How to Resolve Warning Messages When Adding Header Files in Qt 6.8.1

 

 

Hello,

 

 I'd like to share how to resolve the persistent warning messages that appear when adding header files while using Qt 6.8.1.

 

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1. Warning Message

 

Even when creating a basic Qt widget project, the following warning message appeared (with QMake configuration):

 

D:\project\02_qt\01_error_test01\widget.cpp:2:
warning: Included header ui_widget.h is not used directly (fix available)

 

 

 

 I thought it was a QMake characteristic, so I created the same project with CMake. Unlike the project created with QMake, the CMake project did not show warnings for the ui_widget.h file in the widget.cpp file.

 

 

 

 So, I thought it was a QMake issue. However, when I created and added a person class, the warning reappeared. Ultimately, it wasn't a QMake or CMake issue.

 

 The program runs without problems despite the warning message.

 

 

 

2. Solution (?)

 

 I searched the internet for ways to eliminate the warning message and tested them. I tried several methods, such as implementing the code directly in the header file or actually using the code, but none of them worked.

 

 Even after creating a person class in person.h and adding extern, code implementation, and function calls to the code, the warning message persisted in the person.h file.

 

 

 

 As a workaround, I found a way to disable the Clangd feature. Simply uncheck "Use clangd" in the "Edit > Preference > C++ > Clangd" menu.

 

 

 

 However, I realized that disabling Clangd also disables other warning messages. So, I looked for a way to suppress only the header file warning messages.

 

 Click the configuration link (here) at the bottom of "Edit > Preference > C++ > Clangd" (keep "Use clangd" checked).

 

 

 The config.yaml file appears in the editor, and it's configured as follows: Change "UnusedIncludes: Strict" to "None" and save.

 

 

 

 Now, you can see that the initial warning message for person.h has disappeared from the widget.cpp file.

 

 

 

 Clangd provides various alerts for optimization, but I haven't found the exact reason for this message yet.

 

 If anyone knows the correct solution other than the above method, please leave a comment.

 

 

Thank you.

 

 

<Reference Sites>

1. Qt Creator :: Included [file] is not used (fix available)

https://www.ovenproof-linux.com/2022/07/qt-creator-included-file-is-not-used.html

2. [clangd][include-cleaner] False warning: Included header X is not used directly

https://github.com/llvm/llvm-project/issues/75777

3. clangd Configuration

https://clangd.llvm.org/config