Path: utzoo!attcan!uunet!synaptx!glenn
From: glenn@synaptx.Synaptics.Com (Glenn Gribble)
Newsgroups: comp.lang.c++
Subject: Re: cfront bug
Message-ID: <1026@synaptx.Synaptics.Com>
Date: 6 Jul 90 23:41:55 GMT
References: <1022@synaptx.Synaptics.Com>
Reply-To: glenn@synaptx.UUCP (Glenn Gribble)
Organization: Synaptics Inc., San Jose, CA
Lines: 66

In article <1022@synaptx.Synaptics.Com> I wrote:
>The following bit of C++ generates illegal C code:
>
>  int x;
>  int y = x = 0;

In this example, it is not clear that these are *GLOBAL* variables.

Here is another example that is totally clear and shows another part
of the same problem.

The two problems here:
  1) Cfront generated illegal C code.
  2) Cfront reports a warning in the local-variable case, but not in the
     global variable case--it should have also warned:
       "bug.cxx", line 5: warning: a used before set

synaptx% cat -n bug.cxx
   1  extern int f(int);
   2  extern int x;
   3  int y = (x = f(x));
   4
   5  int a = (x = f(a));
   6
   7  void foo()
   8  {
   9    int b = (x = f(b));
  10  }
synaptx% CC -c +i bug.cxx
CC  bug.cxx:
"bug.cxx", line 9: warning:  b used before set
cc  -Qpath /usr/CC/sun3   -c -I/usr/CC/incl  bug.c
"bug.c", line 16: illegal initialization
"bug.c", line 16: cannot recover from earlier errors: goodbye!
synaptx% cat -n /tmp/bug..c
   1
   2  /* <<AT&T C++ Translator 2.00.02 08/25/89>> */
   3  /* < bug.cxx > */
   4
   5  char *__vec_new ();
   6
   7  char __vec_delete ();
   8  typedef int (*__vptp)();
   9  struct __mptr {short d; short i; __vptp f; };
  10
  11
  12  extern int x ;
  13
  14  extern int f__Fi ();
  15
  16  int y = (x = f__Fi ( x ) );
  17
  18  int a = (x = f__Fi ( a ) );
  19
  20  char foo__Fv ()
  21  {
  22  int __1b ;
  23
  24  __1b = (x = f__Fi ( __1b ) );
  25
  26  }
  27
  28
  29  /* the end */
-- 
Glenn Gribble	 	glenn@synaptics.com 	uunet!synaptx!glenn