[BareMetal] Disappeared highlighting of a compiler defines in a header files

I use QtC with QBS project manager for the bare-metal projects, using new added KEIL, IAR or SDCC toolchains (also a GCC toolchains).

When I create a Kit which contains only one C-compiler (or KEIL, or IAR, or SDCC, or GCC), then the highlighting of a compiler defines does not work for a header files if this files located in a group without of a sources.

= Example 1 = (this project also is attached):

CppApplication {
    name: "bug"
    Group { files: [ "foo.h"] } /// << HERE HIGHLIGHTING BROKEN !!!
    Group { files: ["main.c", "bar.h"] }
}

in this example the highlighting of the compiler defines does not work for a file 'foo.h', but for files 'main.c' and 'bar.h' it does work.

= Example 2 =

CppApplication {
    name: "bug"
    Group { files: ["main.c", "bar.h", "foo.h"] } /// << HERE ALL FINE FOR ALL FILES !!!
}

in this case all does work.

= Example 3 =

CppApplication {
    name: "bug"
    Group { files: [ "foo.h", "bar.h"] } /// << HERE HIGHLIGHTING BROKEN !!!
    Group { files: ["main.c"] }
}

in this case the highlighting does not work for files 'foo.h' and 'bar.h'...

So, as you can see, that if a group contains only a header files, then the highlighting does not work.

But, if to add to the Kit and the C++ compiler, then all becomes working.

This issue reproduces as with a new 'bare-metal' toolchains (KEIL, IAR, SDCC), but also and with GCC.