feat(config): Stabilize `resolver.lockfile-path` config by epage · Pull Request #16694 · rust-lang/cargo

epage · 2026-03-03T17:20:30Z

What does this PR try to resolve?

Overall, this seems like a low policy knob for users to tweak in config (ie out of the way) so this seems relatively safe to stabilize.

resolver.lockfile-path is a mechanism to override the default location for lockfiles for local development

The filename must be specified and must be Cargo.lock
Making a decision about template support generally, and which variables more specifically, was deferred out
- { and } are reserved to keep this a two-way door
Besides changing the location, all other lockfile behavior remains the same, e.g. automatic creation of the lockfile, automatic parent directory creation, how --locked works'
this remains consistent with config behavior
- like resolver.incompatible-rust-version, resolver.lockfile-path does not apply to cargo install
- like other paths in config, paths are relative to .cargos parent directory if .cargo/config.toml is used and the current working directory for env variables and CLI.

This started out as a principled workaround to no or outdated lockfiles on read-only filesystems. This could also help with users who juggle multiple lockfiles (e.g. "latest" vs "msrv") particularly when they can have dedicated config files for the different lockfiles and override other relevant resolver settings in the same config file.

Alternatives

--lockfile-path: which this feature started its life as, see RFE: add option to specify path to Cargo.lock #5707
- Allow to set lockfile-path via an environment variable #15510 has a use case for this also to be done via an env variable (pain on user to always specify the flag)
- A dedicated CLI flag doesn't feel like it carries its own weight (see also Is --out-dir justified or can we find another way of accomplishing it? #6100)
- A config field more obvious semantics ("change the default") vs a flag which questions like "should cargo install --lockfile-path foo imply --locked?"

How to test and review this PR?

rustbot · 2026-03-03T17:20:36Z

r? @ehuss

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Owners of files modified in this PR: @ehuss, @epage, @weihanglo
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epage · 2026-03-03T17:21:01Z

@rfcbot fcp merge cargo

rust-rfcbot · 2026-03-03T17:21:03Z

Team member @epage has proposed to merge this. The next step is review by the rest of the tagged team members:

Concerns:

~~install~~ resolved by feat(config): Stabilize resolver.lockfile-path config #16694 (comment)

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!

See this document for info about what commands tagged team members can give me.

epage · 2026-03-03T17:21:43Z

@rfcbot fcp concern install

Inconsistency in resolver table being applied to cargo install

Should we remove install support or have this inconsistent?

0xPoe

Thanks!

The changes look good.

View changes since this review

0xPoe · 2026-03-03T17:53:28Z

Should we remove install support or have this inconsistent?

In which cases would we need to specify the lockfile path and install binaries? This configuration is primarily for using read-only source directories. I couldn't wrap my head around coming up with a use case for it.

weihanglo · 2026-03-05T17:43:50Z

Should we remove install support or have this inconsistent?

Just remind that we also have an inconsistency of install not respecting [patch] #12855.

weihanglo · 2026-03-05T17:47:48Z

Do we think the support of unsetting the lockfile path a blocker? Currently there is no way to do that. And without that, it is hard for people to unset if a global resolver.lockfile-path is applied to cargo-install.

ehuss · 2026-03-06T15:23:06Z

I'm not quite clear which inconsistency we're talking about.

That cargo install requires --locked to honor resolver.lockfile-path?
That cargo install with --locked and resolver.lockfile-path doesn't honor other settings in the resolver table?
Something else?

Also, is there a more detailed description of this feature? Overall I'd like to see a more detailed stabilization report. For example, it seems to reserve {} substitutions, but I don't see that mentioned anywhere. There also seems to be various small details, like it seems to create intermediate directories (which is good). Is the path relative to the workspace root? The current directory? The consideration of an config value versus CLI flag was captured out in #15510 (comment). Things like that would help in understanding what is being proposed here.

epage · 2026-04-02T13:00:18Z

@rfcbot fcp resolved install

#16823 removed support from cargo install.

rust-rfcbot · 2026-04-07T16:41:40Z

🔔 This is now entering its final comment period, as per the review above. 🔔

rust-rfcbot · 2026-04-17T16:42:04Z

The final comment period, with a disposition to merge, as per the review above, is now complete.

As the automated representative of the governance process, I would like to thank the author for their work and everyone else who contributed.

rustbot · 2026-04-17T20:22:39Z

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.

weihanglo · 2026-04-17T20:34:06Z

Thanks!

Update cargo submodule 26 commits in eb94155a9a60943bd7b1cb04abec42f5d0de6ddc..3bf1388b8823ec4eab622340036593381d8871aa 2026-04-09 13:10:20 +0000 to 2026-04-17 23:27:26 +0000 - Add global HTTP timeout tracking to http_async (rust-lang/cargo#16903) - feat(config): Stabilize `resolver.lockfile-path` config (rust-lang/cargo#16694) - chore(deps): update msrv (1 version) to v1.95 (rust-lang/cargo#16897) - fix: rebuild rustdoc json for different versions of a same crate (rust-lang/cargo#16773) - Add effective_url to http_async (rust-lang/cargo#16899) - Make crate downloads process as a queue rather than a stack (rust-lang/cargo#16898) - fix: sparse registry fetch progress reporting (rust-lang/cargo#16900) - chore: bump to 0.98.0; update changelog (rust-lang/cargo#16892) - docs(semver-check): update diagnostics to Rust 1.95 (rust-lang/cargo#16895) - docs(ref): Better highlight 'package --list' for include/exclude (rust-lang/cargo#16891) - docs: `include` doesnt apply gitignore from repo (rust-lang/cargo#16890) - fix: Update `bash` and `zsh` Autocompletion Documents to add `-m` (rust-lang/cargo#16888) - Add `-m` shorthand for `--manifest-path` (rust-lang/cargo#16858) - Fix a typo (rust-lang/cargo#16885) - Always take a shared lock on `.cargo-lock` (rust-lang/cargo#16886) - fix(toml): Teach users how to pin edition (rust-lang/cargo#16851) - fix: Prefer defined lint levels over default (rust-lang/cargo#16879) - chore(deps): bump rand from 0.10.0 to 0.10.1 (rust-lang/cargo#16883) - fix(lints): Ignore unused_crate_dependencies status (rust-lang/cargo#16877) - Copy cargo clean target-dir validation tests to clean_new_layout.rs (rust-lang/cargo#16878) - cargo clean: Add target directory validation (rust-lang/cargo#16712) - Docs: "api" in the configuration should not include a trailing slash (rust-lang/cargo#16869) - fix(core): use `closest_msg` to suggest similar member name for mistyped `-p` (rust-lang/cargo#16844) - chore(ci): Pin GitHub Actions to commit SHAs (rust-lang/cargo#16868) - chore(ci): Update `actions/checkout` from v5 to v6 (rust-lang/cargo#16867) - Add test for cargo install with github fastpath (rust-lang/cargo#16866) r? ghost

Update cargo submodule 28 commits in eb94155a9a60943bd7b1cb04abec42f5d0de6ddc..7ecf0285ebb408d596e4a8ac76a0980d8edb7005 2026-04-09 13:10:20 +0000 to 2026-04-18 15:34:11 +0000 - fix: use `portable-atomic` for 64-bit atomics (rust-lang/cargo#16906) - fix: rename incorrectly documented target-spec-json to json-target-sp… (rust-lang/cargo#16905) - Add global HTTP timeout tracking to http_async (rust-lang/cargo#16903) - feat(config): Stabilize `resolver.lockfile-path` config (rust-lang/cargo#16694) - chore(deps): update msrv (1 version) to v1.95 (rust-lang/cargo#16897) - fix: rebuild rustdoc json for different versions of a same crate (rust-lang/cargo#16773) - Add effective_url to http_async (rust-lang/cargo#16899) - Make crate downloads process as a queue rather than a stack (rust-lang/cargo#16898) - fix: sparse registry fetch progress reporting (rust-lang/cargo#16900) - chore: bump to 0.98.0; update changelog (rust-lang/cargo#16892) - docs(semver-check): update diagnostics to Rust 1.95 (rust-lang/cargo#16895) - docs(ref): Better highlight 'package --list' for include/exclude (rust-lang/cargo#16891) - docs: `include` doesnt apply gitignore from repo (rust-lang/cargo#16890) - fix: Update `bash` and `zsh` Autocompletion Documents to add `-m` (rust-lang/cargo#16888) - Add `-m` shorthand for `--manifest-path` (rust-lang/cargo#16858) - Fix a typo (rust-lang/cargo#16885) - Always take a shared lock on `.cargo-lock` (rust-lang/cargo#16886) - fix(toml): Teach users how to pin edition (rust-lang/cargo#16851) - fix: Prefer defined lint levels over default (rust-lang/cargo#16879) - chore(deps): bump rand from 0.10.0 to 0.10.1 (rust-lang/cargo#16883) - fix(lints): Ignore unused_crate_dependencies status (rust-lang/cargo#16877) - Copy cargo clean target-dir validation tests to clean_new_layout.rs (rust-lang/cargo#16878) - cargo clean: Add target directory validation (rust-lang/cargo#16712) - Docs: "api" in the configuration should not include a trailing slash (rust-lang/cargo#16869) - fix(core): use `closest_msg` to suggest similar member name for mistyped `-p` (rust-lang/cargo#16844) - chore(ci): Pin GitHub Actions to commit SHAs (rust-lang/cargo#16868) - chore(ci): Update `actions/checkout` from v5 to v6 (rust-lang/cargo#16867) - Add test for cargo install with github fastpath (rust-lang/cargo#16866)

epage added the T-cargo Team: Cargo label Mar 3, 2026

rustbot assigned ehuss Mar 3, 2026

rustbot added A-documenting-cargo-itself Area: Cargo's documentation A-unstable Area: nightly unstable support A-workspaces Area: workspaces S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Mar 3, 2026

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epage force-pushed the lockfile-path branch from 499d9af to 1878e85 Compare March 3, 2026 18:20

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Cargo RFC for min publish age rust-lang/rfcs#3923

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fix(install): Ignore resolver.lockfile-path #16823

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feat(config): Stabilize resolver.lockfile-path

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epage force-pushed the lockfile-path branch from 1878e85 to ff664cb Compare April 2, 2026 12:57

epage force-pushed the lockfile-path branch from d5dd700 to b1d5eaa Compare April 2, 2026 20:37

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rust-rfcbot added final-comment-period FCP — a period for last comments before action is taken and removed proposed-final-comment-period An FCP proposal has started, but not yet signed off. labels Apr 7, 2026

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Merged via the queue into rust-lang:master with commit da06c61 Apr 17, 2026
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Update cargo submodule rust-lang/rust#155470

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