c++/10621: Calling a non-qualified member function within a sizeof() expression leads to "invalid use of undefined type"

[giovannibajo@libero.it]

>Number:         10621
>Category:       c++
>Synopsis:       Calling a non-qualified member function within a sizeof() expression leads to "invalid use of undefined type"
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          rejects-legal
>Submitter-Id:   net
>Arrival-Date:   Sun May 04 14:56:01 UTC 2003
>Closed-Date:
>Last-Modified:
>Originator:     Giovanni Bajo
>Release:        3.3 CVS 20030503, 3.4 CVS 20030503
>Organization:
>Environment:
i686-pc-cygwin
>Description:
The following code has always been rejected by GCC:

-----------------------------------
struct Foo
{
    static int func(void);

    enum { value = sizeof(func()) };
};
-----------------------------------
gccbug1.cpp:5: error: invalid use of undefined type `struct Foo'
gccbug1.cpp:2: error: forward declaration of `struct Foo'
gccbug1.cpp:5: error: enumerator value for `value' not integer constant

Notice that it's possible to make the code compile simply 
by qualifying the function name: sizeof(Foo::func()).
>How-To-Repeat:
Compile the above snippet
>Fix:
Qualify the function name
>Release-Note:
>Audit-Trail:
>Unformatted: