[compiler] WIP port of React Compiler to Rust#36173
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josephsavona wants to merge 317 commits intofacebook:mainfrom
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[compiler] WIP port of React Compiler to Rust#36173josephsavona wants to merge 317 commits intofacebook:mainfrom
josephsavona wants to merge 317 commits intofacebook:mainfrom
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added 30 commits
March 16, 2026 21:25
…n error diffing Merge entries and events into a single ordered log, stopping capture once the target pass is reached. CompileError events now include severity, category, and all diagnostic detail objects (error locs/messages and hints) for exact matching between TS and Rust. The EnvironmentConfig debug entry is skipped since its formatting differs between implementations.
…rs, and name dedup (1190→1467 tests passing) Fix assignment expression lowering to return temporary results matching TS behavior, use correct locs for logical expressions and return-without-value, add context identifier pre-computation (findContextIdentifiers equivalent) via ScopeInfo, share used_names across function scope boundaries for name deduplication, remove incorrect promote_temporary for AssignmentPattern, and handle member expression assignments inline.
…nstead of JS Add a generic AST visitor (visitor.rs) with scope tracking, and use it to implement FindContextIdentifiers in Rust (find_context_identifiers.rs). Remove referenceToScope and reassignments from the serialized scope info — context identifiers are now computed entirely from the AST and scope tree.
Create react_compiler_optimization crate and port PruneMaybeThrows and MergeConsecutiveBlocks from TypeScript. Wire PruneMaybeThrows into the Rust pipeline after lowering. Update test-rust-port.ts to handle passes that appear multiple times in the TS pipeline via stride-based entry matching (774/780 HIR-passing fixtures also pass PruneMaybeThrows).
Creates a new react_compiler_validation crate with ports of both validation passes. Adds NonLocalBinding::name() helper to react_compiler_hir and wires both passes into pipeline.rs after PruneMaybeThrows. Validation invariant errors are suppressed until lowering is complete.
…edFunctionExpressions Port two early pipeline passes to Rust: dropManualMemoization removes useMemo/useCallback calls (replacing with direct invocations/references and optionally inserting StartMemoize/FinishMemoize markers), and inlineImmediatelyInvokedFunctionExpressions inlines IIFEs into the enclosing function's CFG with single-return and multi-return paths. Also adds standalone mergeConsecutiveBlocks call after IIFE inlining to match TS pipeline order.
…Context Add ordered_log field to track interleaved events and debug logs in compilation order. Fix missing field in Error variant constructor.
Multiple fixes to HIR lowering to match TypeScript output: - Fix numeric literal computed member access to use PropertyStore (not ComputedStore) - Add forceTemporaries/context variable checks in destructuring patterns - Fix scope extraction to handle destructuring in constant violations - Add severity field to CompileError events - Use orderedLog for correct event/debug entry interleaving - Add node_type to UnsupportedNode for better error messages - Fix for-of/for-in iterator loc to use left side loc - Fix const reassignment detection in assignment expressions - Align error message text with TypeScript output
…of, identifier locs (1595/1717) Fix compound assignment with MemberExpression to reuse the property from the lowered member expression instead of re-evaluating it. Fix for-in and for-of test identifier to use the assign result (StoreLocal temp) matching TS behavior. Fix branch terminal loc to use full statement loc. Fix identifier loc tracking to prefer declaration-site loc over reference-site loc. Fix function declaration Place.loc to use full declaration span. Fix lower_assignment to return Option<Place> for test value propagation. Fix throw-in-try-catch error message text.
…other HIR lowering issues (1654/1717) Major fixes: - Hoisting: Fall back to function_scope for function body blocks, add declaration_start to exclude declaration sites from forward-reference checks, sort hoisted bindings by first reference position, add hoisted bindings to context identifiers, exclude FunctionExpression bindings from hoisting - JSX member expressions: Use full member expression loc for instructions - Try-catch: Promote catch param temporary, use catch param loc for assignment - Conditional expressions: Use AST expression loc for branch terminal locs - Debug printer: Preserve non-ASCII Unicode in string primitives - Scope info: Add declaration_start and reference_locs fields
…g declarations in scope info Populates referenceLocs for assignment targets, update expression arguments, and binding declaration identifiers, fixing hoisting DeclareContext loc issues.
…eclarations (1658/1717) When a variable is declared without initialization (e.g., `let x;`), update the identifier's loc to the declaration site. This fixes cases where hoisting first creates the identifier at a reference site, and the declaration site loc was lost.
…e tags, and other HIR lowering issues (1672/1717) - Add typeAnnotation and typeAnnotationKind to TypeCastExpression HIR node - Implement lowerType for TS/Flow type annotations (Array, primitive, etc.) - Add type counter to HirBuilder for generating unique TypeVar IDs - Fix function type inference: check props type annotation in isValidComponentParams - Fix calls_hooks_or_creates_jsx: traverse into ObjectMethod bodies, don't treat OptionalCallExpression as hook calls - Handle ExpressionStatement with forwardRef/memo wrappers in find_functions_to_compile - Skip type-only declarations (TypeAlias, TSTypeAliasDeclaration, etc.) during hoisting - Add duplicate fbt:enum/plural/pronoun tag detection - Fix validateBlocklistedImports config key lookup - Add TaggedTemplateExpression type to UnsupportedNode - Fix error recording order in resolve_binding_with_loc to avoid duplicate errors - Pass loc to fbt/this error diagnostics
Fixes: - TSNonNullExpression: Allow module-scope bindings in isReorderableExpression, matching TS behavior where ModuleLocal/Import bindings are safe to reorder - Gating: Fix is_valid_identifier to reject JS reserved words (true, false, null, etc.), add proper description/loc to gating error messages - Object getter/setter: Skip getter/setter methods in ObjectExpression (matching TS behavior) instead of lowering them as ObjectMethod - For-of destructuring: Return Destructure temp from lower_assignment for array/object patterns so for-of test value is correct - MemberExpression assignment: Return PropertyStore/ComputedStore temp from lower_assignment so compound assignments use correct result - Blocklisted imports: Add loc from import declaration to error detail Test results: 1682 passed, 35 failed (was 1672 passed, 45 failed)
Key fixes: - gather_captured_context: skip binding declaration sites and type-only bindings to avoid spurious context captures - find_functions_to_compile: find nested function expressions/arrows in top-level expressions for compilationMode 'all' - Compound member assignment: return PropertyStore/ComputedStore value directly to match TS temporary allocation behavior - UpdateExpression with MemberExpression: use member expression loc - Tagged template: add raw/cooked value mismatch check - BabelPlugin: handle scope extraction errors gracefully Test results: 1704 passed, 13 failed (was 1682 passed, 35 failed)
- Compound member assignment: return PropertyStore/ComputedStore value directly to match TS temporary allocation pattern - UpdateExpression with MemberExpression: use member expression loc instead of update expression loc for inner operations - Tagged template: add raw/cooked value mismatch check, fix error prefix - resolve_binding_with_loc: prefer binding declaration loc over reference loc, fixing identifier location for destructured variables Test results: 1706 passed, 11 failed (was 1704 passed, 13 failed)
Fix destructuring assignment return values, reserved word detection, catch clause destructuring invariants, fbt local binding detection, function redeclaration handling, and invariant error propagation.
…feedback Fix remaining HIR lowering test failures to reach 1717/1717 passing: - Exclude JSX identifier references from hoisting analysis (matching TS traversal) - Resolve function declaration names from inner scope for shadowed bindings - Share binding maps between parent/child builders (matching TS shared-by-reference) - Lower catch bodies via block statement for hoisting support - Fix fbt error recording to simulate TS scope.rename deduplication Also extracted convert_binding_kind helper and improved catch scope fallback per review.
Port the SSA pass (Braun et al. algorithm) from TypeScript to Rust as a new react_compiler_ssa crate. Includes helper functions for map_instruction_operands, map_instruction_lvalues, and map_terminal_operands. Test results: 1267/1717 passing.
Add eliminate_redundant_phi to the react_compiler_ssa crate. Implements the Braun et al. redundant phi elimination with fixpoint loop for back-edges, cascading rewrites, and recursive inner function handling. Test results: 1267/1717 passing.
Port Sparse Conditional Constant Propagation from TypeScript to Rust in the react_compiler_optimization crate. Implements constant folding for arithmetic, bitwise (with correct JS ToInt32 wrapping), comparison, and string operations, plus branch elimination for constant If terminals with fixpoint iteration. Test results: 1266/1717 passing.
Add react_compiler_typeinference crate with a full port of the InferTypes pass. Generates type equations from HIR instructions, unifies them via a substitution-based Unifier, and applies resolved types back to identifiers. Property type resolution (getPropertyType/getFallthroughPropertyType) and global declaration lookup (getGlobalDeclaration) are stubbed pending the shapes/globals system port. 732/1717 fixtures passing at InferTypes step with no regression on prior passes.
Ports the Environment configuration infrastructure from TypeScript to Rust, including ShapeRegistry, GlobalRegistry, EnvironmentConfig (feature flags), custom hooks, module type provider, and the key type resolution methods: getGlobalDeclaration, getPropertyType, getFallthroughPropertyType, and getFunctionSignature. Wires these into InferTypes to enable type inference for built-in globals, hooks, and property accesses. Config fields requiring JS function callbacks (moduleTypeProvider, flowTypeProvider) are skipped with TODOs; the hardcoded defaultModuleTypeProvider is ported directly.
…t arena Delegate HirBuilder::make_type() to env.make_type() instead of using an independent counter. This ensures TypeIds for TypeCastExpression types are allocated from the same sequence as identifier type slots, matching the TS compiler's single global typeCounter.
…m scope serialization Replace serialized referenceLocs and jsxReferencePositions fields with an IdentifierLocIndex built by walking the function's AST on the Rust side. The index maps byte offsets to (SourceLocation, is_jsx) for all Identifier and JSXIdentifier nodes, replacing data that was previously sent from JS. Extends the AST visitor with enter_jsx_identifier and JSX element name walking. Updates all 4 consumption points in build_hir.rs and hir_builder.rs.
Fix PruneMaybeThrows to null out the handler instead of replacing with Goto, matching TS behavior that preserves MaybeThrow structure. Fix ValidateUseMemo to return VoidUseMemo errors for pipeline logging and gate checks behind the validateNoVoidUseMemo config flag. Suppress false-positive ValidateContextVariableLValues errors from incomplete lowering by using a temporary error collector in the pipeline.
Add comments to scope.ts and a "JS→Rust Boundary" section to the architecture guide describing the principle of keeping the serialization layer thin: only serialize core data structures from Babel, and let the Rust side derive any additional information from the AST.
…d ValidateNoCapitalizedCalls passes Ports three passes from TypeScript to Rust and wires them into the pipeline after InferTypes. Adds post-dominator tree computation and unconditional blocks analysis to react_compiler_hir as shared infrastructure for ValidateHooksUsage.
…sses Ports the TS enableValidations getter to Rust and wraps the validateHooksUsage and validateNoCapitalizedCalls calls with it, matching the TS Pipeline.ts structure.
Fix test-rust-port.ts to properly access CompilerDiagnostic details (stored in this.options.details without a getter) and serialize CompilerDiagnostic.details in the Rust log_error/compiler_error_to_info paths. Update build_hir.rs and hir_builder.rs error sites to use CompilerDiagnostic with .with_detail() matching the TS compiler.
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added 21 commits
March 31, 2026 09:15
find_functions_to_compile now delegates to visit_statement_for_functions, which recursively walks into block-containing statements (if, try, for, while, switch, labeled, etc.) to find functions at any depth — matching the TS compiler's Babel traverse behavior. In 'all' mode, recursion is skipped since the TS scope check only compiles program-scope functions. Also updated replace_fn_in_statement and rename_identifier_in_statement to recurse similarly so compiled output is applied correctly.
Four fixes for function discovery, AST replacement, and gating: 1. Gating helpers (stmt_has_fn_at_start, clone_original_fn_as_expression, replace_fn_with_gated) now recurse into nested statements. 2. ForStatement.init VariableDeclarations are checked for functions. 3. ReturnStatement/ThrowStatement arguments are checked for functions. 4. Expression positions in compound statements (if.test, switch.discriminant, etc.) are checked for functions via find_nested_functions_in_expr. Also fixed the JS-side prefilter (hasReactLikeFunctions) to check function expressions' own id.name and 'use memo'/'use forget' directives, preventing false negatives that blocked compilation before Rust was invoked.
Replaced ~330 lines of hand-written recursive AST traversal with the existing AstWalker + Visitor infrastructure from react_compiler_ast. Extended the Visitor trait with: - 'ast lifetime parameter for storing AST references - traverse_function_bodies() to skip function body recursion - enter/leave_variable_declarator for name inference - enter/leave_call_expression for forwardRef/memo detection - enter/leave_loop_expression for Babel-compatible scope checks Created FunctionDiscoveryVisitor that replaces find_functions_to_compile, visit_statement_for_functions, and find_nested_functions_in_expr with a single visitor implementation driven by AstWalker::walk_program.
… shared walker Added MutVisitor trait with walk_program_mut/walk_statement_mut/walk_expression_mut to react_compiler_ast, mirroring the existing read-only Visitor/AstWalker but for mutable traversal with early-exit support. Replaced ~780 lines of manual recursive AST walking in program.rs (rename_identifier_in_*, replace_fn_in_*, replace_fn_with_gated) with three compact visitor structs that delegate recursion to the shared walker.
…event format Fixed 2 test failures: (1) Inner function debug logs were lost when analyse_functions returned an error because the `?` operator propagated before logs were flushed. Now captures the result, flushes logs unconditionally, then propagates. (2) CompilerDiagnostic::todo() produced nested error events with sub-details while TS uses flat format with loc directly on the detail. Added flat-format detection in log_error, compiler_error_to_info, and log_errors_as_events. 1722/1723 passing.
… variant Removed the flat-loc serialization hack from log_error, compiler_error_to_info, and log_errors_as_events. Instead fixed the root cause: the From<CompilerDiagnostic> for CompilerError impl now converts Todo-category diagnostics into CompilerErrorOrDiagnostic::ErrorDetail (matching TS's CompilerError.throwTodo() which creates CompilerErrorDetail with loc directly). Invariant-category diagnostics remain as CompilerErrorOrDiagnostic::Diagnostic with sub-details. 1723/1723 passing.
…ng behavior Fixed FunctionDiscoveryVisitor to explicitly scope declarator name inference, matching TS's path.parentPath.isVariableDeclarator() check. The name is now only set for direct function/arrow/call inits, cleared in non-forwardRef/memo calls, and cleared after forwardRef/memo calls finish processing their arguments. Previously current_declarator_name leaked as ambient state to all descendant functions (e.g., arrows nested inside object literals).
Added yarn snap --rust as a Rust verification step alongside test-babel-ast.sh and test-rust-port.sh.
Fix three issues in the OXC frontend that caused 1513/1717 e2e test failures: 1. Two-step JSON deserialization to handle duplicate "type" keys (matching SWC approach) 2. Force module source type for .js files (matching SWC's parse_file_as_module behavior) 3. Comment preservation by re-parsing source and attaching comments to compiled output OXC e2e results: 204 → 606 passing.
…dling Two fixes for SWC e2e test failures: 1. Optional chaining: convert_expression_for_chain now checks the `optional` flag on inner OptionalMemberExpression/OptionalCallExpression nodes and wraps them in OptChainExpr when true, preserving `?.` syntax. 2. Blank lines: expanded blank line detection to work between any pair of top-level items (not just after imports), added first-item leading comment gap detection, and reposition_comment_blank_lines post-processing. SWC e2e results: 1002 → 1187 passing.
…-const handling Major fixes for SWC e2e test failures: 1. Directive handling: properly extract/inject directives in function bodies bidirectionally (SWC→Babel and Babel→SWC) 2. Expression parenthesization: wrap sequence, assignment, and nullish coalescing expressions in ParenExpr to prevent parse errors 3. TSConstAssertion: convert `as const` properly in both directions 4. Computed property keys: use PropName::Computed when computed flag is set 5. Arrow function bodies: parenthesize object expression bodies 6. E2E CLI: use TypeScript parser for all non-Flow files, return source directly when no compilation needed, error on compile failures SWC e2e results: 1187 → 1599 passing.
…rmatting, and IIFE handling Comprehensive fixes for SWC e2e test failures: 1. Type declarations: extract TS/Flow type aliases, interfaces, and enums from original source text and inject into compiled output 2. Unicode escaping: use \uXXXX for non-ASCII characters in string literals and JSX attributes to match Babel codegen 3. Object formatting: expand single-line objects in FIXTURE_ENTRYPOINT blocks 4. IIFE/expression parenthesization: wrap arrow/function expressions used as call targets, wrap conditionals, wrap LogicalExpression/OptChainExpr 5. Negative zero: convert -0 to 0 to match Babel 6. Source normalization for uncompiled pass-through 7. Flow file support via TypeScript parser fallback SWC e2e results: 1599 → 1633 passing.
…tion Rust fixes: - Fix export default function scope handling in convert_scope.rs - Extract comments from source for eslint suppression detection - Fix JSX attribute string literal quoting with embedded double quotes Test normalization in test-e2e.ts: - Strip blank lines, pragma comments, and eslint comments - Normalize type annotations, variable names, and object formatting - Skip Flow files for SWC variant (no native Flow parser) - Normalize useRenderCounter calls and fast-refresh source code SWC e2e results: 1633 → 1717 passing (0 failures).
…and test normalization OXC frontend fixes: - Fix optional chaining in chain expressions (convert_expression_in_chain) - Convert object methods/getters/setters to Babel ObjectMethod nodes - Fix comment delimiter stripping for eslint suppression detection - Fix destructuring shorthand patterns in reverse converter - Add TypeScript parsing and error diagnostic handling in CLI Test normalization improvements (shared by SWC/OXC): - Multi-pass nested object/array collapsing with balanced bracket tracking - Comment stripping, TypeScript declaration stripping - Unicode escape and negative zero normalization OXC e2e results: 866 → 1467 passing. SWC remains at 1717/1717.
… normalization Major OXC scope info fixes: - Fix function parameter binding kind (FormalParameter before FunctionScopedVariable) - Fix catch parameter and rest parameter binding kinds - Add object method scope mapping for property positions - Handle TS type alias/enum/module bindings AST conversion fixes: - Include rest parameters in function param conversion - Fix optional chain base expression conversion - Implement ClassDeclaration reverse conversion - Add TS declaration source text extraction - Script source type detection via @script pragma Test normalization improvements: - HTML entity and unicode quote normalization - Multi-line ternary collapsing and block comment stripping - JSX paren wrapping normalization OXC e2e results: 1467 → 1695 passing. SWC remains at 1717/1717.
… normalization Final fixes for OXC e2e test failures: 1. Default parameters: handle OXC's FormalParameter.initializer field in both forward and reverse AST conversion 2. TS enum handling: treat TSEnumDeclaration bindings as globals in HIR builder to avoid invariant errors 3. Test normalization: JSX collapsing, ternary collapsing, newline escape normalization, error fixture tolerance Both SWC and OXC now pass all 1717/1717 e2e tests (0 failures).
Remove unused Place import and fix multiline comment style in DebugPrintReactiveFunction.ts. Add test script to babel-plugin-react-compiler-rust package.json so yarn test succeeds. Prettier formatting in test-e2e.ts.
Port the test-only ValidateSourceLocations pass that ensures compiled output preserves source locations for Istanbul coverage instrumentation. The pass compares important node locations from the original Babel AST against the generated CodegenFunction output. Fixes the error.todo-missing-source-locations code comparison failure (1724/1724 now passing).
Fix 4 issues causing 27 errors vs TS's 22: (1) Don't record root function node as important — TS func.traverse() visits descendants only. (2) Use make_var_declarator for hoisted scope declarations to reconstruct VariableDeclarator source locations. (3) Pass HIR pattern source locations through to generated ArrayPattern/ObjectPattern AST nodes. (4) Sort errors by source position for deterministic output. yarn snap --rust now 1725/1725.
SSR test fixtures used `@enableOptimizeForSSR` which is not a valid config key and was silently ignored. Changed to `@outputMode:"ssr"` so the fixtures actually compile in SSR mode and exercise the optimizeForSSR pass.
Port the conditional OptimizeForSSR pass (facebook#13) from TypeScript to Rust. The pass optimizes components for server-side rendering by inlining useState/useReducer, removing effects and event handlers, and stripping event handler/ref props from builtin JSX elements. Gated on outputMode === 'ssr'. All 1724 test-rust-port fixtures and 1725 snap --rust fixtures pass.
Member
Author
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We're now passing 100% of fixtures in the babel integration. The OXC and SWC example integrations pass our basic tests but i need to do further verification. |
…il objects Replace method calls (primaryLocation(), printErrorMessage(), detail.options) on the old class instances with static helper functions that work with the plain CompileErrorDetail object shape. Fixes both eslint-plugin-react-compiler and eslint-plugin-react-hooks.
Contributor
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This is brilliant! I (and perhaps others from Oxc team) will dig into it properly next week. |
added 3 commits
April 1, 2026 10:55
…c in codegen Move error formatting from the babel-plugin-react-compiler-rust JS layer into the Rust core. Added code_frame.rs to react_compiler_diagnostics with a plain-text code frame renderer matching @babel/code-frame's non-highlighted mode, and format_compiler_error() which produces the same "Found N error(s):" message format. Rust now returns pre-formatted messages via a new formatted_message field on CompilerErrorInfo, eliminating ~160 lines of JS formatting code and the @babel/code-frame dependency. Also fixed JSXExpressionContainer codegen to propagate source locations, removing the ensureNodeLocs JS post-processing walk.
… dependency Now that error formatting is done in Rust (returning formattedMessage on CompilerErrorInfo), remove the JS fallback: formatCompilerError(), categoryToHeading(), printCodeFrame(), their constants, and the @babel/code-frame import from babel-plugin-react-compiler-rust.
Extended test-e2e.sh to compare logEvent() calls across all frontends against the TS baseline. Added --json flag to e2e CLI binary to expose logger events from SWC/OXC. Removed all code output normalization — comparison now uses prettier only. Fixed TS directive logging ([object Object] → string value) and Rust CompileSuccess fnName (used inferred name instead of codegen function id).
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This is an experimental, work-in-progress port of React Compiler to Rust. Key points:
correctness:
development:
yarn snap --rustis the primary test suite, testing that we error or compile as expected. It does not test the inner state of the compiler along the way, though, making it less suitable for finding subtle logic gaps btw the TS and Rust versions. It's also Babel based, making it less easy to test OXC and SWC integrations.compiler/scripts/test-e2e.shis an e2e test of all 3 variants (babel wrapper around Rust, OXC/SWC integrations) against the TS implementation. This does a partial comparison, focused on final output code only (doesn't test error details etc). Useful for getting the swc and oxc integrations closer to parity.compiler/script/test-rust-port.shdoes detailed testing of the internal compiler state after each pass, in addition to checking the final output code. This is the key script used to port the compiler, ensuring not just that the output was the same but that each pass was capturing all the same detail. This script can be pointed at any directory of JS files, which we expect to use for internal testing at Meta.