What's needed for using C++17

[anonymous_user_3f526e57]

@[YAF

Lightbringer;n1812444]If you modify the UnrealBuildTool, you can also use the PCH. I ran into the same issue with c++20 now (September 2020), and this is obviously a horrible hackish way to do it, but since I spent 3 hours R&Ding it, I might as well post it here:

• Open the VS project UE_4.25\Engine\Source\Programs\UnrealBuildTool\UnrealBuildTool.csproj
• Depending on which .NET SDK is intalled on your machine, you might need to change the target framework
• Find the file Platform\Windows\VCToolChain.cs in that solution
• Go to the end of the method AppendCLArguments_Global (it’s around line 537 at the time of writing)
• Add

Arguments.Add("/std:c++latest");

there, or whatever c++ standard you want the compiler to use

• build the solution. It should build to UE_4.25\Engine\Binaries\DotNET\UnrealBuildTool.exe

Now build your game project with the build settings set to:

PCHUsage = PCHUsageMode.UseExplicitOrSharedPCHs;
CppStandard = CppStandardVersion.Latest;

Thanks a lot. I just build the project and encountered lots warning and error in UE headers. But after applying these I still get some erros.

1>E:\Program Files\Epic Games\UE_4.26\Engine\Source\Runtime\Engine\Classes\Engine/NetSerialization.h(1980): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
1>E:\Program Files\Epic Games\UE_4.26\Engine\Source\Runtime\Engine\Classes\Engine/NetSerialization.h(2026): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
1>E:\Program Files\Epic Games\UE_4.26\Engine\Source\Runtime\Engine\Classes\Engine/NetSerialization.h(2072): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
1>E:\Program Files\Epic Games\UE_4.26\Engine\Source\Runtime\Engine\Classes\Engine/NetSerialization.h(2116): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
1> [3/6] HostGameModeBase.cpp
1>C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.28.29910\INCLUDE\sal.h(2361): error C2144: syntax error: ‘int’ should be preceded by ‘;’
1>C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.28.29910\INCLUDE\sal.h(2361): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
1>E:\Program Files\Epic Games\UE_4.26\Engine\Source\Runtime\Core\Public\GenericPlatform/GenericPlatform.h(9): error C2143: syntax error: missing ‘;’ before ‘<L_GRAMMAR_template_head_l>’
1>E:\Program Files\Epic Games\UE_4.26\Engine\Source\Runtime\Core\Public\GenericPlatform/GenericPlatform.h(10): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
1>E:\Program Files\Epic Games\UE_4.26\Engine\Source\Runtime\Engine\Classes\Engine/NetSerialization.h(1980): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
1>E:\Program Files\Epic Games\UE_4.26\Engine\Source\Runtime\Engine\Classes\Engine/NetSerialization.h(2026): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
1>E:\Program Files\Epic Games\UE_4.26\Engine\Source\Runtime\Engine\Classes\Engine/NetSerialization.h(2072): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
1>E:\Program Files\Epic Games\UE_4.26\Engine\Source\Runtime\Engine\Classes\Engine/NetSerialization.h(2116): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
1> [4/6] HostGameModeBase.gen.cpp
1>E:\Program Files\Epic Games\UE_4.26\Engine\Source\Runtime\Engine\Classes\Engine/NetSerialization.h(1980): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
1>E:\Program Files\Epic Games\UE_4.26\Engine\Source\Runtime\Engine\Classes\Engine/NetSerialization.h(2026): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
1>E:\Program Files\Epic Games\UE_4.26\Engine\Source\Runtime\Engine\Classes\Engine/NetSerialization.h(2072): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
1>E:\Program Files\Epic Games\UE_4.26\Engine\Source\Runtime\Engine\Classes\Engine/NetSerialization.h(2116): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
1>E:\BlurringShadow\Documents\Learning\GraduationProject\Polycumic\UnrealEngine\Intermediate\Build\Win64\UE4\Inc\Host\HostGameModeBase.gen.cpp(76): warning C5054: operator ‘&’: deprecated between enumerations of different types