fix(react_compiler): codegen destructuring reassignment targets#24131
Merged
Conversation
Merging this PR will not alter performance
Comparing 
Footnotes
|
The reactive-function codegen only knew how to turn a plain
`BindingIdentifier` lvalue into an `AssignmentTarget`; array/object
destructuring reassignments (`[x] = arr`, `({a} = obj)`) hit an
unported `invariant_err`. Because `codegen_function` swallows any
emission error and falls back to an empty body, every function
containing a destructuring assignment to an existing binding compiled
to `function f() {}` (params and body dropped) with no diagnostic.
Port `ox_binding_pattern_to_assignment_target` to recursively reshape
`BindingPattern` -> `AssignmentTarget`, handling array/object patterns,
rest elements, nested patterns, defaults, and shorthand vs keyed object
properties. Mirrors Babel, which reuses the pattern nodes as the
assignment LHS.
Fixes/improves 23 corpus snapshots (all move toward the fork, none
regress); 14 now match the fork golden exactly. The remaining residual
on the ternary-destruction fixtures is codegen-only (sequence-expression
parenthesisation and object-literal whitespace).
Boshen
marked this pull request as ready for review
July 4, 2026 02:43
Boshen
added a commit
that referenced
this pull request
Jul 6, 2026
### 🚀 Features - 260425f semantic/examples: Include unresolved references (#24214) (camc314) - 2d9b0b3 minifier: Fold boolean-literal ternary branches in value contexts (#24110) (Dunqing) - 61fbf10 ast: Implement `ReplaceWith` on all AST types (#24013) (overlookmotel) - 7db7a29 allocator: Add `ReplaceWith` trait (#24012) (overlookmotel) - 4eb074e mangler: Add `reserved` option for names that must not be mangled (#24041) (Dunqing) - 2e62012 data_structures: Add `StringExt` trait (#24006) (overlookmotel) - 60e7160 minifier: Drop side-effect-free IIFEs whose result is unused (#23967) (Dunqing) - 26dd9e2 ast: Add method to widen inherited enum ref to parent ref (#23961) (overlookmotel) ### 🐛 Bug Fixes - e8b50ee transformer: Clean up semantics for stripped TypeScript syntax (#24180) (camc314) - d966d0b react_compiler: Remove clippy allows (#24168) (Boshen) - 854ef8d react_compiler: Compile generic functions instead of over-bailing on type-param hoisting (#24158) (Boshen) - 093586c react_compiler: Align memoization cache-slot allocation with Babel (#24157) (Boshen) - 09c8f59 react_compiler: Normalize snapshot fixture paths (#24142) (camc314) - f13df97 react_compiler: Drop stray empty statement from catch bindings (#24133) (Boshen) - cb2a505 react_compiler: Codegen destructuring reassignment targets (#24131) (Boshen) - b82c394 react_compiler: Propagate codegen invariants instead of emitting empty bodies (#24128) (Boshen) - 5771982 react_compiler: Render unchanged programs as source in fixture snapshots (#24129) (Boshen) - 4b16e1a transformer/async-to-generator: Preserve direct eval scope flags (#24136) (camc314) - 4e9194f react_compiler: Lower `delete obj.prop` to Property/ComputedDelete (#24123) (Boshen) - 0b25582 ast: Type binding node `typeAnnotation` as `TSTypeAnnotation | null` (#23113) (Boshen) - 018c0e5 transformer: Hoist lowered async declarations (#22770) (camc314) - 652fbaf mangler: Keep names of destructured exported bindings (#24036) (Dunqing) - e274415 minifier: Don't drop global calls that throw despite pure arguments (#23917) (Dunqing) - 59abb30 minifier: Only merge string literals in `try_fold_add` when the inner operator is `+` (#23622) (Jerry Zhao) ### ⚡ Performance - c5ca77b transformer: Avoid cloning refresh options (#24191) (camc314) - bf1a151 react_compiler: Compile out debug printers (#24184) (Boshen) - abb44a0 transformer: Build fixed object-rest arguments (#24190) (camc314) - a4db731 isolated_declarations: Use `ReplaceWith` instead of `TakeIn` (#24016) (overlookmotel) - ff10855 transformer: Use `ReplaceWith` instead of `TakeIn` (#24015) (overlookmotel) - bd49aff ecmascript: Avoid heap-allocating Math.min/max/imul operands (#23941) (Lawrence Lin) - e4b708b react_compiler: Skip compiled files before prefilters (#24171) (Boshen) - c59f2fe rust: Return impl ExactSizeIterator from slice-backed accessors (#24144) (Boshen) - 5d6d04a codegen: SWAR-skip boring byte runs in sourcemap line/column scan (#24023) (Boshen) - a55e0be traverse: Reduce string operations in `get_var_name_from_node` (#24007) (overlookmotel) - e6d48e1 transformer/nullish_coalescing: Move cold path into separate function (#23989) (overlookmotel) - c4e35b5 transformer/object_rest_spread: Pre-allocate capacity in `Vec` (#23988) (overlookmotel) - 527b8e5 transformer/decorators: Narrow type earlier (#23987) (overlookmotel) ### 📚 Documentation - 30d17f5 allocator: Clarify docs for `TakeIn::take_in_box` (#24093) (overlookmotel) - 675e6a8 ast: Correct doc comment for `PrivateFieldExpression` (#24008) (overlookmotel) - e4c30e6 minifier: Explain what `dce` mode means (#23994) (Dunqing) - 37cbf88 ast_macros: Document fields of `StructDetails` (#23959) (overlookmotel) - 4de3e54 ast: Correct doc comment (#23948) (overlookmotel) Co-authored-by: Boshen <1430279+Boshen@users.noreply.github.com>
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
1 participant
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
Root cause
The reactive-function backend (
codegen_reactive_function.rs) only knew how to turn a plainBindingIdentifierlvalue into anAssignmentTarget. Any destructuring reassignment to an existing binding —[x] = arr,({a} = obj),({a} = {a:{}}), ([x] = [[]])— hit an unportedinvariant_err("Destructuring reassignment targets are not yet ported to oxc").codegen_functiondeliberately swallows any emission error and falls back to an empty body (a shim from the de-Babel batches). So every function containing such an assignment silently compiled tofunction f() {}— params and body both dropped — with no diagnostic. This is a hard miscompile, not a whitespace diff.Fix
Port
ox_binding_pattern_to_assignment_targetto recursively reshapeBindingPattern→AssignmentTarget, since oxc (unlike Babel) models declaration patterns and assignment targets as distinct node families. Adds handling for:ArrayAssignmentTarget(elements + holes + rest)ObjectAssignmentTarget, distinguishing shorthand ({a}/{a = 1}→AssignmentTargetPropertyIdentifier) from keyed ({a: b}→AssignmentTargetPropertyProperty)...x)AssignmentTargetWithDefault)Mirrors Babel, which reuses the same pattern nodes as the assignment LHS.
Impact
23 corpus snapshots changed — all move toward the fork golden, none regress; 14 now match the fork exactly. Verified old-vs-new token distance to each fork golden.
Within this batch (
reduce-reactive-deps/propagate-scope-deps-hir-fork):ssa-renaming-via-destructuring-with-mutation— was empty function, now matches the fork exactly.ssa-renaming-ternary-destruction/ssa-renaming-ternary-destruction-with-mutation— were empty functions, now compile with matching dependency sets, cache keys, scope boundaries, and dead-code elimination; the only residual is codegen-only (sequence-expression parenthesisation([x]=[[]], …)vs(([x]=[[]]), …)and object-literal whitespace).Other improved fixtures across the corpus (also previously empty-bodied):
destructuring,destructuring-assignment,destructuring-assignment-array-default,destructure-direct-reassignment,destructure-in-branch-ssa,destructuring-object-pattern-within-rest,escape-analysis-destructured-rest-element,call-args-destructuring-assignment,array-pattern-spread-creates-array, thenonmutated-spread-*set,repro-reassign-props,switch-with-only-default,new-mutability__ssa-renaming-ternary-destruction.Remaining work (out of scope here)
The rest of the batch's diffs are pure codegen and live in
oxc_codegen, not the dependency passes:(a=[], b)vs((a=[]), b))The two
try-catch-*fixtures (stray;) belong to a siblingfix/rc-try-catchbranch and are left untouched.