[Inkscape-devel] G_BEGIN_DECLS

I was studying the code structure in ' gimpcolorwheel.h ' .

I see 'G_BEGIN_DECLS' which is a miscellaneous macro : https://developer.gnome.org/glib/2.33/glib-Miscellaneous-Macros.html#G-BEGIN...

Is it used only for the files that are C based and compiled using a C++ compiler ? What is its relevance with the given file ? Thankyou for the help.