ICE on FnOnce

[P-E-P]

The provided code gives an ICE

Code

#[lang = "sized"]
pub trait Sized {
    // Empty.
}

#[lang = "fn_once"]
pub trait FnOnce<Args> {
    /// The returned type after the call operator is used.
    #[lang = "fn_once_output"]
    type Output;

    /// Performs the call operation.
    extern "rust-call" fn call_once(self, args: Args) -> Self::Output;
}

pub enum Ordering {
    /// An ordering where a compared value is less than another.
    Less = -1,
    /// An ordering where a compared value is equal to another.
    Equal = 0,
    /// An ordering where a compared value is greater than another.
    Greater = 1,
}

pub fn max_by<T, F: FnOnce(&T, &T) -> Ordering>(v1: T, v2: T, compare: F) -> T {
    match compare(&v1, &v2) {
        Ordering::Less | Ordering::Equal => v2,
        Ordering::Greater => v1,
    }
}

pub fn min_by<T, F: FnOnce(&T, &T) -> Ordering>(v1: T, v2: T, compare: F) -> T {
    match compare(&v1, &v2) {
        Ordering::Less | Ordering::Equal => v1,
        Ordering::Greater => v2,
    }
}

https://godbolt.org/z/4Gjbbd4dK

Meta

• 611d0bd

Error output

crab1: internal compiler error: in TyVar, at rust/typecheck/rust-tyty-util.cc:31

Backtrace

crab1: internal compiler error: in TyVar, at rust/typecheck/rust-tyty-util.cc:31
0x1574d65 Rust::TyTy::TyVar::TyVar(unsigned int)
  /home/patryp/Documents/gccrs/build/gcc/../../gcc/rust/typecheck/rust-tyty-util.cc:31
0x155897a Rust::TyTy::PlaceholderType::resolve() const
  /home/patryp/Documents/gccrs/build/gcc/../../gcc/rust/typecheck/rust-tyty.cc:3561
0x155784e Rust::TyTy::BaseType::destructure() const
  /home/patryp/Documents/gccrs/build/gcc/../../gcc/rust/typecheck/rust-tyty.cc:538
0x155a534 Rust::TyTy::BaseType::needs_generic_substitutions() const
  /home/patryp/Documents/gccrs/build/gcc/../../gcc/rust/typecheck/rust-tyty.cc:831
0x155f5fa Rust::TyTy::FnType::handle_substitions(Rust::TyTy::SubstitutionArgumentMappings&)
  /home/patryp/Documents/gccrs/build/gcc/../../gcc/rust/typecheck/rust-tyty.cc:2018
0x161fa00 Rust::Resolver::SubstMapperInternal::visit(Rust::TyTy::FnType&)
  /home/patryp/Documents/gccrs/build/gcc/../../gcc/rust/typecheck/rust-substitution-mapper.cc:198
0x155e91d Rust::TyTy::FnType::accept_vis(Rust::TyTy::TyVisitor&)
  /home/patryp/Documents/gccrs/build/gcc/../../gcc/rust/typecheck/rust-tyty.cc:1879
0x161f7d1 Rust::Resolver::SubstMapperInternal::Resolve(Rust::TyTy::BaseType*, Rust::TyTy::SubstitutionArgumentMappings&)
  /home/patryp/Documents/gccrs/build/gcc/../../gcc/rust/typecheck/rust-substitution-mapper.cc:146
0x15a151a Rust::TyTy::TypeBoundPredicateItem::get_tyty_for_receiver(Rust::TyTy::BaseType const*)
  /home/patryp/Documents/gccrs/build/gcc/../../gcc/rust/typecheck/rust-tyty-bounds.cc:600
0x1603c6e Rust::Resolver::MethodResolver::get_predicate_items(Rust::HIR::PathIdentSegment const&, Rust::TyTy::BaseType const&, std::vector<Rust::TyTy::TypeBoundPredicate, std::allocator<Rust::TyTy::TypeBoundPredicate> > const&)
  /home/patryp/Documents/gccrs/build/gcc/../../gcc/rust/typecheck/rust-hir-dot-operator.cc:472
0x1603ab2 Rust::Resolver::MethodResolver::try_hook(Rust::TyTy::BaseType const&)
  /home/patryp/Documents/gccrs/build/gcc/../../gcc/rust/typecheck/rust-hir-dot-operator.cc:89
0x161ebc7 Rust::Resolver::AutoderefCycle::try_autoderefed(Rust::TyTy::BaseType*)
  /home/patryp/Documents/gccrs/build/gcc/../../gcc/rust/typecheck/rust-autoderef.cc:421
0x161e77a Rust::Resolver::AutoderefCycle::cycle(Rust::TyTy::BaseType*)
  /home/patryp/Documents/gccrs/build/gcc/../../gcc/rust/typecheck/rust-autoderef.cc:330
0x16037aa Rust::Resolver::MethodResolver::Probe(Rust::TyTy::BaseType*, Rust::HIR::PathIdentSegment const&, bool)
  /home/patryp/Documents/gccrs/build/gcc/../../gcc/rust/typecheck/rust-hir-dot-operator.cc:40
0x15cd048 Rust::Resolver::TypeCheckExpr::resolve_fn_trait_call(Rust::HIR::CallExpr&, Rust::TyTy::BaseType*, Rust::TyTy::BaseType**)
  /home/patryp/Documents/gccrs/build/gcc/../../gcc/rust/typecheck/rust-hir-type-check-expr.cc:1896
0x15ccef9 Rust::Resolver::TypeCheckExpr::visit(Rust::HIR::CallExpr&)
  /home/patryp/Documents/gccrs/build/gcc/../../gcc/rust/typecheck/rust-hir-type-check-expr.cc:217
0x14429f0 Rust::HIR::CallExpr::accept_vis(Rust::HIR::HIRExpressionVisitor&)
  /home/patryp/Documents/gccrs/build/gcc/../../gcc/rust/hir/tree/rust-hir.cc:4831
0x15cc3c9 Rust::Resolver::TypeCheckExpr::Resolve(Rust::HIR::Expr*)
  /home/patryp/Documents/gccrs/build/gcc/../../gcc/rust/typecheck/rust-hir-type-check-expr.cc:42
0x15d4726 Rust::Resolver::TypeCheckExpr::visit(Rust::HIR::MatchExpr&)
  /home/patryp/Documents/gccrs/build/gcc/../../gcc/rust/typecheck/rust-hir-type-check-expr.cc:1469
0x14428a0 Rust::HIR::MatchExpr::accept_vis(Rust::HIR::HIRExpressionVisitor&)
  /home/patryp/Documents/gccrs/build/gcc/../../gcc/rust/hir/tree/rust-hir.cc:4789
Please submit a full bug report, with preprocessed source (by using -freport-bug).
Please include the complete backtrace with any bug report.
See <https://gcc.gnu.org/bugs/> for instructions.