Updating crates.io index after every `cargo clean`

[amv-dev]

rust-analyzer version: rust-analyzer 0.3.2509-standalone
(also reproduced in later versions, including nightly)

rustc version: rustc 1.88.0 (6b00bc388 2025-06-23), rustc 1.87.0 (17067e9ac 2025-05-09)

editor or extension: neovim v0.11.2, default rust analyzer settings

code snippet to reproduce:

# Create new project
cargo init sample
cd sample

# run editor
nvim src/main.rs

Rust analyzer starts to show status "updating crates.io index". After sometime message "cargo metadata: ?" also appears. It blocks if there is no connection to the Internet.

On the other hand I can simply run cargo clean && cargo metadata without connection to the Internet.

Also I tried to set rust-analyzer.cargo.noDeps: true and rust-analyzer.cargo.autoreload: true, this does not solve the problem.

[ShoyuVanilla]

Well, I guess this is because rust-analyzer tries to pull the dependencies of the Rust standard library and they are necessary for properly analyzing the workspace.

cargo metadata doesn't pull them by itself because standard libraries are prebuilt and vendored with the Rust compiler, so for normal Rust rust projects, those "dependencies of standard libraries" are not real dependencies.
But rust-analyzer need them with the above reason and it requests cargo for those dependencies.

Perhaps we might utilize those "vendored" standard library or at least vendored dependencies of standard library to analyze standard library, but I guess it's virtually impossible to do so because rustc and rust-analyzer's compiler frontend are similar but quite different in details and we cannot use *.rlib or *.rmeta files compiled by rustc directly without their source codes.

[ShoyuVanilla]

I found that we are not using noDeps option for sysroot metadata fetch and issued a PR

[ShoyuVanilla]

I guess this might be fixed in our latest stable release if you set rust-analyzer.cargo.noDeps: true