Trait generic defaults cause panic on cycle

[Agapurnis]

Trace

Click here to expand.

thread 'Worker' panicked at 'called `Option::unwrap()` on a `None` value', /Users/runner/.cargo/registry/src/index.crates.io-6f17d22bba15001f/salsa-0.17.0-pre.2/src/runtime.rs:306:18
stack backtrace:
   0: _rust_begin_unwind
   1: core::panicking::panic_fmt
   2: core::panicking::panic
   3: salsa::runtime::Runtime::report_unexpected_cycle
   4: salsa::derived::slot::Slot<Q,MP>::read
   5: <salsa::derived::DerivedStorage<Q,MP> as salsa::plumbing::QueryStorageOps<Q>>::try_fetch
   6: <DB as hir_ty::db::HirDatabase>::generic_defaults::__shim
   7: <DB as hir_ty::db::HirDatabase>::generic_defaults
   8: hir_ty::lower::TyLoweringContext::substs_from_args_and_bindings
   9: hir_ty::lower::TyLoweringContext::lower_trait_ref_from_path
  10: hir_ty::lower::TyLoweringContext::lower_type_bound
  11: <core::iter::adapters::flatten::FlatMap<I,U,F> as core::iter::traits::iterator::Iterator>::next
  12: <alloc::vec::Vec<T> as alloc::vec::spec_from_iter::SpecFromIter<T,I>>::from_iter
  13: hir_ty::lower::TyLoweringContext::lower_dyn_trait
  14: hir_ty::lower::TyLoweringContext::lower_ty_ext
  15: core::ops::function::impls::<impl core::ops::function::FnOnce<A> for &mut F>::call_once
  16: <alloc::vec::Vec<T> as alloc::vec::spec_from_iter::SpecFromIter<T,I>>::from_iter
  17: hir_ty::lower::generic_defaults_query
  18: salsa::runtime::Runtime::execute_query_implementation
  19: salsa::derived::slot::Slot<Q,MP>::read_upgrade
  20: salsa::derived::slot::Slot<Q,MP>::maybe_changed_since
  21: <salsa::derived::DerivedStorage<Q,MP> as salsa::plumbing::QueryStorageOps<Q>>::maybe_changed_since
  22: salsa::derived::slot::MemoRevisions::validate_memoized_value
  23: salsa::derived::slot::Slot<Q,MP>::read_upgrade
  24: salsa::derived::slot::Slot<Q,MP>::maybe_changed_since
  25: <salsa::derived::DerivedStorage<Q,MP> as salsa::plumbing::QueryStorageOps<Q>>::maybe_changed_since
  26: salsa::derived::slot::MemoRevisions::validate_memoized_value
  27: salsa::derived::slot::Slot<Q,MP>::read_upgrade
  28: salsa::derived::slot::Slot<Q,MP>::read
  29: <salsa::derived::DerivedStorage<Q,MP> as salsa::plumbing::QueryStorageOps<Q>>::try_fetch
  30: <DB as hir_ty::db::HirDatabase>::trait_environment::__shim
  31: <DB as hir_ty::db::HirDatabase>::trait_environment
  32: hir_ty::lower::trait_environment_for_body_query
  33: <DB as hir_ty::db::HirDatabase>::trait_environment_for_body
  34: hir_ty::infer::infer_query
  35: salsa::runtime::Runtime::execute_query_implementation
  36: salsa::derived::slot::Slot<Q,MP>::read_upgrade
  37: salsa::derived::slot::Slot<Q,MP>::read
  38: <salsa::derived::DerivedStorage<Q,MP> as salsa::plumbing::QueryStorageOps<Q>>::try_fetch
  39: <DB as hir_ty::db::HirDatabase>::infer_query::__shim
  40: <DB as hir_ty::db::HirDatabase>::infer_query
  41: hir_ty::db::infer_wait
  42: <DB as hir_ty::db::HirDatabase>::infer
  43: hir::Local::ty
  44: ide::syntax_highlighting::highlight::highlight_def
  45: ide::syntax_highlighting::highlight::name_like
  46: ide::syntax_highlighting::highlight
  47: std::panicking::try
  48: rust_analyzer::handlers::request::handle_semantic_tokens_full_delta
  49: std::panicking::try
  50: core::ops::function::FnOnce::call_once{{vtable.shim}}

Reproduction Steps

pub trait Bar <T: ?Sized = dyn Foo<dyn std::any::Any>> {}
pub trait Foo <T: ?Sized + Bar = dyn Bar> {
    fn baz(&self) -> ! {
        unimplemented!();
    }
}

Hover on one of either: &self, baz, unimplemented!(), or Foo's T.

It will also occur when attempting to do other stuff that might end up needing details regarding one of the above traits.

Environment Details

• rust-analyzer version: 0.3.1541-standalone (2f1b7cedc 2023-06-04)
• rustc version: rustc 1.70.0 (90c541806 2023-05-31)

Related Issues

• 'called Option::unwrap() on a None value' when editing KAS GUI applications #10386
• "called Option::unwrap() on a None value" in salsa #5001

[lowr]

I can reproduce this issue, but only when I type something and rust-analyzer reanalyzes. Because we do handle generic defaults cycles gracefully, and because the call stack shows we're panicking at salsa::runtime::Runtime::report_unexpected_cycle that was removed after salsa v0.17.0-pre.2 (the version we're using) was published, I'm beginning to suspect this is a salsa bug that was addressed by salsa-rs/salsa#285.

[Veykril]

Seems to be fixed now with salsa bumped