feat(rsc): bind accessed member expression value for `use server` closure by hi-ogawa · Pull Request #1172 · vitejs/vite-plugin-react

hi-ogawa · 2026-04-05T04:40:01Z

Description

Closes server action closures should capture member access paths, not whole objects #1171
Stacked on fix(rsc): handle shadowing for use server variable binding #1170

TODO

review slop
handle optional chain (maybe later)

…of whole root Captures like `x.y.z` now bind `{ y: { z: x.y.z } }` and keep the original root name as the hoisted function parameter, avoiding serialization of the whole root object over the network. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Co-authored-by: Codex <noreply@openai.com>

Copilot

Pull request overview

This PR enhances the RSC server-action hoisting transform so closures that reference member-access chains (e.g. config.api.key) bind only the accessed subtree instead of serializing/binding the full root object. This reduces RSC payload size and avoids runtime serialization failures when the root contains non-serializable values.

Changes:

Extend scope analysis to track the “outermost bindable” reference node per identifier (identifier vs. non-computed member-expression chain, with callee trimming).
Update hoist binding to synthesize partial object literals per root identifier and bind those (while keeping the hoisted function parameter as the root name).
Add/refresh fixtures + snapshots and add design notes; update formatter ignore patterns for new *.snap.js files.

Reviewed changes

Copilot reviewed 31 out of 31 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
packages/plugin-rsc/src/transforms/utils.ts	Adds a shared `DefaultMap` helper (moved out of tests).
packages/plugin-rsc/src/transforms/scope.ts	Tracks member-expression chains per reference (`referenceToNode`) and applies callee trimming.
packages/plugin-rsc/src/transforms/scope.test.ts	Updates scope serializer to optionally display the tracked reference node; uses shared `DefaultMap`.
packages/plugin-rsc/src/transforms/hoist.ts	Changes bind-var extraction to synthesize partial-object bind expressions for member chains.
packages/plugin-rsc/src/transforms/hoist.test.ts	Adds fixture-based snapshot testing for hoist output and updates/clarifies some existing edge-case comments.
packages/plugin-rsc/src/transforms/fixtures/scope/reference-node/member-chain.js	New fixture for plain member chain reference-node tracking.
packages/plugin-rsc/src/transforms/fixtures/scope/reference-node/member-chain.js.snap.json	Snapshot for plain member chain reference-node tracking.
packages/plugin-rsc/src/transforms/fixtures/scope/reference-node/member-chain-optional.js	New fixture for optional-chain boundary behavior.
packages/plugin-rsc/src/transforms/fixtures/scope/reference-node/member-chain-optional.js.snap.json	Snapshot for optional-chain boundary behavior.
packages/plugin-rsc/src/transforms/fixtures/scope/reference-node/member-chain-computed.js	New fixture for computed-access boundary behavior.
packages/plugin-rsc/src/transforms/fixtures/scope/reference-node/member-chain-computed.js.snap.json	Snapshot for computed-access boundary behavior.
packages/plugin-rsc/src/transforms/fixtures/scope/reference-node/member-chain-callee.js	New fixture for callee-trimming behavior.
packages/plugin-rsc/src/transforms/fixtures/scope/reference-node/member-chain-callee.js.snap.json	Snapshot for callee-trimming behavior.
packages/plugin-rsc/src/transforms/fixtures/hoist/member-chain.js	New hoist fixture for partial-object binding of member chains.
packages/plugin-rsc/src/transforms/fixtures/hoist/member-chain.js.snap.js	Snapshot for member-chain partial-object binding.
packages/plugin-rsc/src/transforms/fixtures/hoist/member-chain-siblings.js	New hoist fixture for merging sibling paths under one root.
packages/plugin-rsc/src/transforms/fixtures/hoist/member-chain-siblings.js.snap.js	Snapshot for sibling-path merge binding.
packages/plugin-rsc/src/transforms/fixtures/hoist/member-chain-root.js	New hoist fixture where direct root access forces binding the whole root.
packages/plugin-rsc/src/transforms/fixtures/hoist/member-chain-root.js.snap.js	Snapshot for root-access override binding.
packages/plugin-rsc/src/transforms/fixtures/hoist/member-chain-optional.js	New hoist fixture for optional-chain conservative fallback behavior.
packages/plugin-rsc/src/transforms/fixtures/hoist/member-chain-optional.js.snap.js	Snapshot for optional-chain fallback behavior.
packages/plugin-rsc/src/transforms/fixtures/hoist/member-chain-dedupe.js	New hoist fixture for prefix dedupe behavior.
packages/plugin-rsc/src/transforms/fixtures/hoist/member-chain-dedupe.js.snap.js	Snapshot for prefix-dedupe binding result.
packages/plugin-rsc/src/transforms/fixtures/hoist/member-chain-computed.js	New hoist fixture for computed-access conservative fallback behavior.
packages/plugin-rsc/src/transforms/fixtures/hoist/member-chain-computed.js.snap.js	Snapshot for computed-access fallback behavior.
packages/plugin-rsc/src/transforms/fixtures/hoist/member-chain-callee.js	New hoist fixture verifying callee trimming preserves receiver capture.
packages/plugin-rsc/src/transforms/fixtures/hoist/member-chain-callee.js.snap.js	Snapshot for callee-trimming hoist output.
packages/plugin-rsc/src/transforms/fixtures/hoist/member-chain-unsupported.js	New hoist fixture covering multiple unsupported patterns.
packages/plugin-rsc/src/transforms/fixtures/hoist/member-chain-unsupported.js.snap.js	Snapshot for unsupported-pattern binding behavior.
packages/plugin-rsc/docs/notes/2026-04-05-rsc-member-chain-binding-plan.md	Design note documenting the chosen approach and rationale.
packages/plugin-rsc/docs/notes/2026-04-05-member-chain-optional-computed-follow-up.md	Follow-up note outlining optional/computed access support considerations.
.oxfmtrc.json	Expands ignore pattern to cover `.snap.` (including new `*.snap.js`).

Comments suppressed due to low confidence (1)

packages/plugin-rsc/src/transforms/scope.test.ts:10

Typo in comment: “snaphsot” → “snapshot”.

// - use single markdown as snaphsot? (cf. review-scope-fixtures.ts)

describe('fixtures', () => {

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Copilot · 2026-04-06T04:27:03Z

packages/plugin-rsc/src/transforms/hoist.ts

+  function serialize(node: TrieNode, segments: string[]): string {
+    if (node.size === 0) {
+      return root + segments.map((segment) => `.${segment}`).join('')
+    }
+    const entries = [...node.entries()]
+      .map(([k, child]) => `${k}: ${serialize(child, [...segments, k])}`)


serialize emits object-literal keys as bare identifiers (e.g. { __proto__: ... }). If a captured segment is __proto__, this changes the resulting object's prototype (prototype pollution / semantic change). Consider emitting a computed key for __proto__ (e.g. ['__proto__']) or otherwise guarding special keys when generating the partial object literal.

Suggested change

function serialize(node: TrieNode, segments: string[]): string {

if (node.size === 0) {

return root + segments.map((segment) => `.${segment}`).join('')

}

const entries = [...node.entries()]

.map(([k, child]) => `${k}: ${serialize(child, [...segments, k])}`)

function serializeObjectKey(segment: string): string {

return segment === '__proto__' ? `["${segment}"]` : segment

}

function serialize(node: TrieNode, segments: string[]): string {

if (node.size === 0) {

return root + segments.map((segment) => `.${segment}`).join('')

}

const entries = [...node.entries()]

.map(

([k, child]) =>

`${serializeObjectKey(k)}: ${serialize(child, [...segments, k])}`,

)

Copilot · 2026-04-06T04:27:03Z

packages/plugin-rsc/src/transforms/scope.test.ts

+      return node.name
+    }
+    // <unknown>/computed/optional shouldn't show up
+    // since they aren't colelcted as reference node yet.


Typo in comment: “colelcted” → “collected”.

Suggested change

// since they aren't colelcted as reference node yet.

// since they aren't collected as reference node yet.

Copilot · 2026-04-06T04:27:04Z

packages/plugin-rsc/src/transforms/hoist.test.ts

+      const snaphsot = result.output.hasChanged()
+        ? result.output.toString()
+        : '/* NO CHANGE */'
+      await expect(snaphsot).toMatchFileSnapshot(file + '.snap.js')


Typo in variable name: snaphsot → snapshot (and corresponding uses). Keeping consistent spelling makes fixture failures easier to scan.

Suggested change

const snaphsot = result.output.hasChanged()

? result.output.toString()

: '/* NO CHANGE */'

await expect(snaphsot).toMatchFileSnapshot(file + '.snap.js')

const snapshot = result.output.hasChanged()

? result.output.toString()

: '/* NO CHANGE */'

await expect(snapshot).toMatchFileSnapshot(file + '.snap.js')

hi-ogawa and others added 2 commits April 5, 2026 11:34

chore: todo comment

3892031

hi-ogawa changed the title ~~feat(rsc): bind only accessed member expression value for use server closure~~ feat(rsc): bind accessed member expression value for use server closure Apr 5, 2026

hi-ogawa and others added 12 commits April 5, 2026 14:03

test(plugin-rsc): add fixture-based tests for hoist transform

f85e547

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

test: add targeted RSC member-chain hoist fixtures

eb8b4f3

Co-authored-by: Codex <noreply@openai.com>

refactor: de-slop

8998f65

chore: todo slop

467c84a

refactor: de-slop

376bfd6

refactor: remove source slicing from RSC bind var analysis

47e1cc0

Co-authored-by: Codex <noreply@openai.com>

refactor: nit

aa5d118

chore: todo for computed and optional access

0376890

fix: stop unsupported member binding at safe prefix

e9851ff

Co-authored-by: Codex <noreply@openai.com>

docs: add RSC member-chain task notes

623102d

Co-authored-by: Codex <noreply@openai.com>

docs: clarify optional and computed member-chain follow-up

ca081d4

Co-authored-by: Codex <noreply@openai.com>

refactor: nit

3307d06

hi-ogawa mentioned this pull request Apr 5, 2026

feat(rsc): custom scope analyzer to replace periscopic #1157

Open

hi-ogawa and others added 14 commits April 6, 2026 11:14

test(plugin-rsc): add optional reference node snapshots

97f2700

Co-authored-by: Codex <noreply@openai.com>

refactor: de-slop

d99a90d

test: tweak serializeReferenceNode

0a2a7d7

test: nit

2fb1a27

test: more

de579d9

refactor: deslop

af07ac2

refactor: deslop

4f3c0da

test: more

be555fd

refactor: de-slop

557b59a

chore: move DefaultMap

2c289a0

refactor(plugin-rsc): simplify bind var grouping

44bac65

Co-authored-by: Codex <noreply@openai.com>

refactor: nit

45fa0c5

chore: still de-slopping

37e704b

refactor: de-slop

cc7b257

hi-ogawa and others added 6 commits April 6, 2026 12:30

refactor: de-slop

7119748

refactor: de-slop

9591c6b

refactor(plugin-rsc): tighten prefix path dedupe

2a46b06

Co-authored-by: Codex <noreply@openai.com>

chore: comment

b6db313

refactor: de-slop

fb4fade

test: update

ad8ef95

hi-ogawa requested a review from Copilot April 6, 2026 04:23

Copilot started reviewing on behalf of hi-ogawa April 6, 2026 04:24 View session

chore: cleanup

e25a88f

hi-ogawa marked this pull request as ready for review April 6, 2026 04:26

Copilot AI reviewed Apr 6, 2026

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feat(rsc): bind accessed member expression value for `use server` closure#1172

feat(rsc): bind accessed member expression value for `use server` closure#1172
hi-ogawa wants to merge 35 commits intotest-rsc-add-test-for-use-server-binding-and-shadowingfrom
feat-bind-member-expr

hi-ogawa commented Apr 5, 2026 •

edited

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	// since they aren't collected as reference node yet.

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hi-ogawa commented Apr 5, 2026 •

edited

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