Re: preprocessor/2900

[neil at gcc dot gnu dot org]

The following reply was made to PR preprocessor/2900; it has been noted by GNATS.

From: neil@gcc.gnu.org
To: gcc-gnats@gcc.gnu.org, nobody@gcc.gnu.org, sean@mcneil.com
Cc:  
Subject: Re: preprocessor/2900
Date: 22 May 2001 18:38:46 -0000

 Synopsis: Does not handle concatenation of macros properly
 
 State-Changed-From-To: open->closed
 State-Changed-By: neil
 State-Changed-When: Tue May 22 11:38:46 2001
 State-Changed-Why:
     This is not a bug - your code is not conforming ISO C.
     GCC 3.0 is more strict than earlier versions of GCC.
     
     By invoking
     
     #define RECURSE(han, label, count, saves, cleanup)  \
          {  void **new = mc_stack_ptr + count + 1;      \
             PUSH_VALUES ## count ## saves;              \
          }
     
     with
     
         RECURSE(cb, "label", 2, (void *, h, int, parentMark), cb);
     
     CPP pastes PUSH_VALUES and 2 to get PUSH_VALUES2.  It then tries to paste
     PUSH_VALUES2 and '(', the first token of "saves", which is an invalid
     operation.
     
     The fix in this case is to redefine RECURSE as 
     
     #define RECURSE(han, label, count, saves, cleanup)  \
          {  void **new = mc_stack_ptr + count + 1;      \
             PUSH_VALUES ## count saves;                 \
          }
     
     Whether that does what you want in general is a different
     question.
     
     Neil.
 
 http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view&pr=2900&database=gcc