[PATH][_GLIBCXX_DEBUG] Fix unordered container merge

[Jonathan Wakely]

On Wed, 10 Nov 2021 at 05:47, François Dumont <frs.dumont@gmail.com> wrote:

> On 09/11/21 5:25 pm, Jonathan Wakely wrote:
>
>
>
> On Mon, 8 Nov 2021 at 21:36, François Dumont <frs.dumont@gmail.com> wrote:
>
>> Yet another version this time with only 1 guard implementation. The
>> predicate to invalidate the safe iterators has been externalized.
>>
>> Ok to commit ?
>>
>
> I like this version a lot - thanks for persisting with it.
>
> OK to commit, thanks.
>
>
> As an aside ...
>
> --- a/libstdc++-v3/testsuite/util/testsuite_abi.h
> +++ b/libstdc++-v3/testsuite/util/testsuite_abi.h
> @@ -24,7 +24,11 @@
>  #include <locale>
>  #if __cplusplus >= 201103L
>  # include <unordered_map>
> +# ifdef _GLIBCXX_DEBUG
> +namespace unord = std::_GLIBCXX_STD_C;
> +# else
>  namespace unord = std;
> +# endif
>  #else
>  # include <tr1/unordered_map>
>  namespace unord = std::tr1;
>
>
> Several times I've been annoyed by the fact that we don't have a way to
> refer to std::_GLIBCXX_STD_C::vector etc. that is always valid, in normal
> mode and debug mode.
>
> Maybe we should add:
>
> namespace std { namespace _GLIBCXX_STD_C = ::std; }
>
> That way we can refer to std::_GLIBCXX_STD_C::foo in normal mode, and it
> will mean the same thing as in debug mode. So we don't need to use #if
> conditions like this.
>
>
> Good idea, I'll prepare it.
>

Alternatively we could do this:

namespace std
{
namespace __cxx1998 { }
#ifdef _GLIBCXX_DEBUG
namespace __cont = __cxx1998;
#else
namespace __cont = ::std::
#endif
}

And then define this so it's always the same name:
#define _GLIBCXX_STD_C __cont

Then we can refer to std::_GLIBCXX_STD_C::vector in any context, and it
refers to the right thing. And we could also stop using the SHOUTING macro,
and just refer to std::__cont::vector instead.

We could also make this work as std::__cxx1998::vector, but maybe we should
move away from the "1998" name, because it doesn't make much sense for
forward_list and unordered_map which are not in C++98.