Warn.onOverflow

typeof(~ Lhs()) onOverflow(string x, Lhs)(ref Lhs lhs)

Called automatically upon an overflow during a unary or binary operation.

`x`	The operator involved
`Lhs`	The first argument of `Checked`, e.g. `int` if the left-hand side of the operator is `Checked!int`
`Rhs`	The right-hand side type involved in the operator

mixin(x ~ "lhs") for unary, mixin("lhs" ~ x ~ "rhs") for

binary

typeof(Lhs() + Rhs()) onOverflow(string x, Lhs, Rhs)(Lhs lhs, Rhs rhs)

ditto