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feat(profile): Add built-in profile debug #17214

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epage wants to merge 3 commits into
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epage:debug-profile
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feat(profile): Add built-in profile debug #17214
epage wants to merge 3 commits into
rust-lang:masterfrom
epage:debug-profile

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@epage

@epage epage commented Jul 14, 2026 •
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What does this PR try to resolve?

Key points:

  • It inherits from dev
    • Conceptually, debugging is part of the development process
    • The hope is this will smooth out the transition for people
  • cargo install --debug now uses debug instead of dev
  • debug changes nothing from dev right now.
    dev will evolve in the future
    (with debug overriding those values to leave it effectively unchanged)
    but that is deferred out to offer a transition period where debug
    can be used without but isn't required for debugging as people deal
    with multiple Rust versions. This also shrinks the change and
    decouples what the conversation around what the settings should be.
  • dev still uses target/debug: this does not change any calculation for the transition cost and any conflicts between the profiles should mostly be in the artifact-dir (which are just hard links), especially once the new build layout lands
  • --dev/--debug flags are deferred out, needing more evaluation to decide if they are worth it

See also https://github.com/rust-lang/cargo-team/blob/main/meetings/sync-meeting/2026-07-14.md#splitting-dev-and-debug-profiles

How to test and review this PR?

This is part of #15931

@rustbot rustbot added the A-cli Area: Command-line interface, option parsing, etc. label Jul 14, 2026
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epage marked this pull request as draft July 14, 2026 20:18
@rustbot rustbot added the A-cli-help Area: built-in command-line help label Jul 14, 2026
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rustbot commented Jul 14, 2026

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r? @ehuss

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The reviewer was selected based on:

  • Owners of files modified in this PR: @ehuss, @epage, @weihanglo
  • @ehuss, @epage, @weihanglo expanded to ehuss, epage, weihanglo
  • Random selection from ehuss, weihanglo

@rustbot rustbot added A-documenting-cargo-itself Area: Cargo's documentation A-manifest Area: Cargo.toml issues A-profiles Area: profiles S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Jul 14, 2026
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epage marked this pull request as ready for review July 15, 2026 00:10
@rustbot rustbot added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Jul 15, 2026
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@weihanglo

weihanglo commented Jul 16, 2026

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Should we include the meeting note in the PR description?
https://github.com/rust-lang/cargo-team/blob/main/meetings/sync-meeting/2026-07-14.md#splitting-dev-and-debug-profiles

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epage commented Jul 17, 2026

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Added the link and what looked like I might have been missing

weihanglo
weihanglo approved these changes Jul 17, 2026
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I think this is less risky as debug has been a reserved profile for a long while, and people kinda agree on the direction in the meeting this week, so probably don't need an FCP. What do you think?

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@weihanglo weihanglo added the T-cargo Team: Cargo label Jul 17, 2026
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@weihanglo

weihanglo commented Jul 17, 2026

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@rfcbot fcp merge T-cargo

This is a one-way-door decision that debug becomes an actual profile. See the PR description for details.

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rust-rfcbot commented Jul 17, 2026 •
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@weihanglo has proposed to merge this. The next step is review by the rest of the tagged team members:

No concerns currently listed.

Once a majority of reviewers approve (and at most 2 approvals are outstanding), this will enter its final comment period. If you spot a major issue that hasn't been raised at any point in this process, please speak up!

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@rust-rfcbot rust-rfcbot added proposed-final-comment-period An FCP proposal has started, but not yet signed off. disposition-merge FCP with intent to merge labels Jul 17, 2026
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epage commented Jul 17, 2026

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While we can pivot, I think an FCP is important as this is setting a direction and can be disruptive to the ecosystem if we pivoted on that direction.

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epage added 2 commits July 17, 2026 16:03
@epage
test(profile): Expand debug profile coverage
ea73b8f
@epage
feat(profile): Add built-in profile debug
88c5c58 
Key points:
- It inherits from `dev`
  - Conceptually, debugging is part of the development process
  - The hope is this will smooth out the transition for people
- `cargo install --debug` now uses `debug` instead of `dev`
- `debug` changes nothing from `dev` right now.
  `dev` will evolve in the future
  (with `debug` overriding those values to leave it effectively unchanged)
  but that is deferred out to offer a transition period where `debug`
  can be used without but isn't required for debugging as people deal
  with multiple Rust versions. This also shrinks the change and
  decouples what the conversation around what the settings should be.
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rustbot commented Jul 17, 2026

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This PR was rebased onto a different master 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.

@ehuss ehuss moved this to FCP merge in Cargo status tracker Jul 21, 2026
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@weihanglo weihanglo weihanglo approved these changes

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@ehuss ehuss

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A-cli Area: Command-line interface, option parsing, etc. A-cli-help Area: built-in command-line help A-documenting-cargo-itself Area: Cargo's documentation A-manifest Area: Cargo.toml issues A-profiles Area: profiles disposition-merge FCP with intent to merge proposed-final-comment-period An FCP proposal has started, but not yet signed off. S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-cargo Team: Cargo

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