Return rejected promise when stringify import specifier throws (#15290)

Fixes #15261

Author: SuperSodaSea

packages/babel-helper-module-transforms/src/dynamic-import.ts

@@ -4,6 +4,7 @@
 import * as t from "@babel/types";
 import template from "@babel/template";
 
+// TODO(Babel 8): Remove this
 export function getDynamicImportSource(
   node: t.CallExpression,
 ): t.StringLiteral | t.TemplateLiteral {
@@ -13,3 +14,49 @@ export function getDynamicImportSource(
     ? source
     : (template.expression.ast`\`\${${source}}\`` as t.TemplateLiteral);
 }
+
+export function buildDynamicImport(
+  node: t.CallExpression,
+  deferToThen: boolean,
+  wrapWithPromise: boolean,
+  builder: (specifier: t.Expression) => t.Expression,
+): t.Expression {
+  const [specifier] = node.arguments;
+
+  if (
+    t.isStringLiteral(specifier) ||
+    (t.isTemplateLiteral(specifier) && specifier.quasis.length === 0)
+  ) {
+    if (deferToThen) {
+      return template.expression.ast`
+        Promise.resolve().then(() => ${builder(specifier)})
+      `;
+    } else return builder(specifier);
+  }
+
+  const specifierToString = t.isTemplateLiteral(specifier)
+    ? t.identifier("specifier")
+    : t.templateLiteral(
+        [t.templateElement({ raw: "" }), t.templateElement({ raw: "" })],
+        [t.identifier("specifier")],
+      );
+
+  if (deferToThen) {
+    return template.expression.ast`
+      (specifier =>
+        new Promise(r => r(${specifierToString}))
+          .then(s => ${builder(t.identifier("s"))})
+      )(${specifier})
+    `;
+  } else if (wrapWithPromise) {
+    return template.expression.ast`
+      (specifier =>
+        new Promise(r => r(${builder(specifierToString)}))
+      )(${specifier})
+    `;
+  } else {
+    return template.expression.ast`
+      (specifier => ${builder(specifierToString)})(${specifier})
+    `;
+  }
+}

packages/babel-helper-module-transforms/src/index.ts

@@ -35,7 +35,7 @@ import type {
 } from "./normalize-and-load-metadata";
 import type { NodePath } from "@babel/traverse";
 
-export { getDynamicImportSource } from "./dynamic-import";
+export { buildDynamicImport, getDynamicImportSource } from "./dynamic-import";
 
 export { default as getModuleName } from "./get-module-name";
 export type { PluginOptions } from "./get-module-name";

packages/babel-plugin-proposal-dynamic-import/test/fixtures/amd/to-string/input.js

@@ -0,0 +1 @@
+import(2);

packages/babel-plugin-proposal-dynamic-import/test/fixtures/amd/to-string/output.js

@@ -0,0 +1,3 @@
+define(["require"], function (_require) {
+  (specifier => new Promise((_resolve, _reject) => _require([`${specifier}`], imported => _resolve(babelHelpers.interopRequireWildcard(imported)), _reject)))(2);
+});

packages/babel-plugin-proposal-dynamic-import/test/fixtures/commonjs/exec-template-literal/1.js

@@ -0,0 +1 @@
+module.exports = 1;

packages/babel-plugin-proposal-dynamic-import/test/fixtures/commonjs/exec-template-literal/exec.js

@@ -0,0 +1,3 @@
+let x = 1;
+return expect(import(`./${x}.js`))
+  .resolves.toHaveProperty("default", 1);

packages/babel-plugin-proposal-dynamic-import/test/fixtures/commonjs/exec-template-literal/options.json

@@ -0,0 +1,5 @@
+{
+  "parserOpts": {
+    "allowReturnOutsideFunction": true
+  }
+}

packages/babel-plugin-proposal-dynamic-import/test/fixtures/commonjs/exec-throw/exec.js

@@ -0,0 +1,11 @@
+expect(() => {
+  function f() { throw "should throw"; }
+  import(f());
+}).toThrow("should throw");
+
+expect(() => {
+  const a = {
+    get x() { throw "should throw"; },
+  };
+  import(a.x);
+}).toThrow("should throw");

packages/babel-plugin-proposal-dynamic-import/test/fixtures/commonjs/exec-to-primitive/exec.js

@@ -0,0 +1,6 @@
+return expect(import({
+  [Symbol.toPrimitive](hint) {
+    if (hint === "string") return "./foo.js";
+    return null;
+  }
+})).resolves.toHaveProperty("default", "foo");

packages/babel-plugin-proposal-dynamic-import/test/fixtures/commonjs/exec-to-primitive/foo.js

@@ -0,0 +1 @@
+module.exports = "foo";