Conflicting variables generated from mix of regular and default module exports

[mislav]

• Rollup Version: 1.6.0
• earliest affected Rollup version: 1.2.0
• Operating System (or Browser): macOS 10.14.3
• Node Version: v10.8.0

How Do We Reproduce?

Clone https://github.com/mislav/rollup-shadowing and run npm it.

Basically, there are two source files:

//# src/index.js
import './foo'

//# src/foo.js
export function foo() {
  return "foo"
}

export default function() {
  return "default"
}

Note the mix of a normal export and a default export from the foo.js module.

Expected Behavior

Generating a rollup bundle from src/index.js yields no conflicting variable/function names.

Actual Behavior

The generated rollup bundle has two conflicting declarations of function foo() { ... } in the same scope:

//# dist/index.js
function foo() {
  return "foo"
}

function foo() {
  return "default"
}

This was discovered by pulling in dependencies from d3-geo and d3-shape modules, both of which have sub-modules which mix normal exports with default exports.

/cc @lukastaegert #2689

[lukastaegert]

Minimal REPL version: https://rollupjs.org/repl?version=1.6.0&shareable=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

The key here is that the default export has an id that matches the other export. Hope to look into this soon.

[lukastaegert]

It seems my previous example was wrong as this was just a basic parse error. The actual issue was that default exports were not always properly included when not tree-shaking. Fix at #2758