From 04588d9c8b98f8702abf9988195262d118a0374d Mon Sep 17 00:00:00 2001
From: Mateusz Pusz <mateusz.pusz@gmail.com>
Date: Sat, 30 Sep 2023 21:36:23 -0600
Subject: [PATCH] feat: `Magnitude / Unit` operator added

---
 src/core/include/mp-units/unit.h                       | 9 +++++++++
 src/systems/si/include/mp-units/systems/si/constants.h | 2 +-
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/src/core/include/mp-units/unit.h b/src/core/include/mp-units/unit.h
index c4343c45..5810c4a7 100644
--- a/src/core/include/mp-units/unit.h
+++ b/src/core/include/mp-units/unit.h
@@ -430,6 +430,15 @@ template<Unit Lhs, Unit Rhs>
     return detail::expr_multiply<derived_unit, struct one, detail::type_list_of_unit_less>(lhs, rhs);
 }
 
+/**
+ * Returns the result of multiplication with an inverse unit.
+ */
+template<Magnitude M, Unit U>
+[[nodiscard]] MP_UNITS_CONSTEVAL Unit auto operator/(M mag, const U u)
+{
+  return mag * (1 / u);
+}
+
 /**
  * `scaled_unit` specializations have priority in this operation. This means that the library framework
  * prevents passing it as an element to the `derived_unit`. In such case only the reference unit is passed
diff --git a/src/systems/si/include/mp-units/systems/si/constants.h b/src/systems/si/include/mp-units/systems/si/constants.h
index a0ad268d..b342ba5d 100644
--- a/src/systems/si/include/mp-units/systems/si/constants.h
+++ b/src/systems/si/include/mp-units/systems/si/constants.h
@@ -41,7 +41,7 @@ inline constexpr struct elementary_charge :
 inline constexpr struct boltzmann_constant :
   named_unit<"k", mag<ratio{1'380'649, 1'000'000}> * mag_power<10, -23> * joule / kelvin> {} boltzmann_constant;
 inline constexpr struct avogadro_constant :
-  named_unit<"N_A", mag<ratio{602'214'076, 100'000'000}> * mag_power<10, 23> * (1 / mole)> {} avogadro_constant;
+  named_unit<"N_A", mag<ratio{602'214'076, 100'000'000}> * mag_power<10, 23> / mole> {} avogadro_constant;
 inline constexpr struct luminous_efficacy :
   named_unit<"K_cd", mag<683> * lumen / watt> {} luminous_efficacy;
 // clang-format on