Fwd: cc-mode adds newlines

Fwd: cc-mode adds newlines

[Andrew Pinski]

forwarding since few people actually read gcc-bugs@.

Thanks,
Andrew Pinski

Begin forwarded message:

> From: Alan Mackenzie <acm@muc.de>
> Date: November 25, 2004 3:35:07 PM EST
> To: Richard Stallman <rms@gnu.org>, bug-gcc@gnu.org
> Cc: emacs-devel@gnu.org
> Subject: Re: cc-mode adds newlines
>
> Hi, Richard, Hi, Emacs developers, Hi, gcc maintainers!
>
> On Wed, 24 Nov 2004, Richard Stallman wrote:
>
> [Subject: gcc's acceptance of string constants which straddle lines.]
>>    Accepting such strings is a violation of the C++ standard, I 
>> think.  I'll
>>    need to complain about this to GCC.  Possibly, I'll not be the 
>> first.
>
>> We do not "violate" the C++ standard, we diverge from it.  We do not
>> regard standards as authorities.  We make our own decisions.
>
> OK.  That's fine by me, but .....
>
> The situation which bit me was this:  In our embedded system, commands
> get sent from device to device as strings of ASCII, a fairly normal
> thing.
>
> One particular command string was, in essence, coded thus:
>
> const char *command =
>     "aaaa
>      bbbb" ;
>
> which normally compiles to "aaaa<LF>     bbbb".  The receiving device
> ignores the white space.
>
> However, due to a mixup with proprietory version control systems and
> editors, this source file somehow got to the build process with
> "proprietory" line terminators.  gcc compiled the file without 
> complaint
> (on QNX, a proprietory Posix system), but the command string ended up 
> as
>
> "aaaa<CR><LF>    bbbb".
>
> To the receiving device, the <CR> meant something like "do not process
> the rest of this command".  To track the resulting bug down took about 
> 40
> hours of work, all told.
>
> This is, I think, the reason why the C and C++ standards don't allow
> strings to straddle lines:  the meaning of a source file can change 
> with
> the EOL convention.
>
> Now, I like proprietory file formats almost as little as you do, and 
> over
> the decades, in projects like ours, they must have wasted untold 
> billions
> of dollars, pounds, Marks, Yen, Francs, ...., not to mention trillions 
> of
> Lira and Pesetas ;-).
>
> It would have been nice to have got at least a warning message here.  
> Of
> course, the Right Thing is for me to put the appropriate option 
> (perhaps
> -traditional-cpp?) into the build scripts.  The solution I actually
> adopted was to purge all such strings from the source files (all ~2200 
> of
> them - it's a very slackly written program :-(  It took me ~half a day 
> to
> write a regular expression to find them).  However, those 40 hours of
> work are lost forever :-(.
>
> But I _do_ understand the need for having strings straddling lines, 
> too.
> It's would be a pain in the donkey to have to end every line of, for
> example, the doc string in a DEFUN macro with ....\n", and things like
> that.  And I _do_ understand that it's desirable, sometimes, to compile
> those strings with the target OS's EOL convention.
>
>> Complain if you wish, but I will not agree to the absurd limitation of
>> string constants to a single line.
>
> By "complain", I meant simply to draw my experiences to the attention 
> of
> the gcc maintainers, and ask them to consider, perhaps, whether the gcc
> options (or their defaults) might be modified in some way so as to help
> other projects avoid falling into the same trap as mine did, whilst at
> the same time not inconveniencing those who positively need such 
> strings.
>
> I was not proposing throwing some sort of temper fit.  I think you know
> me better than that by now.  ;-)
>
> So, gcc people:  is there a way?
>
> Thanks in advance!
>
> -- 
> Alan Mackenzie (Munich, Germany)
>