+++
title = "`OUTCOME_REQUIRES(...)`"
description = "A C++ 20 `requires(...)`, if available."
+++

A C++ 20 `requires(...)`, if available.

*Overridable*: Define before inclusion.

*Default*: To `requires(...)` if on C++ 20 or later, else to nothing.

*Header*: `<outcome/config.hpp>`