feat/bug: slow check times -> perhaps add dependency aware version of check.workspace=false

Today, in our company workspace, when I save a file in a binary leaf crate - e.g. an alteration to main.rs, it takes:

• 40 seconds for rust-analyzer to run clippy on all the members
• or 40 seconds for it to run check on all the members
• or 2 seconds to run clippy on the member
• or 2 seconds to run check on the member

Depending on what check-on-save command I am using and the value of check.workspace.

With just cargo at the command line,

• 1 second to run clippy --workspace
• or 1 second to run check --workspace

Changing a mid-layer crate, and clippy --workspace takes ~ 4 seconds or so.

Which is fine, but the times from RA itself are not.

With check.workspace = True, every crate in a workspace - we're at 90 - has the check command run when a file is saved.
This takes some time but when a public interface is changed and causes another crate to fail, that is picked up immediately.

With check.workspace = False, only the package the file belongs to is rechecked, but changes that alter public interfaces go unnoticed until those other crates are saved.

What I would love is a version that runs check on the closure of the reverse dependencies of the package the saved file was in.

For example, imagine that we have a proc macro crate, a library that works in concert with that proc macro crate - including re-exporting it, and a binary:

binary

• library
  • proc-macro

saving a file in binary would check binary
saving a file in library would check binary and library
saving a file in proc-macro would check binary and library and proc-macro

Alternatively, if RA would literally run 'clippy --workspace' or 'check --workspace' that would also solve things.

Start by tracing how rust-analyzer handles the check.workspace setting and invokes cargo check or clippy on save. Compare workspace checking with package checking, then define and test the reverse-dependency closure behavior described in the examples; done means affected dependent crates are checked without checking the entire workspace.