Function branch_always_exits 

pub fn branch_always_exits(gcx: Gcx<'_>, stmt: &Stmt<'_>) -> bool

True when executing stmt provably prevents control from continuing past it: return, revert, selfdestruct, require(false, ..) / assert(false), a block containing any such statement, an if whose both arms exit, a try whose every clause exits, or a do-while whose body exits without break/continue.