Rust Team Calls for Testing New Cargo Build Directory Layout
The Rust development team has issued a call for community testing regarding a proposed change to the internal directory layout of Cargo, the language's package manager and build tool. The new layout, accessible via the nightly-only flag -Zbuild-dir-new-layout, aims to separate intermediate build artifacts from final outputs. Although the build directory structure is considered internal, many existing tools and projects rely on its unspecified details due to historical feature gaps in Cargo. Following an initial automated crater run, the team seeks manual verification to identify tools that may break under the new system. Developers are urged to test their workflows using Nightly 2026-03-10 or later and report issues to upstream projects or the central tracking issue. The article outlines known failure modes, such as path inference errors in tests and build scripts, and provides mitigation strategies like using specific environment variables. It also lists the compatibility status of popular testing libraries, noting that some have already been fixed while others still require updates. This initiative ensures a smoother transition before the potential default change, maintaining ecosystem stability.
Wire timeline
Rust Team Calls for Testing New Cargo Build Directory Layout
The Rust development team has issued a call for community testing regarding a proposed change to the internal directory layout of Cargo, the language's package manager and build tool. The new layout, accessible via the nightly-only flag -Zbuild-dir-new-layout, aims to separate intermediate build artifacts from final outputs. Although the build directory structure is considered internal, many existing tools and projects rely on its unspecified details due to historical feature gaps in Cargo. Following an initial automated crater run, the team seeks manual verification to identify tools that may break under the new system. Developers are urged to test their workflows using Nightly 2026-03-10 or later and report issues to upstream projects or the central tracking issue. The article outlines known failure modes, such as path inference errors in tests and build scripts, and provides mitigation strategies like using specific environment variables. It also lists the compatibility status of popular testing libraries, noting that some have already been fixed while others still require updates. This initiative ensures a smoother transition before the potential default change, maintaining ecosystem stability.
Rust Blog