fix(minify): set the default value of esbuild's legalComments option to external

packages/vite/src/node/plugins/css.ts

@@ -1885,7 +1885,8 @@ function resolveMinifyCssEsbuildOptions(
     logLevel: options.logLevel,
     logLimit: options.logLimit,
     logOverride: options.logOverride,
-    legalComments: options.legalComments,
+    legalComments:
+      options.legalComments === 'linked' ? 'external' : options.legalComments,
   }
 
   if (

packages/vite/src/node/plugins/esbuild.ts

@@ -53,6 +53,7 @@ export interface ESBuildOptions extends TransformOptions {
    * This option is not respected. Use `build.minify` instead.
    */
   minify?: never
+  legalComments?: 'none' | 'inline' | 'eof' | 'linked' | 'external'
 }
 
 export type ESBuildTransformResult = Omit<TransformResult, 'map'> & {
@@ -165,6 +166,7 @@ export async function transformWithEsbuild(
   }
 
   const resolvedOptions: TransformOptions = {
+    legalComments: 'linked',
     sourcemap: true,
     // ensure source file name contains full query
     sourcefile: filename,
@@ -173,6 +175,10 @@ export async function transformWithEsbuild(
     tsconfigRaw,
   }
 
+  if (resolvedOptions.legalComments === 'linked') {
+    resolvedOptions.legalComments = 'external'
+  }
+
   // Some projects in the ecosystem are calling this function with an ESBuildOptions
   // object and esbuild throws an error for extra fields
   // @ts-expect-error include exists in ESBuildOptions
@@ -303,6 +309,8 @@ const rollupToEsbuildFormatMap: Record<
 }
 
 export const buildEsbuildPlugin = (config: ResolvedConfig): Plugin => {
+  const collectLegalComments: string[] = []
+
   return {
     name: 'vite:esbuild-transpile',
     async renderChunk(code, chunk, opts) {
@@ -319,6 +327,10 @@ export const buildEsbuildPlugin = (config: ResolvedConfig): Plugin => {
 
       const res = await transformWithEsbuild(code, chunk.fileName, options)
 
+      if (res.legalComments) {
+        collectLegalComments.push(res.legalComments)
+      }
+
       if (config.build.lib) {
         // #7188, esbuild adds helpers out of the UMD and IIFE wrappers, and the
         // names are minified potentially causing collision with other globals.
@@ -348,6 +360,36 @@ export const buildEsbuildPlugin = (config: ResolvedConfig): Plugin => {
 
       return res
     },
+
+    generateBundle(options, bundle) {
+      if (collectLegalComments.length && options.dir) {
+        const referenceId = this.emitFile({
+          name: 'LEGAL.txt',
+          type: 'asset',
+          source: collectLegalComments.join('\n'),
+        })
+
+        if (config.esbuild && config.esbuild.legalComments === 'linked') {
+          const legalCommentsFileName = this.getFileName(referenceId)
+          const linkedComments = `/*! For license information please see ${legalCommentsFileName} */`
+
+          for (const file in bundle) {
+            const chunk = bundle[file]
+
+            if (
+              chunk.fileName.endsWith('.css') ||
+              chunk.fileName.endsWith('.js')
+            ) {
+              if (chunk.type === 'asset') {
+                chunk.source += linkedComments
+              } else if (chunk.type === 'chunk') {
+                chunk.code += linkedComments
+              }
+            }
+          }
+        }
+      }
+    },
   }
 }
 

playground/minify/__tests__/minify.spec.ts

@@ -1,21 +1,82 @@
 import fs from 'node:fs'
 import path from 'node:path'
-import { expect, test } from 'vitest'
+import { describe, expect, test } from 'vitest'
 import { isBuild, readFile, testDir } from '~utils'
 
-test.runIf(isBuild)('no minifySyntax', () => {
-  const assetsDir = path.resolve(testDir, 'dist/assets')
+function getJsAndCssContent(assetsDir: string) {
   const files = fs.readdirSync(assetsDir)
 
   const jsFile = files.find((f) => f.endsWith('.js'))
-  const jsContent = readFile(path.resolve(assetsDir, jsFile))
+  const jsContent = readFile(path.resolve(assetsDir, jsFile)).trim()
 
   const cssFile = files.find((f) => f.endsWith('.css'))
-  const cssContent = readFile(path.resolve(assetsDir, cssFile))
+  const cssContent = readFile(path.resolve(assetsDir, cssFile)).trim()
 
-  expect(jsContent).toContain('{console.log("hello world")}')
-  expect(jsContent).not.toContain('/*! explicit comment */')
+  return { jsContent, cssContent }
+}
 
-  expect(cssContent).toContain('color:#ff0000')
-  expect(cssContent).not.toContain('/*! explicit comment */')
+function getLegalFileContent(assetsDir: string) {
+  const files = fs.readdirSync(assetsDir)
+
+  for (const fileName of files) {
+    if (fileName.startsWith('LEGAL')) {
+      return readFile(path.join(assetsDir, fileName))
+    }
+  }
+}
+
+const legalComments = '/*! explicit comment */'
+
+describe.runIf(isBuild)('minify', () => {
+  test('Do not preserve any legal comments', () => {
+    const { jsContent, cssContent } = getJsAndCssContent(
+      path.resolve(testDir, 'dist/none/assets'),
+    )
+
+    expect(jsContent).toContain('{console.log("hello world")}')
+    expect(jsContent).not.toContain(legalComments)
+    expect(cssContent).toContain('color:#ff0000')
+    expect(cssContent).not.toContain(legalComments)
+  })
+
+  test('Preserve legal comments', () => {
+    const { jsContent, cssContent } = getJsAndCssContent(
+      path.resolve(testDir, 'dist/inline/assets'),
+    )
+
+    expect(jsContent).toContain(legalComments)
+    expect(cssContent).toContain(legalComments)
+  })
+
+  test('Move all legal comments to the end of the file.', () => {
+    const { jsContent, cssContent } = getJsAndCssContent(
+      path.resolve(testDir, 'dist/eof/assets'),
+    )
+
+    expect(jsContent.endsWith(legalComments)).toBeTruthy()
+    expect(cssContent.endsWith(legalComments)).toBeTruthy()
+  })
+
+  test('Move all legal comments to a LEGAL.txt file but to not link to them.', () => {
+    const assetsPath = path.resolve(testDir, 'dist/external/assets')
+    const { jsContent, cssContent } = getJsAndCssContent(assetsPath)
+    const legaContent = getLegalFileContent(assetsPath)
+
+    expect(jsContent).not.toContain(legalComments)
+    expect(cssContent).not.toContain(legalComments)
+    expect(legaContent).toContain(legalComments)
+  })
+
+  test('Move all legal comments to a LEGAL.txt file and link to them with a comment.', () => {
+    const linkedCommentsPre = 'For license information please see'
+    const assetsPath = path.resolve(testDir, 'dist/linked/assets')
+    const { jsContent, cssContent } = getJsAndCssContent(assetsPath)
+    const legaContent = getLegalFileContent(assetsPath)
+
+    expect(jsContent).not.toContain(legalComments)
+    expect(jsContent.includes(linkedCommentsPre)).toBeTruthy()
+    expect(cssContent).not.toContain(legalComments)
+    expect(cssContent.includes(linkedCommentsPre)).toBeTruthy()
+    expect(legaContent).toContain(legalComments)
+  })
 })

playground/minify/__tests__/serve.ts

@@ -0,0 +1,47 @@
+// this is automatically detected by playground/vitestSetup.ts and will replace
+// the default e2e test serve behavior
+
+import path from 'node:path'
+import { ports, rootDir } from '~utils'
+
+export const port = ports.lib
+
+export async function serve() {
+  const { build } = await import('vite')
+  await build({
+    root: rootDir,
+    configFile: path.resolve(__dirname, '../vite.legal-comments-eof.config.js'),
+  })
+
+  await build({
+    root: rootDir,
+    configFile: path.resolve(
+      __dirname,
+      '../vite.legal-comments-external.config.js',
+    ),
+  })
+
+  await build({
+    root: rootDir,
+    configFile: path.resolve(
+      __dirname,
+      '../vite.legal-comments-inline.config.js',
+    ),
+  })
+
+  await build({
+    root: rootDir,
+    configFile: path.resolve(
+      __dirname,
+      '../vite.legal-comments-none.config.js',
+    ),
+  })
+
+  await build({
+    root: rootDir,
+    configFile: path.resolve(
+      __dirname,
+      '../vite.legal-comments-linked.config.js',
+    ),
+  })
+}

playground/minify/vite.legal-comments-eof.config.js

@@ -0,0 +1,11 @@
+import { defineConfig } from 'vite'
+
+export default defineConfig({
+  esbuild: {
+    legalComments: 'eof',
+    minifySyntax: false,
+  },
+  build: {
+    outDir: 'dist/eof',
+  },
+})

playground/minify/vite.legal-comments-external.config.js

@@ -0,0 +1,11 @@
+import { defineConfig } from 'vite'
+
+export default defineConfig({
+  esbuild: {
+    legalComments: 'external',
+    minifySyntax: false,
+  },
+  build: {
+    outDir: 'dist/external',
+  },
+})

playground/minify/vite.legal-comments-inline.config.js

@@ -0,0 +1,11 @@
+import { defineConfig } from 'vite'
+
+export default defineConfig({
+  esbuild: {
+    legalComments: 'inline',
+    minifySyntax: false,
+  },
+  build: {
+    outDir: 'dist/inline',
+  },
+})

playground/minify/vite.legal-comments-linked.config.js

@@ -0,0 +1,11 @@
+import { defineConfig } from 'vite'
+
+export default defineConfig({
+  esbuild: {
+    legalComments: 'linked',
+    minifySyntax: false,
+  },
+  build: {
+    outDir: 'dist/linked',
+  },
+})

playground/minify/vite.config.js → playground/minify/vite.legal-comments-none.config.js

@@ -5,4 +5,7 @@ export default defineConfig({
     legalComments: 'none',
     minifySyntax: false,
   },
+  build: {
+    outDir: 'dist/none',
+  },
 })