From d4976caf1d9d510de903151506fc894ad33595c3 Mon Sep 17 00:00:00 2001
From: Mateusz Pusz <mateusz.pusz@gmail.com>
Date: Sat, 16 Nov 2019 18:28:13 +0100
Subject: [PATCH] `operator-` constraints fixed

---
 src/include/units/quantity.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/include/units/quantity.h b/src/include/units/quantity.h
index 7429151c..c876cf68 100644
--- a/src/include/units/quantity.h
+++ b/src/include/units/quantity.h
@@ -258,8 +258,8 @@ namespace units {
 
     template<typename T = Rep>
     [[nodiscard]] constexpr quantity operator-() const
-//      requires std::magma<std::ranges::negate, T, T>
-//      requires std::magma<std::ranges::negate, rep, rep>  // TODO gated by gcc-9 (fixed in gcc-10)
+      requires std::regular_invocable<std::ranges::negate, T>
+//      requires std::regular_invocable<std::ranges::negate, rep>  // TODO gated by gcc-9 (fixed in gcc-10)
     { 
       return quantity(-count());
     }