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From: kendall@talcott.UUCP (Sam Kendall)
Newsgroups: net.bugs.4bsd
Subject: cpp bug, #line does not reset cpp's own idea of the line number
Message-ID: <425@talcott.UUCP>
Date: Wed, 1-May-85 20:52:29 EDT
Article-I.D.: talcott.425
Posted: Wed May  1 20:52:29 1985
Date-Received: Fri, 3-May-85 04:29:42 EDT
Distribution: net
Organization: Delft Consulting Corp., New York
Lines: 86

Index:	lib/cpp/cpp.c 4.2BSD

Description:
	#line directives to the C preprocessor are passed through to
	the compiler proper, but they should also be remembered by the
	preprocessor.  Currently the preprocessor remembers the file
	name that #line gives, but not the line number.  This can
	confuse error messages and dbx(1) about line numbers,
	particularly on files produced by preprocessors such as
	yacc(1).  (This problem is fixed in SysV; V7 cpp's remember
	neither the line number nor the filename.)
	There are two other, much less serious problems with
	"cpp.c".  First, it is missing external function declarations;
	and second, one part of code performs a pointer subtraction
	with the right operand sometimes null; this is not legal C,
	although the code happens to work on most machines.
Repeat-By:
	Type to the shell
		$ /lib/cpp
		#line 999 "wombat.c"
		__LINE__ __FILE__
	The cpp's last line in response will be
		2 "wombat.c"
	But it should be
		999 "wombat.c"
Fix:
	There are three changes to "cpp.c".  The first adds external
	function declarations; the second makes #line reset the line
	number; and the third fixes the piece of code the does a
	pointer subtraction with a null right operand.

*** old/cpp.c	Thu Apr 11 12:47:18 1985
--- cpp.c	Thu Apr 11 12:55:12 1985
***************
*** 10,15
  
  # include "stdio.h"
  # include "ctype.h"
  /* C command
  /* written by John F. Reiser
  /* July/August 1978

--- 10,17 -----
  
  # include "stdio.h"
  # include "ctype.h"
+ extern char *calloc(), *strcat(), *strcpy(), *rindex();
+ 
  /* C command
  /* written by John F. Reiser
  /* July/August 1978
***************
*** 760,765
			cp = outp + 1;
			while (isspace(*cp) && cp < inp)
				cp++;
			while (isdigit(*cp) && cp < inp)
				cp++;
			while (*cp != '"' && cp < inp)

--- 762,768 -----
			cp = outp + 1;
			while (isspace(*cp) && cp < inp)
				cp++;
+ 			lineno[ifno] = atoi(cp);	/* reset __LINE__ */
			while (isdigit(*cp) && cp < inp)
				cp++;
			while (*cp != '"' && cp < inp)
***************
*** 891,897
	int  nlines = 0;
  
	if (0==(vp=sp->value)) return(p);
! 	if ((p-macforw)<=macdam) {
		if (++maclvl>symsiz && !rflag) {
			pperror("%s: macro recursion",sp->name); return(p);
		}

--- 894,900 -----
	int  nlines = 0;
  
	if (0==(vp=sp->value)) return(p);
! 	if (macforw!=NULL && (p-macforw)<=macdam) {
		if (++maclvl>symsiz && !rflag) {
			pperror("%s: macro recursion",sp->name); return(p);
		}