Re: cpplib: Start moving switch handling to front ends

[Zack Weinberg <zack at codesourcery dot com>]

On Thu, Aug 08, 2002 at 10:34:11AM -0700, Stan Shebs wrote:
> Heh, we tried that argument with our users, but with literally thousands
> of headers assuming #import or #pragma once, both internal and external
> to Apple, plus an Objective-C book or two recommending the practice,
> the response was, shall we say, "negative".  It was pretty clear they
> were going to keep firing compiler folks until they found one who was
> willing to un-deprecate #import. 1/2 :-)
>
> In the users' defense, it must be said that #import has been working
> well on a huge amount of code - in the 2 1/2 years that I've been at
> Apple, we've seen dozens of ICEs for instance, but no failures of
> #import to find the right file.  So it's not surprising that users
> wonder why we're trying to fix something that doesn't seem broken.

Understood.

Apple's in a different boat from FSF GCC - you are only interested in
one platform, and you can make sure that ino/dev comparisons work
properly there.  I suppose I could live with a patch to disable that
warning for Darwin and Objective C only.  However, you could at least
update your own documentation to encourage use of #include and #ifndef
wrappers instead.  You could borrow the rationale from cpp.texi
(I wrote that text; you have my permission to use it)

There's also a concern about what it means to use both #include and
#import on the same file.  From the manual:

|    In the present implementation, a single use of `#import' will
| prevent the file from ever being read again, by either `#import' or
| `#include'.  You should not rely on this; do not use both `#import'
| and `#include' to refer to the same header file.

Is #pragma once in active use as well as #import?  Neil wanted to
ditch #pragma once.

zw