[esm-integration] Fix acorn optimizer to handle ESM imports/exports (#24059)

Closure compiler still can't handle these sadly.

Author: sbc100

test/js_optimizer/JSDCE-output.js

@@ -33,6 +33,20 @@ function h(a) {
 
 print(h(123));
 
+export function i(a) {
+  return a + 1;
+}
+
+function j(a) {
+  return a + 1;
+}
+
+export { j as k };
+
+export default function l(a) {
+  return a + 1;
+}
+
 (function() {
   var z = fleefl();
   var zz = fleefl();

test/js_optimizer/JSDCE.js

@@ -31,6 +31,23 @@ function h(a) {
 }
 print(h(123));
 
+// ES6 exported
+export function i(a) {
+  return a+1;
+}
+
+// ES6 export via export specifier
+function j(a) {
+  return a+1;
+}
+
+export { j as k };
+
+// ES6 default export
+export default function l(a) {
+  return a+1;
+}
+
 // inner workings
 (function() {
   var x;

test/test_core.py

@@ -9562,6 +9562,19 @@ def test_wasm_worker_malloc(self):
   def test_wasm_worker_wait_async(self):
     self.do_runf('atomic/test_wait_async.c', emcc_args=['-sWASM_WORKERS'])
 
+  @requires_node_canary
+  @no_wasm64("wasm64 requires wasm export wrappers")
+  def test_esm_integration(self):
+    # TODO(sbc): WASM_ESM_INTEGRATION doesn't currently work with closure.
+    # self.maybe_closure()
+    self.node_args += ['--experimental-wasm-modules', '--no-warnings']
+    self.run_process([EMCC, '-o', 'hello_world.mjs', '-sWASM_ESM_INTEGRATION', '-Wno-experimental', test_file('hello_world.c')] + self.get_emcc_args())
+    create_file('runner.mjs', '''
+      import init from "./hello_world.mjs";
+      await init();
+    ''')
+    self.assertContained('hello, world!', self.run_js('runner.mjs'))
+
 
 # Generate tests for everything
 def make_run(name, emcc_args, settings=None, env=None,

test/test_other.py

@@ -367,16 +367,6 @@ def test_esm_source_phase_imports(self):
     self.assertContained('import source wasmModule from', read_file('hello_world.mjs'))
     self.assertContained('hello, world!', self.run_js('hello_world.mjs'))
 
-  @requires_node_canary
-  def test_esm_integration(self):
-    self.node_args += ['--experimental-wasm-modules', '--no-warnings']
-    self.run_process([EMCC, '-o', 'hello_world.mjs', '-sWASM_ESM_INTEGRATION', '-Wno-experimental', test_file('hello_world.c')])
-    create_file('runner.mjs', '''
-      import init from "./hello_world.mjs";
-      await init();
-    ''')
-    self.assertContained('hello, world!', self.run_js('runner.mjs'))
-
   @parameterized({
     '': ([],),
     'node': (['-sENVIRONMENT=node'],),
@@ -2941,7 +2931,7 @@ def test_extern_prepost(self):
   @parameterized({
     'minifyGlobals': (['minifyGlobals'],),
     'minifyLocals': (['minifyLocals'],),
-    'JSDCE': (['JSDCE'],),
+    'JSDCE': (['JSDCE', '--export-es6'],),
     'JSDCE-hasOwnProperty': (['JSDCE'],),
     'JSDCE-defaultArg': (['JSDCE'],),
     'JSDCE-fors': (['JSDCE'],),

tools/acorn-optimizer.mjs

@@ -440,6 +440,23 @@ function JSDCE(ast, aggressive) {
         const name = node.name;
         ensureData(scopes[scopes.length - 1], name).use = 1;
       },
+      ExportDefaultDeclaration(node, c) {
+        const name = node.declaration.id.name;
+        ensureData(scopes[scopes.length - 1], name).use = 1;
+        c(node.declaration);
+      },
+      ExportNamedDeclaration(node, c) {
+        if (node.declaration) {
+          const name = node.declaration.id.name;
+          ensureData(scopes[scopes.length - 1], name).use = 1;
+          c(node.declaration);
+        } else {
+          for (const specifier of node.specifiers) {
+            const name = specifier.local.name;
+            ensureData(scopes[scopes.length - 1], name).use = 1;
+          }
+        }
+      },
     });
 
     // toplevel