fix(exports): correctly generate export paths for nested index files (#559)

Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>

Author: userquin

src/features/exports.test.ts

@@ -317,6 +317,89 @@ describe.concurrent('generateExports', () => {
       }
     `)
   })
+
+  test('windows-like paths for subpackages', async ({ expect }) => {
+    const results = generateExports(
+      FAKE_PACKAGE_JSON,
+      cwd,
+      {
+        es: [
+          genChunk('index.js'),
+          genChunk('index.d.ts'),
+          genChunk(String.raw`foo\index.js`),
+          genChunk(String.raw`foo\index.d.ts`),
+          genChunk(String.raw`bar\baz.js`),
+          genChunk(String.raw`bar\baz.d.ts`),
+        ],
+      },
+      {},
+    )
+    await expect(results).resolves.toMatchInlineSnapshot(`
+      {
+        "exports": {
+          ".": "./index.js",
+          "./bar/baz": "./bar/baz.js",
+          "./foo": "./foo/index.js",
+          "./package.json": "./package.json",
+        },
+        "main": "./index.js",
+        "module": "./index.js",
+        "publishExports": undefined,
+        "types": "./index.d.ts",
+      }
+    `)
+  })
+
+  test('windows-like paths for subpackages with dual format', async ({
+    expect,
+  }) => {
+    const results = generateExports(
+      FAKE_PACKAGE_JSON,
+      cwd,
+      {
+        es: [
+          genChunk('index.js'),
+          genChunk('index.d.ts'),
+          genChunk(String.raw`foo\index.js`),
+          genChunk(String.raw`foo\index.d.ts`),
+          genChunk(String.raw`bar\baz.js`),
+          genChunk(String.raw`bar\baz.d.ts`),
+        ],
+        cjs: [
+          genChunk('index.cjs'),
+          genChunk('index.d.cts'),
+          genChunk(String.raw`foo\index.cjs`),
+          genChunk(String.raw`foo\index.d.cts`),
+          genChunk(String.raw`bar\baz.cjs`),
+          genChunk(String.raw`bar\baz.d.cts`),
+        ],
+      },
+      {},
+    )
+    await expect(results).resolves.toMatchInlineSnapshot(`
+      {
+        "exports": {
+          ".": {
+            "import": "./index.js",
+            "require": "./index.cjs",
+          },
+          "./bar/baz": {
+            "import": "./bar/baz.js",
+            "require": "./bar/baz.cjs",
+          },
+          "./foo": {
+            "import": "./foo/index.js",
+            "require": "./foo/index.cjs",
+          },
+          "./package.json": "./package.json",
+        },
+        "main": "./index.cjs",
+        "module": "./index.js",
+        "publishExports": undefined,
+        "types": "./index.d.cts",
+      }
+    `)
+  })
 })
 
 function genChunk(fileName: string) {

src/features/exports.ts

@@ -116,15 +116,16 @@ export async function generateExports(
     for (const chunk of chunksByFormat) {
       if (chunk.type !== 'chunk' || !chunk.isEntry) continue
 
+      const normalizedName = slash(chunk.fileName)
       const ext = path.extname(chunk.fileName)
-      let name = chunk.fileName.slice(0, -ext.length)
+      let name = normalizedName.slice(0, -ext.length)
 
       const isDts = name.endsWith('.d')
       if (isDts) {
         name = name.slice(0, -2)
       }
       const isIndex = onlyOneEntry || name === 'index'
-      const distFile = `${outDirRelative ? `./${outDirRelative}` : '.'}/${chunk.fileName}`
+      const distFile = `${outDirRelative ? `./${outDirRelative}` : '.'}/${normalizedName}`
 
       if (isIndex) {
         name = '.'
@@ -141,9 +142,10 @@ export async function generateExports(
             module = distFile
           }
         }
+      } else if (name.endsWith('/index')) {
+        name = `./${name.slice(0, -6)}`
       } else {
-        const isDirIndex = name.endsWith('/index')
-        name = isDirIndex ? `./${name.slice(0, -6)}` : `./${name}`
+        name = `./${name}`
       }
 
       let subExport = exportsMap.get(name)