Add `attr.label_list_dict` #27119

fmeum · 2025-09-30T09:51:47Z

Motivating examples for adding this type:

Packaging rules that bundle targets into substructures (e.g. subdirectories).
Providing hints to aspects via a well-known implicit attribute mapping the names of other attributes to a list of well-known targets representing the semantic meaning of an edge (e.g. "compile time dep", "runtime dep", "third party dep", ...) for use in SBOM generation and packaging.
rules_js and other rulesets have patches parameters on their module extensions that accept lists of patches to apply per external dependency. With WORKSPACE, they relied on attr.string_list_dict, but the lack of repo mapping means that there is no direct port. Users would need to migrate to individual tags per hub repo and dep to supply patches.

Adding this type doesn't incur a significant maintenance cost:

The native attribute type LABEL_LIST_DICT already exists (added for exec_group_compatible_with), so this only requires wiring it up in Starlark. In fact, some of the added logic (duplicate checking) is relevant for this existing use case, we just forgot to add it.
A Starlark type with equivalent BUILD syntax already exists (attr.string_list_dict), so there is no need for tooling to explicitly support the new type.

RELNOTES[NEW]: The new attr.label_list_dict type accepts a dict in which keys are strings and values are lists of labels.

fmeum · 2025-09-30T14:34:52Z

@lberki Choosing you as a reviewer based on #7989 (comment) :-)

meteorcloudy · 2025-10-14T14:33:46Z

ping @lberki

lberki

Apologies for the delay. Even today, I only had time to review the production code, but not the tests.

src/main/java/com/google/devtools/build/lib/analysis/RuleContext.java

src/main/java/com/google/devtools/build/lib/bazel/repository/AttributeUtils.java

Motivating examples for adding this type: * Packaging rules that bundle targets into substructures (e.g. subdirectories). * Providing hints to aspects via a well-known implicit attribute mapping the names of other attributes to a list of well-known targets representing the semantic meaning of an edge (e.g. "compile time dep", "runtime dep", "third party dep", ...) for use in SBOM generation and packaging. * rules_js and other rulesets have `patches` parameters on their module extensions that accept lists of patches to apply per external dependency. With WORKSPACE, they relied on `attr.string_list_dict`, but the lack of repo mapping means that there is no direct port. Users would need to migrate to individual tags per hub repo and dep to supply patches. Adding this type doesn't incur a significant maintenance cost: * The native attribute type `LABEL_LIST_DICT` already exists (added for `exec_group_compatible_with`), so this only requires wiring it up in Starlark. * A Starlark type with equivalent BUILD syntax already exists (`attr.string_list_dict`), so there is no need for tooling to explicitly support the new type. RELNOTES[NEW]: The new `attr.label_list_dict` type accepts a dict in which keys are strings and values are lists of labels.

lberki · 2025-10-29T19:36:03Z

Let's merge this then. @fmeum 's been waiting long enough.

tetromino

Fabian, can you please also add the new type to AttributeType in stardoc_output.proto, and add support for it in AttributeInfoExtractor.java?

fmeum · 2025-10-30T15:42:12Z

Fabian, can you please also add the new type to AttributeType in stardoc_output.proto, and add support for it in AttributeInfoExtractor.java?

That's already on master as the native type existed before I added the Starlark type in this PR.

tetromino

Fabian, can you please also add the new type to AttributeType in stardoc_output.proto, and add support for it in AttributeInfoExtractor.java?

That's already on master as the native type existed before I added the Starlark type in this PR.

Ahh - of course, you added it in f99a46f. I apologize for misreading.

fmeum · 2025-11-05T18:09:52Z

@bazel-io fork 9.0.0

Motivating examples for adding this type: * Packaging rules that bundle targets into substructures (e.g. subdirectories). * Providing hints to aspects via a well-known implicit attribute mapping the names of other attributes to a list of well-known targets representing the semantic meaning of an edge (e.g. "compile time dep", "runtime dep", "third party dep", ...) for use in SBOM generation and packaging. * rules_js and other rulesets have `patches` parameters on their module extensions that accept lists of patches to apply per external dependency. With WORKSPACE, they relied on `attr.string_list_dict`, but the lack of repo mapping means that there is no direct port. Users would need to migrate to individual tags per hub repo and dep to supply patches. Adding this type doesn't incur a significant maintenance cost: * The native attribute type `LABEL_LIST_DICT` already exists (added for `exec_group_compatible_with`), so this only requires wiring it up in Starlark. In fact, some of the added logic (duplicate checking) is relevant for this existing use case, we just forgot to add it. * A Starlark type with equivalent BUILD syntax already exists (`attr.string_list_dict`), so there is no need for tooling to explicitly support the new type. Fixes bazelbuild#7989 RELNOTES[NEW]: The new `attr.label_list_dict` type accepts a dict in which keys are strings and values are lists of labels. Closes bazelbuild#27119. PiperOrigin-RevId: 828510272 Change-Id: Ibf5ba97d049e592af2f61d91dbaa42cfe264f0bb

aignas · 2025-11-06T05:45:16Z

Can this also be cherry-picked to 8.x so that we have broader coverage? If the users start using attr.label_list_dict, they are locked to particular bazel versions.

fmeum · 2025-11-06T06:31:53Z

@bazel-io fork 8.5.0

Motivating examples for adding this type: * Packaging rules that bundle targets into substructures (e.g. subdirectories). * Providing hints to aspects via a well-known implicit attribute mapping the names of other attributes to a list of well-known targets representing the semantic meaning of an edge (e.g. "compile time dep", "runtime dep", "third party dep", ...) for use in SBOM generation and packaging. * rules_js and other rulesets have `patches` parameters on their module extensions that accept lists of patches to apply per external dependency. With WORKSPACE, they relied on `attr.string_list_dict`, but the lack of repo mapping means that there is no direct port. Users would need to migrate to individual tags per hub repo and dep to supply patches. Adding this type doesn't incur a significant maintenance cost: * The native attribute type `LABEL_LIST_DICT` already exists (added for `exec_group_compatible_with`), so this only requires wiring it up in Starlark. In fact, some of the added logic (duplicate checking) is relevant for this existing use case, we just forgot to add it. * A Starlark type with equivalent BUILD syntax already exists (`attr.string_list_dict`), so there is no need for tooling to explicitly support the new type. Fixes #7989 RELNOTES[NEW]: The new `attr.label_list_dict` type accepts a dict in which keys are strings and values are lists of labels. Closes #27119. PiperOrigin-RevId: 828510272 Change-Id: Ibf5ba97d049e592af2f61d91dbaa42cfe264f0bb Commit b0f51a9 Co-authored-by: Fabian Meumertzheim <fabian@meumertzhe.im>

fmeum force-pushed the 7989-label-list-dict branch 2 times, most recently from 138edea to 6146d60 Compare September 30, 2025 14:02

fmeum requested a review from lberki September 30, 2025 14:34

fmeum marked this pull request as ready for review September 30, 2025 14:34

fmeum requested review from a team, Wyverald and meteorcloudy as code owners September 30, 2025 14:34

fmeum requested review from gregestren and removed request for a team, Wyverald, gregestren and meteorcloudy September 30, 2025 14:34

github-actions bot added team-Configurability platforms, toolchains, cquery, select(), config transitions team-ExternalDeps External dependency handling, remote repositiories, WORKSPACE file. awaiting-review PR is awaiting review from an assigned reviewer labels Sep 30, 2025

lberki reviewed Oct 27, 2025

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src/main/java/com/google/devtools/build/lib/analysis/RuleContext.java Show resolved Hide resolved

src/main/java/com/google/devtools/build/lib/bazel/repository/AttributeUtils.java Outdated Show resolved Hide resolved

fmeum added 2 commits October 28, 2025 15:28

Address comment

a7e165e

fmeum force-pushed the 7989-label-list-dict branch from 6146d60 to a7e165e Compare October 28, 2025 14:46

fmeum requested a review from lberki October 28, 2025 14:48

Fix CI

eda14f1

lberki requested review from Wyverald and meteorcloudy October 29, 2025 11:27

lberki added awaiting-PR-merge PR has been approved by a reviewer and is ready to be merge internally and removed awaiting-review PR is awaiting review from an assigned reviewer labels Oct 29, 2025

lberki approved these changes Oct 29, 2025

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copybara-service bot closed this in b0f51a9 Nov 5, 2025

github-actions bot removed the awaiting-PR-merge PR has been approved by a reviewer and is ready to be merge internally label Nov 5, 2025

fmeum deleted the 7989-label-list-dict branch November 5, 2025 18:09

bazel-io mentioned this pull request Nov 5, 2025

[9.0.0] Add attr.label_list_dict #27549

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bazel-io mentioned this pull request Nov 5, 2025

[9.0.0] Add attr.label_list_dict #27550

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bazel-io mentioned this pull request Nov 6, 2025

[8.5.0] Add attr.label_list_dict #27556

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