Re: [Patch] [libstdc++] [constexpr] use macros in place of 'constexpr' to allow for disabling constexpr until fully supported by compiler

[Marc Glisse <marc dot glisse at inria dot fr>]

On Thu, 17 Feb 2011, Jonathan Wakely wrote:

> On 17 February 2011 19:02, Marc Glisse wrote:
> > On Thu, 17 Feb 2011, Jonathan Wakely wrote:
> >
> > > On 17 February 2011 16:11, Paolo Carlini wrote:
> > > > On 02/17/2011 03:06 PM, Adam Butcher wrote:
> > > > > http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46472
> >
> > [...]
> > > I don't much like the idea of patching the library and having to ship
> > > those changes in 4.6.0 to workaround that bug (I think the two PRs are
> > > the same issue.) ?Especially as neither of those PRs shows code which
> > > is affected by using constexpr in the library (I'm sure such code
> > > exists, but the testcases provided don't show a library-related
> > > problem.)
> >
> > Er, the one cited above shows an error with:
> > std::array<std::pair<int,int>,2> myvar;
>
> I beg to differ.  It shows code that certainly looks as though it was
> derived from that, but I get no error for
>
> #include <utility>
> #include <array>
> std::array<std::pair<int,int>,2> myvar;

Indeed, that's funny.

> Maybe the library has been changed to avoid the error since you
> submitted the PR, but that's even more reason not to patch the
> library.
>
> I repeat the request for a testcase using libstdc++ which passed with
> 4.5 and fails with 4.6

#include <utility>
#include <array>
struct A {
        A(){}
};
std::array< std::pair<int,A>, 2> x;


--
Marc Glisse