On 12/08/2020 21.37, Jens Gustedt via Liaison wrote:
> Since it seems that designated initializers are new in C++20, had that
> particular property much been used before?

Assuming you refer to defined ordering in something like

  int x = 0;
  int a[] = { x++, x++, x++ }; // 3 elements with values 0, 1, 2

(with no designated initializers): yes, C++ code relies on it.

The guaranteed ordering is used heavily when handling variadic
templates iteratively (instead of recursively), for example

  template<class ... T>
  void g(T...args)
  {
     int dummy[] = { (f(args), 0) ... };
  }

Here, we want to call f for each argument, in order.

Jens