cppcheck considers .h header files to be C style if qt_add_qml_module is used in CMake project

When using CMake and the experimental cppcheck plugin, if the CMake project file uses qt_add_qml_module, .h header files are considered C style.

.../testobject.h
.../testobject.h:6: Code 'classTestObject:' is invalid C code. Use --std or --language to configure the language.

Doing the suggested --std or --language flags do not change anything. Following warning is shown in the Qt Creator, but selecting the suggested parser output for C++ does not help either. See attached image.

Note: Multiple parse contexts are available for this file. Choose the preferred one from the editor toolbar.

This can be reproduced with the for example the "adding" Qt example (<examples>\qml\referenceexamples\adding). In that project the culprit lines in CMakeLists. are:

qt_add_qml_module(adding
    URI People
    VERSION 1.0
    QML_FILES example.qml
    NO_RESOURCE_TARGET_PATH
)