• Clone the repo, which uses rollup-plugin-vue to build a component library via "npm run build".
• Copy the file "dist/testlib.esm.js" (the es module build) to a minimal vue-cli app.
• In the vue-cli app, add "import { larry, moe } from '@/testlib.esm.js';" to import only two of the three vue components provided by the library, and display them on the page.
• Run "npm run build" in the vue-cli app to produce bundled output

Reported via this issue, after which I discovered this solution indicating that the plugin output itself is still an issue.

It seems that each "normalizeComponent" call needs a /*#__PURE__*/ annotation comment for webpack to properly recognize them as tree-shakeable. For example: const __vue_component__$1 = /*#__PURE__*/normalizeComponent({...