From 3d6e50c67a13d111b05957166c9b56b001cfae2b Mon Sep 17 00:00:00 2001
From: Mateusz Pusz <mateusz.pusz@gmail.com>
Date: Sun, 30 Jun 2024 12:06:26 +0200
Subject: [PATCH] refactor: `UnitCompatibleWith` is now exposition-only

---
 docs/users_guide/framework_basics/concepts.md        | 10 ----------
 src/core/include/mp-units/framework/quantity.h       |  8 ++++----
 src/core/include/mp-units/framework/quantity_point.h |  4 ++--
 src/core/include/mp-units/framework/unit_concepts.h  |  6 +-----
 4 files changed, 7 insertions(+), 21 deletions(-)

diff --git a/docs/users_guide/framework_basics/concepts.md b/docs/users_guide/framework_basics/concepts.md
index da21dcd5..aba062e1 100644
--- a/docs/users_guide/framework_basics/concepts.md
+++ b/docs/users_guide/framework_basics/concepts.md
@@ -148,16 +148,6 @@ concept with an associated quantity type implicitly convertible to `V`.
     [nested quantity kind within the dimensionless quantities tree](dimensionless_quantities.md/#nested-quantity-kinds).
 
 
-### `UnitCompatibleWith<T, V1, V2>` { #UnitCompatibleWith }
-
-`UnitCompatibleWith` concept is satisfied for all units `T` when:
-
-- `V1` is a [`Unit`](#Unit),
-- `V2` is a [`QuantitySpec`](#QuantitySpec),
-- `T` and `V1` are defined in terms of the same reference unit,
-- if `T` is an [`AssociatedUnit`](#AssociatedUnit) it should satisfy [`UnitOf<V2>`](#UnitOf).
-
-
 ## `Reference<T>` { #Reference }
 
 `Reference` concept is satisfied by all [quantity reference](../../appendix/glossary.md#reference)
diff --git a/src/core/include/mp-units/framework/quantity.h b/src/core/include/mp-units/framework/quantity.h
index 69949723..36f5216d 100644
--- a/src/core/include/mp-units/framework/quantity.h
+++ b/src/core/include/mp-units/framework/quantity.h
@@ -192,14 +192,14 @@ public:
   quantity& operator=(quantity&&) = default;
 
   // unit conversions
-  template<UnitCompatibleWith<unit, quantity_spec> ToU>
+  template<detail::UnitCompatibleWith<unit, quantity_spec> ToU>
     requires detail::QuantityConvertibleTo<quantity, quantity<detail::make_reference(quantity_spec, ToU{}), Rep>>
   [[nodiscard]] constexpr QuantityOf<quantity_spec> auto in(ToU) const
   {
     return quantity<detail::make_reference(quantity_spec, ToU{}), Rep>{*this};
   }
 
-  template<UnitCompatibleWith<unit, quantity_spec> ToU>
+  template<detail::UnitCompatibleWith<unit, quantity_spec> ToU>
     requires requires(quantity q) { value_cast<ToU{}>(q); }
   [[nodiscard]] constexpr QuantityOf<quantity_spec> auto force_in(ToU) const
   {
@@ -230,14 +230,14 @@ public:
     = delete;
 #endif
 
-  template<UnitCompatibleWith<unit, quantity_spec> U>
+  template<detail::UnitCompatibleWith<unit, quantity_spec> U>
     requires detail::QuantityConvertibleTo<quantity, quantity<detail::make_reference(quantity_spec, U{}), Rep>>
   [[nodiscard]] constexpr rep numerical_value_in(U) const noexcept
   {
     return (*this).in(U{}).numerical_value_is_an_implementation_detail_;
   }
 
-  template<UnitCompatibleWith<unit, quantity_spec> U>
+  template<detail::UnitCompatibleWith<unit, quantity_spec> U>
     requires requires(quantity q) { value_cast<U{}>(q); }
   [[nodiscard]] constexpr rep force_numerical_value_in(U) const noexcept
   {
diff --git a/src/core/include/mp-units/framework/quantity_point.h b/src/core/include/mp-units/framework/quantity_point.h
index a121feb7..fefaa8e9 100644
--- a/src/core/include/mp-units/framework/quantity_point.h
+++ b/src/core/include/mp-units/framework/quantity_point.h
@@ -277,14 +277,14 @@ public:
   }
 
   // unit conversions
-  template<UnitCompatibleWith<unit, quantity_spec> ToU>
+  template<detail::UnitCompatibleWith<unit, quantity_spec> ToU>
     requires detail::QuantityConvertibleTo<quantity_type, quantity<detail::make_reference(quantity_spec, ToU{}), Rep>>
   [[nodiscard]] constexpr QuantityPointOf<quantity_spec> auto in(ToU) const
   {
     return ::mp_units::quantity_point{quantity_ref_from(PO).in(ToU{}), PO};
   }
 
-  template<UnitCompatibleWith<unit, quantity_spec> ToU>
+  template<detail::UnitCompatibleWith<unit, quantity_spec> ToU>
     requires requires(quantity_type q) { value_cast<ToU{}>(q); }
   [[nodiscard]] constexpr QuantityPointOf<quantity_spec> auto force_in(ToU) const
   {
diff --git a/src/core/include/mp-units/framework/unit_concepts.h b/src/core/include/mp-units/framework/unit_concepts.h
index 3a271e90..e68935be 100644
--- a/src/core/include/mp-units/framework/unit_concepts.h
+++ b/src/core/include/mp-units/framework/unit_concepts.h
@@ -197,8 +197,6 @@ template<auto From, auto To>
 concept UnitConvertibleTo =
   Unit<MP_UNITS_REMOVE_CONST(decltype(From))> && Unit<MP_UNITS_REMOVE_CONST(decltype(To))> && (convertible(From, To));
 
-}  // namespace detail
-
 /**
  * @brief A concept matching all units compatible with the provided unit and quantity spec
  *
@@ -210,11 +208,9 @@ concept UnitCompatibleWith =
   Unit<U> && Unit<MP_UNITS_REMOVE_CONST(decltype(FromU))> && QuantitySpec<MP_UNITS_REMOVE_CONST(decltype(QS))> &&
   (!AssociatedUnit<U> || UnitOf<U, QS>)&&detail::UnitConvertibleTo<FromU, U{}>;
 
-namespace detail {
-
 template<typename T>
 concept OffsetUnit = Unit<T> && requires { T::point_origin; };
 
-}
+}  // namespace detail
 
 }  // namespace mp_units