Rust/Cargo: Changing a relative dependency source does not invalidate the project hash

[alexander-heimbuch]

I want to use moon for managing a rust monorepo with multiple workspaces. So far it seems to be a good fit but I encountered an issue when changing something in a used library that an application depends on. Even when declaring a dependsOn in the applicationmoon.yml it replays a cached build task when changing something in the library source.

I guess this is either a quirky workspaces setup or a misconfiguration but couldn't figure it out so far :/

Example:

libs
  example-lib
      src/
        ...
      Cargo.toml
      moon.yml
  Cargo.toml <-- Workspace
apps
  example-app
    src/
      ...
    Cargo.toml
    moon.yml
  Cargo.toml <-- Workspace

libs/example-lib/moon.yml

language: rust
type: library

apps/example-lib/moon.yml

language: rust
type: application

tasks:
  build:
    command: 'cargo build'
    inputs:
      - '@globs(sources)'
 dependsOn:
   - 'example-lib' 

apps/example-lib/Cargo.toml

[dependencies]
lib = { path = "../../libs/example-lib" }

[milesj]

Only task deps are included in a task's hash, not a project's deps. https://moonrepo.dev/docs/config/project#deps

If you want don't want to reference another task in the lib, you can create a "fake" task that is simple used as a touched check.

# lib
tasks:
  touched:
    command: noop

# app 
tasks:
  build:
    command: 'cargo build'
    inputs:
      - '@globs(sources)'
    deps:
      - 'lib:touched'

[alexander-heimbuch]

Ok, thanks for the answer! So there is no logic involved analyzing the Cargo.toml for references?

[milesj]

Right now we don't parse Cargo.toml to infer relationships, but I can look into it.

With that said, modifying a file in a dependent project will never automatically mark a task in the dependency project as dirty, simply because this breaks fine-grained control.