Out-of-bounds panics in Worker thread

[holly-hacker]

rust-analyzer version: 0.4.1783-standalone (85fb463 2023-12-24)

rustc version: rustc 1.74.1 (a28077b28 2023-12-04)

relevant settings: n/a

---

Today when I started using rust-analyzer in a private project, I started getting a lot of errors out of nowhere when typing and hovering over text. The panic message is always an index out of bounds, and it happened on both the current release and current pre-release version of rust-analyzer.

thread 'Worker' panicked at C:\Users\runneradmin\.cargo\registry\src\index.crates.io-6f17d22bba15001f\rust-analyzer-salsa-0.17.0-pre.4\src\interned.rs:107:32:
index out of bounds: the len is 85655 but the index is 4294967039
stack backtrace:
   0: std::panicking::begin_panic_handler
             at /rustc/a28077b28a02b92985b3a3faecf92813155f1ea1/library\std\src\panicking.rs:597
   1: core::panicking::panic_fmt
             at /rustc/a28077b28a02b92985b3a3faecf92813155f1ea1/library\core\src\panicking.rs:72
   2: core::panicking::panic_bounds_check
             at /rustc/a28077b28a02b92985b3a3faecf92813155f1ea1/library\core\src\panicking.rs:180
   3: salsa::QueryTable<Q>::get
   4: <DB as hir_expand::db::ExpandDatabase>::lookup_intern_syntax_context
   5: hir_expand::mod_path::resolve_crate_root
   6: hir_expand::mod_path::convert_path
   7: hir_expand::mod_path::convert_path
   8: hir_expand::mod_path::convert_path
   9: hir_expand::mod_path::convert_path
  10: hir_def::item_tree::lower::Ctx::lower_macro_call
  11: hir_def::item_tree::lower::Ctx::lower_mod_item
  12: hir_def::item_tree::ItemTree::file_item_tree_query
  13: salsa::Cycle::catch
  14: salsa::derived::slot::Slot<Q,MP>::evict
  15: salsa::derived::slot::Slot<Q,MP>::read
  16: <salsa::derived::DerivedStorage<Q,MP> as salsa::plumbing::QueryStorageOps<Q>>::fetch
  17: <DB as hir_def::db::DefDatabase>::file_item_tree
  18: hir_def::nameres::collector::DefCollector::record_resolved_import
  19: hir_def::data::StaticData::static_data_query
  20: hir_def::nameres::DefMap::block_def_map_query
  21: salsa::Cycle::catch
  22: salsa::derived::slot::Slot<Q,MP>::evict
  23: salsa::derived::slot::Slot<Q,MP>::read
  24: <salsa::derived::DerivedStorage<Q,MP> as salsa::plumbing::QueryStorageOps<Q>>::fetch
  25: <DB as hir_def::db::DefDatabase>::block_def_map
  26: hir_def::body::lower::ExprCollector::collect_stmt
  27: hir_def::body::lower::ExprCollector::maybe_collect_expr
  28: hir_def::body::lower::ExprCollector::collect_stmt
  29: <core::iter::adapters::map::Map<I,F> as core::iter::traits::iterator::Iterator>::fold
  30: hir_def::body::lower::ExprCollector::collect_stmt
  31: hir_def::body::lower::ExprCollector::maybe_collect_expr
  32: hir_def::body::lower::ExprCollector::collect_stmt
  33: <core::iter::adapters::map::Map<I,F> as core::iter::traits::iterator::Iterator>::fold
  34: hir_def::body::lower::ExprCollector::check_cfg
  35: hir_def::body::lower::ExprCollector::maybe_collect_expr
  36: <alloc::vec::Vec<T> as alloc::vec::spec_from_iter::SpecFromIter<T,I>>::from_iter
  37: <alloc::boxed::Box<[I]> as core::iter::traits::collect::FromIterator<I>>::from_iter
  38: hir_def::body::lower::ExprCollector::maybe_collect_expr
  39: hir_def::body::lower::ExprCollector::collect_stmt
  40: hir_def::body::lower::ExprCollector::maybe_collect_expr
  41: hir_def::body::lower::ExprCollector::collect_expr_opt
  42: hir_def::body::lower::lower
  43: hir_def::body::Body::body_with_source_map_query
  44: salsa::Cycle::catch
  45: salsa::derived::slot::Slot<Q,MP>::evict
  46: salsa::derived::slot::Slot<Q,MP>::read
  47: <salsa::derived::DerivedStorage<Q,MP> as salsa::plumbing::QueryStorageOps<Q>>::fetch
  48: hir::DefWithBody::diagnostics
  49: hir::ModuleDef::diagnostics
  50: hir::Module::diagnostics
  51: hir::DefWithBody::diagnostics
  52: hir::Module::diagnostics
  53: ide_diagnostics::diagnostics
  54: std::panicking::try
  55: ide::Analysis::assists_with_fixes
  56: rust_analyzer::handlers::request::handle_code_action
  57: std::panicking::try
  58: core::ops::function::FnOnce::call_once{{vtable.shim}}
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.
Panic context:
> 
version: 0.4.1783-standalone (85fb463fc 2023-12-24)
request: textDocument/semanticTokens/full/delta SemanticTokensDeltaParams {
    work_done_progress_params: WorkDoneProgressParams {
        work_done_token: None,
    },
    partial_result_params: PartialResultParams {
        partial_result_token: None,
    },
    text_document: TextDocumentIdentifier {
        uri: Url {
            scheme: "file",
            cannot_be_a_base: false,
            username: "",
            password: None,
            host: None,
            port: None,
            path: "/-snip-/src/routes/api.rs",
            query: None,
            fragment: None,
        },
    },
    previous_result_id: "2",
}

[Exotik850]

Happening to me as well, constantly crashing until it goes to the "Rust-analyzer has crashed 5 times in the last 3 minutes" spiel,
Rustc version: 1.76.0-nightly (6b771f6 2023-11-15)
Rust-analyzer extension version: v0.3.1782
Windows 11

[lnicola]

Does anyone have a way to reproduce this?

[holly-hacker]

I've created a fairly minimal example. It depends on rocket v0.5.0, my apologies for the large dependency.

fn main() {}

#[rocket::get("/my-api?<url>")]
async fn ra_16200_repro(url: &str) -> Result<(), ()> {
    Ok(())
}

The error seems to occur here when overing over Result.

Running cargo expand on this results in a very large blob of code that I can't minimize myself, but I hope this is enough to recreate this panic on your end.

In case exact dependencies are important, I've zipped a cargo clean-ed version of my repro project: ra-16200-repro.zip

---

It's worth noting that in my own codebase, the error happens more often than in this repro (where it only seems to happen when hovering over Result).

[Veykril]

4294967039 is a SyntaxContextId::SELF_REF so we are failing to accomodate for that somewhere

[Veykril]

rust-analyzer/crates/hir-expand/src/hygiene.rs

Line 171 in afbb8f3

let parent = opaque_and_semitransparent;

and

rust-analyzer/crates/hir-expand/src/hygiene.rs

Line 156 in afbb8f3

let parent = opaque;

may point to SELF_REF which breaks my assumption that they only occur in opaque_and_semitransparent and opaque fields, we should do a SELF_REF check when assigning to parent and point that to ctxt in that function if it is a SELF_REF

So those should be let parent = handle_self_ref(ctxt, opaque_and_semitransparent) and let parent = handle_self_ref(ctxt, opaque)

[holly-hacker]

I've tried those changes locally and they do seem to fix the repro case. Strangely, the tooltip now shows an unrelated doc entry, but I assume that's due to a faulty macro (it also happened in places where there was no crash before):