esm: js-string Wasm builtins in ESM Integration

PR-URL: #59020
Reviewed-By: Yagiz Nizipli <yagiz@nizipli.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Chengzhong Wu <legendecas@gmail.com>

Author: guybedford

doc/api/esm.md

@@ -760,6 +760,74 @@ const dynamicLibrary = await import.source('./library.wasm');
 const instance = await WebAssembly.instantiate(dynamicLibrary, importObject);
 ```
 
+### JavaScript String Builtins
+
+<!-- YAML
+added: REPLACEME
+-->
+
+When importing WebAssembly modules, the
+[WebAssembly JS String Builtins Proposal][] is automatically enabled through the
+ESM Integration. This allows WebAssembly modules to directly use efficient
+compile-time string builtins from the `wasm:js-string` namespace.
+
+For example, the following Wasm module exports a string `getLength` function using
+the `wasm:js-string` `length` builtin:
+
+```text
+(module
+  ;; Compile-time import of the string length builtin.
+  (import "wasm:js-string" "length" (func $string_length (param externref) (result i32)))
+
+  ;; Define getLength, taking a JS value parameter assumed to be a string,
+  ;; calling string length on it and returning the result.
+  (func $getLength (param $str externref) (result i32)
+    local.get $str
+    call $string_length
+  )
+
+  ;; Export the getLength function.
+  (export "getLength" (func $get_length))
+)
+```
+
+```js
+import { getLength } from './string-len.wasm';
+getLength('foo'); // Returns 3.
+```
+
+Wasm builtins are compile-time imports that are linked during module compilation
+rather than during instantiation. They do not behave like normal module graph
+imports and they cannot be inspected via `WebAssembly.Module.imports(mod)`
+or virtualized unless recompiling the module using the direct
+`WebAssembly.compile` API with string builtins disabled.
+
+Importing a module in the source phase before it has been instantiated will also
+use the compile-time builtins automatically:
+
+```js
+import source mod from './string-len.wasm';
+const { exports: { getLength } } = await WebAssembly.instantiate(mod, {});
+getLength('foo'); // Also returns 3.
+```
+
+### Reserved Wasm Namespaces
+
+<!-- YAML
+added: REPLACEME
+-->
+
+When importing WebAssembly modules through the ESM Integration, they cannot use
+import module names or import/export names that start with reserved prefixes:
+
+* `wasm-js:` - reserved in all module import names, module names and export
+  names.
+* `wasm:` - reserved in module import names and export names (imported module
+  names are allowed in order to support future builtin polyfills).
+
+Importing a module using the above reserved names will throw a
+`WebAssembly.LinkError`.
+
 <i id="esm_experimental_top_level_await"></i>
 
 ## Top-level `await`
@@ -1202,6 +1270,7 @@ resolution for ESM specifiers is [commonjs-extension-resolution-loader][].
 [Source Phase Imports]: https://github.com/tc39/proposal-source-phase-imports
 [Terminology]: #terminology
 [URL]: https://url.spec.whatwg.org/
+[WebAssembly JS String Builtins Proposal]: https://github.com/WebAssembly/js-string-builtins
 [`"exports"`]: packages.md#exports
 [`"type"`]: packages.md#type
 [`--input-type`]: cli.md#--input-typetype

lib/internal/modules/esm/translators.js

@@ -506,7 +506,10 @@ translators.set('wasm', async function(url, source) {
     // TODO(joyeecheung): implement a translator that just uses
     // compiled = new WebAssembly.Module(source) to compile it
     // synchronously.
-    compiled = await WebAssembly.compile(source);
+    compiled = await WebAssembly.compile(source, {
+      // The ESM Integration auto-enables Wasm JS builtins by default when available.
+      builtins: ['js-string'],
+    });
   } catch (err) {
     err.message = errPath(url) + ': ' + err.message;
     throw err;
@@ -518,6 +521,13 @@ translators.set('wasm', async function(url, source) {
     if (impt.kind === 'global') {
       ArrayPrototypePush(wasmGlobalImports, impt);
     }
+    // Prefix reservations per https://webassembly.github.io/esm-integration/js-api/index.html#parse-a-webassembly-module.
+    if (impt.module.startsWith('wasm-js:')) {
+      throw new WebAssembly.LinkError(`Invalid Wasm import "${impt.module}" in ${url}`);
+    }
+    if (impt.name.startsWith('wasm:') || impt.name.startsWith('wasm-js:')) {
+      throw new WebAssembly.LinkError(`Invalid Wasm import name "${impt.module}" in ${url}`);
+    }
     importsList.add(impt.module);
   }
 
@@ -527,6 +537,9 @@ translators.set('wasm', async function(url, source) {
     if (expt.kind === 'global') {
       wasmGlobalExports.add(expt.name);
     }
+    if (expt.name.startsWith('wasm:') || expt.name.startsWith('wasm-js:')) {
+      throw new WebAssembly.LinkError(`Invalid Wasm export name "${expt.name}" in ${url}`);
+    }
     exportsList.add(expt.name);
   }
 

test/es-module/test-esm-wasm.mjs

@@ -403,4 +403,95 @@ describe('ESM: WASM modules', { concurrency: !process.env.TEST_PARALLEL }, () =>
     strictEqual(stdout, '');
     notStrictEqual(code, 0);
   });
+
+  it('should reject wasm: import names', async () => {
+    const { code, stderr, stdout } = await spawnPromisified(execPath, [
+      '--no-warnings',
+      '--experimental-wasm-modules',
+      '--input-type=module',
+      '--eval',
+      `import(${JSON.stringify(fixtures.fileURL('es-modules/invalid-import-name.wasm'))})`,
+    ]);
+
+    match(stderr, /Invalid Wasm import name/);
+    strictEqual(stdout, '');
+    notStrictEqual(code, 0);
+  });
+
+  it('should reject wasm-js: import names', async () => {
+    const { code, stderr, stdout } = await spawnPromisified(execPath, [
+      '--no-warnings',
+      '--experimental-wasm-modules',
+      '--input-type=module',
+      '--eval',
+      `import(${JSON.stringify(fixtures.fileURL('es-modules/invalid-import-name-wasm-js.wasm'))})`,
+    ]);
+
+    match(stderr, /Invalid Wasm import name/);
+    strictEqual(stdout, '');
+    notStrictEqual(code, 0);
+  });
+
+  it('should reject wasm-js: import module names', async () => {
+    const { code, stderr, stdout } = await spawnPromisified(execPath, [
+      '--no-warnings',
+      '--experimental-wasm-modules',
+      '--input-type=module',
+      '--eval',
+      `import(${JSON.stringify(fixtures.fileURL('es-modules/invalid-import-module.wasm'))})`,
+    ]);
+
+    match(stderr, /Invalid Wasm import/);
+    strictEqual(stdout, '');
+    notStrictEqual(code, 0);
+  });
+
+  it('should reject wasm: export names', async () => {
+    const { code, stderr, stdout } = await spawnPromisified(execPath, [
+      '--no-warnings',
+      '--experimental-wasm-modules',
+      '--input-type=module',
+      '--eval',
+      `import(${JSON.stringify(fixtures.fileURL('es-modules/invalid-export-name.wasm'))})`,
+    ]);
+
+    match(stderr, /Invalid Wasm export/);
+    strictEqual(stdout, '');
+    notStrictEqual(code, 0);
+  });
+
+  it('should reject wasm-js: export names', async () => {
+    const { code, stderr, stdout } = await spawnPromisified(execPath, [
+      '--no-warnings',
+      '--experimental-wasm-modules',
+      '--input-type=module',
+      '--eval',
+      `import(${JSON.stringify(fixtures.fileURL('es-modules/invalid-export-name-wasm-js.wasm'))})`,
+    ]);
+
+    match(stderr, /Invalid Wasm export/);
+    strictEqual(stdout, '');
+    notStrictEqual(code, 0);
+  });
+
+  it('should support js-string builtins', async () => {
+    const { code, stderr, stdout } = await spawnPromisified(execPath, [
+      '--no-warnings',
+      '--experimental-wasm-modules',
+      '--input-type=module',
+      '--eval',
+      [
+        'import { strictEqual } from "node:assert";',
+        `import * as wasmExports from ${JSON.stringify(fixtures.fileURL('es-modules/js-string-builtins.wasm'))};`,
+        'strictEqual(wasmExports.getLength("hello"), 5);',
+        'strictEqual(wasmExports.concatStrings("hello", " world"), "hello world");',
+        'strictEqual(wasmExports.compareStrings("test", "test"), 1);',
+        'strictEqual(wasmExports.compareStrings("test", "different"), 0);',
+      ].join('\n'),
+    ]);
+
+    strictEqual(stderr, '');
+    strictEqual(stdout, '');
+    strictEqual(code, 0);
+  });
 });

test/fixtures/es-modules/invalid-export-name-wasm-js.wasm

@@ -0,0 +1,7 @@
+;; Test WASM module with invalid export name starting with 'wasm-js:'
+(module
+  (func $test (result i32)
+    i32.const 42
+  )
+  (export "wasm-js:invalid" (func $test))
+)

test/fixtures/es-modules/invalid-export-name-wasm-js.wat

@@ -0,0 +1,7 @@
+;; Test WASM module with invalid export name starting with 'wasm:'
+(module
+  (func $test (result i32)
+    i32.const 42
+  )
+  (export "wasm:invalid" (func $test))
+)

test/fixtures/es-modules/invalid-export-name.wasm

@@ -0,0 +1,8 @@
+;; Test WASM module with invalid import module name starting with 'wasm-js:'
+(module
+  (import "wasm-js:invalid" "test" (func $invalidImport (result i32)))
+  (export "test" (func $test))
+  (func $test (result i32)
+    call $invalidImport
+  )
+)