Re: c++/10212: Preprocessor ## problem

[Martin Sebor <sebor@roguewave.com>]

The following reply was made to PR c++/10212; it has been noted by GNATS.

From: Martin Sebor <sebor@roguewave.com>
To: gcc-gnats@gcc.gnu.org
Cc:  
Subject: Re: c++/10212: Preprocessor ## problem
Date: Wed, 26 Mar 2003 11:47:53 -0700

 zack@gcc.gnu.org wrote:
 > Synopsis: Preprocessor ## problem
 > 
 > State-Changed-From-To: open->closed
 > State-Changed-By: zack
 > State-Changed-When: Tue Mar 25 18:32:08 2003
 > State-Changed-Why:
 >     Not a bug.  C++98 [cpp.concat]/3:
 >     
 >       If the result [of pasting two tokens together] is not 
 >       a valid preprocessing token, the behavior is undefined.  
 >     
 >     GCC chooses to issue a hard error.
 >     
 >     The ## in the macro in your example is totally unnecessary.  Remove it and your program will work correctly both with GCC 3.3 and with all other compilers.
 
 FWIW, I certainly see value in making the compiler as strict as
 possible (e.g., with -pedantic) so that programs first compiled
 with gcc are easily portable to other platforms. But I also see
 value in making gcc as permissive as possible (e.g., with another
 option or by default) so that programs first compiled with other,
 less restrictive compilers, compile successfully when ported to
 gcc.
 
 In this particular case, all of EDG (all its derivatives, such
 as Intel C++), IBM VAC++, and SunPro compile the code without
 complaint and with the result expected by the submitter, so it
 would not, IMHO, be entirely inappropriate for gcc to do so as
 well in the interest of portability.
 
 Regards
 Martin
 
 > 
 > http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=10212