From 9581f7b10ed46573db1903fdfd59e95edfa5dced Mon Sep 17 00:00:00 2001
From: Wojtek Figat <wojtek@figat.pl>
Date: Mon, 29 Mar 2021 14:41:29 +0200
Subject: [PATCH] Fix using cross-module references inside C++ game project

---
 Source/Tools/Flax.Build/Build/Builder.cs      | 11 ++++++++++
 .../Build/NativeCpp/Builder.NativeCpp.cs      | 20 +++++++++++++++++++
 2 files changed, 31 insertions(+)

diff --git a/Source/Tools/Flax.Build/Build/Builder.cs b/Source/Tools/Flax.Build/Build/Builder.cs
index 187a59776..1bcfca18e 100644
--- a/Source/Tools/Flax.Build/Build/Builder.cs
+++ b/Source/Tools/Flax.Build/Build/Builder.cs
@@ -82,6 +82,17 @@ namespace Flax.Build
             return GetModuleProject(module, buildData.Project);
         }
 
+        /// <summary>
+        /// Checks if the project that contains a given module (checks for modules located in the given project Source folder).
+        /// </summary>
+        /// <param name="module">The module.</param>
+        /// <param name="project">The project to check.</param>
+        /// <returns>True if project contains that module inside, otherwise it's external or referenced.</returns>
+        public static bool IsModuleFromProject(Module module, ProjectInfo project)
+        {
+            return GetModuleProject(module, project) == project;
+        }
+
         /// <summary>
         /// Builds the targets.
         /// </summary>
diff --git a/Source/Tools/Flax.Build/Build/NativeCpp/Builder.NativeCpp.cs b/Source/Tools/Flax.Build/Build/NativeCpp/Builder.NativeCpp.cs
index 5b748a481..0c3eedd53 100644
--- a/Source/Tools/Flax.Build/Build/NativeCpp/Builder.NativeCpp.cs
+++ b/Source/Tools/Flax.Build/Build/NativeCpp/Builder.NativeCpp.cs
@@ -696,6 +696,26 @@ namespace Flax.Build
                             {
                                 // Export symbols from binary module
                                 moduleOptions.CompileEnv.PreprocessorDefinitions.Add(binaryModuleNameUpper + (target.UseSymbolsExports ? "_API=" + toolchain.DllExport : "_API="));
+
+                                // Import symbols from binary modules containing the referenced modules (from this project only, external ones are handled via ReferenceBuilds below)
+                                foreach (var moduleName in moduleOptions.PrivateDependencies)
+                                {
+                                    var dependencyModule = buildData.Rules.GetModule(moduleName);
+                                    if (dependencyModule != null && !string.IsNullOrEmpty(dependencyModule.BinaryModuleName) && dependencyModule.BinaryModuleName != binaryModule.Key && IsModuleFromProject(dependencyModule, project) && buildData.Modules.TryGetValue(dependencyModule, out var dependencyOptions))
+                                    {
+                                        // Import symbols from referenced binary module
+                                        moduleOptions.CompileEnv.PreprocessorDefinitions.Add(dependencyModule.BinaryModuleName.ToUpperInvariant() + "_API=" + toolchain.DllImport);
+                                    }
+                                }
+                                foreach (var moduleName in moduleOptions.PublicDependencies)
+                                {
+                                    var dependencyModule = buildData.Rules.GetModule(moduleName);
+                                    if (dependencyModule != null && !string.IsNullOrEmpty(dependencyModule.BinaryModuleName) && dependencyModule.BinaryModuleName != binaryModule.Key && IsModuleFromProject(dependencyModule, project) && buildData.Modules.TryGetValue(dependencyModule, out var dependencyOptions))
+                                    {
+                                        // Import symbols from referenced binary module
+                                        moduleOptions.CompileEnv.PreprocessorDefinitions.Add(dependencyModule.BinaryModuleName.ToUpperInvariant() + "_API=" + toolchain.DllImport);
+                                    }
+                                }
                             }
                             else
                             {