Using pointers-to-members and address spaces in Cl

问题:

I'm working on C++ code on a target that has multiple address spaces. The code I would like to use has pointers to members:

struct foo {
    int bar;
    int baz;
};

typedef int foo::*foo_member;
foo_member m = &foo::bar;

#define AS1 __attribute__((address_space(1)))

int main()
{
    foo AS1* f = /* ... */;
    f->*m = 4;
}

So far so good. However, things get funny when I try to get a pointer to the actual member:

int main()
{
    foo AS1* f = /* ... */;
    int AS1* x = &(f->*m);
}

Clang 3.7.0 (tags/RELEASE_370/final) complains:

test.cpp:14:11: error: cannot initialize a variable of type
      '__attribute__((address_space(1))) int *' with an rvalue of type 'int *'
        int AS1* x = &(f->*m);
                 ^   ~~~~~~~~

It seems that the address-of operator (or the member dereference?) drops the address space qualifier.

How can I use pointers to members with address spaces while ensuring that the address space is not dropped?

回答1:

It's a compiler bug. It's been reported and a patch has been submitted.