Bug in cpplib (was: Re: typos in f77 docs)

[Daniel Jacobowitz]

On Thu, Mar 25, 1999 at 04:41:53PM -0500, Zack Weinberg wrote:
> cpplib uses @ as an escape character internally.  Look in cpphash.c at
> macroexpand(), macarg(), and their subroutines.  The bug will be related to
> the fact that @ is not considered to be an escape inside a quoted string. 
> It is doubled when read since it's not in a string then, but the
> string-quote operator isn't taking it out again.
> 
> I'll look at this eventually, but I can't do any real development right now
> since my computer is dead.

Well, I have a fix to this based on your description.

My only doubt about it is whether the string being stringified will
always be escaped already; I can't see any reason it wouldn't be, but I
haven't spent a lot of time working through cpplib.  Here's a patch
that fixes the problem for me; bootstrapped on
powerpc-debian-linux-gnu.

Dan

/--------------------------------\  /--------------------------------\
|       Daniel Jacobowitz        |__|     CMU, CS class of 2002      |
|   Debian GNU/Linux Developer    __   Part-Time Systems Programmer  |
|         dan@debian.org         |  |        drow@cs.cmu.edu         |
\--------------------------------/  \--------------------------------/

Sat Mar 27 00:10:21 1999  Daniel Jacobowitz <dan@debian.org>

	* Unescape '@@' inside macro arguments.

Index: gcc/cpphash.c
===================================================================
RCS file: /egcs/carton/cvsfiles/egcs/gcc/cpphash.c,v
retrieving revision 1.16
diff -u -r1.16 cpphash.c
--- cpphash.c	1999/03/16 13:10:15	1.16
+++ cpphash.c	1999/03/27 05:00:53
@@ -1203,6 +1203,7 @@
 		  int arglen = arg->raw_length;
 		  int escaped = 0;
 		  int in_string = 0;
+		  int at_sign = 0;
 		  int c;
 		  /* Initially need_space is -1.  Otherwise, 1 means the
 		     previous character was a space, but we suppressed it;
@@ -1215,6 +1216,23 @@
 		  for (; i < arglen; i++)
 		    {
 		      c = (ARG_BASE + arg->raw)[i];
+
+		      /* The argument has already been @ escaped.
+		         Undouble the @'s which got doubled. */
+		      if (!in_string && (c == '@'))
+			{
+			  if(at_sign)
+			    {
+			      at_sign = 0;
+			      continue;
+			    }
+			  else
+			    {
+			      CPP_PUTC (pfile, '@');
+			      at_sign = 1;
+			      continue;
+			    }
+			}
 
 		      if (!in_string)
 			{