Function initTNodeFlags

packages/core/src/render3/view/directives.ts:554–566

* Initializes the flags on the current node, setting all indices to the initial index, * the directive count to 0, and adding the isComponent flag. * @param index the initial index

(tNode: TNode, index: number, numberOfDirectives: number)

 * @param index the initial index
 */
function initTNodeFlags(tNode: TNode, index: number, numberOfDirectives: number) {
  ngDevMode &&
    assertNotEqual(
      numberOfDirectives,
      tNode.directiveEnd - tNode.directiveStart,
      'Reached the max number of directives',
    );
  tNode.flags |= TNodeFlags.isDirectiveHost;
  // When the first directive is created on a node, save the index
  tNode.directiveStart = index;
  tNode.directiveEnd = index + numberOfDirectives;
  tNode.providerIndexes = index;
}

function assertNoDuplicateDirectives(directives: DirectiveDef<unknown>[]): void {
  // The array needs at least two elements in order to have duplicates.