Ac6 and C++ issue

[kisvegabor]

In the new-ac6 branch I'm working on a migration guide to Ac6 toolchain. The original GCC project (in master) is already converted to C++. After selecting Ac6 and adding some basic settings it seems Ac6 tries to compile all c files as cpp and produces all sort of Cpp related errors. E.g.

../src/lvgl/src/widgets/scale/lv_scale.c:1473:26: error: cannot initialize a variable of type 'lv_point_precise_t *' with an rvalue of type 'void *'
 1473 |     lv_point_precise_t * needle_line_points = lv_event_get_user_data(e);
      |             

This is how a compile command looks like:

-fno-exceptions -O0 -g -xc++ -std=c++98 -MD -MP -c -o "src/lvgl/src/widgets/win/lv_win.o" "../src/lvgl/src/widgets/win/lv_win.c"

I believe -xc++ selects the Cpp mode, however if I'm trying to overwrite it with -xc it doesn't work as the custom flags are added before the flags above.

@jeremy-baker do you have any ideas for it?