Reduce usage of `compiler_for` in bootstrap by Kobzol · Pull Request #145310 · rust-lang/rust

Kobzol · 2025-08-12T15:25:43Z

While working on refactoring/fixing dist steps, I realized that build.full-bootstrap does much more than it should, and that it its documentation is wrong. It seems that the main purpose of this option should be to enable/disable stdlib/compiler uplifting (https://rust-lang.zulipchat.com/#narrow/channel/326414-t-infra.2Fbootstrap/topic/Purpose.20of.20.60build.2Efull-bootstrap.60/with/533985624), but currently it also affects staging, or more precisely which compiler will be used to build selected steps, because this option is used in the cursed compiler_for function.

I would like to change the option it so that it only affects uplifting, and doesn't affect stage selection, which I (partially) did in this PR. I removed the usage of compiler_for from the Std and Rustc steps, and explicitly implemented uplifting, without going through compiler_for.

The only remaining usages of compiler_for are in dist steps (which I'm currently refactoring, will send a PR later) and test steps (which I will take a look at after dist). After that we can finally remove the function.

I tried to document the case when uplifting was happening during cross-compilation, which was very implicit before. I also did a slight change in the uplifting logic for rustc when cross-compiling. Before, we would attempt to uplift a stage1 rustc, but that is not really a thing when cross-compiling.

r? @jieyouxu

rustbot · 2025-08-12T15:25:48Z

This PR modifies bootstrap.example.toml.

If appropriate, please update CONFIG_CHANGE_HISTORY in src/bootstrap/src/utils/change_tracker.rs.

bors · 2025-08-13T02:29:57Z

☔ The latest upstream changes (presumably #145295) made this pull request unmergeable. Please resolve the merge conflicts.

jieyouxu

Thanks. The staging reasoning looks right to me. You can r=me once the tracing PR merges then rebase, as I think there might be a merge conflict there.

jieyouxu · 2025-08-13T13:11:01Z

src/bootstrap/src/core/build_steps/compile.rs

            fields(
                target = ?self.target,
-                compiler = ?self.compiler,
+                build_compiler = ?self.build_compiler,


Remark: I think this will merge-conflict with #145340

Actually, why should it? That only modified check and this modifies compile 🤔

Ah, you probably meant the #[instrument] removal PR.

jieyouxu · 2025-08-13T13:15:08Z

@rustbot author

bors · 2025-08-15T03:55:01Z

☔ The latest upstream changes (presumably #145407) made this pull request unmergeable. Please resolve the merge conflicts.

… not stage selection

Kobzol · 2025-08-15T06:25:19Z

Rebased.

@bors r=jieyouxu

bors · 2025-08-15T06:25:22Z

📌 Commit f2c2d3e has been approved by jieyouxu

It is now in the queue for this repository.

Rollup of 11 pull requests Successful merges: - #144210 (std: thread: Return error if setting thread stack size fails) - #145310 (Reduce usage of `compiler_for` in bootstrap) - #145311 (ci: clean windows disk space in background) - #145340 (Split codegen backend check step into two and don't run it with `x check compiler`) - #145408 (Deduplicate -L search paths) - #145412 (Windows: Replace `GetThreadId`+`GetCurrentThread` with `GetCurrentThreadId`) - #145413 (bootstrap: Reduce dependencies) - #145426 (Fix typos in bootstrap.example.toml) - #145430 (Fix wrong spans with external macros in the `dropping_copy_types` lint) - #145431 (Enhance UI test output handling for runtime errors) - #145448 (Autolabel `src/tools/{rustfmt,rust-analyzer}` changes with `T-{rustfmt,rust-analyzer}`) r? `@ghost` `@rustbot` modify labels: rollup

Rollup merge of #145310 - Kobzol:compiler-for-revamp, r=jieyouxu Reduce usage of `compiler_for` in bootstrap While working on refactoring/fixing `dist` steps, I realized that `build.full-bootstrap` does much more than it should, and that it its documentation is wrong. It seems that the main purpose of this option should be to enable/disable stdlib/compiler uplifting (https://rust-lang.zulipchat.com/#narrow/channel/326414-t-infra.2Fbootstrap/topic/Purpose.20of.20.60build.2Efull-bootstrap.60/with/533985624), but currently it also affects staging, or more precisely which compiler will be used to build selected steps, because this option is used in the cursed `compiler_for` function. I would like to change the option it so that it *only* affects uplifting, and doesn't affect stage selection, which I (partially) did in this PR. I removed the usage of `compiler_for` from the `Std` and `Rustc` steps, and explicitly implemented uplifting, without going through `compiler_for`. The only remaining usages of `compiler_for` are in dist steps (which I'm currently refactoring, will send a PR later) and test steps (which I will take a look at after dist). After that we can finally remove the function. I tried to document the case when uplifting was happening during cross-compilation, which was very implicit before. I also did a slight change in the uplifting logic for rustc when cross-compiling. Before, we would attempt to uplift a stage1 rustc, but that is not really a thing when cross-compiling. r? `@jieyouxu`

Fix uplifting in `Assemble` step In rust-lang#145310, I removed [this line](https://github.com/rust-lang/rust/pull/145310/files#diff-5a1e05f2688d271039171a547d407d0c8a96715ee64d35562fc76b4c9a874303L2109), which adjusted the stage of the build compiler if an uplift has happened. This broke stage3+ uplifted rustc builds (rust-lang#145534). I could swear I tested this in the PR, but somehow I missed it. Instead of keeping the original returned stage, I made it more explicit by returning the actually used `build_compiler` from the `Rustc` step, and then use that in the `Assemble` step. The changes to `RustcLink` were needed to fix `ui-fulldeps`, which apparently build a stage3 rustc, because I haven't fixed the test steps yet 😅 Hopefully we might be able to remove `RustcLink` if the approach from rust-lang#144252 will work. Should fix rust-lang#145534. r? `@jieyouxu`

Fix uplifting in `Assemble` step In rust-lang#145310, I removed [this line](https://github.com/rust-lang/rust/pull/145310/files#diff-5a1e05f2688d271039171a547d407d0c8a96715ee64d35562fc76b4c9a874303L2109), which adjusted the stage of the build compiler if an uplift has happened. This broke stage3+ uplifted rustc builds (rust-lang#145534). I could swear I tested this in the PR, but somehow I missed it. Instead of keeping the original returned stage, I made it more explicit by returning the actually used `build_compiler` from the `Rustc` step, and then use that in the `Assemble` step. The changes to `RustcLink` were needed to fix `ui-fulldeps`, which apparently build a stage3 rustc, because I haven't fixed the test steps yet 😅 Hopefully we might be able to remove `RustcLink` if the approach from rust-lang#144252 will work. Should fix rust-lang#145534. r? ``@jieyouxu``

Rollup merge of #145557 - Kobzol:rustc-link-fix, r=jieyouxu Fix uplifting in `Assemble` step In #145310, I removed [this line](https://github.com/rust-lang/rust/pull/145310/files#diff-5a1e05f2688d271039171a547d407d0c8a96715ee64d35562fc76b4c9a874303L2109), which adjusted the stage of the build compiler if an uplift has happened. This broke stage3+ uplifted rustc builds (#145534). I could swear I tested this in the PR, but somehow I missed it. Instead of keeping the original returned stage, I made it more explicit by returning the actually used `build_compiler` from the `Rustc` step, and then use that in the `Assemble` step. The changes to `RustcLink` were needed to fix `ui-fulldeps`, which apparently build a stage3 rustc, because I haven't fixed the test steps yet 😅 Hopefully we might be able to remove `RustcLink` if the approach from #144252 will work. Should fix #145534. r? ``@jieyouxu``

Fix uplifting in `Assemble` step In rust-lang/rust#145310, I removed [this line](https://github.com/rust-lang/rust/pull/145310/files#diff-5a1e05f2688d271039171a547d407d0c8a96715ee64d35562fc76b4c9a874303L2109), which adjusted the stage of the build compiler if an uplift has happened. This broke stage3+ uplifted rustc builds (rust-lang/rust#145534). I could swear I tested this in the PR, but somehow I missed it. Instead of keeping the original returned stage, I made it more explicit by returning the actually used `build_compiler` from the `Rustc` step, and then use that in the `Assemble` step. The changes to `RustcLink` were needed to fix `ui-fulldeps`, which apparently build a stage3 rustc, because I haven't fixed the test steps yet 😅 Hopefully we might be able to remove `RustcLink` if the approach from rust-lang/rust#144252 will work. Should fix rust-lang/rust#145534. r? ``@jieyouxu``

rustbot assigned jieyouxu Aug 12, 2025

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-bootstrap Relevant to the bootstrap subteam: Rust's build system (x.py and src/bootstrap) labels Aug 12, 2025

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Kobzol force-pushed the compiler-for-revamp branch from b4c6c8e to 39ff9a3 Compare August 12, 2025 18:15

Kobzol force-pushed the compiler-for-revamp branch from 39ff9a3 to 4d9cbfd Compare August 13, 2025 06:06

jieyouxu approved these changes Aug 13, 2025

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rustbot added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Aug 13, 2025

Kobzol added 4 commits August 15, 2025 08:21

Rename compiler to build_compiler in the compile::Std step

8a7be4a

Remove usage of compiler_for from the compile::Std step

d8a51f5

Remove usage of compiler_for from the compile::Rustc step

36dfed6

Clarify that build.full-bootstrap is only used to affect uplifting,…

f2c2d3e

… not stage selection

Kobzol force-pushed the compiler-for-revamp branch from 4d9cbfd to f2c2d3e Compare August 15, 2025 06:24

bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Aug 15, 2025

Kobzol mentioned this pull request Aug 15, 2025

Rollup of 11 pull requests #145450

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bors merged commit 87d677b into rust-lang:master Aug 15, 2025
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rustbot added this to the 1.91.0 milestone Aug 15, 2025

Kobzol deleted the compiler-for-revamp branch August 15, 2025 18:52

This was referenced Aug 18, 2025

nightly cross build started failing 2025-08-16 #145534

Closed

Fix uplifting in Assemble step #145557

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github-actions bot mentioned this pull request Aug 18, 2025

Toolchain upgrade to nightly-2025-08-18 flux-rs/flux#1249

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Reduce usage of `compiler_for` in bootstrap#145310

Reduce usage of `compiler_for` in bootstrap#145310
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