UnrealEngineUWP/Engine/Source/Programs/UnrealBuildTool/Linux/LinuxToolChain.cs

// Copyright 1998-2016 Epic Games, Inc. All Rights Reserved.

using System;
using System.Collections.Generic;
using System.Text.RegularExpressions;
using System.Diagnostics;
using System.IO;
using Microsoft.Win32;

namespace UnrealBuildTool
{
	class LinuxToolChain : UEToolChain
	{
		LinuxPlatformContext PlatformContext;

		public LinuxToolChain(LinuxPlatformContext InPlatformContext) 
			: base(CPPTargetPlatform.Linux)
		{
			PlatformContext = InPlatformContext;
			if (!CrossCompiling())
			{
				// use native linux toolchain
				string[] ClangNames = { "clang++", "clang++-3.7", "clang++-3.6", "clang++-3.5", "clang++-3.3" };
				foreach (var ClangName in ClangNames)
				{
					ClangPath = Which(ClangName);
					if (!String.IsNullOrEmpty(ClangPath))
					{
						break;
					}
				}
				GCCPath = Which("g++");
				ArPath = Which("ar");
				RanlibPath = Which("ranlib");
				StripPath = Which("strip");

				// if clang is available, zero out gcc (@todo: support runtime switching?)
				if (!String.IsNullOrEmpty(ClangPath))
				{
					GCCPath = null;
				}
			}
			else
			{
				// use cross linux toolchain if LINUX_ROOT is specified
				BaseLinuxPath = Environment.GetEnvironmentVariable("LINUX_ROOT");

				// don't register if we don't have an LINUX_ROOT specified
				if (String.IsNullOrEmpty(BaseLinuxPath))
					throw new BuildException("LINUX_ROOT environment variable is not set; cannot instantiate Linux toolchain");

				BaseLinuxPath = BaseLinuxPath.Replace("\"", "");

				// set up the path to our toolchains
				GCCPath = "";
				ClangPath = Path.Combine(BaseLinuxPath, @"bin\clang++.exe");
				// ar and ranlib will be switched later to match the architecture
				ArPath = "ar.exe";
				RanlibPath = "ranlib.exe";
				StripPath = "strip.exe";
			}

			if (!DetermineCompilerVersion())
			{
				throw new BuildException("Could not determine version of the compiler, not registering Linux toolchain.");
			}

			// refuse to use compilers that we know won't work
			// disable that only if you are a dev and you know what you are doing
			if (!UsingClang())
			{
				throw new BuildException("This version of the engine can only be compiled by clang - refusing to register the Linux toolchain.");
			}
			else if (CompilerVersionMajor == 3 && CompilerVersionMinor == 4)
			{
				throw new BuildException("clang 3.4.x is known to miscompile the engine - refusing to register the Linux toolchain.");
			}
			// prevent unknown clangs since the build is likely to fail on too old or too new compilers
			else if ((CompilerVersionMajor * 10 + CompilerVersionMinor) > 37 || (CompilerVersionMajor * 10 + CompilerVersionMinor) < 33)
			{
				// do not mention 3.3 as it doesn't really get tested anymore, but allow it since it may still compile
				throw new BuildException(
					string.Format("This version of the Unreal Engine can only be compiled with clang 3.6 and 3.5. clang {0} may not build it - please use a different version.",
						CompilerVersionString)
					);
			}
		}

		protected static bool CrossCompiling()
		{
			return BuildHostPlatform.Current.Platform != UnrealTargetPlatform.Linux;
		}

		protected static bool UsingClang()
		{
			return !String.IsNullOrEmpty(ClangPath);
		}

		private string Which(string name)
		{
			Process proc = new Process();
			proc.StartInfo.FileName = "/bin/sh";
			proc.StartInfo.Arguments = String.Format("-c 'which {0}'", name);
			proc.StartInfo.UseShellExecute = false;
			proc.StartInfo.CreateNoWindow = true;
			proc.StartInfo.RedirectStandardOutput = true;
			proc.StartInfo.RedirectStandardError = true;

			proc.Start();
			proc.WaitForExit();

			string path = proc.StandardOutput.ReadLine();
			Log.TraceVerbose(String.Format("which {0} result: ({1}) {2}", name, proc.ExitCode, path));

			if (proc.ExitCode == 0 && String.IsNullOrEmpty(proc.StandardError.ReadToEnd()))
			{
				return path;
			}
			return null;
		}

		/// <summary>
		/// Splits compiler version string into numerical components, leaving unchanged if not known
		/// </summary>
		private void DetermineCompilerMajMinPatchFromVersionString()
		{
			string[] Parts = CompilerVersionString.Split('.');
			if (Parts.Length >= 1)
			{
				CompilerVersionMajor = Convert.ToInt32(Parts[0]);
			}
			if (Parts.Length >= 2)
			{
				CompilerVersionMinor = Convert.ToInt32(Parts[1]);
			}
			if (Parts.Length >= 3)
			{
				CompilerVersionPatch = Convert.ToInt32(Parts[2]);
			}
		}

		/// <summary>
		/// Queries compiler for the version
		/// </summary>
		private bool DetermineCompilerVersion()
		{
			CompilerVersionString = null;
			CompilerVersionMajor = -1;
			CompilerVersionMinor = -1;
			CompilerVersionPatch = -1;

			Process Proc = new Process();
			Proc.StartInfo.UseShellExecute = false;
			Proc.StartInfo.CreateNoWindow = true;
			Proc.StartInfo.RedirectStandardOutput = true;
			Proc.StartInfo.RedirectStandardError = true;

			if (!String.IsNullOrEmpty(GCCPath) && File.Exists(GCCPath))
			{
				Proc.StartInfo.FileName = GCCPath;
				Proc.StartInfo.Arguments = " -dumpversion";

				Proc.Start();
				Proc.WaitForExit();

				if (Proc.ExitCode == 0)
				{
					// read just the first string
					CompilerVersionString = Proc.StandardOutput.ReadLine();
					DetermineCompilerMajMinPatchFromVersionString();
				}
			}
			else if (!String.IsNullOrEmpty(ClangPath) && File.Exists(ClangPath))
			{
				Proc.StartInfo.FileName = ClangPath;
				Proc.StartInfo.Arguments = " --version";

				Proc.Start();
				Proc.WaitForExit();

				if (Proc.ExitCode == 0)
				{
					// read just the first string
					string VersionString = Proc.StandardOutput.ReadLine();

					Regex VersionPattern = new Regex("version \\d+(\\.\\d+)+");
					Match VersionMatch = VersionPattern.Match(VersionString);

					// version match will be like "version 3.3", so remove the "version"
					if (VersionMatch.Value.StartsWith("version "))
					{
						CompilerVersionString = VersionMatch.Value.Replace("version ", "");

						DetermineCompilerMajMinPatchFromVersionString();
					}
				}
			}
			else
			{
				// icl?
			}

			if (!CrossCompiling() && !ProjectFileGenerator.bGenerateProjectFiles)
			{
				Console.WriteLine("Using {0} version '{1}' (string), {2} (major), {3} (minor), {4} (patch)",
					String.IsNullOrEmpty(ClangPath) ? "gcc" : "clang",
					CompilerVersionString, CompilerVersionMajor, CompilerVersionMinor, CompilerVersionPatch);
			}
			return !String.IsNullOrEmpty(CompilerVersionString);
		}

		/// <summary>
		/// Checks if compiler version matches the requirements
		/// </summary>
		private static bool CompilerVersionGreaterOrEqual(int Major, int Minor, int Patch)
		{
			return CompilerVersionMajor > Major ||
				(CompilerVersionMajor == Major && CompilerVersionMinor > Minor) ||
				(CompilerVersionMajor == Major && CompilerVersionMinor == Minor && CompilerVersionPatch >= Patch);
		}

		/// <summary>
		/// Architecture-specific compiler switches
		/// </summary>
		static string ArchitectureSpecificSwitches(string Architecture)
		{
			string Result = "";

			if (Architecture.StartsWith("arm"))
			{
				Result += " -fsigned-char";

				// FreeType2's ftconfig.h will trigger this
				Result += " -Wno-deprecated-register";
			}

			return Result;
		}

		static string ArchitectureSpecificDefines(string Architecture)
		{
			string Result = "";

			if (Architecture.StartsWith("x86_64"))
			{
				Result += " -D_LINUX64";
			}

			return Result;
		}

		/// <summary>
		/// Gets architecture-specific ar paths
		/// </summary>
		private static string GetArPath(string Architecture)
		{
			if (CrossCompiling())
			{
				return Path.Combine(Path.Combine(BaseLinuxPath, String.Format("bin/{0}-{1}", Architecture, ArPath)));
			}

			return ArPath;
		}

		/// <summary>
		/// Gets architecture-specific ranlib paths
		/// </summary>
		private static string GetRanlibPath(string Architecture)
		{
			if (CrossCompiling())
			{
				return Path.Combine(Path.Combine(BaseLinuxPath, String.Format("bin/{0}-{1}", Architecture, RanlibPath)));
			}

			return RanlibPath;
		}

		/// <summary>
		/// Gets architecture-specific strip path
		/// </summary>
		private static string GetStripPath(string Architecture)
		{
			if (CrossCompiling())
			{
				return Path.Combine(Path.Combine(BaseLinuxPath, String.Format("bin/{0}-{1}", Architecture, StripPath)));
			}

			return StripPath;
		}

		static string GetCLArguments_Global(CPPEnvironment CompileEnvironment)
		{
			string Result = "";

			// build up the commandline common to C and C++
			Result += " -c";
			Result += " -pipe";

			if (CrossCompiling())
			{
				// There are exceptions used in the code base (e.g. UnrealHeadTool).  @todo: weed out exceptions
				// So this flag cannot be used, at least not for native Linux builds.
				Result += " -fno-exceptions";               // no exceptions
				Result += " -DPLATFORM_EXCEPTIONS_DISABLED=1";
			}
			else
			{
				Result += " -DPLATFORM_EXCEPTIONS_DISABLED=0";
			}

			Result += " -Wall -Werror";
			// test without this next line?
			Result += " -funwind-tables";               // generate unwind tables as they seem to be needed for stack tracing (why??)
			Result += " -Wsequence-point";              // additional warning not normally included in Wall: warns if order of operations is ambigious
			//Result += " -Wunreachable-code";            // additional warning not normally included in Wall: warns if there is code that will never be executed - not helpful due to bIsGCC and similar 
			//Result += " -Wshadow";                      // additional warning not normally included in Wall: warns if there variable/typedef shadows some other variable - not helpful because we have gobs of code that shadows variables

			Result += ArchitectureSpecificSwitches(CompileEnvironment.Config.Target.Architecture);

			Result += " -fno-math-errno";               // do not assume that math ops have side effects
			Result += " -fno-rtti";                     // no run-time type info

			if (String.IsNullOrEmpty(ClangPath))
			{
				// GCC only option
				Result += " -fno-strict-aliasing";
				Result += " -Wno-sign-compare"; // needed to suppress: comparison between signed and unsigned integer expressions
				Result += " -Wno-enum-compare"; // Stats2.h triggers this (ALIGNOF(int64) <= DATA_ALIGN)
				Result += " -Wno-return-type"; // Variant.h triggers this
				Result += " -Wno-unused-local-typedefs";
				Result += " -Wno-multichar";
				Result += " -Wno-unused-but-set-variable";
				Result += " -Wno-strict-overflow"; // Array.h:518
			}
			else
			{
				// Clang only options
				if (CrossCompiling())
				{
					Result += " -fdiagnostics-format=msvc";     // make diagnostics compatible with MSVC when cross-compiling
				}
				Result += " -Wno-unused-private-field";     // MultichannelTcpSocket.h triggers this, possibly more
				// this hides the "warning : comparison of unsigned expression < 0 is always false" type warnings due to constant comparisons, which are possible with template arguments
				Result += " -Wno-tautological-compare";

				// this switch is understood by clang 3.5.0, but not clang-3.5 as packaged by Ubuntu 14.04 atm
				if (CompilerVersionGreaterOrEqual(3, 5, 0))
				{
					Result += " -Wno-undefined-bool-conversion";	// hides checking if 'this' pointer is null
				}

				if (CompilerVersionGreaterOrEqual(3, 6, 0))
				{
					Result += " -Wno-unused-local-typedef";	// clang is being overly strict here? PhysX headers trigger this.
					Result += " -Wno-inconsistent-missing-override";	// these have to be suppressed for UE 4.8, should be fixed later.
				}
			}

			Result += " -Wno-unused-variable";
			// this will hide the warnings about static functions in headers that aren't used in every single .cpp file
			Result += " -Wno-unused-function";
			// this hides the "enumeration value 'XXXXX' not handled in switch [-Wswitch]" warnings - we should maybe remove this at some point and add UE_LOG(, Fatal, ) to default cases
			Result += " -Wno-switch";
			Result += " -Wno-unknown-pragmas";			// Slate triggers this (with its optimize on/off pragmas)
			// needed to suppress warnings about using offsetof on non-POD types.
			Result += " -Wno-invalid-offsetof";
			// we use this feature to allow static FNames.
			Result += " -Wno-gnu-string-literal-operator-template";

			if (CompileEnvironment.Config.bEnableShadowVariableWarning)
			{
				Result += " -Wshadow" + (BuildConfiguration.bShadowVariableErrors ? "" : " -Wno-error=shadow");
			}

			//Result += " -DOPERATOR_NEW_INLINE=FORCENOINLINE";

			// shipping builds will cause this warning with "ensure", so disable only in those case
			if (CompileEnvironment.Config.Target.Configuration == CPPTargetConfiguration.Shipping)
			{
				Result += " -Wno-unused-value";

				// Not stripping debug info in Shipping @FIXME: temporary hack for FN to enable callstack in Shipping builds (proper resolution: UEPLAT-205)
				Result += " -fomit-frame-pointer";
			}
			// switches to help debugging
			else if (CompileEnvironment.Config.Target.Configuration == CPPTargetConfiguration.Debug)
			{
				Result += " -fno-inline";                   // disable inlining for better debuggability (e.g. callstacks, "skip file" in gdb)
				Result += " -fno-omit-frame-pointer";       // force not omitting fp
				Result += " -fstack-protector";             // detect stack smashing
				//Result += " -fsanitize=address";            // detect address based errors (support properly and link to libasan)
			}

			// debug info (bCreateDebugInfo is normally set for all configurations, and we don't want it to affect Shipping performance)
			if (CompileEnvironment.Config.bCreateDebugInfo && CompileEnvironment.Config.Target.Configuration != CPPTargetConfiguration.Shipping)
			{
				Result += " -g3";
			}
			// Applying to all configurations, including Shipping @FIXME: temporary hack for FN to enable callstack in Shipping builds (proper resolution: UEPLAT-205)
			else
			{
				Result += " -gline-tables-only"; // include debug info for meaningful callstacks
			}

			// libdwarf (from elftoolchain 0.6.1) doesn't support DWARF4
			Result += " -gdwarf-3";

			// optimization level
			if (CompileEnvironment.Config.Target.Configuration == CPPTargetConfiguration.Debug)
			{
				Result += " -O0";
			}
			else
			{
				Result += " -O2";	// warning: as of now (2014-09-28), clang 3.5.0 miscompiles PlatformerGame with -O3 (bitfields?)
			}

			if (CompileEnvironment.Config.bIsBuildingDLL)
			{
				Result += " -fPIC";
				// Use local-dynamic TLS model. This generates less efficient runtime code for __thread variables, but avoids problems of running into
				// glibc/ld.so limit (DTV_SURPLUS) for number of dlopen()'ed DSOs with static TLS (see e.g. https://www.cygwin.com/ml/libc-help/2013-11/msg00033.html)
				Result += " -ftls-model=local-dynamic";
			}

			if (CompileEnvironment.Config.bEnableExceptions)
			{
				Result += " -fexceptions";
			}

			//Result += " -v";                            // for better error diagnosis

			Result += ArchitectureSpecificDefines(CompileEnvironment.Config.Target.Architecture);
			if (CrossCompiling())
			{
				if (UsingClang())
				{
					Result += String.Format(" -target {0}", CompileEnvironment.Config.Target.Architecture);        // Set target triple
				}
				Result += String.Format(" --sysroot=\"{0}\"", BaseLinuxPath);
			}

			return Result;
		}

		static string GetCompileArguments_CPP()
		{
			string Result = "";
			Result += " -x c++";
			Result += " -std=c++11";
			return Result;
		}

		static string GetCompileArguments_C()
		{
			string Result = "";
			Result += " -x c";
			return Result;
		}

		static string GetCompileArguments_MM()
		{
			string Result = "";
			Result += " -x objective-c++";
			Result += " -fobjc-abi-version=2";
			Result += " -fobjc-legacy-dispatch";
			Result += " -fno-rtti";
			Result += " -std=c++11";
			return Result;
		}

		static string GetCompileArguments_M()
		{
			string Result = "";
			Result += " -x objective-c";
			Result += " -fobjc-abi-version=2";
			Result += " -fobjc-legacy-dispatch";
			Result += " -std=c++11";
			return Result;
		}

		static string GetCompileArguments_PCH()
		{
			string Result = "";
			Result += " -x c++-header";
			Result += " -std=c++11";
			return Result;
		}

		static string GetLinkArguments(LinkEnvironment LinkEnvironment)
		{
			string Result = "";

			// debugging symbols
			// Applying to all configurations @FIXME: temporary hack for FN to enable callstack in Shipping builds (proper resolution: UEPLAT-205)
			Result += " -rdynamic";   // needed for backtrace_symbols()...

			if (LinkEnvironment.Config.bIsBuildingDLL)
			{
				Result += " -shared";
			}
			else
			{
				// ignore unresolved symbols in shared libs
				Result += string.Format(" -Wl,--unresolved-symbols=ignore-in-shared-libs");
			}

			// RPATH for third party libs
			Result += " -Wl,-rpath=${ORIGIN}";
			Result += " -Wl,-rpath-link=${ORIGIN}";
			Result += " -Wl,-rpath=${ORIGIN}/../../../Engine/Binaries/Linux";
			Result += " -Wl,-rpath=${ORIGIN}/..";	// for modules that are in sub-folders of the main Engine/Binary/Linux folder
			// FIXME: really ugly temp solution. Modules need to be able to specify this
			Result += " -Wl,-rpath=${ORIGIN}/../../../Engine/Binaries/ThirdParty/ICU/icu4c-53_1/Linux/x86_64-unknown-linux-gnu";
			Result += " -Wl,-rpath=${ORIGIN}/../../../Engine/Binaries/ThirdParty/LinuxNativeDialogs/Linux/x86_64-unknown-linux-gnu";

			if (CrossCompiling())
			{
				if (UsingClang())
				{
					Result += String.Format(" -target {0}", LinkEnvironment.Config.Target.Architecture);        // Set target triple
				}
				string SysRootPath = BaseLinuxPath.TrimEnd(new char[] { '\\', '/' });
				Result += String.Format(" \"--sysroot={0}\"", SysRootPath);
			}

			return Result;
		}

		static string GetArchiveArguments(LinkEnvironment LinkEnvironment)
		{
			return " rc";
		}

		public static void CompileOutputReceivedDataEventHandler(Object Sender, DataReceivedEventArgs e)
		{
			string Output = e.Data;
			if (String.IsNullOrEmpty(Output))
			{
				return;
			}

			if (CrossCompiling())
			{
				// format the string so the output errors are clickable in Visual Studio

				// Need to match following for clickable links
				string RegexFilePath = @"^[A-Z]\:([\\\/][A-Za-z0-9_\-\.]*)+\.(cpp|c|mm|m|hpp|h)";
				string RegexLineNumber = @"\:\d+\:\d+\:";
				string RegexDescription = @"(\serror:\s|\swarning:\s|\snote:\s).*";

				// Get Matches
				string MatchFilePath = Regex.Match(Output, RegexFilePath).Value.Replace("Engine\\Source\\..\\..\\", "");
				string MatchLineNumber = Regex.Match(Output, RegexLineNumber).Value;
				string MatchDescription = Regex.Match(Output, RegexDescription).Value;

				// If any of the above matches failed, do nothing
				if (MatchFilePath.Length == 0 ||
					MatchLineNumber.Length == 0 ||
					MatchDescription.Length == 0)
				{
					Console.WriteLine(Output);
					return;
				}

				// Convert Path
				string RegexStrippedPath = @"\\Engine\\.*"; //@"(Engine\/|[A-Za-z0-9_\-\.]*\/).*";
				string ConvertedFilePath = Regex.Match(MatchFilePath, RegexStrippedPath).Value;
				ConvertedFilePath = Path.GetFullPath("..\\.." + ConvertedFilePath);

				// Extract Line + Column Number
				string ConvertedLineNumber = Regex.Match(MatchLineNumber, @"\d+").Value;
				string ConvertedColumnNumber = Regex.Match(MatchLineNumber, @"(?<=:\d+:)\d+").Value;

				// Write output
				string ConvertedExpression = "  " + ConvertedFilePath + "(" + ConvertedLineNumber + "," + ConvertedColumnNumber + "):" + MatchDescription;
				Console.WriteLine(ConvertedExpression); // To create clickable vs link
			}
			else
			{
				// native platform tools expect this in stderror

				Console.Error.WriteLine(Output);
			}
		}

		// cache the location of NDK tools
		static string BaseLinuxPath;
		static string ClangPath;
		static string GCCPath;
		static string ArPath;
		static string RanlibPath;
		static string StripPath;

		/// <summary>
		/// Version string of the current compiler, whether clang or gcc or whatever
		/// </summary>
		static string CompilerVersionString;
		/// <summary>
		/// Major version of the current compiler, whether clang or gcc or whatever
		/// </summary>
		static int CompilerVersionMajor = -1;
		/// <summary>
		/// Minor version of the current compiler, whether clang or gcc or whatever
		/// </summary>
		static int CompilerVersionMinor = -1;
		/// <summary>
		/// Patch version of the current compiler, whether clang or gcc or whatever
		/// </summary>
		static int CompilerVersionPatch = -1;

		/// <summary>
		/// Track which scripts need to be deleted before appending to
		/// </summary>
		private bool bHasWipedFixDepsScript = false;

		private static List<FileItem> BundleDependencies = new List<FileItem>();

		public override CPPOutput CompileCPPFiles(UEBuildTarget Target, CPPEnvironment CompileEnvironment, List<FileItem> SourceFiles, string ModuleName)
		{
			string Arguments = GetCLArguments_Global(CompileEnvironment);
			string PCHArguments = "";

			if (CompileEnvironment.Config.PrecompiledHeaderAction == PrecompiledHeaderAction.Include)
			{
				// Add the precompiled header file's path to the include path so Clang can find it.
				// This needs to be before the other include paths to ensure Clang uses it instead of the source header file.
				var PrecompiledFileExtension = UEBuildPlatform.GetBuildPlatform(UnrealTargetPlatform.Linux).GetBinaryExtension(UEBuildBinaryType.PrecompiledHeader);
				PCHArguments += string.Format(" -include \"{0}\"", CompileEnvironment.PrecompiledHeaderFile.AbsolutePath.Replace(PrecompiledFileExtension, ""));
			}

			// Add include paths to the argument list.
			foreach (string IncludePath in CompileEnvironment.Config.CPPIncludeInfo.IncludePaths)
			{
				Arguments += string.Format(" -I\"{0}\"", IncludePath);
			}
			foreach (string IncludePath in CompileEnvironment.Config.CPPIncludeInfo.SystemIncludePaths)
			{
				Arguments += string.Format(" -I\"{0}\"", IncludePath);
			}

			// Add preprocessor definitions to the argument list.
			foreach (string Definition in CompileEnvironment.Config.Definitions)
			{
				Arguments += string.Format(" -D \"{0}\"", Definition);
			}

			var BuildPlatform = UEBuildPlatform.GetBuildPlatformForCPPTargetPlatform(CompileEnvironment.Config.Target.Platform);

			// Create a compile action for each source file.
			CPPOutput Result = new CPPOutput();
			foreach (FileItem SourceFile in SourceFiles)
			{
				Action CompileAction = new Action(ActionType.Compile);
				string FileArguments = "";
				string Extension = Path.GetExtension(SourceFile.AbsolutePath).ToUpperInvariant();

				// Add C or C++ specific compiler arguments.
				if (CompileEnvironment.Config.PrecompiledHeaderAction == PrecompiledHeaderAction.Create)
				{
					FileArguments += GetCompileArguments_PCH();
				}
				else if (Extension == ".C")
				{
					// Compile the file as C code.
					FileArguments += GetCompileArguments_C();
				}
				else if (Extension == ".CC")
				{
					// Compile the file as C++ code.
					FileArguments += GetCompileArguments_CPP();
				}
				else if (Extension == ".MM")
				{
					// Compile the file as Objective-C++ code.
					FileArguments += GetCompileArguments_MM();
				}
				else if (Extension == ".M")
				{
					// Compile the file as Objective-C code.
					FileArguments += GetCompileArguments_M();
				}
				else
				{
					FileArguments += GetCompileArguments_CPP();

					// only use PCH for .cpp files
					FileArguments += PCHArguments;
				}

				// Add the C++ source file and its included files to the prerequisite item list.
				AddPrerequisiteSourceFile(Target, BuildPlatform, CompileEnvironment, SourceFile, CompileAction.PrerequisiteItems);

				if (CompileEnvironment.Config.PrecompiledHeaderAction == PrecompiledHeaderAction.Create)
				{
					var PrecompiledFileExtension = UEBuildPlatform.GetBuildPlatform(UnrealTargetPlatform.Linux).GetBinaryExtension(UEBuildBinaryType.PrecompiledHeader);
					// Add the precompiled header file to the produced item list.
					FileItem PrecompiledHeaderFile = FileItem.GetItemByFileReference(
						FileReference.Combine(
							CompileEnvironment.Config.OutputDirectory,
							Path.GetFileName(SourceFile.AbsolutePath) + PrecompiledFileExtension
							)
						);

					CompileAction.ProducedItems.Add(PrecompiledHeaderFile);
					Result.PrecompiledHeaderFile = PrecompiledHeaderFile;

					// Add the parameters needed to compile the precompiled header file to the command-line.
					FileArguments += string.Format(" -o \"{0}\"", PrecompiledHeaderFile.AbsolutePath, false);
				}
				else
				{
					if (CompileEnvironment.Config.PrecompiledHeaderAction == PrecompiledHeaderAction.Include)
					{
						CompileAction.bIsUsingPCH = true;
						CompileAction.PrerequisiteItems.Add(CompileEnvironment.PrecompiledHeaderFile);
					}

					var ObjectFileExtension = UEBuildPlatform.GetBuildPlatform(UnrealTargetPlatform.Linux).GetBinaryExtension(UEBuildBinaryType.Object);
					// Add the object file to the produced item list.
					FileItem ObjectFile = FileItem.GetItemByFileReference(
						FileReference.Combine(
							CompileEnvironment.Config.OutputDirectory,
							Path.GetFileName(SourceFile.AbsolutePath) + ObjectFileExtension
							)
						);
					CompileAction.ProducedItems.Add(ObjectFile);
					Result.ObjectFiles.Add(ObjectFile);

					FileArguments += string.Format(" -o \"{0}\"", ObjectFile.AbsolutePath, false);
				}

				// Add the source file path to the command-line.
				FileArguments += string.Format(" \"{0}\"", SourceFile.AbsolutePath);

				CompileAction.WorkingDirectory = UnrealBuildTool.EngineSourceDirectory.FullName;
				if (!UsingClang())
				{
					CompileAction.CommandPath = GCCPath;
				}
				else
				{
					CompileAction.CommandPath = ClangPath;
				}
				CompileAction.CommandArguments = Arguments + FileArguments + CompileEnvironment.Config.AdditionalArguments;
				CompileAction.CommandDescription = "Compile";
				CompileAction.StatusDescription = Path.GetFileName(SourceFile.AbsolutePath);
				CompileAction.bIsGCCCompiler = true;

				// Don't farm out creation of pre-compiled headers as it is the critical path task.
				CompileAction.bCanExecuteRemotely =
					CompileEnvironment.Config.PrecompiledHeaderAction != PrecompiledHeaderAction.Create ||
					BuildConfiguration.bAllowRemotelyCompiledPCHs;

				CompileAction.OutputEventHandler = new DataReceivedEventHandler(CompileOutputReceivedDataEventHandler);
			}

			return Result;
		}

		/// <summary>
		/// Creates an action to archive all the .o files into single .a file
		/// </summary>
		public FileItem CreateArchiveAndIndex(LinkEnvironment LinkEnvironment)
		{
			// Create an archive action
			Action ArchiveAction = new Action(ActionType.Link);
			ArchiveAction.WorkingDirectory = UnrealBuildTool.EngineSourceDirectory.FullName;
			bool bUsingSh = BuildHostPlatform.Current.Platform != UnrealTargetPlatform.Win64 && BuildHostPlatform.Current.Platform != UnrealTargetPlatform.Win32;
			if (bUsingSh)
			{
				ArchiveAction.CommandPath = "/bin/sh";
				ArchiveAction.CommandArguments = "-c '";
			}
			else
			{
				ArchiveAction.CommandPath = "cmd.exe";
				ArchiveAction.CommandArguments = "/c \"";
			}

			// this will produce a final library
			ArchiveAction.bProducesImportLibrary = true;

			// Add the output file as a production of the link action.
			FileItem OutputFile = FileItem.GetItemByFileReference(LinkEnvironment.Config.OutputFilePath);
			ArchiveAction.ProducedItems.Add(OutputFile);
			ArchiveAction.CommandDescription = "Archive";
			ArchiveAction.StatusDescription = Path.GetFileName(OutputFile.AbsolutePath);
			ArchiveAction.CommandArguments += string.Format("\"{0}\" {1} \"{2}\"", GetArPath(LinkEnvironment.Config.Target.Architecture), GetArchiveArguments(LinkEnvironment), OutputFile.AbsolutePath);

			// Add the input files to a response file, and pass the response file on the command-line.
			List<string> InputFileNames = new List<string>();
			foreach (FileItem InputFile in LinkEnvironment.InputFiles)
			{
				string InputAbsolutePath = InputFile.AbsolutePath.Replace("\\", "/");
				InputFileNames.Add(string.Format("\"{0}\"", InputAbsolutePath));
				ArchiveAction.PrerequisiteItems.Add(InputFile);
				ArchiveAction.CommandArguments += string.Format(" \"{0}\"", InputAbsolutePath);
			}

			// add ranlib
			ArchiveAction.CommandArguments += string.Format(" && \"{0}\" \"{1}\"", GetRanlibPath(LinkEnvironment.Config.Target.Architecture), OutputFile.AbsolutePath);

			// Add the additional arguments specified by the environment.
			ArchiveAction.CommandArguments += LinkEnvironment.Config.AdditionalArguments;
			ArchiveAction.CommandArguments.Replace("\\", "/");

			if (bUsingSh)
			{
				ArchiveAction.CommandArguments += "'";
			}
			else
			{
				ArchiveAction.CommandArguments += "\"";
			}

			// Only execute linking on the local PC.
			ArchiveAction.bCanExecuteRemotely = false;

			return OutputFile;
		}

		public FileItem FixDependencies(LinkEnvironment LinkEnvironment, FileItem Executable)
		{
			if (!LinkEnvironment.Config.bIsCrossReferenced)
			{
				return null;
			}

			Log.TraceVerbose("Adding postlink step");

			bool bUseCmdExe = BuildHostPlatform.Current.Platform == UnrealTargetPlatform.Win64 || BuildHostPlatform.Current.Platform == UnrealTargetPlatform.Win32;
			string ShellBinary = bUseCmdExe ? "cmd.exe" : "/bin/sh";
			string ExecuteSwitch = bUseCmdExe ? " /C" : ""; // avoid -c so scripts don't need +x
			string ScriptName = bUseCmdExe ? "FixDependencies.bat" : "FixDependencies.sh";

			FileItem FixDepsScript = FileItem.GetItemByFileReference(FileReference.Combine(LinkEnvironment.Config.LocalShadowDirectory, ScriptName));

			Action PostLinkAction = new Action(ActionType.Link);
			PostLinkAction.WorkingDirectory = UnrealBuildTool.EngineSourceDirectory.FullName;
			PostLinkAction.CommandPath = ShellBinary;
			PostLinkAction.StatusDescription = string.Format("{0}", Path.GetFileName(Executable.AbsolutePath));
			PostLinkAction.CommandDescription = "FixDeps";
			PostLinkAction.bCanExecuteRemotely = false;
			PostLinkAction.CommandArguments = ExecuteSwitch;

			PostLinkAction.CommandArguments += bUseCmdExe ? " \"" : " -c '";

			FileItem OutputFile = FileItem.GetItemByFileReference(FileReference.Combine(LinkEnvironment.Config.LocalShadowDirectory, Path.GetFileNameWithoutExtension(Executable.AbsolutePath) + ".link"));

			// Make sure we don't run this script until the all executables and shared libraries
			// have been built.
			PostLinkAction.PrerequisiteItems.Add(Executable);
			foreach (FileItem Dependency in BundleDependencies)
			{
				PostLinkAction.PrerequisiteItems.Add(Dependency);
			}

			PostLinkAction.CommandArguments += ShellBinary + ExecuteSwitch + " \"" + FixDepsScript.AbsolutePath + "\" && ";

			string Touch = bUseCmdExe ? "echo \"\" >> \"{0}\" && copy /b \"{0}\" +,," : "touch \"{0}\"";

			PostLinkAction.CommandArguments += String.Format(Touch, OutputFile.AbsolutePath);
			PostLinkAction.CommandArguments += bUseCmdExe ? "\"" : "'";

			System.Console.WriteLine("{0} {1}", PostLinkAction.CommandPath, PostLinkAction.CommandArguments);

			PostLinkAction.ProducedItems.Add(OutputFile);
			return OutputFile;
		}


		public override FileItem LinkFiles(LinkEnvironment LinkEnvironment, bool bBuildImportLibraryOnly)
		{
			Debug.Assert(!bBuildImportLibraryOnly);

			List<string> RPaths = new List<string>();

			if (LinkEnvironment.Config.bIsBuildingLibrary || bBuildImportLibraryOnly)
			{
				return CreateArchiveAndIndex(LinkEnvironment);
			}

			// Create an action that invokes the linker.
			Action LinkAction = new Action(ActionType.Link);
			LinkAction.WorkingDirectory = UnrealBuildTool.EngineSourceDirectory.FullName;
			if (String.IsNullOrEmpty(ClangPath))
			{
				LinkAction.CommandPath = GCCPath;
			}
			else
			{
				LinkAction.CommandPath = ClangPath;
			}

			// Get link arguments.
			LinkAction.CommandArguments = GetLinkArguments(LinkEnvironment);

			// Tell the action that we're building an import library here and it should conditionally be
			// ignored as a prerequisite for other actions
			LinkAction.bProducesImportLibrary = LinkEnvironment.Config.bIsBuildingDLL;

			// Add the output file as a production of the link action.
			FileItem OutputFile = FileItem.GetItemByFileReference(LinkEnvironment.Config.OutputFilePath);
			LinkAction.ProducedItems.Add(OutputFile);
			LinkAction.CommandDescription = "Link";
			LinkAction.StatusDescription = Path.GetFileName(OutputFile.AbsolutePath);

			// Add the output file to the command-line.
			LinkAction.CommandArguments += string.Format(" -o \"{0}\"", OutputFile.AbsolutePath);

			// Add the input files to a response file, and pass the response file on the command-line.
			List<string> InputFileNames = new List<string>();
			foreach (FileItem InputFile in LinkEnvironment.InputFiles)
			{
				InputFileNames.Add(string.Format("\"{0}\"", InputFile.AbsolutePath.Replace("\\", "/")));
				LinkAction.PrerequisiteItems.Add(InputFile);
			}

			FileReference ResponseFileName = GetResponseFileName(LinkEnvironment, OutputFile);
			LinkAction.CommandArguments += string.Format(" -Wl,@\"{0}\"", ResponseFile.Create(ResponseFileName, InputFileNames));

			if (LinkEnvironment.Config.bIsBuildingDLL)
			{
				LinkAction.CommandArguments += string.Format(" -Wl,-soname={0}", OutputFile);
			}

			// Start with the configured LibraryPaths and also add paths to any libraries that
			// we depend on (libraries that we've build ourselves).
			List<string> AllLibraryPaths = LinkEnvironment.Config.LibraryPaths;
			foreach (string AdditionalLibrary in LinkEnvironment.Config.AdditionalLibraries)
			{
				string PathToLib = Path.GetDirectoryName(AdditionalLibrary);
				if (!String.IsNullOrEmpty(PathToLib))
				{
					// make path absolute, because FixDependencies script may be executed in a different directory
					string AbsolutePathToLib = Path.GetFullPath(PathToLib);
					if (!AllLibraryPaths.Contains(AbsolutePathToLib))
					{
						AllLibraryPaths.Add(AbsolutePathToLib);
					}
				}

				if ((AdditionalLibrary.Contains("Plugins") || AdditionalLibrary.Contains("Binaries/ThirdParty") || AdditionalLibrary.Contains("Binaries\\ThirdParty")) && Path.GetDirectoryName(AdditionalLibrary) != Path.GetDirectoryName(OutputFile.AbsolutePath))
				{
					string RelativePath = Utils.MakePathRelativeTo(Path.GetDirectoryName(AdditionalLibrary), Path.GetDirectoryName(OutputFile.AbsolutePath));
					if (!RPaths.Contains(RelativePath))
					{
						RPaths.Add(RelativePath);
						LinkAction.CommandArguments += string.Format(" -Wl,-rpath=\"${{ORIGIN}}/{0}\"", RelativePath);
					}
				}
			}

			LinkAction.CommandArguments += string.Format(" -Wl,-rpath-link=\"{0}\"", Path.GetDirectoryName(OutputFile.AbsolutePath));

			// Add the library paths to the argument list.
			foreach (string LibraryPath in AllLibraryPaths)
			{
				// use absolute paths because of FixDependencies script again
				LinkAction.CommandArguments += string.Format(" -L\"{0}\"", Path.GetFullPath(LibraryPath));
			}

			// add libraries in a library group
			LinkAction.CommandArguments += string.Format(" -Wl,--start-group");

			List<string> EngineAndGameLibraries = new List<string>();
			foreach (string AdditionalLibrary in LinkEnvironment.Config.AdditionalLibraries)
			{
				if (String.IsNullOrEmpty(Path.GetDirectoryName(AdditionalLibrary)))
				{
					// library was passed just like "jemalloc", turn it into -ljemalloc
					LinkAction.CommandArguments += string.Format(" -l{0}", AdditionalLibrary);
				}
				else if (Path.GetExtension(AdditionalLibrary) == ".a")
				{
					// static library passed in, pass it along but make path absolute, because FixDependencies script may be executed in a different directory
					string AbsoluteAdditionalLibrary = Path.GetFullPath(AdditionalLibrary);
					if (AbsoluteAdditionalLibrary.Contains(" "))
					{
						AbsoluteAdditionalLibrary = string.Format("\"{0}\"", AbsoluteAdditionalLibrary);
					}
					LinkAction.CommandArguments += (" " + AbsoluteAdditionalLibrary);
					LinkAction.PrerequisiteItems.Add(FileItem.GetItemByPath(AdditionalLibrary));
				}
				else
				{
					// Skip over full-pathed library dependencies when building DLLs to avoid circular
					// dependencies.
					FileItem LibraryDependency = FileItem.GetItemByPath(AdditionalLibrary);

					var LibName = Path.GetFileNameWithoutExtension(AdditionalLibrary);
					if (LibName.StartsWith("lib"))
					{
						// Remove lib prefix
						LibName = LibName.Remove(0, 3);
					}
					string LibLinkFlag = string.Format(" -l{0}", LibName);

					if (LinkEnvironment.Config.bIsBuildingDLL && LinkEnvironment.Config.bIsCrossReferenced)
					{
						// We are building a cross referenced DLL so we can't actually include
						// dependencies at this point. Instead we add it to the list of
						// libraries to be used in the FixDependencies step.
						EngineAndGameLibraries.Add(LibLinkFlag);
						if (!LinkAction.CommandArguments.Contains("--allow-shlib-undefined"))
						{
							LinkAction.CommandArguments += string.Format(" -Wl,--allow-shlib-undefined");
						}
					}
					else
					{
						LinkAction.PrerequisiteItems.Add(LibraryDependency);
						LinkAction.CommandArguments += LibLinkFlag;
					}
				}
			}
			LinkAction.CommandArguments += " -lrt"; // needed for clock_gettime()
			LinkAction.CommandArguments += " -lm"; // math
			LinkAction.CommandArguments += string.Format(" -Wl,--end-group");

			// Add the additional arguments specified by the environment.
			LinkAction.CommandArguments += LinkEnvironment.Config.AdditionalArguments;
			LinkAction.CommandArguments = LinkAction.CommandArguments.Replace("\\\\", "/");
			LinkAction.CommandArguments = LinkAction.CommandArguments.Replace("\\", "/");

			// prepare a linker script
			FileReference LinkerScriptPath = FileReference.Combine(LinkEnvironment.Config.LocalShadowDirectory, "remove-sym.ldscript");
			if (!LinkEnvironment.Config.LocalShadowDirectory.Exists())
			{
				LinkEnvironment.Config.LocalShadowDirectory.CreateDirectory();
			}
			if (LinkerScriptPath.Exists())
			{
				LinkerScriptPath.Delete();
			}

			using (StreamWriter Writer = File.CreateText(LinkerScriptPath.FullName))
			{
				Writer.WriteLine("UE4 {");
				Writer.WriteLine("  global: *;");
				Writer.WriteLine("  local: _Znwm;");
				Writer.WriteLine("         _ZnwmRKSt9nothrow_t;");
				Writer.WriteLine("         _Znam;");
				Writer.WriteLine("         _ZnamRKSt9nothrow_t;");
				Writer.WriteLine("         _ZdaPv;");
				Writer.WriteLine("         _ZdaPvRKSt9nothrow_t;");
				Writer.WriteLine("         _ZdlPv;");
				Writer.WriteLine("         _ZdlPvRKSt9nothrow_t;");
				Writer.WriteLine("};");
			};

			LinkAction.CommandArguments += string.Format(" -Wl,--version-script=\"{0}\"", LinkerScriptPath);

			// Only execute linking on the local PC.
			LinkAction.bCanExecuteRemotely = false;

			// Prepare a script that will run later, once all shared libraries and the executable
			// are created. This script will be called by action created in FixDependencies()
			if (LinkEnvironment.Config.bIsCrossReferenced && LinkEnvironment.Config.bIsBuildingDLL)
			{
				bool bUseCmdExe = BuildHostPlatform.Current.Platform == UnrealTargetPlatform.Win64 || BuildHostPlatform.Current.Platform == UnrealTargetPlatform.Win32;
				string ScriptName = bUseCmdExe ? "FixDependencies.bat" : "FixDependencies.sh";

				string FixDepsScriptPath = Path.Combine(LinkEnvironment.Config.LocalShadowDirectory.FullName, ScriptName);
				if (!bHasWipedFixDepsScript)
				{
					bHasWipedFixDepsScript = true;
					Log.TraceVerbose("Creating script: {0}", FixDepsScriptPath);
					StreamWriter Writer = File.CreateText(FixDepsScriptPath);

					if (bUseCmdExe)
					{
						Writer.Write("@echo off\n");
						Writer.Write("rem Automatically generated by UnrealBuildTool\n");
						Writer.Write("rem *DO NOT EDIT*\n\n");
					}
					else
					{
						Writer.Write("#!/bin/sh\n");
						Writer.Write("# Automatically generated by UnrealBuildTool\n");
						Writer.Write("# *DO NOT EDIT*\n\n");
						Writer.Write("set -o errexit\n");
					}
					Writer.Close();
				}

				StreamWriter FixDepsScript = File.AppendText(FixDepsScriptPath);

				string EngineAndGameLibrariesString = "";
				foreach (string Library in EngineAndGameLibraries)
				{
					EngineAndGameLibrariesString += Library;
				}

				FixDepsScript.Write(string.Format("echo Fixing {0}\n", Path.GetFileName(OutputFile.AbsolutePath)));
				if (!bUseCmdExe)
				{
					FixDepsScript.Write(string.Format("TIMESTAMP=`stat --format %y \"{0}\"`\n", OutputFile.AbsolutePath));
				}
				string FixDepsLine = LinkAction.CommandPath + " " + LinkAction.CommandArguments;
				string Replace = "-Wl,--allow-shlib-undefined";

				FixDepsLine = FixDepsLine.Replace(Replace, EngineAndGameLibrariesString);
				string OutputFileForwardSlashes = OutputFile.AbsolutePath.Replace("\\", "/");
				FixDepsLine = FixDepsLine.Replace(OutputFileForwardSlashes, OutputFileForwardSlashes + ".fixed");
				FixDepsLine = FixDepsLine.Replace("$", "\\$");
				FixDepsScript.Write(FixDepsLine + "\n");
				if (bUseCmdExe)
				{
					FixDepsScript.Write(string.Format("move /Y \"{0}.fixed\" \"{0}\"\n", OutputFile.AbsolutePath));
				}
				else
				{
					FixDepsScript.Write(string.Format("mv \"{0}.fixed\" \"{0}\"\n", OutputFile.AbsolutePath));
					FixDepsScript.Write(string.Format("touch -d \"$TIMESTAMP\" \"{0}\"\n\n", OutputFile.AbsolutePath));
				}
				FixDepsScript.Close();
			}

			//LinkAction.CommandArguments += " -v";

			return OutputFile;
		}

		public override void CompileCSharpProject(CSharpEnvironment CompileEnvironment, FileReference ProjectFileName, FileReference DestinationFile)
		{
			throw new BuildException("Linux cannot compile C# files");
		}

		public override void SetupBundleDependencies(List<UEBuildBinary> Binaries, string GameName)
		{
			foreach (UEBuildBinary Binary in Binaries)
			{
				BundleDependencies.Add(FileItem.GetItemByFileReference(Binary.Config.OutputFilePath));
			}
		}

		/// <summary>
		/// Converts the passed in path from UBT host to compiler native format.
		/// </summary>
		public override string ConvertPath(string OriginalPath)
		{
			if (BuildHostPlatform.Current.Platform == UnrealTargetPlatform.Linux)
			{
				return OriginalPath.Replace("\\", "/");
			}
			else
			{
				return OriginalPath;
			}
		}

		public override ICollection<FileItem> PostBuild(FileItem Executable, LinkEnvironment BinaryLinkEnvironment)
		{
			var OutputFiles = base.PostBuild(Executable, BinaryLinkEnvironment);

			if (BinaryLinkEnvironment.Config.bIsBuildingDLL || BinaryLinkEnvironment.Config.bIsBuildingLibrary)
			{
				return OutputFiles;
			}

			FileItem FixDepsOutputFile = FixDependencies(BinaryLinkEnvironment, Executable);
			if (FixDepsOutputFile != null)
			{
				OutputFiles.Add(FixDepsOutputFile);
			}

			return OutputFiles;
		}

		public override void StripSymbols(string SourceFileName, string TargetFileName)
		{
			File.Copy(SourceFileName, TargetFileName, true);

			ProcessStartInfo StartInfo = new ProcessStartInfo();
			StartInfo.FileName = GetStripPath(PlatformContext.GetActiveArchitecture());
			StartInfo.Arguments = "--strip-debug \"" + TargetFileName + "\"";
			StartInfo.UseShellExecute = false;
			StartInfo.CreateNoWindow = true;
			Utils.RunLocalProcessAndLogOutput(StartInfo);
		}
	}
}