From 19043bdde3d89ff3c3f3e0da3095af9ab02a3478 Mon Sep 17 00:00:00 2001
From: sapphi-red <49056869+sapphi-red@users.noreply.github.com>
Date: Thu, 5 Mar 2026 15:52:04 +0900
Subject: [PATCH 1/5] perf(react): improve react compiler preset so that
 slightly more modules are filtered out

---
 packages/plugin-react/src/reactCompilerPreset.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/plugin-react/src/reactCompilerPreset.ts b/packages/plugin-react/src/reactCompilerPreset.ts
index 9c06590b1..e71ae0e08 100644
--- a/packages/plugin-react/src/reactCompilerPreset.ts
+++ b/packages/plugin-react/src/reactCompilerPreset.ts
@@ -17,7 +17,7 @@ export const reactCompilerPreset = (
       code:
         options.compilationMode === 'annotation'
           ? /['"]use memo['"]/
-          : /\b[A-Z]|\buse/,
+          : /\b[A-Z]|\buse[A-Z0-9]/,
     },
     applyToEnvironmentHook: (env) => env.config.consumer === 'client',
     optimizeDeps: {

From 1806a16471acd9a579bba1a331f1bc490731fc3f Mon Sep 17 00:00:00 2001
From: sapphi-red <49056869+sapphi-red@users.noreply.github.com>
Date: Tue, 7 Apr 2026 14:58:14 +0900
Subject: [PATCH 2/5] feat: add tests and regex

---
 .../src/reactCompilerPreset.test.ts           | 124 ++++++++++++++++++
 .../plugin-react/src/reactCompilerPreset.ts   |   5 +-
 2 files changed, 128 insertions(+), 1 deletion(-)
 create mode 100644 packages/plugin-react/src/reactCompilerPreset.test.ts

diff --git a/packages/plugin-react/src/reactCompilerPreset.test.ts b/packages/plugin-react/src/reactCompilerPreset.test.ts
new file mode 100644
index 000000000..cf18ce373
--- /dev/null
+++ b/packages/plugin-react/src/reactCompilerPreset.test.ts
@@ -0,0 +1,124 @@
+import { describe, expect, test } from 'vitest'
+import { defaultCodeFilter } from './reactCompilerPreset'
+
+describe('defaultCodeFilter', () => {
+  const cases: Record<string, [code: string, expected: boolean]> = {
+    directive: ['"use memo";', true],
+
+    'component declaration': ['function App() { return <></> }', true],
+    'component arrow expression': [
+      'const MyComponent = () => { return <></> }',
+      true,
+    ],
+    'component arrow expressions': [
+      'const a = 0, MyComponent = () => { return <></> }',
+      true,
+    ],
+    'component arrow expressions (let)': [
+      'let a = 0, MyComponent = () => { return <></> }',
+      true,
+    ],
+    'component function expression': [
+      'const MyComponent = function() { return <></> }',
+      true,
+    ],
+    'component function expression (let)': [
+      'let MyComponent = function() { return <></> }',
+      true,
+    ],
+    'component function expression (var)': [
+      'var MyComponent = function() { return <></> }',
+      true,
+    ],
+    'exported component declaration': [
+      'export default function Page() { return <></> }',
+      true,
+    ],
+    'component assignment': [
+      'let MyComponent; MyComponent = function() { return <></> }',
+      true,
+    ],
+    'component default declaration': [
+      'const { MyComponent = function() { return <></> } } = {}',
+      true,
+    ],
+    'component default assignment': [
+      'let MyComponent; ({ MyComponent = function() { return <></> } }) = {}',
+      true,
+    ],
+    'component property': [
+      'const components = { MyComponent: () => <></> }',
+      true,
+    ],
+    'component method': [
+      'const components = { MyComponent() { return <></> } }',
+      true,
+    ],
+
+    'hook declaration': ['function useEffect() { return <></> }', true],
+    'hook arrow expression': ['const useMyHook = () => { return <></> }', true],
+    'hook function expression': [
+      'const useMyHook = function() { return <></> }',
+      true,
+    ],
+    'hook with digit': ['function use0() { return <></> }', true],
+    'hook using hooks': [
+      'function useMyHook() { return useOtherHook() }',
+      true,
+    ],
+    'hook using nested hooks': [
+      'function useMyHook() { return Foo.useOtherHook() }',
+      true,
+    ],
+
+    'React.forwardRef': ['React.forwardRef(() => <></>)', true],
+    'React.memo': ['React.memo(() => <></>)', true],
+    forwardRef: [
+      'import { forwardRef } from "react"; forwardRef(() => <></>)',
+      true,
+    ],
+    memo: ['import { memo } from "react"; memo(() => <></>)', true],
+
+    'edge case: memo callback with hooks': [
+      `import React, { useState } from "react";
+import { jsx } from "react/jsx-runtime"
+
+export const components = {
+  A: React.memo(() => {
+    const [state, setState] = useState(0);
+
+    return jsx("div", { children: state })
+  })
+}`,
+      true,
+    ],
+    'edge case: memo without namespace': [
+      `import { memo, useState } from "react";
+
+export default memo(() => {
+  const [count, setCount] = useState(0);
+  return <div>{count}</div>
+})`,
+      true,
+    ],
+    'edge case: memo without namespace from re-export': [
+      `import { memo, useState } from "my-react";
+
+export default memo(() => {
+  const [count, setCount] = useState(0);
+  return <div>{count}</div>
+})`,
+      true,
+    ],
+
+    'simple variable': ['const foo = 1', false],
+    'lowercase function': ['function bar() {}', false],
+    'lowercase arrow function': ['let baz = () => {}', false],
+  }
+
+  for (const [name, [code, expected]] of Object.entries(cases)) {
+    test(name, () => {
+      expect(defaultCodeFilter.test(code)).toBe(expected)
+    })
+  }
+})
diff --git a/packages/plugin-react/src/reactCompilerPreset.ts b/packages/plugin-react/src/reactCompilerPreset.ts
index 15930559a..a1caae0d8 100644
--- a/packages/plugin-react/src/reactCompilerPreset.ts
+++ b/packages/plugin-react/src/reactCompilerPreset.ts
@@ -3,6 +3,9 @@ import type {
   RolldownBabelPreset,
 } from '#optionalTypes'
 
+export const defaultCodeFilter =
+  /forwardRef|memo|function\s+(?:[A-Z]|use[A-Z0-9])|(?:[A-Z]|use[A-Z0-9])\S*\s*[:=(]/
+
 export const reactCompilerPreset = (
   options: Pick<
     ReactCompilerBabelPluginOptions,
@@ -18,7 +21,7 @@ export const reactCompilerPreset = (
       code:
         options.compilationMode === 'annotation'
           ? /['"]use memo['"]/
-          : /\b[A-Z]|\buse[A-Z0-9]/,
+          : defaultCodeFilter,
     },
     applyToEnvironmentHook: (env) => env.config.consumer === 'client',
     optimizeDeps: {

From e0acfac3d76701fdda0feeaf4edc4f5ce667f56f Mon Sep 17 00:00:00 2001
From: sapphi-red <49056869+sapphi-red@users.noreply.github.com>
Date: Tue, 7 Apr 2026 15:08:27 +0900
Subject: [PATCH 3/5] feat: exclude more cases

---
 packages/plugin-react/src/reactCompilerPreset.test.ts | 4 ++++
 packages/plugin-react/src/reactCompilerPreset.ts      | 2 +-
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/packages/plugin-react/src/reactCompilerPreset.test.ts b/packages/plugin-react/src/reactCompilerPreset.test.ts
index cf18ce373..8736817c5 100644
--- a/packages/plugin-react/src/reactCompilerPreset.test.ts
+++ b/packages/plugin-react/src/reactCompilerPreset.test.ts
@@ -114,6 +114,10 @@ export default memo(() => {
     'simple variable': ['const foo = 1', false],
     'lowercase function': ['function bar() {}', false],
     'lowercase arrow function': ['let baz = () => {}', false],
+    'non assignments (1)': ['(0,useState)()', false],
+    'non assignments (2)': ['[useState][0]()', false],
+    'non assignments (3)': ['useState;s()', false],
+    'non assignments (4)': ['useState,s()', false],
   }
 
   for (const [name, [code, expected]] of Object.entries(cases)) {
diff --git a/packages/plugin-react/src/reactCompilerPreset.ts b/packages/plugin-react/src/reactCompilerPreset.ts
index a1caae0d8..6e46e46e2 100644
--- a/packages/plugin-react/src/reactCompilerPreset.ts
+++ b/packages/plugin-react/src/reactCompilerPreset.ts
@@ -4,7 +4,7 @@ import type {
 } from '#optionalTypes'
 
 export const defaultCodeFilter =
-  /forwardRef|memo|function\s+(?:[A-Z]|use[A-Z0-9])|(?:[A-Z]|use[A-Z0-9])\S*\s*[:=(]/
+  /forwardRef|memo|function\s+(?:[A-Z]|use[A-Z0-9])|(?:[A-Z]|use[A-Z0-9])[^\s:=(){}[\],;]*\s*[:=(]/
 
 export const reactCompilerPreset = (
   options: Pick<

From a906dd50d4f6992351da18a110a9b69bcac005ce Mon Sep 17 00:00:00 2001
From: sapphi-red <49056869+sapphi-red@users.noreply.github.com>
Date: Tue, 7 Apr 2026 15:30:43 +0900
Subject: [PATCH 4/5] feat: avoid object without methods

---
 packages/plugin-react/src/reactCompilerPreset.test.ts | 8 +++++++-
 packages/plugin-react/src/reactCompilerPreset.ts      | 2 +-
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/packages/plugin-react/src/reactCompilerPreset.test.ts b/packages/plugin-react/src/reactCompilerPreset.test.ts
index 8736817c5..7f9f8e0f7 100644
--- a/packages/plugin-react/src/reactCompilerPreset.test.ts
+++ b/packages/plugin-react/src/reactCompilerPreset.test.ts
@@ -46,7 +46,11 @@ describe('defaultCodeFilter', () => {
       'let MyComponent; ({ MyComponent = function() { return <></> } }) = {}',
       true,
     ],
-    'component property': [
+    'component property function expression': [
+      'const components = { MyComponent: function() { return <></> } }',
+      true,
+    ],
+    'component property arrow function expression': [
       'const components = { MyComponent: () => <></> }',
       true,
     ],
@@ -118,6 +122,8 @@ export default memo(() => {
     'non assignments (2)': ['[useState][0]()', false],
     'non assignments (3)': ['useState;s()', false],
     'non assignments (4)': ['useState,s()', false],
+    'object without methods (1)': ['const obj = { useState: 1 }', false],
+    'object without methods (2)': ['const obj = { Foo: 1 }', false],
   }
 
   for (const [name, [code, expected]] of Object.entries(cases)) {
diff --git a/packages/plugin-react/src/reactCompilerPreset.ts b/packages/plugin-react/src/reactCompilerPreset.ts
index 6e46e46e2..477b7fe79 100644
--- a/packages/plugin-react/src/reactCompilerPreset.ts
+++ b/packages/plugin-react/src/reactCompilerPreset.ts
@@ -4,7 +4,7 @@ import type {
 } from '#optionalTypes'
 
 export const defaultCodeFilter =
-  /forwardRef|memo|function\s+(?:[A-Z]|use[A-Z0-9])|(?:[A-Z]|use[A-Z0-9])[^\s:=(){}[\],;]*\s*[:=(]/
+  /forwardRef|memo|function\s+(?:[A-Z]|use[A-Z0-9])|(?:[A-Z]|use[A-Z0-9])[^\s:=(){}[\],;]*\s*(?:\(|[:=]\s*(?:function|\())/
 
 export const reactCompilerPreset = (
   options: Pick<

From 923bbdcb568000ad7f40c1ba6674d8185482e55c Mon Sep 17 00:00:00 2001
From: sapphi-red <49056869+sapphi-red@users.noreply.github.com>
Date: Tue, 7 Apr 2026 17:17:46 +0900
Subject: [PATCH 5/5] fix: match code with explicit types

---
 .../src/reactCompilerPreset.test.ts           | 32 +++++++++++++++++++
 .../plugin-react/src/reactCompilerPreset.ts   |  2 +-
 2 files changed, 33 insertions(+), 1 deletion(-)

diff --git a/packages/plugin-react/src/reactCompilerPreset.test.ts b/packages/plugin-react/src/reactCompilerPreset.test.ts
index 7f9f8e0f7..8cc1a8f1b 100644
--- a/packages/plugin-react/src/reactCompilerPreset.test.ts
+++ b/packages/plugin-react/src/reactCompilerPreset.test.ts
@@ -6,10 +6,26 @@ describe('defaultCodeFilter', () => {
     directive: ['"use memo";', true],
 
     'component declaration': ['function App() { return <></> }', true],
+    'component declaration with types': [
+      'function App(): Type { return <></> }',
+      true,
+    ],
     'component arrow expression': [
       'const MyComponent = () => { return <></> }',
       true,
     ],
+    'component arrow expression with types (1)': [
+      'const MyComponent = (): Type => { return <></> }',
+      true,
+    ],
+    'component arrow expression with types (2)': [
+      'const MyComponent: Type = () => { return <></> }',
+      true,
+    ],
+    'component arrow expression with types (3)': [
+      'const MyComponent: SomeComplexType<Generic, number> = () => { return <></> }',
+      true,
+    ],
     'component arrow expressions': [
       'const a = 0, MyComponent = () => { return <></> }',
       true,
@@ -22,6 +38,18 @@ describe('defaultCodeFilter', () => {
       'const MyComponent = function() { return <></> }',
       true,
     ],
+    'component function expression with types (1)': [
+      'const MyComponent = function(): Type { return <></> }',
+      true,
+    ],
+    'component function expression with types (2)': [
+      'const MyComponent: Type = function() { return <></> }',
+      true,
+    ],
+    'component function expression with types (3)': [
+      'const MyComponent: SomeComplexType<Generic, number> = function() { return <></> }',
+      true,
+    ],
     'component function expression (let)': [
       'let MyComponent = function() { return <></> }',
       true,
@@ -34,6 +62,10 @@ describe('defaultCodeFilter', () => {
       'export default function Page() { return <></> }',
       true,
     ],
+    'exported component declaration with types': [
+      'export default function Page(): Type { return <></> }',
+      true,
+    ],
     'component assignment': [
       'let MyComponent; MyComponent = function() { return <></> }',
       true,
diff --git a/packages/plugin-react/src/reactCompilerPreset.ts b/packages/plugin-react/src/reactCompilerPreset.ts
index 477b7fe79..cc8bb42af 100644
--- a/packages/plugin-react/src/reactCompilerPreset.ts
+++ b/packages/plugin-react/src/reactCompilerPreset.ts
@@ -4,7 +4,7 @@ import type {
 } from '#optionalTypes'
 
 export const defaultCodeFilter =
-  /forwardRef|memo|function\s+(?:[A-Z]|use[A-Z0-9])|(?:[A-Z]|use[A-Z0-9])[^\s:=(){}[\],;]*\s*(?:\(|[:=]\s*(?:function|\())/
+  /forwardRef|memo|(?:const|let|var|function)\s+(?:[A-Z]|use[A-Z0-9])|(?:[A-Z]|use[A-Z0-9])[^\s:=(){}[\],;]*\s*(?:\(|[:=]\s*(?:function|\())/
 
 export const reactCompilerPreset = (
   options: Pick<