Annoying compile issue in 4.17 preview 3

[Ben_Marsh]

@TheJamsh;747716

Thanks Ben. Could you also just quickly have a look into the issue I posted above yours? I’m not sure if it’s related, but improved logging there would have made it much easier to fix!

I’ve submitted a fix for this to a development stream, but it’s not visible on GitHub yet. We’ll include it in the 4.17.2 hotfix (we’ve already stopped taking changes for the 4.17.1 hotfix to try and get the other issue on this thread out of the door). The fix is to insert a check that the Instance.Modules list doesn’t already contain a module in the UEBuildTarget.AddPlugin function here (in Engine/Source/Programs/UnrealBuildTool/Configuration/UEBuildTarget.cs):

	// Create modules for this plugin
	UEBuildBinaryType BinaryType = ShouldCompileMonolithic() ? UEBuildBinaryType.StaticLibrary : UEBuildBinaryType.DynamicLinkLibrary;
	if (Info.Descriptor.Modules != null)
	{
		foreach (ModuleDescriptor ModuleInfo in Info.Descriptor.Modules)
		{
			if (ModuleInfo.IsCompiledInConfiguration(Platform, TargetType, Rules.bBuildDeveloperTools, Rules.bBuildEditor, Rules.bBuildRequiresCookedData))
			{
				UEBuildModule Module = FindOrCreateModuleByName(ModuleInfo.Name, PluginReferenceChain);
// BEGIN PATCH
				if(!Instance.Modules.Contains(Module))
				{
// END PATCH
					if (!Module.RulesFile.IsUnderDirectory(Info.Directory))
					{
						throw new BuildException("Plugin '{0}' (referenced via {1}) does not contain the '{2}' module, but lists it in '{3}'.", Info.Name, ReferenceChain, ModuleInfo.Name, Info.File);
					}
					Instance.bDescriptorNeededAtRuntime = true;
					Instance.Modules.Add(Module);
// BEGIN PATCH
				}
// END PATCH
			}
		}
	}