From f9ac5831cf660398fee52e75c1e6de10c687ad7a Mon Sep 17 00:00:00 2001
From: kayomn <kayomn@kayomn.net>
Date: Wed, 22 Feb 2023 22:59:33 +0000
Subject: [PATCH] Improve compile-time safety of coral::callable

---
 source/coral.cpp | 20 +++++++++++---------
 1 file changed, 11 insertions(+), 9 deletions(-)

diff --git a/source/coral.cpp b/source/coral.cpp
index 9705c49..1fcf1ea 100644
--- a/source/coral.cpp
+++ b/source/coral.cpp
@@ -426,12 +426,12 @@ export namespace coral {
 	 * Type-erasing wrapper for functor types that have a call operator with a return value
 	 * matching `return_value` and arguments matching `argument_values`.
 	 */
-	template<typename return_value, typename... argument_values> struct callable<return_value(argument_values...)> {
-		using function = return_value(*)(argument_values...);
+	template<typename returns, typename... arguments> struct callable<returns(arguments...)> {
+		using function = returns(*)(arguments...);
 
 		callable(function callable_function) {
-			this->dispatcher = [](u8 const * userdata, argument_values... arguments) -> return_value {
-				return (*reinterpret_cast<function const *>(userdata))(arguments...);
+			this->dispatcher = [](u8 const * context, arguments... dispatch_arguments) -> returns {
+				return (*reinterpret_cast<function const *>(context))(dispatch_arguments...);
 			};
 
 			new (this->capture) function{callable_function};
@@ -440,21 +440,23 @@ export namespace coral {
 		callable(callable const &) = delete;
 
 		template<typename functor> callable(functor const & callable_functor) {
-			this->dispatcher = [](u8 const * userdata, argument_values... arguments) -> return_value {
-				return (*reinterpret_cast<functor const*>(userdata))(arguments...);
+			static_assert(sizeof(functor) < capture_size);
+
+			this->dispatcher = [](u8 const * context, arguments... dispatch_arguments) -> returns {
+				return (*reinterpret_cast<functor const*>(context))(dispatch_arguments...);
 			};
 
 			new (this->capture) functor{callable_functor};
 		}
 
-		return_value operator()(argument_values const &... arguments) const {
-			return this->dispatcher(this->capture, arguments...);
+		returns operator()(arguments const &... call_arguments) const {
+			return this->dispatcher(this->capture, call_arguments...);
 		}
 
 		private:
 		static constexpr usize capture_size = 24;
 
-		return_value(* dispatcher)(u8 const * userdata, argument_values... arguments);
+		returns(* dispatcher)(u8 const *, arguments...);
 
 		u8 capture[capture_size];
 	};