[Bug c++/11633] g++ does not initialize structures when auto-increment variables are used

["msimons at simons-clan dot com" <gcc-bugzilla at gcc dot gnu dot org>]

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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11633



------- Additional Comments From msimons at simons-clan dot com  2003-07-22 23:19 -------
  A friend pointed out language in the gcc.info file which appears to cover
the 'comma' ordering case:
===
   * Making side effects happen in the same order as in some other
     compiler.

     It is never safe to depend on the order of evaluation of side
     effects.  For example, a function call like this may very well
     behave differently from one compiler to another:

          void func (int, int);
          
          int i = 2;
          func (i++, i++);

     There is no guarantee (in either the C or the C++ standard language
     definitions) that the increments will be evaluated in any
     particular order.  Either increment might happen first.  `func'
     might get the arguments `2, 3', or it might get `3, 2', or even
     `2, 2'.
===

  I'm not sure if this applies here... and if it *does* apply it seems
inconsistant that things like: ++foo-1, ++foo-1 ... foo++ + 0, foo++ + 0 ...
and value(), value()... all get evaluated left to right, but foo++, foo++ value
gets looked up once, and gets somehow the increment happens N times.

  I am very interested in what the c++ language lawyers have to say about this 
sample.  If it is truely undefined I am *amazed* that practically all of the
remaining commercial unix, c++ compilers do it the same way.