`declarationDir` not used in extended tsconfig.json

What happens and why it is wrong

When using a tsconfig.json that extends another tsconfig configuraiton file, the declarationDir is ignored unless "declaration": true is set in the extended tsconfig.json specified in the rollup.config

Expected behavior: The plugin respects "declaration": true in the base tsconfig file.

Environment

do not believe this to be relevant

Versions

• typescript: 2.9.2
• rollup: 0.63.4
• rollup-plugin-typescript2: 0.16.1

rollup.config.js

// Lib
import path from 'path';
import * as pkg from './package.json';

// Plugins
import commonjs from 'rollup-plugin-commonjs';
import resolve from 'rollup-plugin-node-resolve';
import typescript from 'rollup-plugin-typescript2';

const moduleName = pkg.name;
const distDir = path.resolve(__dirname, '../../dist');

export default {
  input: path.resolve(__dirname, './src/index.ts'),
  output: {
    file: path.resolve(distDir, `${moduleName}.js`),
    format: 'cjs',
    sourcemap: true,
  },
  plugins: [
    resolve(),
    typescript({
      clean: true,
      include: [
        './src/**/*.ts',
      ],
      rollupCommonJSResolveHack: true,
      tsconfig: path.resolve(__dirname, './tsconfig.json'),
      useTsconfigDeclarationDir: true,
    }),
    commonjs(),
  ],
};

tsconfig.json

tsconfig.json

{
  "extends": "../tsconfig.base",
  "compilerOptions": {
    "declarationDir": "../../dist/types",
    "outDir": "../../dist",
    "rootDir": "./src"
  },
  "exclude": [
    "test"
  ]
}

tsconfig.base.json

{
  "formatCodeOptions": {
    "indentSize": 2,
    "tabSize": 2
  },
  "compilerOptions": {
    "target": "es5",
    "module": "es2015",
    "allowJs": false,
    "checkJs": false,
    "declaration": true,
    "declarationMap": true,
    "removeComments": false,
    "downlevelIteration": true,
    "strict": true,
    "noUnusedLocals": true,
    "noUnusedParameters": true,
    "noImplicitReturns": true,
    "noFallthroughCasesInSwitch": true,
    "moduleResolution": "node",
    "esModuleInterop": true
  }
}

package.json

plugin output with verbosity 3

[SteveByerly]

great, thanks for the update. i’ll do my best to get something going in the next week.

fortunately this isn’t blocking anything - workaround is just to set the declaration in the extended tsconfig.

[ezolenko]

Looks like this is because rpt2 resets declarationDir if it doesn’t detect declaration in raw tsconfig (before ts had a chance to parse it and merge things from tsconfig.base).

PR is always welcome! Best way to fix it would be changing getOptionsOverrides to use parsed tsconfig (returned by tsModule.parseJsonConfigFileContent) and then apply generated overrides and parse tsconfig again before returning it from parseTsConfig. This way we’ll be most consistent with what tsc does on its own.