feat: Implementation and tests for `multiple-build-scripts` #15704

namanlp · 2025-06-25T19:09:05Z

Hi Everyone!

This is PR for the implementation of the first milestone of GSoC Project : Build Script Delegation

This will provide actual implementation for #15630

What does this PR try to resolve?

Now, multiple build scripts are parsed, this PR aims to implement the functioning the feature. This PR will allow users to use multiple build scripts, and is backward compatible with single script as well as boolean values.

Motivation : This will help users to maintain separate smaller and cleaner build scripts instead of one large build script. This is also necessary for build script delegation.

Deferred

Accessing each build script's OUT_DIR: This will be handled in a follow up PR. For now, each build script writes to its own OUT_DIR and OUT_DIR for the regular build targets is set to the build script with the lexicographically largest name..
User control over which build script wins in a conflict. This will be handled in a follow up PR. If two build scripts write to the same env variable, which gets applied to the binary? Currently, its the build script with the lexicographically largest name. This makes it deterministic. With some futzing, users can control this for now. However, with build script delegation, users won't be able to control this. We likely want it based off of the order the user assigns into the build script array.
Something about linking a C library is actually preferring lexicographically smallest name. We should handle conflicts consistently. We need to dig into what parts are doing it based on smallest and make sure that whatever priority scheme we use for env variables applies here as well.

How to test and review this PR?

There is a feature gate multiple-build-scripts that can be passed via cargo-features in Cargo.toml. So, you have to add

cargo-features = ["multiple-build-scripts"]

Preferably on the top of the Cargo.toml and use nightly toolchain to use the feature

epage · 2025-06-26T14:53:21Z

This is PR for the manifest parsing of the first milestone of GSoC Project : Build Script Delegation

Bad copy/paste?

src/cargo/core/compiler/build_runner/mod.rs

src/cargo/core/compiler/compilation.rs

src/cargo/core/compiler/build_runner/mod.rs

tests/testsuite/build_scripts_multiple.rs

src/cargo/core/compiler/unit_dependencies.rs

namanlp · 2025-06-30T19:44:19Z

I am marking this PR Ready for Review. Please do let me know if I have missed anything

rustbot · 2025-06-30T19:44:29Z

r? @weihanglo

rustbot has assigned @weihanglo.
They will have a look at your PR within the next two weeks and either review your PR or reassign to another reviewer.

Use r? to explicitly pick a reviewer

namanlp · 2025-06-30T19:46:43Z

r? @epage

src/cargo/core/compiler/build_runner/mod.rs

src/cargo/core/compiler/compilation.rs

epage · 2025-07-01T14:10:15Z

Also, another case we need to handle is OUT_DIR. That could be a follow up PR.

tests/testsuite/build_scripts_multiple.rs

epage

Thanks!

Update cargo 14 commits in 930b4f62cfcd1f0eabdb30a56d91bf6844b739bf..eabb4cd923deb73e714f7ad3f5234d68ca284dbe 2025-06-28 14:58:43 +0000 to 2025-07-09 22:07:55 +0000 - feat: Implementation and tests for `multiple-build-scripts` (rust-lang/cargo#15704) - perf: Speed up TOML parsing by upgrading toml (rust-lang/cargo#15736) - Mark cachelock tests that rely on interprocess blocking behaviour as unsupported on AIX. (rust-lang/cargo#15734) - feat(publish): Stabilize multi-package publishing (rust-lang/cargo#15636) - Update to Rust 2024 (rust-lang/cargo#15732) - Clarify package ID specifications in SBOMs are fully qualified (rust-lang/cargo#15731) - chore(deps): update cargo-semver-checks to v0.42.0 (rust-lang/cargo#15730) - test: Switch config tests to use snapshots (rust-lang/cargo#15729) - implement package feature unification (rust-lang/cargo#15684) - chore: Upgrade dependencies (rust-lang/cargo#15722) - Report valid file name when we can't find a build target for `name = "foo.rs"` (rust-lang/cargo#15707) - chore(release): Publish build-rs on release (rust-lang/cargo#15708) - Override `Cargo.lock` checksums when doing a dry-run `publish` (rust-lang/cargo#15711) - test(rustfix): Update for nightly (rust-lang/cargo#15717) r? ghost

) Hi Everyone! This PR is aimed to have some improvements over #15704 ### What does this PR try to resolve? Now, multiple build scripts are built correctly. But there are some underlying issues, that this PR is targeting. - Preserving the order of the build scripts: Earlier the build scripts were sorted by default, but now, the order will be preserved. ### How to test and review this PR? There is a feature gate `multiple-build-scripts` that can be passed via `cargo-features` in `Cargo.toml`. So, you have to add ```toml cargo-features = ["multiple-build-scripts"] ``` Preferably on the top of the `Cargo.toml` and use nightly toolchain to use the feature

rustbot added A-build-execution Area: anything dealing with executing the compiler A-build-scripts Area: build.rs scripts A-dep-info Area: dep-info, .d files Command-run Command-test labels Jun 25, 2025