From 7af0dc1b439311dee0e8454d9bba681bcc867476 Mon Sep 17 00:00:00 2001
From: Wojtek Figat <wojtek@figat.pl>
Date: Sun, 7 Aug 2022 16:46:17 +0200
Subject: [PATCH] Add support for setting C++ version for build module
 compilation

---
 .../Build/NativeCpp/CompileEnvironment.cs     | 34 ++++++++++++++++++-
 .../Platforms/Unix/UnixToolchain.cs           | 16 ++++++++-
 .../Platforms/Windows/WindowsToolchainBase.cs | 17 ++++++++++
 3 files changed, 65 insertions(+), 2 deletions(-)

diff --git a/Source/Tools/Flax.Build/Build/NativeCpp/CompileEnvironment.cs b/Source/Tools/Flax.Build/Build/NativeCpp/CompileEnvironment.cs
index bae5957a3..522099c62 100644
--- a/Source/Tools/Flax.Build/Build/NativeCpp/CompileEnvironment.cs
+++ b/Source/Tools/Flax.Build/Build/NativeCpp/CompileEnvironment.cs
@@ -1,4 +1,4 @@
-// Copyright (c) 2012-2022 Wojciech Figat. All rights reserved.
+// Copyright (c) 2012-2022 Wojciech Figat. All rights reserved.
 
 using System;
 using System.Collections.Generic;
@@ -26,11 +26,42 @@ namespace Flax.Build.NativeCpp
         SmallCode
     }
 
+    /// <summary>
+    /// The compilation optimization hint.
+    /// </summary>
+    public enum CppVersion
+    {
+        /// <summary>
+        /// C++14
+        /// </summary>
+        Cpp14,
+
+        /// <summary>
+        /// C++17
+        /// </summary>
+        Cpp17,
+
+        /// <summary>
+        /// C++20
+        /// </summary>
+        Cpp20,
+
+        /// <summary>
+        /// The latest version supported by the compiler.
+        /// </summary>
+        Latest,
+    }
+
     /// <summary>
     /// The C++ compilation environment required to build source files in the native modules.
     /// </summary>
     public class CompileEnvironment : ICloneable
     {
+        /// <summary>
+        /// C++ standard version to use for compilation.
+        /// </summary>
+        public CppVersion CppVersion = CppVersion.Cpp14;
+
         /// <summary>
         /// Selects a predefined set of options that affect the size and speed of generated code.
         /// </summary>
@@ -131,6 +162,7 @@ namespace Flax.Build.NativeCpp
         {
             var clone = new CompileEnvironment
             {
+                CppVersion = CppVersion,
                 FavorSizeOrSpeed = FavorSizeOrSpeed,
                 EnableExceptions = EnableExceptions,
                 RuntimeTypeInfo = RuntimeTypeInfo,
diff --git a/Source/Tools/Flax.Build/Platforms/Unix/UnixToolchain.cs b/Source/Tools/Flax.Build/Platforms/Unix/UnixToolchain.cs
index bc35c1dd5..5418575c6 100644
--- a/Source/Tools/Flax.Build/Platforms/Unix/UnixToolchain.cs
+++ b/Source/Tools/Flax.Build/Platforms/Unix/UnixToolchain.cs
@@ -284,7 +284,21 @@ namespace Flax.Build.Platforms
                 commonArgs.Add("-pipe");
                 commonArgs.Add("-x");
                 commonArgs.Add("c++");
-                commonArgs.Add("-std=c++14");
+
+                // C++ version
+                switch (compileEnvironment.CppVersion)
+                {
+                case CppVersion.Cpp14:
+                    commonArgs.Add("-std=c++14");
+                    break;
+                case CppVersion.Cpp17:
+                case CppVersion.Latest:
+                    commonArgs.Add("-std=c++17");
+                    break;
+                case CppVersion.Cpp20:
+                    commonArgs.Add("-std=c++20");
+                    break;
+                }
 
                 commonArgs.Add("-Wdelete-non-virtual-dtor");
                 commonArgs.Add("-fno-math-errno");
diff --git a/Source/Tools/Flax.Build/Platforms/Windows/WindowsToolchainBase.cs b/Source/Tools/Flax.Build/Platforms/Windows/WindowsToolchainBase.cs
index 1a7ebc0fd..3919fcafa 100644
--- a/Source/Tools/Flax.Build/Platforms/Windows/WindowsToolchainBase.cs
+++ b/Source/Tools/Flax.Build/Platforms/Windows/WindowsToolchainBase.cs
@@ -433,6 +433,23 @@ namespace Flax.Build.Platforms
                 // Compile Without Linking
                 commonArgs.Add("/c");
 
+                // C++ version
+                switch (compileEnvironment.CppVersion)
+                {
+                case CppVersion.Cpp14:
+                    commonArgs.Add("/std:c++14");
+                    break;
+                case CppVersion.Cpp17:
+                    commonArgs.Add("/std:c++17");
+                    break;
+                case CppVersion.Cpp20:
+                    commonArgs.Add("/std:c++20");
+                    break;
+                case CppVersion.Latest:
+                    commonArgs.Add("/std:c++latest");
+                    break;
+                }
+
                 // Generate Intrinsic Functions
                 if (compileEnvironment.IntrinsicFunctions)
                     commonArgs.Add("/Oi");