mergeConfig can't unset manualChunks with inlineDynamicImports

[fallemand]

Describe the bug

I have a problem trying to unset manualChunks from the default config using mergeConfig.

My default config defines some manualChunks:

const defaultConfig: {
  build: {
    rollupOptions: {
      output: {
        manualChunks: { ... }
      },
    },
  },
}

My appConfig defines inlineDynamicImports=true, so I need to set manualChunks=undefined. But this is not possible.

const appConfig: {
  build: {
    rollupOptions: {
      output: {
        manualChunks: undefined, // This will ignore it and use the manualChunks from the defaultConfig
        manualChunks: {} // This will fail. Invalid value for option "output.manualChunks" - this option is not supported for "output.inlineDynamicImports".
        manualChunks: () => {} // This will fail. Invalid value for option "output.manualChunks" - this option is not supported for "output.inlineDynamicImports".
        inlineDynamicImports: true,
      },
    },
  },
}

export default mergeConfig(defaultConfig, appConfig);

Vite should allow

inlineDynamicImports: true,
manualChunks: {},

How can I achieve this?

Reproduction

https://stackblitz.com/edit/vitejs-vite-1hhvb7yf?file=vite.config.ts

Steps to reproduce

npm i && num run build

System Info

-

Used Package Manager

npm

Logs

No response

Validations

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[hi-ogawa]

I think some limitations of mergeConfig is expected unfortunately. For your use case, would it suffice using config hook to mutate the options? Something like:

      {
        name: 'test',
        config(config) {
          delete config.build.rollupOptions.output.manualChunks;
          config.build.rollupOptions.output.inlineDynamicImports = true;
        }
      }

[patak-dev]

I think you can also use manualChunks: () => {} here.

We could support something like manualChunks: enforceValue(undefined) that creates something like a EnforcedValue class but I don't know if the added complexity in typing for defineConfig will make this worth it. For now, I would say that we can close this issue and wait for more use cases of a way to enforce value overrides.

[fallemand]

Unfortunately, manualChunks: () => {} doesn't work either.

Invalid value for option "output.manualChunks" - this option is not supported for "output.inlineDynamicImports".

I know the plugin option; it's what I'm currently using, but I was checking if there was a cleaner and more straightforward way 👍

[hi-ogawa]

Let me close this as it seems reasonable to rely on plugins for further control. FYI, there's an issue discussing a similar situation about null/undefined handling in #18943.