philippejer authored Dec 18, 2019 and Rico Tzschichholz committed Aug 06, 2021

This implements support for the "null-safe" operator of C#
(also called "safe navigation" operator).

  var foo = bar?.foo;
  var foo = bar?.foo();
  var foo = bar?[3];
  var foo = bar?[1:2];

It applies to plain member access, method calls, element access and
slice expressions (including void method calls, which are simply bypassed
if the inner expression is null).

Fixes GNOME/vala#522