It lets complier to make extra optimization.
See:
https://gcc.godbolt.org/#compilers:!((compiler:g6,options:'-O2+-Wall++-
xc%2B%2B+-
std%3Dc%2B%2B11',sourcez:MYGwhgzhAECC0G8BQAHArgIxAS2ALiWiOgDdsAnAFzTBFIHtsATaAMwAoBKaAXmgAYA3EgC%2BwpKEgwAQtDzR0WXHESpMOfIWIlGLDt1bYAdrWj0SAU3LlmF4WKQTwUaAGE5C9cvjJFGgsQMzGxcZpbWtvbiOsGs9PTs0gBk0BjcyIEYAHT69o4xLBhg5OyuKcDpWkTAOVz2QAA%3D%3D)),filterAsm:
(commentOnly:!t,directives:!t,intel:!t,labels:!t),version:3
Removed raw State pointers in favour of unique_ptrs
Avoid allowing control flow to re-enter States that have exited
Defer releasing states until the end of the frame