Add `--quiet` flag to x.py and bootstrap to suppress output by erickt · Pull Request #154616 · rust-lang/rust

erickt · 2026-03-31T01:01:31Z

This adds a --quiet flag to x.py and bootstrap to suppress some of the output when compiling Rust. It conflicts with --verbose, matching the behavior of cargo which does not allow --verbose and --quiet.

It works by passing quiet flags down to the underlying cargo, or LLVM build processes. Note that for LLVM, we only can suppress logs when we explicitly configure it with ninja. Otherwise we won't know what flag to pass along to whichever build system cmake decides to use.

This can be helpful with AI workloads in the Rust codebase to help shrink down the output to reduce token usage, which can help prevent context pollution and lower costs.

This patch was partially generated with Gemini, but I've reviewed the changes it made.

rustbot · 2026-03-31T01:01:35Z

This PR modifies src/bootstrap/src/core/config.

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

This PR changes how LLVM is built. Consider updating src/bootstrap/download-ci-llvm-stamp.

rustbot · 2026-03-31T01:01:37Z

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jieyouxu · 2026-03-31T02:23:46Z

I can only look into these this weekend, but cc also #154587

(It would be nice to be careful that we don't use --quiet to mean different things)

erickt · 2026-03-31T03:21:52Z

Ha! What a coincidence. I’m certainly intending to have the same semantics as that PR, so I think they should be compatible with each other. I’m happy to wait for it to land since it beat me by a few hours, then I can match the style with whatever you finalize on.

jieyouxu · 2026-03-31T03:23:39Z

(I think either one can land first, I was just remarking just in case we somehow have --quiet do two entirely different things which would be very confusing, but doesn't seem like the case)

jieyouxu · 2026-04-05T08:03:41Z

Thanks for the patience. So I looked at both this PR and the #154587, and I think I would say:

We keep using --quiet in this PR for the more general-purpose operation of suppressing certain build outputs, which seems more common.
We'll use something more specific like --verbose-run-make-subprocess-output for the other use case next doors, because that use case is very niche.

I'll review this PR now.

jieyouxu

Thanks. Have a question and a suggestion.

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rustbot · 2026-04-05T08:36:07Z

Reminder, once the PR becomes ready for a review, use @rustbot ready.

rustbot · 2026-04-15T15:41:16Z

This PR was rebased onto a different main commit. Here's a range-diff highlighting what actually changed.

Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers.

This adds a `--quiet` flag to x.py and bootstrap to suppress some of the output when compiling Rust. It conflicts with `--verbose`, matching the behavior of `cargo` which does not allow `--verbose` and `--quiet`. It works by passing quiet flags down to the underlying cargo, or LLVM build processes. Note that for LLVM, we only can suppress logs when we explicitly configure it with ninja. Otherwise we won't know what flag to pass along to whichever build system cmake decides to use. This can be helpful with AI workloads in the Rust codebase to help shrink down the output to reduce token usage, which can help prevent context pollution and lower costs. This patch was partially generated with Gemini, but I've reviewed the changes it made.

erickt · 2026-04-15T17:07:12Z

@jieyouxu - Thanks for the review! I force pushed a rebased version, and tried to address your comments.

I can't find one though where you asked for the reasoning behind it. I updated the PR doc (and with this version I did use gemini to simplify things, and noted that in the comment). My interest in this was from doing some AI driven bug hunting with Gemini for #150907, and I thought that if we could suppress output from the Rust build we could cut down on wasted tokens to avoid context pollution and avoid spending extra on unnecessary tokens.

@rustbot ready

jieyouxu

Thanks, given that I anticipate this is more for local usage, even if it hides a few too many / too little warnings and whatever it's not a huge problem, because you can always attempt a rebuild without --quiet.

@bors r+ rollup

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rust-bors · 2026-04-16T01:49:23Z

📌 Commit f52f125 has been approved by jieyouxu

It is now in the queue for this repository.

Add `--quiet` flag to x.py and bootstrap to suppress output This adds a `--quiet` flag to x.py and bootstrap to suppress some of the output when compiling Rust. It conflicts with `--verbose`, matching the behavior of `cargo` which does not allow `--verbose` and `--quiet`. It works by passing quiet flags down to the underlying cargo, or LLVM build processes. Note that for LLVM, we only can suppress logs when we explicitly configure it with ninja. Otherwise we won't know what flag to pass along to whichever build system cmake decides to use. This can be helpful with AI workloads in the Rust codebase to help shrink down the output to reduce token usage, which can help prevent context pollution and lower costs. This patch was partially generated with Gemini, but I've reviewed the changes it made.

Rollup of 18 pull requests Successful merges: - #154595 (Emit fatal on invalid const args with nested defs) - #154599 (report the `varargs_without_pattern` lint in deps) - #154699 (`core::unicode`: Replace `Cased` table with `Lt`) - #155353 (resolve: Remove `inaccessible_ctor_reexport` resolver field) - #155357 (Add `--remap-path-scope` as unstable in rustdoc) - #150649 (clippy fix: non_canonical_clone_impl) - #154604 (abort in core) - #154616 (Add `--quiet` flag to x.py and bootstrap to suppress output) - #154970 (rustdoc: preserve `doc(cfg)` on locally re-exported type aliases) - #155215 (Clean up `AttributeLintKind` and refactor diagnostic attribute linting) - #155228 (Check diagnostic output in incremental `cpass` and `rpass` revisions) - #155266 (Adjust release notes for post-merge feedback) - #155326 (Disallow ZST allocations with `TypedArena`.) - #155334 (docs: Use `0b1` instead of `NonZero::MIN` in `NonZero::bit_width` doctests) - #155340 (Handle nonnull pattern types in size skeleton) - #155347 (Add push_mut and new Layout methods to release notes) - #155356 (remove calls to AliasTyKind::def_id) - #155364 (Reduce diagnostic type visibilities.)

Add `--quiet` flag to x.py and bootstrap to suppress output This adds a `--quiet` flag to x.py and bootstrap to suppress some of the output when compiling Rust. It conflicts with `--verbose`, matching the behavior of `cargo` which does not allow `--verbose` and `--quiet`. It works by passing quiet flags down to the underlying cargo, or LLVM build processes. Note that for LLVM, we only can suppress logs when we explicitly configure it with ninja. Otherwise we won't know what flag to pass along to whichever build system cmake decides to use. This can be helpful with AI workloads in the Rust codebase to help shrink down the output to reduce token usage, which can help prevent context pollution and lower costs. This patch was partially generated with Gemini, but I've reviewed the changes it made.

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 Mar 31, 2026

rustbot assigned Mark-Simulacrum Mar 31, 2026

jieyouxu assigned Mark-Simulacrum and jieyouxu and unassigned Mark-Simulacrum Apr 3, 2026

Mark-Simulacrum removed their assignment Apr 4, 2026

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jieyouxu mentioned this pull request Apr 5, 2026

Add --verbose-run-make-subprocess-output flag to suppress verbose run-make output for passing tests #154587

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jieyouxu self-requested a review April 5, 2026 08:25

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Comment thread src/bootstrap/src/core/build_steps/llvm.rs

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 Apr 5, 2026

erickt force-pushed the quiet branch from 81efd42 to ebc3bb2 Compare April 15, 2026 15:41

erickt force-pushed the quiet branch from ebc3bb2 to 3b7bc46 Compare April 15, 2026 15:47

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Apr 15, 2026

erickt requested a review from jieyouxu April 15, 2026 17:07

erickt force-pushed the quiet branch from 3b7bc46 to f52f125 Compare April 15, 2026 17:08

jieyouxu approved these changes Apr 16, 2026

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jhpratt mentioned this pull request Apr 16, 2026

Rollup of 18 pull requests #155373

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jhpratt mentioned this pull request Apr 16, 2026

Rollup of 18 pull requests #155380

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