Compile Unreal Engine 4.24 using FastBuild WIP

Implementation notes

Currently supported platforms

• Win64 - tested with Windows 10, Visual Studio 2019 Community, Unreal Engine 4.23.1, FastBuild v0.98.

Recently supported platforms

• Durango was fully supported using VS2015 at some point in the past, but VS2015 is not supported since 4.22;
• Orbis will require some changes.

Not supported platforms

• Android;
• iOS;
• Linux;
• and others...

Main idea

The main difference from Yassine Riahi & Liam Flookes version is in added support for dependency files. It was implemented using FastBuild "-report" argument. Generated report (see ReportFilePath) contains include files usage. Since there is no source code for cl-filter.exe, it is not possible to guarantee same result. Moreover it is fact, that output contains more include files than when using cl-filter.exe. Maybe more precise filtration could be applied, some ideas:

• exclude pch includes usages from dependent compilation units;
• exclude files from outside engine folder;
• exclude using cl-filter.exe.sn-dbs-tool.ini.

FastBuild version

Don't use FastBuild 0.96 or older versions, since it has processes management error.

For more information see fastbuild/fastbuild#223.

Installation steps

1. Save copy of this file as ...\Engine\Source\Programs\UnrealBuildTool\System\FASTBuild.cs;
2. Add it to UnrealBuildTool project;
3. Add FastBuild executor to ExecuteActions(...) inside ActionGraph.cs:

...
// Figure out which executor to use
ActionExecutor Executor;
if (FASTBuild.IsAvailable())
{
	Executor = new FASTBuild();
}
else if (BuildConfiguration.bAllowHybridExecutor && HybridExecutor.IsAvailable())
...

4. Add "public" access modifier to GetVCToolPath(...) method inside VCEnvironment.cs.

Original version

https://github.com/liamkf/Unreal_FASTBuild