feat(es/react-compiler): Add React Compiler by magic-akari · Pull Request #11917 · swc-project/swc

magic-akari · 2026-06-04T00:39:21Z

Description:

Add experimental SWC support for the Rust React Compiler from react/react#36173.

This adds the swc_ecma_react_compiler bridge, SWC <-> React Compiler AST/scope conversion, .swcrc jsc.transform.reactCompiler configuration, diagnostics forwarding, JS/WASM option types, and tests ported from the upstream SWC integration.

TODO:

Wait for the React Compiler Rust crates to be published, then replace the temporary git dependencies with published crate versions.

BREAKING CHANGE:

Related issue (if exists):

[compiler] Port React Compiler to Rust react/react#36173

changeset-bot · 2026-06-04T00:39:27Z

🦋 Changeset detected

Latest commit: b3b2571

The changes in this PR will be included in the next version bump.

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codspeed-hq · 2026-06-04T00:57:15Z

Merging this PR will not alter performance

✅ 189 untouched benchmarks
⏩ 120 skipped benchmarks¹

_{Comparing feat/react-compiler (b3b2571) with main (677305b)}

120 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

kdy1

Can you use oxc-project/forked-react-compiler for testing?

react/react#36173 (comment)

**Related issue:** - #11917 - #react/react#36173

magic-akari · 2026-06-10T01:41:58Z

Still working on this.

socket-security · 2026-06-13T11:02:57Z

Review the following changes in direct dependencies. Learn more about Socket for GitHub.

Diff	Package	Supply Chain Security	Vulnerability	Quality	Maintenance	License
	cargo/forked_react_compiler@0.1.5
	cargo/forked_react_compiler_ast@0.1.5
	cargo/forked_react_compiler_hir@0.1.5

View full report

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kdy1 · 2026-06-13T13:09:22Z

@magic-akari Can you reflect the unresolved review items? You can mark them as resolved if those are not correct

CPunisher · 2026-06-13T13:26:40Z

ScopeCollector overlaps somewhat with the swc resolver.
oxc directly converts the results of semantic analysis into react compiler ScopeInfo.

In the long run, we should consider merging the swc resolver and ScopeCollector.

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CPunisher · 2026-06-13T13:35:29Z

The binary size increases by ~5MB:
main: https://github.com/swc-project/swc/actions/runs/27246095890
pr: https://github.com/swc-project/swc/actions/runs/27467879740

This is expected but can probably be further optimized. See oxc-project/oxc#22942 (comment).
~~One key point is oxc-project/forked-react-compiler#21 to make react compiler return rust struct rather than serialized JSON.~~

magic-akari · 2026-06-13T15:23:19Z

@magic-akari Can you reflect the unresolved review items? You can mark them as resolved if those are not correct

Done. All issues have been marked as resolved, including two fixes.
I believe some of the problems involving upstream React details cannot be decided on my end, but since we inherited the implementation from the official adapter, I don't have any specific thoughts on it.

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chatgpt-codex-connector · 2026-06-15T00:18:57Z

+            ScopeFlags::Class | ScopeFlags::StrictMode,
+            class_decl.class.span,
+        );
+        class_decl.class.visit_children_with(self);


Keep static-block vars scoped to the block

When a class contains a static {} block, this default class traversal reaches the static block as an ordinary block under the class scope; var declarations inside it then use enclosing_function_scope() and get registered in the outer program/function scope. For inputs like const x = 1; class C { static { var x = 2; } } function App() { return x; }, ScopeInfo can resolve App's x to the static-block-local var even though static-block vars do not escape, so React Compiler dependency/rename analysis can target the wrong binding; handle StaticBlock with its own var scope before visiting its body.

Useful? React with 👍 / 👎.

chatgpt-codex-connector · 2026-06-15T00:18:57Z

+            }),
+            Expression::Import(import) => swc::Callee::Import(swc::Import {
+                span: self.span_from_base(&import.base),
+                phase: swc::ImportPhase::Evaluation,


Preserve dynamic import phases

For source/defer dynamic imports that pass through this bridge, this hard-coded Evaluation phase turns import.source("foo") or import.defer("foo") into a plain import("foo") after React Compiler is enabled. SWC stores the phase on Callee::Import and codegen uses it to print .source/.defer, so preserve the original phase in the call shell instead of resetting it here.

Useful? React with 👍 / 👎.

chatgpt-codex-connector · 2026-06-15T00:18:57Z

+        if self.declaration_starts.contains(&start) {
+            return;
+        }
+        self.reference_identifier(ident);


Skip intrinsic JSX tags in scope references

When a component/file also has a binding named like an intrinsic tag, for example const div = value; function App() { return <div />; }, SWC's JSXElementName::Ident traversal reaches this catch-all identifier visitor and records the lowercase tag as a reference to that binding. If React Compiler later renames that binding, the span-based rename plan can rewrite preserved JSX to <div_0 />, and even without a rename it adds a spurious dependency; add a JSX element-name visitor that only references component-like names/member objects and skips intrinsic tags.

Useful? React with 👍 / 👎.

chatgpt-codex-connector · 2026-06-15T00:18:57Z

+                            for (sym_id, &bind_id) in &symbol_to_binding {
+                                if self.scoping.symbol_name(*sym_id) == name {


Bind default-export refs by declaration span

When another symbol with the same name exists anywhere in the file, this unordered HashMap scan can attach the Babel-style ExportDefaultDeclaration reference for export default function Foo() to the wrong Foo binding. React Compiler consumes this ScopeInfo for export/reference analysis, so a nested or sibling same-named symbol can make the default export nondeterministically point at the wrong binding; use the function ident's declaration span or the current scope instead of a name-only scan.

Useful? React with 👍 / 👎.

…ar boundaries (#11943) **Description:** This PR fixes scope analysis edge cases in the React Compiler where `var` declarations and TypeScript constructs were incorrectly hoisted or leaked across scope boundaries. **Design Notes:** `declare` and `global` are TypeScript type-system annotations that don't affect runtime emission, yet they still create declarations that downstream code can reference. The analyzer must walk their bodies normally and create bindings accordingly, rather than skipping traversal. **Changes:** - **Class static blocks as `var` boundaries** `var` declarations inside `static { }` blocks are now scoped to the block itself, matching ECMAScript semantics, instead of leaking into the enclosing function. - **TypeScript namespace / module scopes** `namespace` and `module` bodies now create proper `TsModuleBlock` scopes. Their members are no longer incorrectly hoisted to the Program scope. - **Consistent binding for `declare enum`** `declare enum` is now registered as a local binding so references resolve correctly. - **Refactoring** Renamed `enclosing_function_scope()` → `enclosing_var_scope()` and updated `ScopeFlags` definitions to make scope-kind checks clearer. **Known Limitations:** **TypeScript namespace merging is not yet supported.** The scope collector treats each `namespace`/`module` declaration as an isolated lexical scope. Exported members in one block are not visible to later merged blocks, and they are modeled as plain local bindings. This is a similar issue described in #11607. **BREAKING CHANGE:**  **Related issue (if exists):** - #11917 (comment)

This was referenced Jun 4, 2026

feat: react-compiler example introduce @swc/react-compiler rstackjs/rstack-examples#308

Closed

[Feature]: Support react compiler with swc web-infra-dev/rsbuild#5134

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magic-akari force-pushed the feat/react-compiler branch from 7b77755 to d3a25d2 Compare June 4, 2026 17:44

kdy1 reviewed Jun 6, 2026

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magic-akari mentioned this pull request Jun 7, 2026

fix(es/codegen): Emit export as namespace correctly #11923

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magic-akari force-pushed the feat/react-compiler branch from d3a25d2 to 871eddb Compare June 7, 2026 06:31

magic-akari changed the base branch from main to fix/codegen-export-as-namespace June 7, 2026 06:32

kdy1 pushed a commit that referenced this pull request Jun 7, 2026

fix(es/codegen): Emit export as namespace correctly (#11923)

4e1f832

**Related issue:** - #11917 - #react/react#36173

Base automatically changed from fix/codegen-export-as-namespace to main June 7, 2026 07:19

magic-akari force-pushed the feat/react-compiler branch from 548bc1a to 78acfef Compare June 7, 2026 07:35

magic-akari force-pushed the feat/react-compiler branch from 78acfef to 6e42318 Compare June 13, 2026 11:01

magic-akari force-pushed the feat/react-compiler branch 4 times, most recently from 4dc33fb to a3d28ed Compare June 13, 2026 12:08

magic-akari marked this pull request as ready for review June 13, 2026 12:38

magic-akari requested review from a team as code owners June 13, 2026 12:38

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Comment thread crates/swc_ecma_react_compiler/src/lib.rs

Comment thread crates/swc_ecma_react_compiler/src/apply_renames.rs Outdated

Comment thread crates/swc_ecma_react_compiler/src/convert_ast.rs

Comment thread crates/swc_ecma_react_compiler/src/convert_scope.rs

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feat(ecma/react-compiler): Integrate React Compiler

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magic-akari force-pushed the feat/react-compiler branch from 292e7e6 to 7f88b5d Compare June 14, 2026 03:39

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Comment thread crates/swc_ecma_react_compiler/src/convert_scope.rs Outdated

Comment thread crates/swc_ecma_react_compiler/src/apply_renames.rs

Comment thread crates/swc_ecma_react_compiler/src/convert_scope.rs Outdated

Comment thread crates/swc_ecma_react_compiler/src/convert_scope.rs

feat: integrate semantic pass with react compiler

a76a723

magic-akari force-pushed the feat/react-compiler branch from 7f88b5d to a76a723 Compare June 14, 2026 04:26

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Comment thread crates/swc_ecma_react_compiler/src/convert_ast.rs

Comment thread crates/swc_ecma_react_compiler/src/convert_ast.rs

kdy1 reviewed Jun 14, 2026

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Comment thread packages/types/index.ts

chore: Add React Compiler changeset

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kdy1 previously approved these changes Jun 14, 2026

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chore(types): bump package version

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kdy1 dismissed their stale review via b3b2571 June 14, 2026 23:55

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kdy1 changed the title ~~feat(ecma/react-compiler): Add React Compiler~~ feat(es/react-compiler): Add React Compiler Jun 14, 2026

kdy1 enabled auto-merge (squash) June 14, 2026 23:56

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kdy1 merged commit b182fbd into main Jun 15, 2026
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kdy1 deleted the feat/react-compiler branch June 15, 2026 00:24

github-actions Bot added this to the Planned milestone Jun 15, 2026

wbinnssmith mentioned this pull request Jun 15, 2026

mirror react_compiler_swc from swc-project vercel/nextjs-react-compiler#17

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lukpsaxo mentioned this pull request Jun 16, 2026

Migrate to official Rust React Compiler #11751

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magic-akari mentioned this pull request Jun 16, 2026

fix(es/react-compiler): Scope ClassStaticBlock and TsModuleBlock as var boundaries #11943

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kdy1 modified the milestones: Planned, v1.15.43 Jun 23, 2026

Copilot AI mentioned this pull request Jun 28, 2026

fix(react-compiler): honour eslintSuppressionRules — bail on matched ESLint-disable comments mattcosta7/swc#1

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		for (sym_id, &bind_id) in &symbol_to_binding {
		if self.scoping.symbol_name(*sym_id) == name {

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