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feat(es/parser): add Hermes Flow parity harness and fixes (#11699) **Description:** This PR completes Flow strip/parser parity work against Hermes Flow corpus from `facebook/hermes` `main`. - Add Hermes corpus sync pipeline for `crates/swc_ecma_parser/tests/flow-hermes/corpus`. - Add generated manifests: - `expected-errors.txt` (error-presence expectation) - `known-fail.txt` (experimental syntax buckets) - `metadata.json` (upstream snapshot metadata) - Add new parity test: `crates/swc_ecma_parser/tests/flow_hermes.rs`. - Runs all 1,493 Hermes Flow cases. - Enforces error-presence parity for core cases. - Keeps experimental syntax in known-fail management. - Fix parser behavior to remove panic and align Flow parsing/error boundaries with Hermes parity for core cases, including: - Flow enum parsing/validation and EOF boundaries. - Flow import/export/type syntax edge cases. - Flow-specific ambiguity/error-boundary handling in expressions/classes/patterns/statements. **BREAKING CHANGE:** None. **Related issue (if exists):** None. ## Verification - `cargo test -p swc_ecma_parser --test flow_hermes --features flow` - `cargo test -p swc_ecma_parser --features flow` - `cargo test -p swc --test flow_strip_correctness --features flow` - `cargo fmt --all` - `cargo clippy --all --all-targets -- -D warnings` - `cargo test -p swc_ecma_parser`

main

28 seconds ago

perf(parser): gate flow-only hot paths in TS parser

kdy1/flow-hermes-parity

8 hours ago

perf(parser): restore non-flow fast paths for flow-strip

kdy1/flow-hermes-parity

11 hours ago

test(parser): align flow object-boundary fixtures with explicit inexact errors

kdy1/flow-hermes-parity

16 hours ago

feat(es/react-compiler): strict upstream parity finalization (crate-only, WIP) (#11697) ## Summary - Finalize crate-only React Compiler SWC port alignment toward upstream parity (`facebook/react@c80a07509582daadf275f36ffe7a88c3b12e9db4`) - Lock strict upstream gate path with `SWC_REACT_COMPILER_STRICT_UPSTREAM=1` - Expand and stabilize upstream fixture sync/harness path and option/entrypoint parity work - Advance reactive lowering/codegen behavior and strict fixture compatibility ## Scope - Crate-only changes in `swc_ecma_react_compiler` - No `.swcrc`, `@swc/types`, or Node package surface changes ## What changed - Synced/expanded upstream fixture coverage and strict test harness wiring - Aligned public option modeling and validation semantics toward upstream behavior - Improved `compile_program` parity for classification/gating/logging paths - Tightened reactive scope lowering/codegen behavior for strict-upstream fixtures ## Verification - `cargo fmt --all` - `cargo test -p swc_ecma_react_compiler` - `cargo clippy -p swc_ecma_react_compiler --all-targets -- -D warnings` ## Current status (remaining) - Strict upstream full-fixture gate is not yet fully green. - Repro: - `RUN_UPSTREAM_FIXTURES=1 SWC_REACT_COMPILER_STRICT_UPSTREAM=1 cargo test -p swc_ecma_react_compiler fixture_cases_upstream -- --nocapture` - First failing fixture currently observed: - `upstream/assignment-in-nested-if/input.js` ## Follow-up in this PR - Continue implementing remaining pipeline parity until upstream fixture target reaches `1718/1718`.

main

16 hours ago

fix(parser): restore flow fixture coverage and CI parity

kdy1/flow-hermes-parity

18 hours ago

fix(parser): restore TS fixture parsing while keeping Flow checks

kdy1/flow-hermes-parity

20 hours ago

docs: clarify workaround comment requirement in AGENTS (#11700) ## Summary - add a code style rule in AGENTS.md for workaround changes - require sufficient comments to explain why the workaround exists and known limitations ## Testing - not run (documentation-only change)

main

20 hours ago

Active Branches

perf(swc_ecma_parser): reduce TS arrow param clone/reparse churn#11678

last run

6 days ago

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perf(react): fix hotspots in swc_ecma_transforms_react (#11654)#11674

last run

6 days ago

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perf(swc_ecma_transforms_typescript): reduce repeated passes and enum clone churn#11675

last run

6 days ago

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