Function doTypeCheck

packages/backends/src/typescript.ts:60–136

(
  args: { entrypoint: string; workPath: string },
  ts: TypeScriptModule
)

};

async function doTypeCheck(
  args: { entrypoint: string; workPath: string },
  ts: TypeScriptModule
): Promise<void> {
  const entryAbsolute = resolve(args.workPath, args.entrypoint);
  const tsconfig = await findNearestTsconfig(args.workPath);

  const formatDiagnostics = process.stdout.isTTY
    ? ts.formatDiagnosticsWithColorAndContext
    : ts.formatDiagnostics;
  const diagnosticHost: FormatDiagnosticsHost = {
    getNewLine: () => ts.sys.newLine,
    getCanonicalFileName: (fileName: string) =>
      ts.sys.useCaseSensitiveFileNames ? fileName : fileName.toLowerCase(),
    getCurrentDirectory: () => args.workPath,
  };

  let options: CompilerOptions;
  let parseDiagnostics: readonly Diagnostic[] = [];

  if (tsconfig) {
    const configRead = ts.readConfigFile(tsconfig, ts.sys.readFile);
    if (configRead.error) {
      const message = formatDiagnostics([configRead.error], diagnosticHost);
      console.error('\nTypeScript type check failed:\n');
      console.error(message);
      throw new Error('TypeScript type check failed');
    }
    const parsed = ts.parseJsonConfigFileContent(
      configRead.config,
      ts.sys,
      dirname(tsconfig),
      undefined,
      tsconfig
    );
    parseDiagnostics = parsed.errors;
    options = {
      ...parsed.options,
      noEmit: true,
      skipLibCheck: true,
      allowJs: true,
      esModuleInterop: true,
    };
  } else {
    options = {
      noEmit: true,
      skipLibCheck: true,
      allowJs: true,
      esModuleInterop: true,
      target: ts.ScriptTarget.ES2022,
      module: ts.ModuleKind.NodeNext,
      moduleResolution: ts.ModuleResolutionKind.NodeNext,
    };
  }

  const compilerHost = ts.createCompilerHost(options);
  compilerHost.getCurrentDirectory = () => args.workPath;