It's neither a variable assignment nor a constructor call (per se). It's called list initialization, it's part of the standard since C++11 and according to some people providing examples and explanations on StackOverflow, it's actually one of very good ways to initialize a variable.[SHELL32]: Fix build on *sane* compilers (wth, is that an assignment without the equal sign, or a called constructor, missing its parentheses?!).
No offense meant, it just seemed there's a (rather rare) opportunity for me to pass on some knowledge.