bindgen incorrectly generates `*mut` instead of `*const` from C++ header, when the parameter type is from another namespace

Input C/C++ Header

namespace root {

namespace ns1 {
struct A{};
}

namespace ns2 {
using ns1::A;
// using A = ns1::A; swtich to this line generates the correct result
struct B{
        void f(const A& a);
};
}


}

Bindgen Invocation

bindgen gen.h -- -xc++

Actual Results

/* automatically generated by rust-bindgen 0.71.1 */

#[repr(C)]
#[derive(Debug, Copy, Clone)]
pub struct root_ns1_A {
    pub _address: u8,
}
#[allow(clippy::unnecessary_operation, clippy::identity_op)]
const _: () = {
    ["Size of root_ns1_A"][::std::mem::size_of::<root_ns1_A>() - 1usize];
    ["Alignment of root_ns1_A"][::std::mem::align_of::<root_ns1_A>() - 1usize];
};
#[repr(C)]
#[derive(Debug, Copy, Clone)]
pub struct root_ns2_B {
    pub _address: u8,
}
#[allow(clippy::unnecessary_operation, clippy::identity_op)]
const _: () = {
    ["Size of root_ns2_B"][::std::mem::size_of::<root_ns2_B>() - 1usize];
    ["Alignment of root_ns2_B"][::std::mem::align_of::<root_ns2_B>() - 1usize];
};
unsafe extern "C" {
    #[link_name = "\u{1}_ZN4root3ns21B1fERKNS_3ns11AE"]
    pub fn root_ns2_B_f(this: *mut root_ns2_B, a: *mut root_ns1_A);
}
impl root_ns2_B {
    #[inline]
    pub unsafe fn f(&mut self, a: *mut root_ns1_A) {
        root_ns2_B_f(self, a)
    }
}

Expected Results

should be

unsafe extern "C" {
    #[link_name = "\u{1}_ZN4root3ns21B1fERKNS_3ns11AE"]
    pub fn root_ns2_B_f(this: *mut root_ns2_B, a: *const root_ns2_A);
}

instead of

unsafe extern "C" {
    #[link_name = "\u{1}_ZN4root3ns21B1fERKNS_3ns11AE"]
    pub fn root_ns2_B_f(this: *mut root_ns2_B, a: *mut root_ns1_A);
}

note that if i replace using ns1::A with using A = ns1::A, it will produce correct result

Reproduce the issue with gen.h and the bindgen gen.h -- -xc++ invocation, comparing the generated function signature for using ns1::A with the expected const pointer. Done means the using-declaration case emits the correct const pointer while the using-alias case remains correct.