From 371859e81be1e10fa88bab745fff31a7e738da74 Mon Sep 17 00:00:00 2001
From: Alexander Grund <Flamefire@users.noreply.github.com>
Date: Tue, 25 Jan 2022 18:28:51 +0100
Subject: [PATCH] Enhance error message for parameter-trait

Also add a comment for when this is usually triggered
---
 include/turtle/detail/parameter.hpp | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/include/turtle/detail/parameter.hpp b/include/turtle/detail/parameter.hpp
index 1db8228..b21a19a 100644
--- a/include/turtle/detail/parameter.hpp
+++ b/include/turtle/detail/parameter.hpp
@@ -60,7 +60,9 @@ namespace mock { namespace detail {
     template<typename Signature, std::size_t n>
     struct parameter
     {
-        static_assert(n < function_arity<Signature>::value, "Function signature has not that many parameters");
+        // This assertion is usually triggered when the arity passed to e.g. MOCK_METHOD exceeds the number of
+        // parameters of the mocked function or the passed function signature
+        static_assert(n < function_arity<Signature>::value, "Parameter index exceeds the number of parameters");
         using type = typename tuple_element<n, typename parameter_types<Signature>::type>::type;
     };
     template<typename T, std::size_t n>