Use HPX_ASSERT to aid the compiler

[eschnett]

With HPX_DISABLE_ASSERTS, HPX_ASSERT(cond) turns into (void)0. Instead, it could expand to HPX_LIKELY(expr), or even to (expr) ? (void)0 : __builtin_unreachable(). A modern version of clang would optimize away the condition, but could still use it for value range propagation.

[hkaiser]

__building_unreachable() is not portable

[eschnett]

Sure. You would check whether it is available, and only use it if it exists.