c++/767: -fno-honor-std impossible on Linux

[wolfgang.bangerth@iwr.uni-heidelberg.de]

>Number:         767
>Category:       c++
>Synopsis:       -fno-honor-std impossible on Linux
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Fri Nov 10 05:56:00 PST 2000
>Closed-Date:
>Last-Modified:
>Originator:     Wolfgang Bangerth
>Release:        unknown-1.0
>Organization:
>Environment:
gcc version 2.97 20001106/Linux 2.2.14
>Description:
Trying to compiler some code we have with -fno-honor-std, I
fell over several hundred errors like
  x.cc:7: declaration of `int remove(const char*)' throws different exceptions
  x.cc:2: than previous declaration `int remove(const char*) throw ()'

They are due to code like this:
-----------------------------------------------
extern "C" {
  extern int remove (__const char *__filename) throw ();
}

namespace std
{
  extern "C" int remove(const char*);
}
------------------------------------------------
The first is included from the system headers (/usr/include/argp.h), where
#   define __P(args)    args throw ()
while the second declaration is from
gcc/include/g++-v3/bits/.

This problem is quite unfortunate, as it will most probably
not allow to compile old code that does not use std::
on Linux. On other systems, the problem may be nonexistent
if __P is not declared using `throw' (e.g., Solaris does
not declare it with `throw').
>How-To-Repeat:

>Fix:
In shadow headers, declare all C-style functions in namespace
std with `throw()' if system headers do that as well.

Alternatively (but I don't know whether that is right): why
are exception specifications important to extern C function
at all? They can't throw any, so one could as well ignore
exception specifications on them.
>Release-Note:
>Audit-Trail:
>Unformatted: