feat: support array of any types in Cargo config #16103

weihanglo · 2025-10-13T22:43:32Z

What does this PR try to resolve?

This adds the support of array of any types in Cargo config.
The motivation of this is mostly from the proposed -Zconfig-include syntax (#7723 (comment))

[[include]]
path = "a.toml"
optional = true
[[include]]
path = "b.toml"
optional = false

which before this Cargo only supported array of string.

Some design decisions:

Insta-stabilization: This is insta- stabilizing a extension of Cargo config. See feat: support array of any types in Cargo config #16103 (comment)
No CARGO_* env support added — Only the --config CLI and file-based configuration start supporting array of any types. CARGO_* config environment still doesn't. The only type you can set through environment variable are still primitive types. For advanced env usage, we left it as follow-up to deal with in -Zadvanced-env
Nothing changed in config merging rule — Nested complex types in array won't merge with any other items, as it still respects the current array merging rule, which appends items.
cargo config get now prints inline array/tables for array of nested array/tables.

fixes #16111

How to test and review this PR?

Starting from the fifth commit, those changes are for handling diagnostic regression, as now Config::from_toml accepts any types and the invalid type error is delayed from the "TOML->ConfigValue" deserialization to "ConfigValue->Target" Type deserialization. Not sure if we should split it to a separate PR, but the solution here I admit is a bit nasty.

rustbot · 2025-10-13T22:43:37Z

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weihanglo · 2025-10-13T22:52:01Z

tests/testsuite/cargo_alias_config.rs

-
-Caused by:
-  expected string but found integer at index 0
+[ERROR] invalid type: integer `1`, expected a string


This is the error message regression that the next commit want to deal with

weihanglo · 2025-10-14T00:35:10Z

src/cargo/util/context/de.rs

+                seed.deserialize(de)
+                    .map_err(|e| {
+                        // This along with ArrayItemKeyPath provide a better error context of the
+                        // ConfigValue definition + the key path within an array item that native
+                        // TOML key path can't express. For example, `foo.bar[3].baz`.
+                        key_path.push_index(i);
+                        e.with_array_item_key_context(&key_path, definition)
+                    })
+                    .map(Some)


While it indeed fixes the this might the less good approach dealing with the diagnostic issue in general. The current approach only track the key path for array items when deserialzation fails. If caller requests for Vec<Value<String>> and performs post-deserialization validation, the key path info is missing for a better error context.

We might want to add an extra optional field array_item_path to Value<T> to preserve the information though. That is why I feel like may we should put off the second half of this PR.

Think more about it. The other option is doing nothing and staying with the current collect-on-error implementation. The caller should be able to compute the index of an item given it has the full picture of the array.

src/cargo/util/context/key.rs

tests/testsuite/bad_config.rs

src/cargo/ops/cargo_config.rs

Address #16103 (comment)

This demonstrates what we have supported today: no nested arrays

Actually it is not supported yet. Will do in the next few commits.

Only add the support to TOML-based Cargo config. Environment variables still only supports array of strings. `-Zadvanced-env` is not yet supported. There is a regression in `cargo_alias_config::alias_malformed_config_list` that the key path error report is missing. This may require a revamp over ConfigKey.

rustbot · 2025-10-26T15:53:30Z

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.

Update cargo submodule 11 commits in 344c4567c634a25837e3c3476aac08af84cf9203..6c1b6100343691341b9e76c5acc594e78220f963 2025-10-15 15:01:32 +0000 to 2025-10-28 16:27:52 +0000 - feat(build-analysis): JSONL-based logging infra (rust-lang/cargo#16150) - feat: support array of any types in Cargo config (rust-lang/cargo#16103) - test(git): add more fetch-index backend interop (rust-lang/cargo#16162) - feat(git): support shallow fetch for Git CLI backend (rust-lang/cargo#16156) - Fix mdman to not incorrectly strip `<p>` tags (rust-lang/cargo#16158) - chore(triagebot): enable range-diff and review-changes-since (rust-lang/cargo#16152) - Avoid specifying which version will change behavior (rust-lang/cargo#16153) - Make shell completion variables private. (rust-lang/cargo#16144) - More warning conversions (rust-lang/cargo#16143) - Bump openssl-src to 300.3.5.4+3.5.4 (rust-lang/cargo#16140) - build: remove duplicate dependency, consolidate over unicode-ident (rust-lang/cargo#16137)

rustbot assigned epage Oct 13, 2025

rustbot added A-configuration Area: cargo config files and env vars S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Oct 13, 2025

weihanglo mentioned this pull request Oct 13, 2025

Tracking issue for config-include #7723

Open

3 tasks

weihanglo force-pushed the array-of-any-types branch from 57ee900 to 0850805 Compare October 13, 2025 22:46

weihanglo changed the title ~~feat: support array of any types in Cargo Config~~ feat: support array of any types in Cargo config Oct 13, 2025

weihanglo commented Oct 13, 2025

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weihanglo force-pushed the array-of-any-types branch from 0850805 to 48fed23 Compare October 13, 2025 23:02

weihanglo commented Oct 14, 2025

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epage reviewed Oct 14, 2025

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src/cargo/util/context/key.rs Show resolved Hide resolved

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weihanglo mentioned this pull request Oct 14, 2025

fix(gctx): types are unsupported not unknown #16109

Merged

github-merge-queue bot pushed a commit that referenced this pull request Oct 14, 2025

fix(gctx): types are unsupported not unknown (#16109)

e6cc50d

Address #16103 (comment)

weihanglo mentioned this pull request Oct 14, 2025

Support array of any types in Cargo config #16111

Closed

weihanglo force-pushed the array-of-any-types branch 3 times, most recently from 4fae025 to 930baee Compare October 20, 2025 01:48

weihanglo force-pushed the array-of-any-types branch from 930baee to 98af008 Compare October 23, 2025 02:23

weihanglo added 7 commits October 26, 2025 11:53

test(cargo-config): print array of any types

bf0ec84

This demonstrates what we have supported today: no nested arrays

test(config): support array of any types

4eabaa2

Actually it is not supported yet. Will do in the next few commits.

refactor(gctx): move KeyOrIdex to key submodule

5082724

refactor(gctx): move source init logic to ValueSource

8af7c17

fix(gctx): provide a richer error context for array item key path

f8b2549

refactor(gctx): prefer let-else

4541603

weihanglo force-pushed the array-of-any-types branch from 98af008 to 4541603 Compare October 26, 2025 15:53

epage approved these changes Oct 28, 2025

View reviewed changes

epage added this pull request to the merge queue Oct 28, 2025

Merged via the queue into rust-lang:master with commit a5566ce Oct 28, 2025
25 checks passed

rustbot removed the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Oct 28, 2025

weihanglo mentioned this pull request Oct 28, 2025

Update cargo submodule rust-lang/rust#148231

Merged

rustbot added this to the 1.93.0 milestone Oct 29, 2025

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feat: support array of any types in Cargo config #16103

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