Show character triggering unknown conversion in error message

1 files changed, 7 insertions, 1 deletions

diff --git a/cxxformat.hpp b/cxxformat.hpp
index 3a45e9f..46d18b4 100644
--- a/cxxformat.hpp
+++ b/cxxformat.hpp
@@ -610,6 +610,12 @@ namespace detail
 		else return substr<i, iAfterPrecision - 1, true>(fmt) + conversion;
 	}
 
+	template<char c, std::size_t size>
+	consteval void showUnknownConversionSpecifier()
+	{
+		static_assert(size == 0, "Unknown conversion specifier!");
+	}
+
 	template<auto fmt, size_t i, size_t argumentIndex, typename Arg, typename... Args>
 	std::string format_s(Arg &&arg, Args &&...args)
 	{
@@ -642,7 +648,7 @@ namespace detail
 			}
 			else
 			{
-				static_assert(fmt.size == 0, "Unknown conversion specifier!");
+				showUnknownConversionSpecifier<conversion, fmt.size>();
 				throw FormatException{std::string{"Unknown conversion specifier: \""} + conversion + "\""};
 			}
 		}