Fix standard incompetence found by MSVC

- requires-expression still not working, because they aren't supported yet outside of a concept

3 files changed, 39 insertions, 37 deletions

diff --git a/core/src/Model/Workflow/Values/BasicValues.cpp b/core/src/Model/Workflow/Values/BasicValues.cpp
index a7cf635..748c652 100644
--- a/core/src/Model/Workflow/Values/BasicValues.cpp
+++ b/core/src/Model/Workflow/Values/BasicValues.cpp
@@ -14,14 +14,13 @@ NumericValue::NumericValue()
 {
 }
 
-template <class T>
+template <class T, int kMaxSize>
 static std::string NumberToString(T value)
 {
-	constexpr auto kSize = std::numeric_limits<T>::max_digits10;
-	char buf[kSize];
+	char buf[kMaxSize];
 
 #if PLATFORM_WIN32
-	auto res = std::to_chars(buf, buf + kSize, value);
+	auto res = std::to_chars(buf, buf + kMaxSize, value);
 	if (res.ec == std::errc()) {
 		return std::string(buf, res.ptr);
 	} else {
@@ -35,17 +34,20 @@ static std::string NumberToString(T value)
 
 std::string NumericValue::GetTruncatedString() const
 {
-	return ::NumberToString((int64_t)mValue);
+	constexpr auto kMaxSize = std::numeric_limits<int64_t>::digits10;
+	return ::NumberToString<int64_t, kMaxSize>((int64_t)mValue);
 }
 
 std::string NumericValue::GetRoundedString() const
 {
-	return ::NumberToString((int64_t)std::round(mValue));
+	constexpr auto kMaxSize = std::numeric_limits<int64_t>::digits10;
+	return ::NumberToString<int64_t, kMaxSize>((int64_t)std::round(mValue));
 }
 
 std::string NumericValue::GetString() const
 {
-	return ::NumberToString(mValue);
+	constexpr auto kMaxSize = std::numeric_limits<double>::max_digits10;
+	return ::NumberToString<double, kMaxSize>(mValue);
 }
 
 int64_t NumericValue::GetInt() const
diff --git a/core/src/Model/Workflow/Workflow.hpp b/core/src/Model/Workflow/Workflow.hpp
index ded9bfb..161400e 100644
--- a/core/src/Model/Workflow/Workflow.hpp
+++ b/core/src/Model/Workflow/Workflow.hpp
@@ -5,6 +5,7 @@
 #include "cplt_fwd.hpp"
 
 #include <imgui_node_editor.h>
+#include <any>
 #include <cstddef>
 #include <cstdint>
 #include <filesystem>
@@ -240,34 +241,27 @@ public:
 
 	/* Graph rebuild */
 
-	struct GraphUpdateResult
+	enum GraphUpdateResult
 	{
-		struct Success
-		{
-		};
-
-		struct NoWorkToDo
-		{
-		};
-
-		struct UnsatisfiedDependencies
-		{
-			std::vector<uint32_t> UnsatisfiedNodes;
-		};
-
-		struct UnreachableNodes
-		{
-			std::vector<uint32_t> UnreachableNodes;
-		};
-
-		using T = std::variant<
-			Success,
-			NoWorkToDo,
-			UnsatisfiedDependencies,
-			UnreachableNodes>;
+		/// Successfully rebuilt graph dependent data.
+		/// Details: nothing is written.
+		GUR_Success,
+		/// Nothing has changed since last time UpdateGraph() was called.
+		/// Details: nothing is written.
+		GUR_NoWorkToDo,
+		/// Details: list of nodes is written.
+		GUR_UnsatisfiedDependencies,
+		/// Details: list of nodes is written.
+		GUR_UnreachableNodes,
 	};
 
-	GraphUpdateResult::T UpdateGraph();
+	using GraphUpdateDetails = std::variant<
+		// Case: nothing
+		std::monostate,
+		// Case: list of nodes (ids)
+		std::vector<uint32_t>>;
+
+	GraphUpdateResult UpdateGraph(GraphUpdateDetails* details = nullptr);
 
 	/* Serialization */
 
diff --git a/core/src/Model/Workflow/Workflow_Main.cpp b/core/src/Model/Workflow/Workflow_Main.cpp
index bfe007c..61cd510 100644
--- a/core/src/Model/Workflow/Workflow_Main.cpp
+++ b/core/src/Model/Workflow/Workflow_Main.cpp
@@ -524,10 +524,10 @@ bool Workflow::DisconnectByDestination(WorkflowNode& destinationNode, uint32_t d
 	return true;
 }
 
-Workflow::GraphUpdateResult::T Workflow::UpdateGraph()
+Workflow::GraphUpdateResult Workflow::UpdateGraph(GraphUpdateDetails* details)
 {
 	if (!mDepthsDirty) {
-		return GraphUpdateResult::NoWorkToDo{};
+		return GUR_NoWorkToDo;
 	}
 
 	// Terminology:
@@ -577,7 +577,10 @@ Workflow::GraphUpdateResult::T Workflow::UpdateGraph()
 		}
 
 		if (!unsatisfiedNodes.empty()) {
-			return GraphUpdateResult::UnsatisfiedDependencies{ std::move(unsatisfiedNodes) };
+			if (details) {
+				details->emplace<decltype(unsatisfiedNodes)>(std::move(unsatisfiedNodes));
+			}
+			return GUR_UnsatisfiedDependencies;
 		}
 	}
 
@@ -624,10 +627,13 @@ Workflow::GraphUpdateResult::T Workflow::UpdateGraph()
 			unreachableNodes.push_back(i);
 		}
 
-		return GraphUpdateResult::UnreachableNodes{ std::move(unreachableNodes) };
+		if (details) {
+			details->emplace<decltype(unreachableNodes)>(std::move(unreachableNodes));
+		}
+		return GUR_UnreachableNodes;
 	}
 
-	return GraphUpdateResult::Success{};
+	return GUR_Success;
 }
 
 Workflow::ReadResult Workflow::ReadFrom(std::istream& stream)