { parent: Some(DefIndex(9544)), disambiguated_data: DisambiguatedDefPathData { data: TypeNs("Option"), disambiguator: 0 } }
             rustc_middle::ty::print::default_print_def_path def_id=DefId(2:45807 ~ core[add1]::option::Option), args=[?11t]
               0ms DEBUG rustc_middle::ty::print key=DefKey { parent: Some(DefIndex(9544)), disambiguated_data: DisambiguatedDefPathData { data: TypeNs("Option"), disambiguator: 0 } }
          // repeats the two lines above ad infinitum
          // ...

[theemathas]

Minimized reproducer:

fn main() {
    let z = Default::default();
    let mut w = (z, z);
    w = z;
}

Correctly gives an error on rust 1.77.0. Hangs on rust 1.78.0.

@rustbot label +regression-from-stable-to-stable