From 34765a2ab1b698a7bb1360ff9ed72cce71d0a69a Mon Sep 17 00:00:00 2001
From: Mateusz Pusz <mateusz.pusz@gmail.com>
Date: Thu, 15 Jun 2023 17:31:08 +0300
Subject: [PATCH] refactor: a few `ratio` functions made `constexpr` for clang

---
 src/core/include/mp-units/bits/external/hacks.h | 10 ++++++++++
 src/core/include/mp-units/bits/ratio.h          | 10 +++++-----
 2 files changed, 15 insertions(+), 5 deletions(-)

diff --git a/src/core/include/mp-units/bits/external/hacks.h b/src/core/include/mp-units/bits/external/hacks.h
index 3eabdaed..def77e85 100644
--- a/src/core/include/mp-units/bits/external/hacks.h
+++ b/src/core/include/mp-units/bits/external/hacks.h
@@ -106,6 +106,16 @@
 
 #endif
 
+#if UNITS_COMP_CLANG
+
+#define CONSTEVAL constexpr
+
+#else
+
+#define CONSTEVAL consteval
+
+#endif
+
 #if UNITS_COMP_MSVC
 
 #define UNITS_CONSTRAINED_AUTO_WORKAROUND(X)
diff --git a/src/core/include/mp-units/bits/ratio.h b/src/core/include/mp-units/bits/ratio.h
index 2792fa18..89c4a52c 100644
--- a/src/core/include/mp-units/bits/ratio.h
+++ b/src/core/include/mp-units/bits/ratio.h
@@ -32,7 +32,7 @@ namespace mp_units {
 namespace detail {
 
 template<typename T>
-[[nodiscard]] consteval T abs(T v) noexcept
+[[nodiscard]] CONSTEVAL T abs(T v) noexcept
 {
   return v < 0 ? -v : v;
 }
@@ -66,7 +66,7 @@ struct ratio {
   std::intmax_t num;
   std::intmax_t den;
 
-  consteval explicit(false) ratio(std::intmax_t n, std::intmax_t d = 1) : num{n}, den{d}
+  CONSTEVAL explicit(false) ratio(std::intmax_t n, std::intmax_t d = 1) : num{n}, den{d}
   {
     gsl_Expects(den != 0);
     if (num == 0)
@@ -81,14 +81,14 @@ struct ratio {
   [[nodiscard]] friend consteval bool operator==(ratio, ratio) = default;
   [[nodiscard]] friend consteval auto operator<=>(ratio lhs, ratio rhs) { return (lhs - rhs).num <=> 0; }
 
-  [[nodiscard]] friend consteval ratio operator-(ratio r) { return ratio{-r.num, r.den}; }
+  [[nodiscard]] friend CONSTEVAL ratio operator-(ratio r) { return ratio{-r.num, r.den}; }
 
-  [[nodiscard]] friend consteval ratio operator+(ratio lhs, ratio rhs)
+  [[nodiscard]] friend CONSTEVAL ratio operator+(ratio lhs, ratio rhs)
   {
     return ratio{lhs.num * rhs.den + lhs.den * rhs.num, lhs.den * rhs.den};
   }
 
-  [[nodiscard]] friend consteval ratio operator-(ratio lhs, ratio rhs) { return lhs + (-rhs); }
+  [[nodiscard]] friend CONSTEVAL ratio operator-(ratio lhs, ratio rhs) { return lhs + (-rhs); }
 
   [[nodiscard]] friend consteval ratio operator*(ratio lhs, ratio rhs)
   {