Run Flax.Build when building main C# project

Source/Tools/Flax.Build/Projects/VisualStudio/CSSDKProjectGenerator.cs

@@ -91,6 +91,11 @@ namespace Flax.Build.Projects.VisualStudio
             var baseOutputDir = Utilities.MakePathRelativeTo(project.CSharp.OutputPath ?? baseConfiguration.TargetBuildOptions.OutputFolder, projectDirectory);
             var baseIntermediateOutputPath = Utilities.MakePathRelativeTo(project.CSharp.IntermediateOutputPath ?? Path.Combine(baseConfiguration.TargetBuildOptions.IntermediateFolder, "CSharp"), projectDirectory);
             
+            bool isMainProject = Globals.Project.ProjectFolderPath == project.WorkspaceRootPath && project.Name != "BuildScripts";
+            var flaxBuildTargetsFilename = isMainProject ? "Flax.Build.CSharp.targets" : "Flax.Build.CSharp.SkipBuild.targets";
+            var cacheProjectsPath = Utilities.MakePathRelativeTo(Path.Combine(Globals.Root, "Cache", "Projects"), projectDirectory);
+            var flaxBuildTargetsPath = !string.IsNullOrEmpty(cacheProjectsPath) ? Path.Combine(cacheProjectsPath, flaxBuildTargetsFilename) : flaxBuildTargetsFilename;
+
             csProjectFileContent.AppendLine("    <TargetFramework>net7.0</TargetFramework>");
             csProjectFileContent.AppendLine("    <ImplicitUsings>disable</ImplicitUsings>");
             csProjectFileContent.AppendLine(string.Format("    <Nullable>{0}</Nullable>", baseConfiguration.TargetBuildOptions.ScriptingAPI.CSharpNullableReferences.ToString().ToLowerInvariant()));
@@ -106,14 +111,14 @@ namespace Flax.Build.Projects.VisualStudio
             csProjectFileContent.AppendLine("    <LangVersion>11.0</LangVersion>");
             csProjectFileContent.AppendLine("    <FileAlignment>512</FileAlignment>");
 
-            // Needed for Hostfxr
-            csProjectFileContent.AppendLine("    <GenerateRuntimeConfigurationFiles>true</GenerateRuntimeConfigurationFiles>");
-            csProjectFileContent.AppendLine("    <EnableDynamicLoading>true</EnableDynamicLoading>");
             //csProjectFileContent.AppendLine("    <CopyLocalLockFileAssemblies>false</CopyLocalLockFileAssemblies>"); // TODO: use it to reduce burden of framework libs
 
-            // This needs to be set here to fix errors in VS
+            // Custom .targets file for overriding MSBuild build tasks
-            csProjectFileContent.AppendLine(string.Format("    <OutDir>{0}</OutDir>", baseOutputDir));
+            csProjectFileContent.AppendLine(string.Format("    <CustomAfterMicrosoftCommonTargets>$(MSBuildThisFileDirectory){0}</CustomAfterMicrosoftCommonTargets>", flaxBuildTargetsPath));
-            csProjectFileContent.AppendLine(string.Format("    <IntermediateOutputPath>{0}</IntermediateOutputPath>", baseIntermediateOutputPath));
+
+            // Hide annoying warnings during build
+            csProjectFileContent.AppendLine("    <RestorePackages>false</RestorePackages>");
+            csProjectFileContent.AppendLine("    <DisableFastUpToDateCheck>True</DisableFastUpToDateCheck>");
 
             csProjectFileContent.AppendLine("  </PropertyGroup>");
             csProjectFileContent.AppendLine("");

Source/Tools/Flax.Build/Projects/VisualStudio/VisualStudioProjectGenerator.cs

@@ -679,6 +679,57 @@ namespace Flax.Build.Projects.VisualStudio
 
                 Utilities.WriteFileIfChanged(dotSettingsUserFilePath, dotSettingsFileContent.ToString());
             }
+
+            // Custom MSBuild .targets file to prevent building Flax C#-projects directly with MSBuild
+            {
+                var targetsFileContent = new StringBuilder();
+                targetsFileContent.AppendLine("<Project>");
+                targetsFileContent.AppendLine("  <!-- Prevent building projects with MSBuild, let Flax.Build handle the building process -->");
+                targetsFileContent.AppendLine("  <Target Name=\"Build\" Condition=\"'false' == 'true'\" />");
+                targetsFileContent.AppendLine("</Project>");
+
+                Utilities.WriteFileIfChanged(Path.Combine(Globals.Root, "Cache", "Projects", "Flax.Build.CSharp.SkipBuild.targets"), targetsFileContent.ToString());
+            }
+
+            // Override MSBuild build tasks to run Flax.Build in C#-only projects
+            {
+                // Build command for the build tool
+                var buildToolPath = Path.ChangeExtension(Utilities.MakePathRelativeTo(typeof(Builder).Assembly.Location, Path.GetDirectoryName(solution.MainProject.Path)), null);
+                
+                var targetsFileContent = new StringBuilder();
+                targetsFileContent.AppendLine("<Project>");
+                targetsFileContent.AppendLine("  <!-- Custom Flax.Build scripts for C# projects. -->");
+                targetsFileContent.AppendLine("  <Target Name=\"Build\">");
+                AppendBuildToolCommands(targetsFileContent, "-build");
+                targetsFileContent.AppendLine("  </Target>");
+                targetsFileContent.AppendLine("  <Target Name=\"Rebuild\">");
+                AppendBuildToolCommands(targetsFileContent, "-rebuild");
+                targetsFileContent.AppendLine("  </Target>");
+                targetsFileContent.AppendLine("  <Target Name=\"Clean\">");
+                AppendBuildToolCommands(targetsFileContent, "-clean");
+                targetsFileContent.AppendLine("  </Target>");
+                targetsFileContent.AppendLine("</Project>");
+
+                Utilities.WriteFileIfChanged(Path.Combine(Globals.Root, "Cache", "Projects", "Flax.Build.CSharp.targets"), targetsFileContent.ToString());
+
+                void AppendBuildToolCommands(StringBuilder str, string extraArgs)
+                {
+                    foreach (var configuration in solution.MainProject.Configurations)
+                    {
+                        var cmdLine = string.Format("{0} -log -mutex -workspace={1} -arch={2} -configuration={3} -platform={4} -buildTargets={5}",
+                                                FixPath(buildToolPath),
+                                                FixPath(solution.MainProject.WorkspaceRootPath),
+                                                configuration.Architecture,
+                                                configuration.Configuration,
+                                                configuration.Platform,
+                                                configuration.Target);
+                        if (!string.IsNullOrEmpty(Configuration.Compiler))
+                            cmdLine += " -compiler=" + Configuration.Compiler;
+
+                        str.AppendLine(string.Format("    <Exec Command=\"{0} {1}\" Condition=\"'$(Configuration)|$(Platform)'=='{2}'\"/>", cmdLine, extraArgs, configuration.Name));
+                    }
+                }
+            }
         }
 
         /// <inheritdoc />
@@ -716,5 +767,14 @@ namespace Flax.Build.Projects.VisualStudio
                 projects.Add(project);
             }
         }
+
+        private static string FixPath(string path)
+        {
+            if (path.Contains(' '))
+            {
+                path = "\"" + path + "\"";
+            }
+            return path;
+        }
     }
 }