Rewatch: feature-gated source directories#8379
Rewatch: feature-gated source directories#8379jfrolich wants to merge 2 commits intorescript-lang:masterfrom
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Add a `feature` tag on source entries so a package can ship optional
slices of its source tree that consumers opt into. The new top-level
`features` map declares transitive implications, and `dependencies` /
`dev-dependencies` accept an object form `{name, features}` so a
consumer can restrict which features of a dep get built.
On the CLI, `rewatch build --features=a,b` (and the same on `watch`)
restricts the current package; dependencies inherit from consumer
declarations in rescript.json (union across consumers). Omitting the
flag keeps all features active.
Filtering runs inside `packages::make` before source files are
discovered, so the watcher automatically skips disabled directories and
the existing diff-based cleanup removes orphan artifacts when a feature
is toggled off. `clean` intentionally ignores `--features` so it
always wipes the full tree.
Cycles in the `features` map are rejected at load time with a message
naming the participants. Empty `--features=` is rejected with guidance
to omit the flag instead.
Includes unit tests for parsing, closure resolution, cycle detection,
and per-package active-set computation; six bash integration tests
covering CLI restriction, transitive expansion, artifact cleanup on
toggle, cycle errors, and empty-flag rejection. Documentation in
rewatch/Features.md and a row added to
rewatch/CompilerConfigurationSpec.md.
Signed-off-by: Jaap Frolich <jaap@tella.com>
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Signed-off-by: Jaap Frolich <jfrolich@gmail.com>
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| .dependencies | ||
| .as_ref() | ||
| .into_iter() | ||
| .flatten() | ||
| .chain(consumer.config.dev_dependencies.as_ref().into_iter().flatten()); |
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compute_active_features always chains dev_dependencies into the consumer scan, so feature requests from dev-only edges are still applied even in --prod builds. In a --prod run, a package can be discovered through dependencies with a restricted feature list, but a separate dev-dependency entry (especially shorthand/object-without-features) will flip any_all_request and force all features on. This pulls in feature-gated code that --prod is expected to exclude and can surface avoidable compile failures in production builds.
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| if !any_all_request && requested.is_empty() { | ||
| any_all_request = true; |
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This fallback treats an empty requested set as all features, which breaks the qualified dependency form when a consumer explicitly sets "features": []. In that case no features are requested, but requested remains empty and this branch forces any_all_request = true, enabling all feature-tagged source dirs for that dependency. That makes it impossible to express an untagged-only dependency build despite using the restrictive object form.
Useful? React with 👍 / 👎.
compute_active_features scanned both dependencies and dev-dependencies on every consumer regardless of the active build mode. In --prod, a dep reached via dependencies with a restricted feature list could still have a shorthand dev-dependencies entry on the same consumer flip any_all_request = true and force all features active — pulling in feature-gated code that --prod is supposed to exclude. Match read_dependencies's rule: dev-dependency edges only contribute to a dep's active feature set when the consumer is local and we're not in --prod. Regression test covers both modes. Signed-off-by: Jaap Frolich <jaap@tella.com> Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com> Signed-off-by: Jaap Frolich <jfrolich@gmail.com>
2 participants
Summary
featuretag onsourcesentries so packages can ship optional slices of their source tree. A top-levelfeaturesmap declares transitive implications, anddependencies/dev-dependenciesaccept a new object form{name, features}so consumers can restrict which features of a dep get built.rewatch build --features=a,b(andwatch) restricts the current package. Dependencies inherit from consumer declarations in rescript.json; multiple consumers union. Omitting the flag keeps all features active. Empty--features=is rejected with guidance.packages::makebefore source discovery, so the watcher naturally skips disabled dirs and the existing diff-based cleanup removes orphan artifacts when a feature is toggled off.cleanintentionally ignores--featuresand wipes the full tree.featuresmap fail fast at load time with a message naming the participants.rewatch/Features.md(dedicated), plus a row inrewatch/CompilerConfigurationSpec.md.Why
Lets a library author gate backend- or platform-specific code behind an opt-in flag without paying the compile cost for consumers who don't need it — and lets consumers restrict heavy deps to only the features they use.
Test plan
cargo build --manifest-path rewatch/Cargo.tomlcargo clippy --manifest-path rewatch/Cargo.toml --all-targets --all-features— no warningscargo fmt --check --manifest-path rewatch/Cargo.toml— cleancargo test --manifest-path rewatch/Cargo.toml --lib— 89 passing (21 new)make test-rewatch— full suite including 6 new feature tests underrewatch/tests/features/(104 assertions pass, 0 fail)Open follow-ups (not in this PR)
rescript-editor-analysis) doesn't yet know aboutfeatures. Feature-gated dirs are still visible to the LSP, so users can jump-to-def into code that won't compile under their current feature set — same UX astype: "dev"today.dependencies(as opposed to feature-gated source dirs within a dep) are out of scope.🤖 Generated with Claude Code