fix: handle dynamic import with .then(m => m.a) (#20117)

Author: sapphi-red

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

@@ -40,7 +40,7 @@ const preloadMarkerRE = new RegExp(preloadMarker, 'g')
 const dynamicImportPrefixRE = /import\s*\(/
 
 const dynamicImportTreeshakenRE =
-  /((?:\bconst\s+|\blet\s+|\bvar\s+|,\s*)(\{[^{}.=]+\})\s*=\s*await\s+import\([^)]+\))|(\(\s*await\s+import\([^)]+\)\s*\)(\??\.[\w$]+))|\bimport\([^)]+\)(\s*\.then\(\s*(?:function\s*)?\(\s*\{([^{}.=]+)\}\))/g
+  /((?:\bconst\s+|\blet\s+|\bvar\s+|,\s*)(\{[^{}.=]+\})\s*=\s*await\s+import\([^)]+\))(?=\s*(?:$|[^[.]))|(\(\s*await\s+import\([^)]+\)\s*\)(\??\.[\w$]+))|\bimport\([^)]+\)(\s*\.then\(\s*(?:function\s*)?\(\s*\{([^{}.=]+)\}\))/g
 
 function toRelativePath(filename: string, importer: string) {
   const relPath = path.posix.relative(path.posix.dirname(importer), filename)

playground/dynamic-import/__tests__/dynamic-import.spec.ts

@@ -184,6 +184,7 @@ test('dynamic import treeshaken log', async () => {
   expect(log).toContain('treeshaken baz3')
   expect(log).toContain('treeshaken baz4')
   expect(log).toContain('treeshaken baz5')
+  expect(log).toContain('treeshaken baz6')
   expect(log).toContain('treeshaken default')
 
   expect(log).not.toContain('treeshaken removed')

playground/dynamic-import/nested/index.js

@@ -174,6 +174,9 @@ import(`../nested/nested/${base}.js`).then((mod) => {
   const foo2 = await import('./treeshaken/syntax.js').then(
     ({ foo = {} }) => foo,
   )
+  const foo3 = await import('./treeshaken/syntax.js').then((m) => m.foo)
+  const e = ('' + window.doesntExist)[3] // to disallow minifier to constant fold
+  const foo4 = await import('./treeshaken/syntax.js')[`th${e}n`]((m) => m.foo)
   await import('./treeshaken/syntax.js').then((mod) => mod.foo({ foo }))
   const obj = [
     '',
@@ -189,6 +192,8 @@ import(`../nested/nested/${base}.js`).then((mod) => {
   other()
   foo()
   foo2()
+  foo3()
+  foo4()
   obj[1].lazy()
 })()