Sample application (-O3) using namespaces from https://github.com/xemdetia/c-namespace-example/tree/5c8279da16b28221180015a591e56652ffa2fed7

test-O3.S

        .file   "test.c"
        .text
        .p2align 4,,15
.globl my_test
        .type   my_test, @function
my_test:
.LFB11:
        .cfi_startproc
        subq    $8, %rsp
        .cfi_def_cfa_offset 16
        call    func1
        call    func1
        addq    $8, %rsp
        ret
        .cfi_endproc
.LFE11:
        .size   my_test, .-my_test
        .ident  "GCC: (Debian 4.4.5-8) 4.4.5"
        .section        .note.GNU-stack,"",@progbits

test.c

#include "NS.h"

int
my_test(void)
{
    NS.func1();
    func1();
}