macro_rules! function_name {
    () => { ... };
}Expand description
This macro returns the name of the enclosing function.
As the internal implementation is based on the std::any::type_name, this macro derives
all the limitations of this function.
§Examples
mod bar {
    pub fn sample_function() {
        assert!(glib::function_name!().ends_with("bar::sample_function"));
    }
}
bar::sample_function();