Panic: no value set for FileSourceRootQuery

[agrover]

Happens every time I git checkout a significantly older version of my Rust project that I'm using rust-analyzer on. Using rust-analyzer via emacs and lsp.

See salsa-rs/salsa#254 : "This is a rust-analyzer bug". "Sounds like you made an input query and then tried to use it like an on-demand one. Input queries have to have a value in them before you can read one."

thread 'main' panicked at 'no value set for FileSourceRootQuery(FileId(6447))', /home/agrover/.cargo/registry/src/github.com-1ecc6299db9ec823/salsa-0.17.0-pre.2/src/input.rs:106:32
stack backtrace:
   0: rust_begin_unwind
             at /rustc/db9d1b20bba1968c1ec1fc49616d4742c1725b4b/library/std/src/panicking.rs:498:5
   1: core::panicking::panic_fmt
             at /rustc/db9d1b20bba1968c1ec1fc49616d4742c1725b4b/library/core/src/panicking.rs:107:14
   2: <salsa::input::InputStorage<Q> as salsa::plumbing::QueryStorageOps<Q>>::try_fetch::{{closure}}
   3: <salsa::input::InputStorage<Q> as salsa::plumbing::QueryStorageOps<Q>>::try_fetch
   4: <DB as base_db::SourceDatabaseExt>::file_source_root::__shim
   5: <core::iter::adapters::copied::Copied<I> as core::iter::traits::iterator::Iterator>::fold
   6: <base_db::SourceRootCratesQuery as salsa::plumbing::QueryFunction>::execute
   7: salsa::runtime::Runtime::execute_query_implementation
   8: salsa::derived::slot::Slot<Q,MP>::read_upgrade
   9: salsa::derived::slot::Slot<Q,MP>::read
  10: <salsa::derived::DerivedStorage<Q,MP> as salsa::plumbing::QueryStorageOps<Q>>::try_fetch
  11: <DB as base_db::SourceDatabaseExt>::source_root_crates::__shim
  12: <base_db::FileLoaderDelegate<&T> as base_db::FileLoader>::relevant_crates
  13: <ide_db::RootDatabase as base_db::FileLoader>::relevant_crates
  14: rust_analyzer::global_state::GlobalState::process_changes
  15: rust_analyzer::reload::<impl rust_analyzer::global_state::GlobalState>::switch_workspaces
  16: rust_analyzer::main_loop::<impl rust_analyzer::global_state::GlobalState>::handle_event
  17: rust_analyzer::main_loop::<impl rust_analyzer::global_state::GlobalState>::run
  18: rust_analyzer::main_loop::main_loop
  19: rust_analyzer::main
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.
thread '<unnamed>' panicked at 'called `Result::unwrap()` on an `Err` value: "SendError(..)"', /home/agrover/.cargo/registry/src/github.com-1ecc6299db9ec823/lsp-server-0.5.2/src/stdio.rs:29:37
stack backtrace:
   0: rust_begin_unwind
             at /rustc/db9d1b20bba1968c1ec1fc49616d4742c1725b4b/library/std/src/panicking.rs:498:5
   1: core::panicking::panic_fmt
             at /rustc/db9d1b20bba1968c1ec1fc49616d4742c1725b4b/library/core/src/panicking.rs:107:14
   2: core::result::unwrap_failed
             at /rustc/db9d1b20bba1968c1ec1fc49616d4742c1725b4b/library/core/src/result.rs:1613:5
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

Process rust-analyzer stderr finished

rust-analyzer version: (eg. output of "Rust Analyzer: Show RA Version" command)
rust-analyzer 8b779e8 2022-01-21 dev

rustc version: (eg. output of rustc -V)
rustc 1.58.1 (db9d1b20b 2022-01-20)

[Veykril]

Needs a reproduction to be actionable

[agrover]

@Veykril 100% reproducible for me. In what format do you need reproduction?

[Veykril]

A repro for which this is reproducible, just git checkout isn't enough as this has yet to happen for me in any repo.

[agrover]

1. checkout rust-analyzer repo master branch
2. open crates/cfg/src/lib.rs or another file that existed at the start of 2021, in Emacs.
3. rust-analyzer should do a bunch of stuff
4. in a terminal run git checkout 2021-01-04
5. Should see above stack trace in rust-analyzer::stderr and should get the prompt: Server rust-analyzer:<num> exited with status exit(check corresponding stderr buffer for details). Do you want to restart it? (y or n)

for reference my Emacs init.el is here.

[Veykril]

So the problem here seems to be https://github.com/rust-analyzer/rust-analyzer/blob/2e124d15fb72482257c8ef10369df77ee24d6a85/crates/rust-analyzer/src/global_state.rs#L193
where we use a query before potentially setting up the source root for the file, which is required in the query.

I expected calling a query at that part would be fishy when I implemented that...