[Bug c++/53628] New: [C++11][DR 712] Compiler requires definition of static member constants when not odr-used

[Bug c++/53628] New: [C++11][DR 712] Compiler requires definition of static member constants when not odr-used

[daniel.kruegler at googlemail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53628

             Bug #: 53628
           Summary: [C++11][DR 712] Compiler requires definition of static
                    member constants when not odr-used
    Classification: Unclassified
           Product: gcc
           Version: 4.8.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: daniel.kruegler@googlemail.com


The following example leads to a linker error when compiled in C++11 mode using
gcc 4.8.0 20120603 (experimental):

//---
struct S
{
  static const int a = 1;
  static const int b = 2;
};

int main(int argc, char** argv)
{
  return argc > 1 ? S::a : S::b;
}
//---

"8|undefined reference to `S::a'|
8|undefined reference to `S::b'"

This example is now valid with the acceptance of

http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_defects.html#712

and should no longer require a definition of either S::a or S::b.

[Bug c++/53628] [C++11][DR 712] Compiler requires definition of static member constants when not odr-used

[daniel.kruegler at googlemail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53628

Daniel Krügler <daniel.kruegler at googlemail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |link-failure

--- Comment #1 from Daniel Krügler <daniel.kruegler at googlemail dot com> 2012-06-10 21:38:56 UTC ---
I would like to add that exactly the same example is still the main example of
the otherwise valid explanations in

http://gcc.gnu.org/wiki/VerboseDiagnostics#missing_static_const_definition

This particular example should be modified as well (or marked to be valid in
C++03 only)

[Bug c++/53628] [C++11][DR 712] Compiler requires definition of static member constants when not odr-used

[daniel.kruegler at googlemail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53628

--- Comment #2 from Daniel Krügler <daniel.kruegler at googlemail dot com> 2012-06-10 21:43:24 UTC ---
(In reply to comment #1)
> I would like to add that exactly the same example is still the main example of
> the otherwise valid explanations in
> 
> http://gcc.gnu.org/wiki/VerboseDiagnostics#missing_static_const_definition
> 
> This particular example should be modified as well (or marked to be valid in
> C++03 only)

Jonathan was quicker than I could write this...

[Bug c++/53628] [C++11][DR 712] Compiler requires definition of static member constants when not odr-used

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53628

--- Comment #3 from Jonathan Wakely <redi at gcc dot gnu.org> 2012-06-10 21:48:51 UTC ---
(In reply to comment #1)
> I would like to add that exactly the same example is still the main example of
> the otherwise valid explanations in
> 
> http://gcc.gnu.org/wiki/VerboseDiagnostics#missing_static_const_definition
> 
> This particular example should be modified as well (or marked to be valid in
> C++03 only)

And C++11, and every released version of G++.

I've added a note to the wiki regarding DR 712 but the point of that page is to
explain common errors people get from G++ and that example is taken from
numerous bug reports. Even when DR 712 is implemented it will remain relevant
for past releases so feel free to update the wiki yourself, but try to keep it
useful for people using old releases who are surprised the example won't link,
e.g. PR 53614 reported this week against GCC 4.4

[Bug c++/53628] [C++11][DR 712] Compiler requires definition of static member constants when not odr-used

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53628

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2013-06-12
     Ever confirmed|0                           |1

[Bug c++/53628] [C++11][DR 712] Compiler requires definition of static member constants when not odr-used

[paolo.carlini at oracle dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=53628

Paolo Carlini <paolo.carlini at oracle dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
      Known to work|                            |4.8.0, 5.0
         Resolution|---                         |FIXED
   Target Milestone|---                         |4.8.0

--- Comment #4 from Paolo Carlini <paolo.carlini at oracle dot com> ---
This works in the released 4.8.0.

[Bug c++/53628] [C++11][DR 712] Compiler requires definition of static member constants when not odr-used

[daniel.kruegler at googlemail dot com]

[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=53628

--- Comment #5 from Daniel Krügler <daniel.kruegler at googlemail dot com> ---
(In reply to Paolo Carlini from comment #4)
> This works in the released 4.8.0.

Thanks, I agree. Confirmed to work for gcc 4.8.1, 4.8.2, 4.9.0, 4.9.1, 4.9.2,
and HEAD 5.0.0 20150323 (experimental).
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https://gcc.gnu.org/bugzilla/show_bug.cgi?ide519

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
  Attachment #35121|0                           |1
        is obsolete|                            |
           Assignee|ebotcazou at gcc dot gnu.org       |rguenth at gcc dot gnu.org

--- Comment #16 from Richard Biener <rguenth at gcc dot gnu.org> ---
Created attachment 35126
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id5126&actioníit
updated patch