c++ weird behaviour of static functions from header

c++ weird behaviour of static functions from header

I have this problem with a static functions declared in a header file. Say
I have this file "test.cpp":
#include <cstdlib>
#include "funcs.hpp"
...do some operations...
void *ptr = my_malloc(size);
...do some operations...
The "funcs.hpp" file contains:
#include <ctime>
#include "../my_allocator.hpp" // my_malloc is defined here as a
// global static function
...some functions...
static int do_operation() {
// variables declaration
void *p = my_malloc(size);
// ...other operations
}
when I compile my program, I get an error 'my_malloc' was not declared in
this scope, referred to the one used in the "funcs.hpp" file, while it
doesn't complain with the one used in "test.cpp".
The function in question is defined as a global static function within the
header "my_allocator.hpp", and all it does is to get an instance of the
allocator object and use the malloc function:
static void * my_malloc(size_t size) {
return MYAllocator::instance()->malloc(size);
}
I'm not sure whether this problem is related to the scope of a function
declared as static global inside a header, but what looks weird to me is
that it complains in one case and not in the other: when I use it in a
static function in a header (funcs.hpp) that includes the header where it
is declared, it results in the error "not declared in this scope"; while
it is OK when used from a file that includes the header "funcs.hpp". Where
am I getting wrong?