Re: Broken include/c_std/bits/std_cerrno.h

[Benjamin Kosnik <bkoz at redhat dot com>]

For "C++" iso/14882
17.4.1.2 Headers
p 5
names which are defined as macros in C shall be defined as macros in the 
C++ stdlib, even if C grants license for implementation as functions. 
(note names defined as macros in C include the following: assert, errno, 
offsetof, setjmp, va_arg, va_end, va_start)

so

cassert
cerrno
cstddef
csetjmp
cstdarg

all needed to be reviewed for conformance with this. I'll do this right 
now and post a patch.

> In include/c_std/bits/, the file std_cerrno.h is just wrong.
> In particular, ISO 14882 _requires_ that in C++ errno be a macro, 
> not a namespaced object.  As it happens, the contents of that file 
> do fail if errno does happen to be a macro.

can you please provide a testcase?

Here's one:


#include <cerrno>

namespace gnu
{
  void test01()
  { 
    int i = errno;
#ifndef errno
    #error "errno_must_be_a_macro"
#endif
  }
}
  
int main()
{
  gnu::test01();
  return 0;
}


> I have attached a patch, but I'm not sure the file shouldn't just
> be deleted outright.  The c_std stuff, if I understand correctly,
> isn't intended to be right anyway, it just shouldn't make old 
> programs stop compiling.  I think deleting the file would accomplish
> that.

Hmm. Can't do that, as include/std/cerrno includes it, and that file has 
to work with all the various "C" compatibility strategies: c, c_std, 
c_shadow. So, we should probably keep the file and do the diffs as you 
suggested.

-benjamin