Linux (Fedora), issues with "- -isystemThirdParty/Unix/LibCxx/include/c++/v1"

[chriztheanvill]

Hi!!!
Upgrading to the new plugin and UE, I got some issues with it. After some tries, I found that .clangd file, has this line, I removed and everything works fine:

- -isystemThirdParty/Unix/LibCxx/include/c++/v1

Should I edit or leave it with out this line ?

This is for Fedora Linux

[boocs]

Dang. Yeah I test mine with Ubuntu. That error could mean a lot of things though.

1. What UE version are you running?
2. Can you check if that directory exists? Should be under /UnrealEngineDir/Engine/Source
3. Is there anything in /UnrealEngineDir/Engine/Source/ThirdParty/Unix ?
4. If it doesn't exist the error might be because it doesn't exist? maybe...
5. When you remove that .clangd line, maybe Unreal includes the correct c++ lib for Fedora already?
6. Or maybe the source code you're looking at doesn't error because it's not hitting any c++ lib that will error if that c++ lib isn't included. I actually think completionHelper.cpp should error without that c++ lib but I forget. Will have to test.

In Ubuntu I'll try to find a source file that will error when that lib isn't included.

My testing will have to be tomorrow though since I'm about to head to bed.

Edit: Updated question 3

[chriztheanvill]

Yep, that path exist: /UnrealEngineDir/Engine/Source/ThirdParty/Unix/LibCxx/include/c++/v1, in my case its in: ~/Documents/My_Pkgs/Unreal_Engine/Engine/Source/ThirdParty/Unix/LibCxx/include/c++/v1.

I am trying to edit that line, but looks like no matter what I test, looks like it works:

- -Isystem/ThirdParty/Unix/LibCxx/include/c++/v1
- -I/ThirdParty/Unix/LibCxx/include/c++/v1

[boocs]

So you're saying it works when you prepend a / to the start of the path?

What version of UE are you using?

[chriztheanvill]

Yep, I tried even using wrong paths and works like: .../c++/v2

Jaja, sorry I am using 5.4.3

Also, one thing, could you remove the last pop up message to setup clang, or set by default for linux OS, the path /usr/bin/clangd

[boocs]

Cool! If it works on Ubuntu I'll prepend it with / as default.

For /usr/bin/clangd , there could be problems with that since different Unreal version need different clangd versions to be the most compatible. What clangd version does /usr/bin/clangd have if someone had multiple clangd versions installed? For example in Ubuntu/UE5.4.# I installed llvm 16.0.6 and used the llvm-16 directory for clangd. In previous Unreal versions I used llvm-15, llvm-14 and so on with their specific versions.

If you scroll down on this page for 'Compiler' you can see what version of clang/clangd is best/most compatible with the engine version.
https://dev.epicgames.com/documentation/en-us/unreal-engine/linux-development-requirements-for-unreal-engine?application_version=5.4

[boocs]

In Ubuntu, using 5.4.3, I removed the line and got errors. I added the line and prepended the path with a / and it failed.

Your error could be because you're using an older or newer version of clangd that only works with relative paths when prepended with a / or something of that sort.

1. Is it possible to check which version of clangd is in your /usr/bin/clangd? You can do so by using: clangd -version

[chriztheanvill]

clangd --version                                                                                                            ──(Sat,Aug10)─┘
clangd version 18.1.6 (Fedora 18.1.6-3.fc40)
Features: linux
Platform: x86_64-unknown-linux-gnu; target=x86_64-redhat-linux-gnu

[boocs]

I've run into problems before using different clang/clangd versions. I've also run into problems running the same clang/clangd versions but a different version then was recommended by Epic. Of course I've also had success.

That said I probably won't fix this. For best compatibility I would run clang/clangd 16.0.6 for UE 5.4.3.

I will look out for this for whenever UE5 starts supporting future clang/clangd versions. Thanks!