From 4c2e288017156470a607012fe55e0c4ac98ce730 Mon Sep 17 00:00:00 2001
From: Mateusz Pusz <mateusz.pusz@gmail.com>
Date: Tue, 1 Aug 2023 17:26:00 +0200
Subject: [PATCH] feat: explicit `this` interfaces added for getters in
 `quantity` and `quantity_point`

---
 src/core/include/mp-units/quantity.h       | 8 ++++++++
 src/core/include/mp-units/quantity_point.h | 8 ++++++++
 2 files changed, 16 insertions(+)

diff --git a/src/core/include/mp-units/quantity.h b/src/core/include/mp-units/quantity.h
index c85bc0be..ba362b48 100644
--- a/src/core/include/mp-units/quantity.h
+++ b/src/core/include/mp-units/quantity.h
@@ -151,10 +151,18 @@ public:
   quantity& operator=(quantity&&) = default;
 
   // data access
+#ifdef __cpp_explicit_this_parameter
+  template<typename Self>
+  [[nodiscard]] constexpr auto&& number(this Self&& self) noexcept
+  {
+    return std::forward<Self>(self).number_;
+  }
+#else
   [[nodiscard]] constexpr rep& number() & noexcept { return number_; }
   [[nodiscard]] constexpr const rep& number() const& noexcept { return number_; }
   [[nodiscard]] constexpr rep&& number() && noexcept { return std::move(number_); }
   [[nodiscard]] constexpr const rep&& number() const&& noexcept { return std::move(number_); }
+#endif
 
   template<Unit U>
     requires requires(quantity q) { q[U{}]; }
diff --git a/src/core/include/mp-units/quantity_point.h b/src/core/include/mp-units/quantity_point.h
index 848f7779..9b185b93 100644
--- a/src/core/include/mp-units/quantity_point.h
+++ b/src/core/include/mp-units/quantity_point.h
@@ -140,10 +140,18 @@ public:
   quantity_point& operator=(quantity_point&&) = default;
 
   // data access
+#ifdef __cpp_explicit_this_parameter
+  template<typename Self>
+  [[nodiscard]] constexpr auto&& relative(this Self&& self) noexcept
+  {
+    return std::forward<Self>(self).q_;
+  }
+#else
   [[nodiscard]] constexpr quantity_type& relative() & noexcept { return q_; }
   [[nodiscard]] constexpr const quantity_type& relative() const& noexcept { return q_; }
   [[nodiscard]] constexpr quantity_type&& relative() && noexcept { return std::move(q_); }
   [[nodiscard]] constexpr const quantity_type&& relative() const&& noexcept { return std::move(q_); }
+#endif
 
   [[nodiscard]] constexpr Quantity auto absolute() const noexcept
   {