I have a cargo workspace in which I also want to use rclrs. I am using edition 2024 with resolver v3:

[workspace]
resolver = "3"

[workspace.package]
edition = "2024"

With the current version of cargo-ament-build, I am getting a parser error:

$ cargo ament-build -p rust_pubsub --install-base install 
Error in cargo-ament-build

Caused by:
    TOML parse error at line 2, column 12
      |
    2 | resolver = "3"
      |            ^^^
    unknown variant `3`, expected `1` or `2`

A potential workaround is to not specify the resolver in this file as it is implicitly defined in the version 2024. However, I still think that this tool should not break existing setups, so this is not a solution for me. cargo-manifest v0.18.0 added support for resolver = "3": https://github.com/LukeMathWalker/cargo-manifest/blob/master/CHANGELOG.md#v0180-2025-01-10, so the proper fix is to bump this dependency. As I am already bumping this dependency version, I opted to use the latest version rather than the lowest one that addresses this issue.

Note that I am aware of the failing CI check named Security audit / security_audit (push) on this dependency, but by sweeping the commits I couldn't find anything sus (e.g. new dependencies), and it seems to be a failing cargo-deny-action run based on this config.

This PR resolves the current issue and I can build now with the workspace:

$ ./src/experiments/cargo-ament-build/target/debug/cargo-ament-build --install-base install

    Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.20s

I didn't perform any other tests.

Caveat:
The current cargo-ament-build still doesn't support workspaces (and likely wasn't intended to?) so this PR only resolves one issue with them, but the steps following the cargo build are still failing:

Error in cargo-ament-build

Caused by:
    Cargo manifest has no package section.

This is out of scope.