From 1c7928021d75b57a738dd012a487621867609d5e Mon Sep 17 00:00:00 2001
From: Mateusz Pusz <mateusz.pusz@gmail.com>
Date: Wed, 13 Sep 2023 10:18:07 +0200
Subject: [PATCH] feat: `force_in(U)` support added

---
 src/core/include/mp-units/quantity.h    | 21 ++++++++++++++-------
 test/unit_test/static/quantity_test.cpp |  4 ++++
 2 files changed, 18 insertions(+), 7 deletions(-)

diff --git a/src/core/include/mp-units/quantity.h b/src/core/include/mp-units/quantity.h
index 563cdcd7..1e07a43e 100644
--- a/src/core/include/mp-units/quantity.h
+++ b/src/core/include/mp-units/quantity.h
@@ -141,6 +141,20 @@ public:
   quantity& operator=(const quantity&) = default;
   quantity& operator=(quantity&&) = default;
 
+  // conversions
+  template<Unit U>
+    requires detail::QuantityConvertibleTo<quantity, quantity<quantity_spec[U{}], Rep>>
+  [[nodiscard]] constexpr quantity<quantity_spec[U{}], Rep> in(U) const
+  {
+    return quantity<quantity_spec[U{}], Rep>{*this};
+  }
+  template<Unit U>
+    requires requires(quantity q) { value_cast<U{}>(q); }
+  [[nodiscard]] constexpr quantity<quantity_spec[U{}], Rep> force_in(U) const
+  {
+    return value_cast<U{}>(*this);
+  }
+
   // data access
 #ifdef __cpp_explicit_this_parameter
   template<typename Self, Unit U>
@@ -190,13 +204,6 @@ public:
     return value_cast<U{}>(*this).numerical_value_in(U{});
   }
 
-  template<Unit U>
-    requires detail::QuantityConvertibleTo<quantity, quantity<quantity_spec[U{}], Rep>>
-  [[nodiscard]] constexpr quantity<quantity_spec[U{}], Rep> in(U) const
-  {
-    return quantity<quantity_spec[U{}], Rep>{*this};
-  }
-
   // member unary operators
   [[nodiscard]] constexpr Quantity auto operator+() const
     requires requires(rep v) {
diff --git a/test/unit_test/static/quantity_test.cpp b/test/unit_test/static/quantity_test.cpp
index 83c43c96..3d04f754 100644
--- a/test/unit_test/static/quantity_test.cpp
+++ b/test/unit_test/static/quantity_test.cpp
@@ -900,6 +900,10 @@ static_assert(value_cast<km>(2000 * m).numerical_value_ref_in(km) == 2);
 static_assert(value_cast<int>(1.23 * m).numerical_value_ref_in(m) == 1);
 static_assert(value_cast<km / h>(2000.0 * m / (3600.0 * s)).numerical_value_ref_in(km / h) == 2);
 
+static_assert((2 * km).force_in(m).numerical_value_ref_in(m) == 2000);
+static_assert((2000 * m).force_in(km).numerical_value_ref_in(km) == 2);
+static_assert((2000.0 * m / (3600.0 * s)).force_in(km / h).numerical_value_ref_in(km / h) == 2);
+
 //////////////////
 // quantity_cast
 //////////////////