Migrating to UE5 => errors in msvc\filesystem

Development Programming & Scripting C++
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1

Hello,

I’m trying to compile my 4.27 project to UE5 and i get a ton of errors on msvc’s filesystem.
A few example:

2>C:\Program Files\Microsoft Visual Studio\2022\Community\VC\Tools\MSVC\14.32.31326\INCLUDE\filesystem(893): error C4003: not enough arguments for function-like macro invocation 'concat'
2>C:\Program Files\Microsoft Visual Studio\2022\Community\VC\Tools\MSVC\14.32.31326\INCLUDE\filesystem(893): error C4227: anachronism used: qualifiers on reference are ignored
2>C:\Program Files\Microsoft Visual Studio\2022\Community\VC\Tools\MSVC\14.32.31326\INCLUDE\filesystem(893): error C2988: unrecognizable template declaration/definition
2>C:\Program Files\Microsoft Visual Studio\2022\Community\VC\Tools\MSVC\14.32.31326\INCLUDE\filesystem(893): error C2143: syntax error: missing ';' before '&'
2>C:\Program Files\Microsoft Visual Studio\2022\Community\VC\Tools\MSVC\14.32.31326\INCLUDE\filesystem(893): error C2365: '_Src': redefinition; previous definition was 'template parameter'
2>C:\Program Files\Microsoft Visual Studio\2022\Community\VC\Tools\MSVC\14.32.31326\INCLUDE\filesystem(892): note: see declaration of '_Src'
2>C:\Program Files\Microsoft Visual Studio\2022\Community\VC\Tools\MSVC\14.32.31326\INCLUDE\filesystem(893): error C2238: unexpected token(s) preceding ';'
2>C:\Program Files\Microsoft Visual Studio\2022\Community\VC\Tools\MSVC\14.32.31326\INCLUDE\filesystem(893): error C2059: syntax error: '&'
2>C:\Program Files\Microsoft Visual Studio\2022\Community\VC\Tools\MSVC\14.32.31326\INCLUDE\filesystem(893): error C2334: unexpected token(s) preceding '{'; skipping apparent function body
2>C:\Program Files\Microsoft Visual Studio\2022\Community\VC\Tools\MSVC\14.32.31326\INCLUDE\filesystem(898): error C2365: '_InIt': redefinition; previous definition was 'template parameter'

I tried various versions of MSVC, i even upgraded from VS2019 to VS2022 to be sure to get the latest everything, but i still get the same list of errors.

I guess my project configuration must be wrong somewhere but i couldn’t find anything related to this on google.

Any idea ?

Thanks
Cedric

2

Did you try a rebuild instead of just build?

3

I did, cleaning, deleting the projects folders (binaries, intermediate, etc), rebuilding, many times, with no visible effect.

4

When looking at this page:

It seems that C4003 is supposed to be a warning but i get an error instead.

So i guess that somewhere in my configuration is something that tells VS to treat warnings as errors.

To be continued…

5

Is there any official windows 10 sdk version to use with UE5 ?
I have tried 18362, 19041 (default), and 20348 with no success.

6

I tried to force versions of C++ (/c++17, /c++20, and nothing to let VS use its default version), but no luck.

7

Ok, problem solved.
_HAS_CXX17 wasn’t defined in my project and because of that, some necessary inclusions in the filesystem file weren’t made, leading to all those errors.
So i just had to define it in my build.cs and it compiled fine.

PublicDefinitions.Add("_HAS_CXX17=0");

Cedric

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