Function createFromPreloadedConfig

src/index.ts:628–1542

(
  foundConfigResult: ReturnType<typeof findAndReadConfig>
)

/** @internal */
export function createFromPreloadedConfig(
  foundConfigResult: ReturnType<typeof findAndReadConfig>
): Service {
  const {
    configFilePath,
    cwd,
    options,
    config,
    compiler,
    projectLocalResolveDir,
    optionBasePaths,
  } = foundConfigResult;

  const projectLocalResolveHelper = createProjectLocalResolveHelper(
    projectLocalResolveDir
  );

  const ts = loadCompiler(compiler);

  // Experimental REPL await is not compatible targets lower than ES2018
  const targetSupportsTla = config.options.target! >= ts.ScriptTarget.ES2018;
  if (options.experimentalReplAwait === true && !targetSupportsTla) {
    throw new Error(
      'Experimental REPL await is not compatible with targets lower than ES2018'
    );
  }
  // Top-level await was added in TS 3.8
  const tsVersionSupportsTla = versionGteLt(ts.version, '3.8.0');
  if (options.experimentalReplAwait === true && !tsVersionSupportsTla) {
    throw new Error(
      'Experimental REPL await is not compatible with TypeScript versions older than 3.8'
    );
  }

  const shouldReplAwait =
    options.experimentalReplAwait !== false &&
    tsVersionSupportsTla &&
    targetSupportsTla;

  // swc implies two other options
  // typeCheck option was implemented specifically to allow overriding tsconfig transpileOnly from the command-line
  // So we should allow using typeCheck to override swc
  if (options.swc && !options.typeCheck) {
    if (options.transpileOnly === false) {
      throw new Error(
        "Cannot enable 'swc' option with 'transpileOnly: false'.  'swc' implies 'transpileOnly'."
      );
    }
    if (options.transpiler) {
      throw new Error(
        "Cannot specify both 'swc' and 'transpiler' options.  'swc' uses the built-in swc transpiler."
      );
    }
  }

  const readFile = options.readFile || ts.sys.readFile;
  const fileExists = options.fileExists || ts.sys.fileExists;
  // typeCheck can override transpileOnly, useful for CLI flag to override config file