import-export-plugin: Rename potentially conflicting declarations at module scope (module, exports, require, global)

packages/metro-transform-plugins/src/__tests__/import-export-plugin-test.js

@@ -186,6 +186,61 @@ test('exports named members', () => {
   compare([importExportPlugin], code, expected, opts);
 });
 
+test('renames existing `exports` declarations in module scope', () => {
+  const code = `
+    const exports = 'foo';
+    export const bar = 'bar';
+    console.log(exports, bar);
+  `;
+
+  const expected = `
+    Object.defineProperty(exports, '__esModule', {value: true});
+    const _exports = 'foo';
+    const bar = 'bar';
+    console.log(_exports, bar);
+    exports.bar = bar;
+  `;
+
+  compare([importExportPlugin], code, expected, opts);
+});
+
+test('handles an export named "exports"', () => {
+  const code = `
+    export const exports = {a: 'foo'};
+  `;
+
+  const expected = `
+    Object.defineProperty(exports, '__esModule', {value: true});
+    const _exports = {
+      a: 'foo',
+    };
+    exports.exports = _exports;
+  `;
+
+  compare([importExportPlugin], code, expected, opts);
+});
+
+test('allows mixed esm and cjs exports', () => {
+  const code = `
+    export const foo = 'foo';
+    exports.bar = 'bar';
+    module.exports.baz = 'baz';
+    export default class {}
+  `;
+
+  const expected = `
+    Object.defineProperty(exports, '__esModule', {value: true});
+    const foo = 'foo';
+    exports.bar = 'bar';
+    module.exports.baz = 'baz';
+    class _default {}
+    exports.default = _default;
+    exports.foo = foo;
+  `;
+
+  compare([importExportPlugin], code, expected, opts);
+});
+
 test('exports destructured named object members', () => {
   const code = `
     export const {foo,bar} = {foo: 'bar',bar: 'baz'};
@@ -266,6 +321,24 @@ test('enables module exporting when something is exported', () => {
   `);
 });
 
+test('renames bindings', () => {
+  const code = `
+    const module = 'foo';
+    let exports = 'bar';
+    var global = 'baz';
+    const require = {};
+  `;
+
+  const expected = `
+    const _module = 'foo';
+    let _exports = 'bar';
+    var _global = 'baz';
+    const _require = {};
+  `;
+
+  compare([importExportPlugin], code, expected, opts);
+});
+
 test('supports `import {default as LocalName}`', () => {
   const code = `
     import {

packages/metro-transform-plugins/src/import-export-plugin.js

@@ -140,7 +140,7 @@
 // eslint-disable-next-line no-redeclare
 /* $FlowFixMe[missing-local-annot] The type annotation(s) required by Flow's
  * LTI update could not be added via codemod */
 function withLocation(node, loc) {
   if (Array.isArray(node)) {
     return node.map(n => withLocation(n, loc));
   }
@@ -495,6 +495,14 @@
           state.imports = [];
           state.importAll = t.identifier(state.opts.importAll);
           state.importDefault = t.identifier(state.opts.importDefault);
+
+          // Rename declarations at module scope that might otherwise conflict
+          // with arguments we inject into the module factory.
+          // Note that it isn't necessary to rename importAll/importDefault
+          // because Metro already uses generateUid to generate unused names.
+          ['module', 'global', 'exports', 'require'].forEach(name =>
+            path.scope.rename(name),
+          );
         },
 
         exit(path: NodePath<Program>, state: State): void {