Summary

When using preserveModules: true with CJS output format, Rolldown does not generate re-export code for transitive export * statements.

The intermediate module correctly re-exports from an external dependency, but the top-level module that re-exports from the intermediate module produces an empty exports object.

In our use-case, we have layers of libraries building on top of each other, so there is transitive export statements in each level.

Reproduction:

https://repl.rolldown.rs/#eNptUD1PxDAM/StWlgAq7Z4bmdnYKENpXAhKk8pJj0pV/jtueukBuiWx/Z4/3lvFINQqjNO41DFssRPqmlei57Rp4OXTBCCcCAO6GGBnBKQzEhNbh8vkKcIDDORHkHWzY/LEM1CoSDOmSpC3VvtvV/feDebj18obyL7cjHnwChoH4/Apw5Aue0qbPLXuOIKZ3Wzzf3Tcra0DPnuao9rOKxJltdX9HDOQSQCDp7HbeP3XhQCgDXFBmxBLJZvBIp+9ni0GBZvIjKX84hKRXGcVvMoSP1rzLt9al+75YMGOHBYWI66FXf8/Y/8MEoknnJlku4ghivQD3FKcmQ==

You can also check this stackblitz and run node with require('./dist') and notice that the module doesn't export zod's own exports.

https://stackblitz.com/edit/abveex9m-czrtm8oq?file=dist%2Fserver.js,dist%2Findex.js,server.ts,index.ts

File structure:

• index.ts: export * from './server';
• server.ts: export * from 'external-lib';
• external-lib: External dependency

Config

{
  format: 'cjs',
  preserveModules: true,
  external: ['external-lib']
}

Expected

index.js should contain re-export code similar to, or re-use the exports from the ./server.

const require_server = require('./server.js');

Object.keys(require_server).forEach(function (k) {
  if (k !== 'default' && !Object.prototype.hasOwnProperty.call(exports, k)) {
    Object.defineProperty(exports, k, {
      enumerable: true,
      get: function () { return require_server[k]; }
    });
  }
});

Actual Behavior

index.js produces an empty exports object:

const require_server = require('./server.js');

var index_exports = {};

Meanwhile, server.js correctly generates the re-export code for external-lib.

Workaround

I'm explicitly re-exporting the transitive export * statements in each entry again.