From 2d2211fffadec55302549dc17febbe3527b6b2a5 Mon Sep 17 00:00:00 2001
From: Mateusz Pusz <mateusz.pusz@gmail.com>
Date: Thu, 18 May 2023 11:33:10 +0200
Subject: [PATCH] refactor: `UnitOf` used in `quantity_spec::operator[]`

---
 src/core/include/mp_units/quantity_spec.h | 9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/src/core/include/mp_units/quantity_spec.h b/src/core/include/mp_units/quantity_spec.h
index d5ca2ae5..f6c9e664 100644
--- a/src/core/include/mp_units/quantity_spec.h
+++ b/src/core/include/mp_units/quantity_spec.h
@@ -97,9 +97,8 @@ template<typename Self>
 #endif
 struct quantity_spec_interface {
 #ifdef __cpp_explicit_this_parameter
-  template<typename Self, AssociatedUnit U>
+  template<typename Self, UnitOf<Self{}> U>
   [[nodiscard]] consteval Reference auto operator[](this Self self, U u) const
-    requires(implicitly_convertible(self, detail::get_associated_quantity(u)))
   {
     return reference<self, u>{};
   }
@@ -111,9 +110,8 @@ struct quantity_spec_interface {
     return std::forward<Q>(q).number() * reference<self, std::remove_cvref_t<Q>::unit>{};
   }
 #else
-  template<AssociatedUnit U>
+  template<UnitOf<Self{}> U>
   [[nodiscard]] consteval Reference auto operator[](U u) const
-    requires(implicitly_convertible(Self{}, detail::get_associated_quantity(u)))
   {
     return reference<Self{}, u>{};
   }
@@ -287,9 +285,8 @@ struct quantity_spec<Self, QS, Args...> : std::remove_const_t<decltype(QS)> {
   static constexpr quantity_character character = detail::quantity_character_init<Args...>(QS.character);
 
 #ifndef __cpp_explicit_this_parameter
-  template<AssociatedUnit U>
+  template<UnitOf<Self{}> U>
   [[nodiscard]] consteval Reference auto operator[](U u) const
-    requires(implicitly_convertible(Self{}, detail::get_associated_quantity(u)))
   {
     return reference<Self{}, u>{};
   }