[Bug c++/67160] New: static_assert feature test macro

[Bug c++/67160] New: static_assert feature test macro

[Casey at Carter dot net]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67160

            Bug ID: 67160
           Summary: static_assert feature test macro
           Product: gcc
           Version: 6.0
            Status: UNCONFIRMED
          Severity: enhancement
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: Casey at Carter dot net
  Target Milestone: ---

Created attachment 36150
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=36150&action=edit
Patch

GCC trunk supports static_assert as defined in N3928 (http://wg21.link/n3928)
but defines the feature test macro __cpp_static_assert to the C++11 value
"200410." The appropriate value for N3928 static_assert is "201411" per N4440
(http://wg21.link/n4440#recs.cpp17). Attached patch updates the predefined
value to "201411".

[Bug c++/67160] static_assert feature test macro

[paolo.carlini at oracle dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67160

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |ASSIGNED
   Last reconfirmed|                            |2015-08-18
           Assignee|unassigned at gcc dot gnu.org      |paolo.carlini at oracle dot com
     Ever confirmed|0                           |1

--- Comment #1 from Paolo Carlini <paolo.carlini at oracle dot com> ---
I think we need something slightly more complex. Looking into it.

[Bug c++/67160] static_assert feature test macro

[paolo at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67160

--- Comment #2 from paolo at gcc dot gnu.org <paolo at gcc dot gnu.org> ---
Author: paolo
Date: Tue Aug 18 14:38:51 2015
New Revision: 226972

URL: https://gcc.gnu.org/viewcvs?rev=226972&root=gcc&view=rev
Log:
c-family/
2015-08-18  Paolo Carlini  <paolo.carlini@oracle.com>

        PR c++/67160
        * c-cppbuiltin.c (c_cpp_builtins): Fix __cpp_static_assert value
        in c++1z mode.

testsuite/
2015-08-18  Paolo Carlini  <paolo.carlini@oracle.com>

        PR c++/67160
        * g++.dg/cpp1z/feat-cxx1z.C: New.

Added:
    trunk/gcc/testsuite/g++.dg/cpp1z/feat-cxx1z.C
Modified:
    trunk/gcc/c-family/ChangeLog
    trunk/gcc/c-family/c-cppbuiltin.c
    trunk/gcc/testsuite/ChangeLog

[Bug c++/67160] static_assert feature test macro

[paolo.carlini at oracle dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67160

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|---                         |FIXED
           Assignee|paolo.carlini at oracle dot com    |unassigned at gcc dot gnu.org
   Target Milestone|---                         |6.0
           Severity|enhancement                 |normal

--- Comment #3 from Paolo Carlini <paolo.carlini at oracle dot com> ---
Fixed.

[Bug c++/67160] static_assert feature test macro

[Casey at Carter dot net]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67160

Casey Carter <Casey at Carter dot net> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |Casey at Carter dot net

--- Comment #4 from Casey Carter <Casey at Carter dot net> ---
A quick check with trunk shows that static_assert(true) works as expected with
-std=c++11 and -std=c++14, with an appropriate warning when -pedantic is set.
There seems to be no reason not to unconditionally advertise the availability
of the feature with the feature test macro. Unlike __cplusplus, the SD-6
feature test macros are not standardized so there's no requirement that it be
exactly 200410 in C++11/14 mode.

[Bug c++/67160] static_assert feature test macro

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67160

--- Comment #5 from Jonathan Wakely <redi at gcc dot gnu.org> ---
And the advantage of the feature-test macro is that users can test for that
specific feature independent of the __cplusplus value.

Of course if it's effected by -pedantic then that means it *isn't* supported
with -std=c++11 -pedantic so the check needs to be more complicated.

In any case, once Paolo says he's done here I'll update
https://gcc.gnu.org/projects/cxx1z.html :-)