[Bug c/54162] New: Does not accept static global anonymous unions or structs

[Bug c/54162] New: Does not accept static global anonymous unions or structs

[josh at joshtriplett dot org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54162

             Bug #: 54162
           Summary: Does not accept static global anonymous unions or
                    structs
    Classification: Unclassified
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: josh@joshtriplett.org


C1X, and numerous other compilers, support static anonymous unions or structs
at file scope.  For example, the following code should work with a C1X
compiler:

static union {
    unsigned x;
    unsigned y;
};

int main(void)
{
    x = 5;
    return y;
}

However, GCC says:

test.c:4:1: warning: unnamed struct/union that defines no instances [enabled by
default]
test.c: In function ‘main’:
test.c:8:5: error: ‘x’ undeclared (first use in this function)
test.c:8:5: note: each undeclared identifier is reported only once for each
function it appears in
test.c:9:12: error: ‘y’ undeclared (first use in this function)

[Bug c/54162] Does not accept static global anonymous unions or structs

[joseph at codesourcery dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54162

--- Comment #1 from joseph at codesourcery dot com <joseph at codesourcery dot com> 2012-08-02 23:23:19 UTC ---
On Thu, 2 Aug 2012, josh at joshtriplett dot org wrote:

> C1X, and numerous other compilers, support static anonymous unions or structs
> at file scope.  For example, the following code should work with a C1X
> compiler:

No it shouldn't.  Anonymous structures and unions are *members* of a 
containing structure or union, not declarations outside such a context; 
see C11 6.7.2.1 paragraph 13.  The constraint in 6.7 paragraph 2 applies: 
"A declaration other than a static_assert declaration shall declare at 
least a declarator (other than the parameters of a function or the members 
of a structure or union), a tag, or the members of an enumeration.".  Your 
union declares none of those.

[Bug c/54162] Does not accept static global anonymous unions or structs

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54162

Richard Guenther <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|                            |INVALID

--- Comment #2 from Richard Guenther <rguenth at gcc dot gnu.org> 2012-08-03 08:07:12 UTC ---
Thus invalid.

[Bug c/54162] Please accept static global anonymous unions or structs as an extension

[josh at joshtriplett dot org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54162

Josh Triplett <josh at joshtriplett dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |UNCONFIRMED
         Resolution|INVALID                     |
            Summary|Does not accept static      |Please accept static global
                   |global anonymous unions or  |anonymous unions or structs
                   |structs                     |as an extension

--- Comment #3 from Josh Triplett <josh at joshtriplett dot org> 2012-08-20 14:50:35 UTC ---
How odd.  Quite a number of sources seem to suggest that C11 allows this.  But
in any case, several other compilers *do* allow this syntax; thus, reopening
this and turning it into a request for an extension.