Cppcheck reports missingIncludeSystem on Qt headers

[therisktaker]

Hi,
I created basic QtWidgets project on Qt 5.15.2. File structure:

.
├── CMakeLists.txt
├── main.cpp
├── mainwindow.cpp
├── mainwindow.h
└── mainwindow.ui

In CMakeLists.txt I added Cppcheck run target (see below for used options):

add_custom_target(cppcheck-check COMMAND ${CPPCHECK}
    --check-level=exhaustive
    --cppcheck-build-dir=${CMAKE_BINARY_DIR}
    --enable=all
    --error-exitcode=1
    --inline-suppr
    --language=c++
    --platform=native
    --project=${CMAKE_BINARY_DIR}/compile_commands.json
    --library=qt
    -i ${CMAKE_BINARY_DIR}
    -j ${N_PROC}
    WORKING_DIRECTORY ${CMAKE_SOURCE_DIR}
    USES_TERMINAL
)

and provided there for example --libarary=qt option. But Cppcheck still reports missingIncludeSystem issues on Qt headers like:

Checking /home/user/sandbox/CppcheckTest/main.cpp ...
/home/user/sandbox/CppcheckTest/mainwindow.h:4:0: information: Include file: <QMainWindow> not found. Please note: Cppcheck does not need standard library headers to get proper results. [missingIncludeSystem]
#include <QMainWindow>
^
/home/user/sandbox/CppcheckTest/main.cpp:2:0: information: Include file: <QApplication> not found. Please note: Cppcheck does not need standard library headers to get proper results. [missingIncludeSystem]
#include <QApplication>

...

Question is: how can I suppress these warnings without using --suppress=missingIncludeSystem? What am I missing?

Project files in attachments. To setup, build and run analysis (assuming you install Qt from Qt Online Installer and using Ninja) run from project root in terminal below commands, change user to yours or provide own path:

cmake -S . -B build -G Ninja  -DCMAKE_PREFIX_PATH=/home/<user>/Qt/5.15.2/gcc_64
ninja -C build
ninja -C build cppcheck-check

Tested on Ubuntu 22.04, Qt 5.15.2 and Cppcheck 2.12.1.

[CHR]

This is by design. Any missing header included by <...> is reported as missingIncludeSystem.

[Daniel Marjamäki]

It is by design.. but well I can understand that it is confusing.

We recommend that you use the --library=qt option when checking qt code. However this does not prevent missingIncludeSystem warnings.

Please ignore the missingIncludeSystem warnings about qt.