Problem with sizeof accessing a class member inside a struct

[behdad]

Bugzilla Link	11036
Version	unspecified
OS	Linux
CC	@berolinux,@efriedma-quic

Extended Description

With the following code:

class C {
        int i;

        void f (void) {
                typedef int a[sizeof (i)];
                typedef struct {
                        int a[sizeof (i)];
                } s;
        }
};

I get the following error from clang:

a.cc:7:18: error: invalid use of nonstatic data member 'i'
                        int a[sizeof (i)];
                                      ^
1 error generated.

Ie. clang doesn't like sizeof(i) in a struct, but it's ok in a non-struct. Looks like a bug to me.

[efriedma-quic]

I'm pretty sure that's actually what the standard requires. IIRC, there are some relevant changes here in C++0x.

[behdad]

Can you elaborate? I have a hard time seeing why that may be the case. Any clues what to look for in the standard?

I hit this in real code using glib's gatomic.h headers. gcc and MSVC don't seem to have any issues with it.

Thanks.

[efriedma-quic]

http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2253.html describes the issue. And I just double-checked: clang does in fact accept this construct in C++0x mode.

We might be able to support this in C++98 as an extension.

[behdad]

Thanks.

[berolinux]

This still happens in current 3.6 (can confirm -std=c++11 is ok, but gnu++98 doesn't accept it).