From 448414873584cb0ed4c0f7b4e44aa5d71699bfc3 Mon Sep 17 00:00:00 2001
From: Mateusz Pusz <mateusz.pusz@gmail.com>
Date: Wed, 8 Feb 2023 21:06:14 -0800
Subject: [PATCH] fix: ambiguity on `common_reference` resolved

---
 src/core/include/mp_units/reference.h | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/src/core/include/mp_units/reference.h b/src/core/include/mp_units/reference.h
index ef3ad9ad..94bbe1cf 100644
--- a/src/core/include/mp_units/reference.h
+++ b/src/core/include/mp_units/reference.h
@@ -158,8 +158,9 @@ template<AssociatedUnit U1, auto Q2, auto U2>
   return common_unit(u1, u2, rest...);
 }
 
-[[nodiscard]] consteval auto common_reference(Reference auto r1, Reference auto r2, Reference auto... rest)
-  requires requires {
+template<Reference R1, Reference R2, Reference... Rest>
+[[nodiscard]] consteval auto common_reference(R1 r1, R2 r2, Rest... rest)
+  requires(!(AssociatedUnit<R1> && AssociatedUnit<R2> && (... && AssociatedUnit<Rest>))) && requires {
     {
       common_quantity_spec(get_quantity_spec(r1), get_quantity_spec(r2), get_quantity_spec(rest)...)
     } -> QuantitySpec;