Re: [v3] install backwards headers in prefix

[Nathan Myers <ncm at nospam dot cantrip dot org>]

On Fri, Dec 15, 2000 at 01:12:43PM +0100, Gabriel Dos Reis wrote:
> Alexandre Oliva <oliva@lsd.ic.unicamp.br> writes:
> | On Dec 15, 2000, Nathan Myers <ncm@nospam.cantrip.org> wrote:
> | > The "-iobsolete" flag would add $(prefix)/backward to the set of
> | > directories searched by g++, as you say.  I just don't want that to 
> | > happen by default.  (It might be "-ibackward", instead, for consistency, 
> | > or $(prefix)/backward might be changed to $(prefix)/obsolete.)
> |  
> | I'm ok with doing it *after* we've had a release in which people are
> | just warned.  We don't want to go out gratuitously breaking
> | everybody's previously-working C++ code.  Warn first, give them time
> | to adjust their programs, and only then disable the feature by
> | default.
> 
> I'm a bit between Nathan's position and Benjamin's:  That is provide
> an option to turn off backward headers; and in subsequent release make
> it the default, and eventually remove them completely. Obviously, we
> should be warning in the next release.

This needs careful attention because we don't have a consensus yet.

<iostream.h> is a very special case, as the only backward/ header that 
is mentioned in textbooks.  That directory has been shoveled full of 
all *kinds* of crap, and we don't do users any favors including from 
it by default.

Here's what I propose now:

1. In the standard include directory, add a header iostream.h as follows:

  #ifndef _GCC_ENORMOUS_IOSTREAM_H_HACK
  #define _GCC_ENORMOUS_IOSTREAM_H_HACK
  #warning <iostream.h> is obsolete; <iostream> is standard.
  #warning Use ``-iobsolete'' to expose obsolete headers.
  #include <backward/iostream.h>
  #endif

2. Add a compiler option ``-iobsolete'' which adds backward/ to the 
   standard search path, so this file wouldn't be seen.

Nathan Myers
ncm at cantrip dot org