[PaulDavisThe1st]

interesting case in point. i just learned today that std::variant and boost::variant differ in their:

   1. exception-safety guarantees
   2. real-time safety

2 is caused by 1, because to be exception safe requires a heap allocation, and that's not RT-safe.

Who would want to work in a language where you could not make these choices?

[jcelerier]

Boost even has variant2 which comes with another set of design tradeoffs

[hn_go_brrrrr]

When does std::variant allocate?

[PaulDavisThe1st]

boost::variant will allocate to save state during construction of a new value type, in order to be able to roll back if the constructor throws an exception.

std::variant does not do this.

[gumby]

Is std::variant forbidden from doing this per standard or is it simply one (or several) implementations that made this choice?