Setting check.workspace to false still emits diagnostics from all members the first time they are seen

rust-analyzer version: v0.3.1906

rustc version: rustc 1.79.0-nightly (1684a753d 2024-04-01)

editor or extension: I've tested this on VSCode, NeoVim, Helix.

relevant settings: check.workspace = false

code snippet to reproduce:

https://github.com/rust-lang/rust-analyzer/pull/16510 brings check.workspace setting, it works well except the first time RA starts.

The reproducing steps are:

• make a workspace containing a member and the root crate: make some diagnostics in both
• set check.workspace to false
• open a file from one of the package, wait for RA starts, then you'll see diagnostics from both pkgs (=> this is the bug)
• save the file, you'll finally see diagnostics from single pkg

Found in https://users.rust-lang.org/t/rust-analyzer-cargo-workspaces-and-members-in-helix-editor/110284/8

Start with the check.workspace implementation introduced by pull request 16510 and reproduce the reported workspace startup sequence using a root crate and member with diagnostics. Compare the initial diagnostics with those after saving a file. Done means check.workspace=false limits diagnostics to the selected package from startup, without requiring a save.