Build targets of workspace crates do not appear to be honoured

[huntc]

rust-analyzer version: rust-analyzer version: 54782428a 2022-01-12 dev

rustc version: rustc 1.59.0-nightly (c5ecc1570 2021-12-15)

Further to the "Respect .cargo/config.toml" PR, the config.toml file of a crate within a workspace does not appear to be honoured. For example, if I have a project named client and it has two crates, app and embedded-app, and embedded-app has a .cargo/config.toml, then the latter does not appear to be considered when determining build targets.

To reproduce this issue:

1. Download the branch at Upgrade Embassy version titanclass/embassy-start#4
2. rustup target add thumbv7em-none-eabihf if you don't have that target
3. Open the project's workspace file (embassy-start.code-workspace) in VSC
4. Navigate to client/embedded-app/src/boards/nrf52840_dk.rs
5. Wait for RA to complete its indexing
6. Note that interrupt::take! on L18 is able to be resolved
7. Remove the "rust-analyzer.cargo.target": "thumbv7em-none-eabihf" from the workspace file
8. Reload RA
9. Wait for RA to complete its indexing
10. Note that interrupt::take! can no longer be resolved

My expectation is that the build target of client/.embedded-app/.cargo/config.toml should be honoured, and that I should not have to declare a rust-analyzer.cargo.target.

Related? #8521

[huntc]

I made some progress by running my own RA build and printing out the cargo.toml's within that were being used to determine the various targets. My eprintln was in cargo_workspace.rs/cargo_config_build_target. In my example, this is what I get:

config ManifestPath { file: AbsPathBuf("/Users/huntc/Projects/titanclass/embassy-start/client/Cargo.toml") } "cargo" "-Z" "unstable-options" "config" "get" "build.target"
result None
config ManifestPath { file: AbsPathBuf("/Users/huntc/Projects/titanclass/embassy-start/network-protocol/Cargo.toml") } "cargo" "-Z" "unstable-options" "config" "get" "build.target"
result None
config ManifestPath { file: AbsPathBuf("/Users/huntc/Projects/titanclass/embassy-start/server/Cargo.toml") } "cargo" "-Z" "unstable-options" "config" "get" "build.target"
result None

...None meaning that no target is being resolved out of the cargo.toml's that are used.

Perhaps client/embedded-app/Cargo.toml and server/embedded-app/Cargo.toml would be needed to determine the needed build targets here?

[huntc]

I've come to the conclusion that RA is working as intended. When it performs a cargo check, it does so at the workspace level if there is one, or if there's not, then just the crate. Cargo workspaces aren't effective when there are multiple targets being used as expressed by config.toml. In fact, config.tomls are only applied when cargo is working within that particular directory.

I have since removed workspaces from situations where there are no common targets between crates.

[robbie-mac]

If rust-analyzer is using cargo check, maybe the different behavior of cargo check when run i a workspace is contributing to the issue:
rust-lang/cargo#15785