Re: vector<bool> _M_start and 0 offset

[Jonathan Wakely <jwakely at redhat dot com>]

On 17/09/18 20:10 +0100, Jonathan Wakely wrote:
> On 17/09/18 21:55 +0300, Ville Voutilainen wrote:
> > On Mon, 17 Sep 2018 at 21:50, Jonathan Wakely <jwakely@redhat.com> wrote:
> > > "I used C++11 syntax because I find it nicer, and the compiler accepts
> > > > it in C++98 mode with just a warning, suppressed in a standard
> > > > header."
> > >
> > > Oh sorry, I just looked at the patch and replied without reading the
> > > top bit.
> > >
> > > > Even with -Wsystem-headers I don't get a warning, I have to precompile
> > > > with -P -E then compile the result to get "warning: extended
> > > > initializer lists only available with -std=c++11 or -std=gnu++11".
> > >
> > > OK for trunk then.
> >
> > Do other compilers besides gcc suppress the same way?
>
> No, clang doesn't:
>
> In file included from bv.cc:1:
> In file included from /home/jwakely/gcc/latest/lib/gcc/x86_64-pc-linux-gnu/9.0.0/../../../../include/c++/9.0.0/vector:65:
> /home/jwakely/gcc/latest/lib/gcc/x86_64-pc-linux-gnu/9.0.0/../../../../include/c++/9.0.0/bits/stl_bvector.h:812:16: error: non-aggregate type 'std::vector<bool, type-parameter-0-0>::iterator' (aka 'std::_Bit_iterator') cannot be initialized with an initializer list
>     { return { this->_M_impl._M_start, 0 }; }

And for the avoidance of doubt, it's the same error if I make the
correct change to the header:

     { return { this->_M_impl._M_start._M_p, 0 }; }


>              ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> bv.cc:6:5: note: in instantiation of member function 'std::vector<bool, std::allocator<bool> >::begin' requested here
> b.begin();
>   ^
> 1 error generated.
>
> So I do think we should stick to C++98 syntax.