Function setupRollupOptionCompat

packages/vite/src/node/utils.ts:1258–1291

(
  buildConfig: T,
  path: string,
)

})()

export function setupRollupOptionCompat<
  T extends Pick<BuildEnvironmentOptions, 'rollupOptions' | 'rolldownOptions'>,
>(
  buildConfig: T,
  path: string,
): asserts buildConfig is T & {
  rolldownOptions: Exclude<T['rolldownOptions'], undefined>
} {
  // if both rollupOptions and rolldownOptions are present,
  // ignore rollupOptions and use rolldownOptions
  buildConfig.rolldownOptions ??= buildConfig.rollupOptions
  if (
    runtimeDeprecatedPath.has(path) &&
    buildConfig.rollupOptions &&
    buildConfig.rolldownOptions !== buildConfig.rollupOptions
  ) {
    rollupOptionsDeprecationCall()
  }

  // proxy rolldownOptions to rollupOptions
  Object.defineProperty(buildConfig, 'rollupOptions', {
    get() {
      return buildConfig.rolldownOptions
    },
    set(newValue) {
      if (runtimeDeprecatedPath.has(path)) {
        rollupOptionsDeprecationCall()
      }
      buildConfig.rolldownOptions = newValue
    },
    configurable: true,
    enumerable: true,
  })
}

const rollupOptionsRootPaths = new Set([
  'build',