refactor: make_reference used to return values from reference opera…

…tions

src/core/CMakeLists.txt

@@ -46,6 +46,7 @@ add_mp_units_module(
             include/mp-units/bits/get_associated_quantity.h
             include/mp-units/bits/get_common_base.h
             include/mp-units/bits/magnitude.h
+            include/mp-units/bits/make_reference.h
             include/mp-units/bits/quantity_cast.h
             include/mp-units/bits/quantity_concepts.h
             include/mp-units/bits/quantity_point_concepts.h

src/core/include/mp-units/bits/make_reference.h

@@ -0,0 +1,39 @@
+// The MIT License (MIT)
+//
+// Copyright (c) 2018 Mateusz Pusz
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+#pragma once
+
+#include <mp-units/bits/quantity_concepts.h>
+#include <mp-units/bits/reference_concepts.h>
+
+namespace mp_units::detail {
+
+template<QuantitySpec QS, Unit U>
+[[nodiscard]] consteval Reference auto make_reference(QS, U u)
+{
+  if constexpr (detail::QuantityKindSpec<QS>)
+    return u;
+  else
+    return reference<QS, U>{};
+}
+
+}  // namespace mp_units::detail

src/core/include/mp-units/quantity_spec.h

@@ -27,6 +27,7 @@
 #include <mp-units/bits/external/type_name.h>
 #include <mp-units/bits/external/type_traits.h>
 #include <mp-units/bits/get_common_base.h>
+#include <mp-units/bits/make_reference.h>
 #include <mp-units/bits/quantity_concepts.h>
 #include <mp-units/bits/quantity_spec_concepts.h>
 #include <mp-units/bits/reference_concepts.h>
@@ -39,17 +40,6 @@ namespace mp_units {
 
 namespace detail {
 
-
-template<QuantitySpec QS, Unit U>
-  requires(!AssociatedUnit<U>) || UnitOf<U, QS{}>
-[[nodiscard]] consteval Reference auto make_reference(QS, U u)
-{
-  if constexpr (detail::QuantityKindSpec<QS>)
-    return u;
-  else
-    return reference<QS, U>{};
-}
-
 // TODO revise the note in the below comment
 /**
  * @brief Returns the most restrictive character from the list

src/core/include/mp-units/reference.h

@@ -22,8 +22,8 @@
 
 #pragma once
 
-#include <mp-units/bits/external/hacks.h>
 #include <mp-units/bits/get_associated_quantity.h>
+#include <mp-units/bits/make_reference.h>
 #include <mp-units/bits/quantity_concepts.h>
 #include <mp-units/bits/reference_concepts.h>
 #include <mp-units/bits/representation_concepts.h>
@@ -68,74 +68,44 @@ struct reference {
   }
 
   template<typename Q2, typename U2>
-  [[nodiscard]] friend consteval reference<std::remove_const_t<decltype(Q{} * Q2{})>,
-                                           std::remove_const_t<decltype(U{} * U2{})>>
-  operator*(reference, reference<Q2, U2>)
+  [[nodiscard]] friend consteval Reference auto operator*(reference, reference<Q2, U2>)
   {
-    return {};
+    return detail::make_reference(Q{} * Q2{}, U{} * U2{});
   }
 
   template<AssociatedUnit U2>
-#if MP_UNITS_COMP_MSVC
-  [[nodiscard]] friend consteval decltype(reference<Q * get_quantity_spec(U2{}), U * U2{}>{}) operator*(reference, U2)
-#else
-  [[nodiscard]] friend consteval reference<std::remove_const_t<decltype(Q{} * get_quantity_spec(U2{}))>,
-                                           std::remove_const_t<decltype(U{} * U2{})>>
-  operator*(reference, U2)
-#endif
+  [[nodiscard]] friend consteval Reference auto operator*(reference, U2)
   {
-    return {};
+    return detail::make_reference(Q{} * get_quantity_spec(U2{}), U{} * U2{});
   }
 
   template<AssociatedUnit U1>
-#if MP_UNITS_COMP_MSVC
-  [[nodiscard]] friend consteval decltype(reference<get_quantity_spec(U1{}) * Q, U1{} * U>{}) operator*(U1, reference)
-#else
-  [[nodiscard]] friend consteval reference<std::remove_const_t<decltype(get_quantity_spec(U1{}) * Q{})>,
-                                           std::remove_const_t<decltype(U1{} * U{})>>
-  operator*(U1, reference)
-#endif
+  [[nodiscard]] friend consteval Reference auto operator*(U1, reference)
   {
-    return {};
+    return detail::make_reference(get_quantity_spec(U1{}) * Q{}, U1{} * U{});
   }
 
   template<typename Q2, typename U2>
-  [[nodiscard]] friend consteval reference<std::remove_const_t<decltype(Q{} / Q2{})>,
-                                           std::remove_const_t<decltype(U{} / U2{})>>
-  operator/(reference, reference<Q2, U2>)
+  [[nodiscard]] friend consteval Reference auto operator/(reference, reference<Q2, U2>)
   {
-    return {};
+    return detail::make_reference(Q{} / Q2{}, U{} / U2{});
   }
 
   template<AssociatedUnit U2>
-#if MP_UNITS_COMP_MSVC
-  [[nodiscard]] friend consteval decltype(reference<Q / get_quantity_spec(U2{}), U / U2{}>{}) operator/(reference, U2)
-#else
-  [[nodiscard]] friend consteval reference<std::remove_const_t<decltype(Q{} / get_quantity_spec(U2{}))>,
-                                           std::remove_const_t<decltype(U{} / U2{})>>
-  operator/(reference, U2)
-#endif
+  [[nodiscard]] friend consteval Reference auto operator/(reference, U2)
   {
-    return {};
+    return detail::make_reference(Q{} / get_quantity_spec(U2{}), U{} / U2{});
   }
 
   template<AssociatedUnit U1>
-#if MP_UNITS_COMP_MSVC
-  [[nodiscard]] friend consteval decltype(reference<get_quantity_spec(U1{}) / Q, U1{} / U>{}) operator/(U1, reference)
-#else
-  [[nodiscard]] friend consteval reference<std::remove_const_t<decltype(get_quantity_spec(U1{}) / Q{})>,
-                                           std::remove_const_t<decltype(U1{} / U{})>>
-  operator/(U1, reference)
-#endif
+  [[nodiscard]] friend consteval Reference auto operator/(U1, reference)
   {
-    return {};
+    return detail::make_reference(get_quantity_spec(U1{}) / Q{}, U1{} / U{});
   }
 
-  [[nodiscard]] friend consteval reference<std::remove_const_t<decltype(inverse(Q{}))>,
-                                           std::remove_const_t<decltype(inverse(U{}))>>
-  inverse(reference)
+  [[nodiscard]] friend consteval Reference auto inverse(reference)
   {
-    return {};
+    return detail::make_reference(inverse(Q{}), inverse(U{}));
   }
 
   /**
@@ -149,11 +119,9 @@ struct reference {
    */
   template<std::intmax_t Num, std::intmax_t Den = 1>
     requires detail::non_zero<Den>
-  [[nodiscard]] friend consteval reference<std::remove_const_t<decltype(pow<Num, Den>(Q{}))>,
-                                           std::remove_const_t<decltype(pow<Num, Den>(U{}))>>
-  pow(reference)
+  [[nodiscard]] friend consteval Reference auto pow(reference)
   {
-    return {};
+    return detail::make_reference(pow<Num, Den>(Q{}), pow<Num, Den>(U{}));
   }
 
   /**
@@ -163,12 +131,7 @@ struct reference {
    *
    * @return The result of computation
    */
-  [[nodiscard]] friend consteval reference<std::remove_const_t<decltype(sqrt(Q{}))>,
-                                           std::remove_const_t<decltype(sqrt(U{}))>>
-  sqrt(reference)
-  {
-    return {};
-  }
+  [[nodiscard]] friend consteval Reference auto sqrt(reference) { return detail::make_reference(sqrt(Q{}), sqrt(U{})); }
 
   /**
    * @brief Computes the cubic root of a reference
@@ -177,12 +140,7 @@ struct reference {
    *
    * @return The result of computation
    */
-  [[nodiscard]] friend consteval reference<std::remove_const_t<decltype(cbrt(Q{}))>,
-                                           std::remove_const_t<decltype(cbrt(U{}))>>
-  cbrt(reference)
-  {
-    return {};
-  }
+  [[nodiscard]] friend consteval Reference auto cbrt(reference) { return detail::make_reference(cbrt(Q{}), cbrt(U{})); }
 
   template<typename Q2, typename U2>
   [[nodiscard]] friend consteval bool convertible(reference, reference<Q2, U2>)
@@ -289,9 +247,9 @@ template<AssociatedUnit auto To, AssociatedUnit From>
 }
 
 template<Unit auto To, QuantitySpec QS, Unit U>
-[[nodiscard]] consteval reference<QS, std::remove_const_t<decltype(To)>> clone_reference_with(reference<QS, U>)
+[[nodiscard]] consteval Reference auto clone_reference_with(reference<QS, U>)
 {
-  return {};
+  return detail::make_reference(QS{}, To);
 }
 
 }  // namespace detail