A small bug with operator% related error messages.

[Theodore Papadopoulo <Theodore dot Papadopoulo at sophia dot inria dot fr>]

In the following program, the error message generated is buggy.

> cat Bug.C
class A {
public:
	A() { }
};

int
main()
{
	const A a;
	return a%a;
}

> g++ Bug.C
Bug.C: In function `int main()':
Bug.C:10: no match for `const A & ¬onst A &'

The reason is that the string in opname_tab (in gcc/cp/lex.c)
used to generate are directly copied into the buf variable of function
cp_thing (in gcc/cp/errfn.c). This variable is then used as a format to
actually output the message. Consequently, in the case above the buffer
contains the string "no match for `const A & % const A &'" which is
misprinted by printf like function, which considers the `%' character to
be part of a `%c' directive (I do not understand why it is so as the printf
manuals I have access to do not describe the ` ' as being a valid modifier
for the %(something) directives).

I can see 3 possible fixes:

1) In all opname_tab[] (and presumably in all assignop_tab[]),
   change `%' into "%%".
2) Create a `formatize_string' function which purpose is to take a string
   and create the format that will produce the string and call it in
   cp_thing at the proper place.
3) Change cp_thing to print buf not as a format but as a string.
   i.e replace something like printf(buffer) into printf("%s",buffer).
   This requires also some small change in the handling of "%%" in
   cp_thing.

To me 1) seems risky as I'm not totally sure that opname_tab are used
only to generate the names of the functions and in any case, I do not
consider this as a very robust fix, 2) sounds very clumsy IMHO...

The small patch below implements the third strategy which I believe
to be the best.

Any comments? Am I missing something ?

	Theo.

1998-09-03  Theodore Papadopoulo <Theodore.Papadopoulo@sophia.inria.fr>

	* errfn.c (cp_thing): Print buf as a string not as a printf format
	to avoid problems with the operator%. Consequently, `%%' sequences
	in format are copied as `%' in buf.

Index: cp/errfn.c
===================================================================
RCS file: /egcs/carton/cvsfiles/egcs/gcc/cp/errfn.c,v
retrieving revision 1.14
diff -c -3 -p -r1.14 errfn.c
*** errfn.c	1998/08/26 08:11:46	1.14
--- errfn.c	1998/09/03 12:18:21
*************** cp_thing (errfn, atarg1, format, ap)
*** 149,166 ****
  	}
        else if (*f == '%')
  	{
! 	  /* A `%%' has occurred in the input string.  Since the
! 	     string we produce here will be passed to vprintf we must
! 	     preserve both `%' characters.  */
  
! 	  len += 2;
! 	  if (len > buflen)
  	    {
  	      buflen = len;
  	      buf = xrealloc (buf, len);
  	    }
! 	  strcpy (buf + offset, "%%");
! 	  offset += 2;
  	}
        else
  	{
--- 149,163 ----
  	}
        else if (*f == '%')
  	{
! 	  /* A `%%' has occurred in the input string. Replace it with
! 	     a `%' in the formatted message buf. */
  
! 	  if (++len > buflen)
  	    {
  	      buflen = len;
  	      buf = xrealloc (buf, len);
  	    }
! 	  buf[offset++] = '%';
  	}
        else
  	{
*************** cp_thing (errfn, atarg1, format, ap)
*** 190,199 ****
      {
        char *file = cp_file_of (atarg);
        int   line = cp_line_of (atarg);
!       (*errfn) (file, line, buf);
      }
    else
!     (*errfn) (buf);
  
  }
  
--- 187,196 ----
      {
        char *file = cp_file_of (atarg);
        int   line = cp_line_of (atarg);
!       (*errfn) (file, line, "%s", buf);
      }
    else
!     (*errfn) ("%s", buf);
  
  }
  


 --------------------------------------------------------------------
 Theodore Papadopoulo
 Email: Theodore.Papadopoulo@sophia.inria.fr Tel: (33) 04 92 38 76 01
 --------------------------------------------------------------------