Question

In section 7.1.1 of the book “The C++ Programming Language” the author states:

“inline function still has a unique address and so do the static variables of an inline function”

I am confused. If I have an inline function then it can’t have address. Does this happen in C also?

Answer 1

The inline attribute is just a hint to the compiler that it should try to inline your function. It’s still possible to take the address of the function, and in that case the compiler will also need to emit a non-inline version.

For example:

#include <stdio.h>

inline void f() {
    printf("hello\n");
}

int main() {
    f();
    void (*g)() = f;
    g();
}

The above code prints hello twice.

My gcc compiler (with -O) emits code something like this:

_main:
        pushl   %ebp
        movl    %esp, %ebp
        pushl   %ebx
        subl    $20, %esp
        call    ___i686.get_pc_thunk.bx
"L00000000002$pb":
        leal    LC0-"L00000000002$pb"(%ebx), %eax
        movl    %eax, (%esp)
        call    L_puts$stub        ; inlined call to f()
        call    L__Z1fv$stub       ; function pointer call to f() (g is optimised away)
        movl    $0, %eax
        addl    $20, %esp
        popl    %ebx
        popl    %ebp
        ret

As you can see, there is first a call to puts() and then a call to L__Z1fv() (which is the mangled name of f()).