Rust-analyzer hangs on file with cyclic traits

[RobinStoll]

rust-analyzer version: rust-analyzer 0.4.1143-standalone (4087535 2022-07-27)
rustc version: rustc 1.62.1 (e092d0b6b 2022-07-16)

Reproduction

1. In a fresh cargo directory, replace src/main.rs by the following

pub trait A {
    type X: B;
}

pub trait B {
    type Y: A<X = Self>;
}

pub fn foo<T: A>()
  where T::X: Clone
{
    foo()
}

fn main() {}

2. Call rust-analyzer analysis-stats .

Result

rust-analyzer outputs

Database loaded:     519.19ms, 61minstr (metadata 344.05ms, 730kinstr; build 137.29ms, 302kinstr)
  crates: 1, mods: 1, decls: 4, fns: 2
Item Collection:     3.14s, 19ginstr
0/2 0% processing: foo

and then hangs, continuing to use 100% of one CPU core.

Stack trace

Here's the output of a stack trace generated by gdb for the hanging process:

Thread 1 (Thread 0x7f805c3ecb00 (LWP 28483) "rust-analyzer"):
#0  0x000055a915d386b4 in <chalk_ir::TyData<I> as core::hash::Hash>::hash ()
#1  0x000055a915cd3657 in <hir_ty::interner::Interner as chalk_ir::interner::Interner>::intern_ty ()
#2  0x000055a915da51cf in <core::iter::adapters::map::Map<I,F> as core::iter::traits::iterator::Iterator>::fold ()
#3  0x000055a915d867bb in alloc::vec::in_place_collect::<impl alloc::vec::spec_from_iter::SpecFromIter<T,I> for alloc::vec::Vec<T>>::from_iter ()
#4  0x000055a915d5531f in chalk_recursive::fulfill::Fulfill<I,Solver>::prove ()
#5  0x000055a915d55cf9 in chalk_recursive::fulfill::Fulfill<I,Solver>::solve ()
#6  0x000055a915e0456e in chalk_recursive::solve::SolveIteration::solve_iteration ()
#7  0x000055a915ca701b in chalk_recursive::fixed_point::RecursiveContext<K,V>::solve_goal ()
#8  0x000055a915d553ff in chalk_recursive::fulfill::Fulfill<I,Solver>::prove ()
#9  0x000055a915d55cf9 in chalk_recursive::fulfill::Fulfill<I,Solver>::solve ()
#10 0x000055a915e0456e in chalk_recursive::solve::SolveIteration::solve_iteration ()
#11 0x000055a915ca701b in chalk_recursive::fixed_point::RecursiveContext<K,V>::solve_goal ()
#12 0x000055a915d553ff in chalk_recursive::fulfill::Fulfill<I,Solver>::prove ()
#13 0x000055a915d55cf9 in chalk_recursive::fulfill::Fulfill<I,Solver>::solve ()
#14 0x000055a915e0456e in chalk_recursive::solve::SolveIteration::solve_iteration ()
#15 0x000055a915ca701b in chalk_recursive::fixed_point::RecursiveContext<K,V>::solve_goal ()
#16 0x000055a915ca7feb in chalk_recursive::fixed_point::RecursiveContext<K,V>::solve_root_goal ()
#17 0x000055a915dcbc2a in <hir_ty::db::TraitSolveQueryQuery as salsa::plumbing::QueryFunction>::execute ()
#18 0x000055a915e17467 in salsa::runtime::Runtime::execute_query_implementation ()
#19 0x000055a915c4a40d in salsa::derived::slot::Slot<Q,MP>::read_upgrade ()
#20 0x000055a915c6b490 in salsa::derived::slot::Slot<Q,MP>::read ()
#21 0x000055a915ce5818 in <salsa::derived::DerivedStorage<Q,MP> as salsa::plumbing::QueryStorageOps<Q>>::try_fetch ()
#22 0x000055a915caf0d0 in salsa::QueryTable<Q>::get ()
#23 0x000055a91650bf25 in <DB as hir_ty::db::HirDatabase>::trait_solve_query ()
#24 0x000055a915dc51d4 in hir_ty::db::trait_solve_wait ()
#25 0x000055a91650bcac in <DB as hir_ty::db::HirDatabase>::trait_solve ()
#26 0x000055a915e20a71 in hir_ty::infer::unify::InferenceTable::register_obligation_in_env::hfc53f915e21eb152 ()
#27 0x000055a915e492db in hir_ty::infer::expr::<impl hir_ty::infer::InferenceContext>::register_obligations_for_call ()
#28 0x000055a915e3f501 in hir_ty::infer::expr::<impl hir_ty::infer::InferenceContext>::infer_expr_inner ()
#29 0x000055a915e3acd8 in hir_ty::infer::expr::<impl hir_ty::infer::InferenceContext>::infer_expr_coerce ()
#30 0x000055a915e46b1b in hir_ty::infer::expr::<impl hir_ty::infer::InferenceContext>::infer_block ()
#31 0x000055a915e3dc50 in hir_ty::infer::expr::<impl hir_ty::infer::InferenceContext>::infer_expr_inner ()
#32 0x000055a915e3acd8 in hir_ty::infer::expr::<impl hir_ty::infer::InferenceContext>::infer_expr_coerce ()
#33 0x000055a915e4e02b in hir_ty::infer::infer_query ()
#34 0x000055a915e14a62 in salsa::runtime::Runtime::execute_query_implementation ()
#35 0x000055a915c2bf3e in salsa::derived::slot::Slot<Q,MP>::read_upgrade ()
#36 0x000055a915c69cbf in salsa::derived::slot::Slot<Q,MP>::read ()
#37 0x000055a915ce5c0e in <salsa::derived::DerivedStorage<Q,MP> as salsa::plumbing::QueryStorageOps<Q>>::try_fetch ()
#38 0x000055a915cae0a8 in salsa::QueryTable<Q>::get ()
#39 0x000055a91650bc22 in <DB as hir_ty::db::HirDatabase>::infer_query ()
#40 0x000055a915dc50cf in hir_ty::db::infer_wait ()
#41 0x000055a916597c86 in rust_analyzer::cli::analysis_stats::<impl rust_analyzer::cli::flags::AnalysisStats>::run_inference ()
#42 0x000055a916595b5d in rust_analyzer::cli::analysis_stats::<impl rust_analyzer::cli::flags::AnalysisStats>::run ()
#43 0x000055a91677c2bb in rust_analyzer::main ()
#44 0x000055a916770d23 in std::sys_common::backtrace::__rust_begin_short_backtrace ()
#45 0x000055a91678d879 in std::rt::lang_start::_$u7b$$u7b$closure$u7d$$u7d$::h58386d473fcb43f3 ()
#46 0x000055a9167e987e in core::ops::function::impls::{impl#2}::call_once<(), (dyn core::ops::function::Fn<(), Output=i32> + core::marker::Sync + core::panic::unwind_safe::RefUnwindSafe)> () at /rustc/e092d0b6b43f2de967af0887873151bb1c0b18d3/library/core/src/ops/function.rs:280
#47 std::panicking::try::do_call<&(dyn core::ops::function::Fn<(), Output=i32> + core::marker::Sync + core::panic::unwind_safe::RefUnwindSafe), i32> () at library/std/src/panicking.rs:492
#48 std::panicking::try<i32, &(dyn core::ops::function::Fn<(), Output=i32> + core::marker::Sync + core::panic::unwind_safe::RefUnwindSafe)> () at library/std/src/panicking.rs:456
#49 std::panic::catch_unwind<&(dyn core::ops::function::Fn<(), Output=i32> + core::marker::Sync + core::panic::unwind_safe::RefUnwindSafe), i32> () at library/std/src/panic.rs:137
#50 std::rt::lang_start_internal::{closure#2} () at library/std/src/rt.rs:128
#51 std::panicking::try::do_call<std::rt::lang_start_internal::{closure_env#2}, isize> () at library/std/src/panicking.rs:492
#52 std::panicking::try<isize, std::rt::lang_start_internal::{closure_env#2}> () at library/std/src/panicking.rs:456
#53 std::panic::catch_unwind<std::rt::lang_start_internal::{closure_env#2}, isize> () at library/std/src/panic.rs:137
#54 std::rt::lang_start_internal () at library/std/src/rt.rs:128
#55 0x000055a91677fea2 in main ()

[detrumi]

Seems to happen only to the recursive solver. Reproduced as chalk test in rust-lang/chalk#773

[yshui]

Is there a way to work around this? this is preventing me from using rust-analyzer entirely.

[detrumi]

Fixed on master, now that we're using Chalk solver fuel again.

[flodiebold]

Well, worked around 😅 the bug is still there...

[Veykril]

We can still close this on our side though, no? Since it is tracked upstream with an issue.

[jonas-schievink]

Agreed, closing.