Doesn't work with rollup >= 1.27.0 about plugins

[marcofugaro]

I also have this warning when using the replace plugin as an output plugin like this

export default {
  input: 'index.js',
  output: {
    dir: 'dist',
    format: 'iife', // amd cjs system esm iife umd
    plugins: [
      replace({'process.env.NODE_ENV': JSON.stringify('production')}),
      terser(),
    ]
  }
}

In my case, I actually need it on the output bundle and it is allowed since #55. So why there is that warning?

[lukastaegert]

Are you sure you placed the plugins option in the correct place? This error can only occur if it is placed inside the output object. In the documentation you linked, it is placed outside the output object.

[shellscape]

@targumon as the issue template mentions, we need a minimal reproduction to triage this. Without that, there's not much we can do.

Issues without minimal reproductions will be closed! Please provide one by:

1. Using the REPL at https://rollupjs.org/repl/, or
2. Work to isolate the problem and provide the exact steps in this issue, or
3. Provide a minimal repository link (Read https://git.io/fNzHA for instructions).
   These may take more time to triage than the other options.

[lukastaegert]

Though it might make sense to be able to use this plugin as an output plugin, it is not supported and also would not really make sense as then it would not benefit from tree-shaking.

[targumon]

Oh, I feel so stupid. I'm not even sure now where did I copy my bad rollup.config.js from (with plugins inside output instead of adjacent to it).

Thanks and my apologies for the trouble!

[targumon]

Found the source of my mistake: before realizing I also need the replace plugin, the first one I used was terser, which is an output plugin... So my initial config had plugins inside output and I naturally thought that that's the place for all plugins.

TL;DR (for whoever gets here from search engines):
There are "regular" plugins and there are output plugins, so your rollup.config.js may contain the plugins option more than once:

export default {
  input: 'index.js',
  output: {
    dir: 'dist',
    format: 'iife', // amd cjs system esm iife umd
    plugins: [
      terser()
    ]
  },
  plugins: [
    replace({'process.env.NODE_ENV': JSON.stringify('production')})
  ]
}

More details here: https://rollupjs.org/guide/en/#using-output-plugins