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Re: 20000802: netcdf 3.5-beta3 installation problem on IBM SP

>From: Harsh Anand <address@hidden>
>Subject: netcdf 3.5-beta3 installation problem on IBM SP
>Organization: LBNL/NERSC
>Keywords: 200008022147.e72LljT08254 netCDF 3.5-beta3

Hi Harsh,

> I got  errors like
> 
>        xlC -c  -I../libsrc -I.  -DNDEBUG netcdf.cpp
> "netcdfcpp.h", line 156.10: 1540-0133 (S) The attributes "friend" are
> not allowed.
> 
> installing C++ interface on the IBM SP3  we have at NERSC Lawrence
> Berkeley Lab:
> 
>  FYI  -- IBM tech support folks tell me that  it is not a bug. According
> to the
> standard   "The attributes "friend" are not allowed".    Could you
> please suggest any workaround for this problem?
> I have successfully compiled this program using  KAI C++ compiler.

See a previous message for a workaround:

  http://www.unidata.ucar.edu/glimpse/netcdf/3814

But I don't understand how this could be non-standard C++.  The draft
standard available from

  http://www.cygnus.com/misc/wp/dec96pub/access.html includes the

following example:

 4 When a friend declaration refers to an overloaded  name  or  operator,
   only  the  function specified by the parameter types becomes a friend.
   A member function of a class X can be a friend of a class  Y.   [Exam-
   ple:
           class Y {
               friend char* X::foo(int);
               // ...
           };

which uses the same syntax we use.  Is it that you can't declare a
private constructor to be a friend?  If so, I haven't seen that
restriction explicitly stated anywhere.  Can you find out where in the
standard this syntax is disallowed, since no other C++ compiler we
have tried objects to it?

A less heavy-handed workaround would be to declare the whole NcFile
class to be a friend rather than just particular member functions,
that is use

  friend NcFile;

instead of

  friend NcFile::NcFile( const char *, FileMode, size_t*, size_t);
  friend NcBool NcFile::sync( void );
  friend NcDim* NcFile::add_dim( NcToken, long );
    // to delete dimensions, since destructor is private
  friend NcBool NcFile::close( void );

and similarly for other places where the compiler objects to the
declarations of particular member functions as friends.  But I don't
understand why this should be necessary ...

--Russ