[Bug c++/23147] New: Missing declaration of static const members

[Bug c++/23147] New: Missing declaration of static const members

[fw at deneb dot enyo dot de]

The program below compiles cleanly with GCC 4.0.1, although the definition of
Foo::foo required by the standard (9.4.2/4) is missing.

It probably makes sense to accept such programs as a GNU extension (as long as
the address of the member is not taken).

#include <cstdio>

struct Foo
{
  static const int foo = 42;
};

int
main ()
{
  std::printf ("%d\n", Foo::foo);
  return 0;
}

-- 
           Summary: Missing declaration of static const members
           Product: gcc
           Version: 4.0.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: fw at deneb dot enyo dot de
                CC: gcc-bugs at gcc dot gnu dot org
 GCC build triplet: i686-pc-linux-gnu
  GCC host triplet: i686-pc-linux-gnu
GCC target triplet: i686-pc-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23147

[Bug c++/23147] Missing declaration of static const members

[falk at debian dot org]

------- Additional Comments From falk at debian dot org  2005-07-30 13:35 -------
Well, the behavior is undefined here, so what we currently do is just fine.

Moreover, this can only be detected at link time, so there's no way for us to
give a warning; at best, we could emit a fake reference and have the linker
hard fail. I don't think we want that, since it wastes space in the binary
for no really good reason other than being pedantic. So I'd say WONTFIX.

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23147

[Bug c++/23147] Missing declaration of static const members

[fw at deneb dot enyo dot de]

------- Additional Comments From fw at deneb dot enyo dot de  2005-07-30 13:45 -------
What about a GNU extension which would make this program well-formed?  I think
it's quite a common pattern, and a requirement to provide a definition would
just increase object code size meaninglessly.

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23147

[Bug c++/23147] Missing declaration of static const members

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-07-30 15:13 -------
Actually the compiler is allowed to "inlined" the value of the constant.  And the missing definition does 
not have to be diagnostic.

So closing as invalid.

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


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23147

[Bug c++/23147] Missing declaration of static const members

[fw at deneb dot enyo dot de]

------- Additional Comments From fw at deneb dot enyo dot de  2005-07-31 09:25 -------
What about permitting this as a GNU extension?  It seems quite useful for
template code.

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23147

[Bug c++/23147] Missing declaration of static const members

[falk at debian dot org]

------- Additional Comments From falk at debian dot org  2005-07-31 13:31 -------
(In reply to comment #4)

> What about permitting this as a GNU extension?  It seems quite useful for
> template code.

With "this" you mean omitting the definition? Well, it saves one line of
typing, but I'm not really convinced that justifies an extension.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23147

[Bug c++/23147] Missing declaration of static const members

[fw at deneb dot enyo dot de]

------- Additional Comments From fw at deneb dot enyo dot de  2005-08-05 21:43 -------
(In reply to comment #5)
> (In reply to comment #4)
> 
> > What about permitting this as a GNU extension?  It seems quite useful for
> > template code.
> 
> With "this" you mean omitting the definition? Well, it saves one line of
> typing, but I'm not really convinced that justifies an extension.

I (incorrectly) feared that GCC would emit the constant for each template
instantiation.  Therefore, I agree with you that no extension is necessary, and
the bug report was completely invalid.  Sorry about that.

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23147