f29e377d   
   From: ike@sverige.freeshell.org   
      
   On 2012-05-22, rado  wrote:   
   >> You have invoked undefined behaviour because your assignment   
   >> statement modifies x twice without an intervening sequence   
   >> point. This is always a no no in C and C++ for built-in types. The   
   >> same rule applies to struct/class types except that in most   
   >> instances where it looks as this has been done (2 modifications to   
   >> same memory between sequence points) there are some hidden sequence   
   >> points because overloaded operators are actually function calls.   
   >   
   > I wonder why decent compilers don't issue a warning in such cases.  Or   
   > maybe they do. Does anybody know?   
   >    -- Radoslav Getov   
      
   $ cat a.c   
   int main(void)   
   {   
      int x = 10;   
      x = x++;   
      return 0;   
   }   
   $ gcc --version   
   gcc (GCC) 4.1.2 20061021 prerelease (NetBSD nb3 20061125)   
   Copyright (C) 2006 Free Software Foundation, Inc.   
   This is free software; see the source for copying conditions.  There is NO   
   warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.   
   $ gcc -Wall a.c   
   a.c: In function 'main':   
   a.c:4: warning: operation on 'x' may be undefined   
      
      
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