Re: libstdc++ test case ext/headers.cc failed on arm-none-eabi

[Jonathan Wakely <jwakely dot gcc at gmail dot com>]

On 7 August 2013 12:08, Florian Weimer wrote:
> On 08/07/2013 01:05 PM, Jonathan Wakely wrote:
>
>> There's not enough context to see what happened, the diagnostic is
>> crap, only showing the macro not where it's used.  The macro is not
>> used as a non-static data member initializers except in C++11 mode, so
>> I don't know how that could happen.
>
>
> I think it's used in C++98 mode, too, but we suppress the error because it's
> a system header.

Yep, as I realised just after I sent my reply.

I suspect what's happening is that gthr-default.h is getting included
before a #pragma GCC system_header, so that when the
__GTHREAD_MUTEX_INIT is later used (in a system header) it's treated
as not coming from a system header e.g.

$ cat g.h
typedef int __gthread_mutex_t;
#define INIT 0

$ cat m.h
#include "g.h"
#pragma GCC system_header

  class __mutex
  {
  private:

    __gthread_mutex_t _M_mutex = INIT;

  public:
    __mutex() { }
  };


$ cat m.cc
#include "m.h"

int main()
{
    __mutex m;
}

$ g++  m.cc
In file included from m.h:1:0,
                 from m.cc:1:
g.h:2:14: warning: non-static data member initializers only available
with -std=c++11 or -std=gnu++11 [enabled by default]
 #define INIT 0
              ^