Policy that checks the value is ≥ 0 and reports violations.

Synopsis

struct check_non_negative;

Description

Intended for quantities that are inherently non-negative (e.g., length, mass, duration). Automatically applied to natural_point_origin<QS> when QS is tagged non_negative in the ISQ.

If the quantity's representation type has a constraint_violation_handler specialization, the handler's on_violation() is called on negative values (providing guaranteed enforcement regardless of build mode). Otherwise, falls back to MP_UNITS_EXPECTS, which may be disabled in release builds.