ClangRTFM x64 must be installed in order to build this target

Development Platform & Builds
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Hello,
I try to building Unreal Engine 5.3.1 from source code.
I download release source code from github. And setup.bat , install Clang v22, GenerateProjectFiles.bat. And Build.
But error as follow:
ClangRTFM x64 must be installed in order to build this target
85>D:\Program\Microsoft Visual Studio\2022Community\MSBuild\Microsoft\VC\v170\Microsoft.MakeFile.Targets(44,5): error MSB3073: 命令“…..\Build\BatchFiles\Build.bat AutoRTFMTests Win64 Development -WaitMutex -FromMsBuild”已退出，代码为 6。

Can anyone give some advise?

By the way , I have used the same way to build UE 5.0.3 5.2.1 ,it all success ,but 5.3.1 failed.
And this time I install cross-compile clang v22 in disk D:\
Did it leads to thie error?

1 Like
2

And I found that someone say skip AutoRTFMTests build.
I wonder what is AutoRTFMTests ?
If I skip it, what function I will miss?

3

I’m wondering if the solution to skip AutoRTFMTests worked? How did you resolve this?

4

I see this error when GenerateProjectFiles.bat for 5.4.

I changed 2 places of “bUseAutoRTFMCompiler = true” to false, then I can generate the projects.

6

Where did you modify the variables in question, because I can’t find where these variables are located among the thousands of files in Unreal :confused:

Thank you.

7

UnrealEngine-5.4\UnrealEngine-5.4\Engine\Source\UnrealEditorVM.Target.cs"
go to this

1 Like
8

Thank you perfect :slight_smile:

9

In .cs files.

10

Generally, you don’t need to compile the ClangRTFM x64 project. The UE github page also says that you can compile the UE5 project (unless you know what you are doing).

If you want to solve this error, install MSBuild support for LLVM (clang-cl) toolset in the Visual Studio Installer. If you don’t have the clang compiler, install C++ Clang Compiler for Windows (18.1.8) separately.
Their load ids:

MSBuild support for LLVM (clang-cl) toolset
Microsoft.VisualStudio.Component.VC.Llvm.Clang

This should solve the error.