From 7ba674c29a1996813787bd8e5e71fffece7b0b1a Mon Sep 17 00:00:00 2001
From: Cheng <ChengSheng@fakemail.ch>
Date: Mon, 2 Oct 2023 01:49:03 +0000
Subject: [PATCH] Cajoled visual studio into issuing intelligent error messages
 when an unserializable type is in the parameter pack.

---
 src/ristretto255.h  | 4 +++-
 src/serialization.h | 3 +++
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/ristretto255.h b/src/ristretto255.h
index 91b0e30..30cc919 100644
--- a/src/ristretto255.h
+++ b/src/ristretto255.h
@@ -195,10 +195,12 @@ namespace ristretto255 {
 			if (i) throw HashReuseException();
 		}
 		template< has_machine_independent_representation T, typename... Args>explicit hash(const T& first, Args... args) {
+			//	not restraining the variant args by concept, because they get caught deeper in,
+			//	and visual studio reporting of variant concept errors sucks.
 			hsh<hashsize> in;
 			in << first;
 			if constexpr (sizeof...(args) > 0) {
-				in.hashinto( args...);
+				in.hashinto( ro::trigger_error(args)...);
 			}
 			int i = crypto_generichash_blake2b_final(
 				&in.st,
diff --git a/src/serialization.h b/src/serialization.h
index 7c4c997..0eaf4ca 100644
--- a/src/serialization.h
+++ b/src/serialization.h
@@ -317,6 +317,9 @@
 	template<typename... Args>
 	concept has_machine_independent_representation = serializable<Args...>();
 
+	template<has_machine_independent_representation T>
+	T trigger_error(T x) { return x; };
+
 	static_assert( !has_machine_independent_representation<double>
 		&& has_machine_independent_representation<std::span<const byte>, char*, std::span<const char>>,
 		"concepts needed");