unknown type name 'uintptr_t' when using clang

Pete Carter

My sys info:

Operating System: Fedora Linux 38
KDE Plasma Version: 5.27.7
KDE Frameworks Version: 5.109.0
Qt Version: 5.15.10
Kernel Version: 6.4.12-200.fc38.x86_64 (64-bit)
Graphics Platform: Wayland

I have been trying to use Clang instead of GCC. When i enable Clang, i get this error:

The error in text:

main.cpp:3:10: In included file: unknown type name 'uintptr_t'; did you mean 'intptr_t'?
shared_ptr_atomic.h:506:24: error occurred here
unistd.h:267:20: 'intptr_t' declared here

This is my clang config:

Any idea how to solve this error ?

This error does not happen when using GCC.
I installed LLVM and clang.

Pete Carter

I used the system version of clangd installed in /usr/bin/clangd instead of the version shipped with QtCreator. Now it works fine and no errors.

The path of the system clangd version can be changed in
Edit -> Preferences -> C++ -> clangd

jsulm

@Pete-Carter Does the application build? The code model in QtCreator can produce false errors.

Pete Carter

@jsulm Yes the app builds successfully. I think the language server has a problem. Any idea how to resolve this error ?

jsulm

@Pete-Carter I don't know how to properly solve this. I think you can disable the CLang plug-in to get rid of such errors. But of course you will not have CLang warning/errors in QtCreator then which can be helpful.

cristian-adam

Please do create a bugreport at https://bugreports.qt.io/

Qt Creator uses clangd for the C++ code model, which means that clang will be doing some "compilation" of the source code.

In order to get this clang to work with gcc Qt Creator will use some of its own includes found at qtcreator/bin/clang/lib/clang/16/include (on Linux the path could be different).

At https://wiki.qt.io/Qt_Creator_Clang_Code_Model there is some information about how to tweak the code model a bit.

Under Tools > Debug Qt Creator > Inspect C/C++ Code Model you could have a look at how the "Header Paths" are taken into consideration by the C++ code model.

Qt Creator should be able to work fine with clang too.

Pete Carter

@cristian-adam

C++ Code Model Inspector:

Created a bug here

Pete Carter

I discovered that this problem happens only when using C++20.

By default the new projects are using C++17:

hello_world.pro:

TEMPLATE = app
CONFIG += console c++17
CONFIG -= app_bundle
CONFIG -= qt

SOURCES += \
        main.cpp

When changing
CONFIG += console c++17
to
CONFIG += console c++20

The error messages appears in main.cpp. The code compiled fine tho.

Clang version: 16.0.6 (Fedora 16.0.6-2.fc38)

Pete Carter

I used the system version of clangd installed in /usr/bin/clangd instead of the version shipped with QtCreator. Now it works fine and no errors.

The path of the system clangd version can be changed in
Edit -> Preferences -> C++ -> clangd